Repair a KRK 10s Subwoofer - parts id

GromTag said:

:Hello: some scattered information, hope somewhat helpful.
The blue resistor (if that is a dark blue stripe on the light blue housing) is 68 Ohm. The other Green a 10 Ohm unknown tolerance. If the stripe after the black is a metallic the tolerance, Gold 5%. for other resistors, Brown 1%, Red 2%, a leap to Silver at 10%. The resistors do look corroded. The transistor (three lead IC) C3206, or 2SC3206 appears to be KEK Korean Electronics. However data listed as an NPN? transistors can show odd results when damaged. However a solution for outer trace Ic's such as 3 pin transistors is to try to follow the Emitter track to either a positive or a lead to common. P channel would usually be Emitter to Positive voltage source, the N channel Emitter to common ground. This can be used under typical situations to identify the type on an existing legible pc board. There are however in some circumstances when transistors are used in many other ways. The transistor (if my results are correct) is a Triple Diffused PCT type, meaning its manufacturing method. Features are 150 Volt DC @ 50mA. a low power switch. So more than likely if the part number matches is a sinking transistor switch configuration, turning on something elsewhere. Cases such as near that ribbon connector? the other end board may require that transistor to act as a switch on to function from the board it's on. Or it could be just for that board, the tracts are a bit tough to see clearly as if that transistors leads connect to that ribbon connector or turn back to that board. as for the IN4148 Schotty diode they are easy to burst when reverse voltage breakdown occurs due to over current or reverse high voltage spike that can result in a crack or complete small firecracker effect.

Click to expand...

Hi Grom Tag! While I'm a relatively new member, I see you are as well, and welcome to the forum!

Thanks for your the detailed feedback! Wow this could be a huge lead for me.. I'll search for the KEK Korean Electronics parts now.

Yes those two resistors were corroded, what seems to be by what came out of the transistor.
I took the two resistors and transistor off the board to isolate and test them.. Resistors showed some sign of life, but I'll replace them
anyway. I put the project on hold because of the dead end with this transistor, and priorities for looking for work.

Where the two resistors and transistor was located definitely was in the path of the ribbon connector which connects
to the pre-amp board which is where the main volume and frequency controls are - see the two arrows and writing on the board:



Thanks, I'll dig in some more with your info

Cheers!

Thank you, and understood about the project being on hold.
As for more of what looks like going on, if that damaged transistor E, Emitter terminal is going to jumper J406 then to J410 to that large capacitors common then that is looking more like an NPN type transistor. It also looks to go to that smaller capacitors common via J406 track passing under J409 to that smaller cap or around it at least. Also if the Collector is connected via tracks on the other side if there are any there... (a moment in thought that those through hole connections would have to connect, I see, the marks I see in that image are the silk screening for mapping the board out) I was a bit slow on realizing that outright. Continuing, if the Collector is connected to AGND then that transistor may more than likely be the common connect switch for the pre amp that due to its low current handling may only switch the op amps for the logic drives for the signal processing chips, or drive a power IC that does a lot of switching on via an enable connection from that IC or even operate a near by transistor such as a PNP channel. 50mA is more than enough to sink a PNP. This might explain the crackle sound that was occurring on power up as the Base is the corroded pin on that problem transistor resulting in poor contact. low Base level saturation of such a low current transistor wold cause device self heating as the saturation current needed at Base could have been too low resulting in the transistor acting as a variable resistor (trimpot) resisting the Collector to Emitter current flow. The voltage of the Transistor part is listed as high 150v, tho the current is low 50mA. An amperage of 1,000 mA = 1 Amp so device is not even 1/10nth an amp. It does something but not much. May (at own convenience) want to check the pre amp board visually for any visible parts looking rough or discoloured or burnt. Also some IC parts can be bad and not show it.

GromTag said:

:Hello: some scattered information, hope somewhat helpful.
The blue resistor (if that is a dark blue stripe on the light blue housing) is 68 Ohm. The other Green a 10 Ohm unknown tolerance. If the stripe after the black is a metallic the tolerance, Gold 5%. for other resistors, Brown 1%, Red 2%, a leap to Silver at 10%. The resistors do look corroded. The transistor (three lead IC) C3206, or 2SC3206 appears to be KEK Korean Electronics. However data listed as an NPN? transistors can show odd results when damaged. However a solution for outer trace Ic's such as 3 pin transistors is to try to follow the Emitter track to either a positive or a lead to common. P channel would usually be Emitter to Positive voltage source, the N channel Emitter to common ground. This can be used under typical situations to identify the type on an existing legible pc board. There are however in some circumstances when transistors are used in many other ways. The transistor (if my results are correct) is a Triple Diffused PCT type, meaning its manufacturing method. Features are 150 Volt DC @ 50mA. a low power switch. So more than likely if the part number matches is a sinking transistor switch configuration, turning on something elsewhere. Cases such as near that ribbon connector? the other end board may require that transistor to act as a switch on to function from the board it's on. Or it could be just for that board, the tracts are a bit tough to see clearly as if that transistors leads connect to that ribbon connector or turn back to that board. as for the IN4148 Schotty diode they are easy to burst when reverse voltage breakdown occurs due to over current or reverse high voltage spike that can result in a crack or complete small firecracker effect.

Click to expand...

I started searching for a possible part match on the transistor...

Curious, when you said KEK Korean Electronics, when I googled it I saw a suggestion to look at KEC Korea Electronics.
That brought up this web site: **broken link removed**

Is this the source you were referring to?

Thanks a bunch!

GromTag said:

Thank you, and understood about the project being on hold.
As for more of what looks like going on, if that damaged transistor E, Emitter terminal is going to jumper J406 then to J410 to that large capacitors common then that is looking more like an NPN type transistor. It also looks to go to that smaller capacitors common via J406 track passing under J409 to that smaller cap or around it at least. Also if the Collector is connected via tracks on the other side if there are any there... (a moment in thought that those through hole connections would have to connect, I see, the marks I see in that image are the silk screening for mapping the board out) I was a bit slow on realizing that outright. Continuing, if the Collector is connected to AGND then that transistor may more than likely be the common connect switch for the pre amp that due to its low current handling may only switch the op amps for the logic drives for the signal processing chips, or drive a power IC that does a lot of switching on via an enable connection from that IC or even operate a near by transistor such as a PNP channel. 50mA is more than enough to sink a PNP. This might explain the crackle sound that was occurring on power up as the Base is the corroded pin on that problem transistor resulting in poor contact. low Base level saturation of such a low current transistor wold cause device self heating as the saturation current needed at Base could have been too low resulting in the transistor acting as a variable resistor (trimpot) resisting the Collector to Emitter current flow. The voltage of the Transistor part is listed as high 150v, tho the current is low 50mA. An amperage of 1,000 mA = 1 Amp so device is not even 1/10nth an amp. It does something but not much. May (at own convenience) want to check the pre amp board visually for any visible parts looking rough or discoloured or burnt. Also some IC parts can be bad and not show it.

Click to expand...

Amazing thought pattern.. You're awesome! I'll check for other areas on the pre-amp board for discoloured or burnt parts/areas.

If I get this fixed thanks to you, and Spec who brought me thru the first part, I'll need to send gift cards out for sure ...
Who knows, maybe I'll take on fixing another set of powered speakers I've had sitting in my closet as well after that. A bit of optimism never hurt right?

Cheers!

That is the a main type branch representation site of the actual Ic production company itself. They are the type that provide mass orders and production of chips to companies that produce electronics of any kind that would use their chips. This part is more than likely phased out of production due to new design as a transistor part. Even in new amps some back stock parts such as older transistors are still found as these were available in droves of hundreds if not thousands for very little cost thus resulting in plenty of stock that could last for months if not years. So the part in question 2SC3206 I have found results from, datasheetcatalog.com. address as http:/datashetcatalog.com <correct one .unusual that a Link when created for here sends my testing of the link feature to the incorrect site? a ww1.datasheetcatalog.com <incorrect one) that has no interaction and a grayed out screen. Recommend manual entry in browser address bar. Should be a site with yellow borders. The search box left of produced by and enter the transistor number of 2SC3206. Now as for KEK parts, some have had issues with the method used in the Ic production resulting in oxide and other material leakage from the pins developing a breach of the parts housing. their ok as a standard switch but as to their reliability can be questionable at times. For the parts voltage to current ratio it is an unusual part to find matching that range closely. Many I've found are obsolete in that range. The voltage yes, however the low current range with the voltage range combined no. The transistor itself can be in that range just for switch on characteristics because of the low current. So I'm leaning toward switching config with high voltage blocking capability when off due to stored energy in the capacitors during shut down conditions when powered off. The part used is a safer use of a part that could handle potential voltage conditions that "may" occur in that board. Questions, are there any other transistors with that numbering or is that the only one? Also is that one resistor green or look like it's been heated and has burnt? It's sort of the only green resistor on the board of blue 1/10nth sized others. :Extra: the only part I've found of yet close, however high on current handling capability by a leap is the KSP43 a Fairchild Semiconductor type the KSP42 handles more voltage by 100 volt at 300 volt max, the KSP43 is 200 volt max. It's just the collector amperage is far greater on these Fairchild types placing them at 500mA half an Amp.

Also thanks for putting up with (if that might be a what am i reading moment) my often running sentences and potential sudden change of direction during topic if and when it occurs.. hmm something to look forward to if hasn't occurred yet....

GromTag said:

That is the a main type branch representation site of the actual Ic production company itself. They are the type that provide mass orders and production of chips to companies that produce electronics of any kind that would use their chips. This part is more than likely phased out of production due to new design as a transistor part. Even in new amps some back stock parts such as older transistors are still found as these were available in droves of hundreds if not thousands for very little cost thus resulting in plenty of stock that could last for months if not years. So the part in question 2SC3206 I have found results from, datasheetcatalog.com. address as http:/datashetcatalog.com <correct one .unusual that a Link when created for here sends my testing of the link feature to the incorrect site? a ww1.datasheetcatalog.com <incorrect one) that has no interaction and a grayed out screen. Recommend manual entry in browser address bar. Should be a site with yellow borders. The search box left of produced by and enter the transistor number of 2SC3206. Now as for KEK parts, some have had issues with the method used in the Ic production resulting in oxide and other material leakage from the pins developing a breach of the parts housing. their ok as a standard switch but as to their reliability can be questionable at times. For the parts voltage to current ratio it is an unusual part to find matching that range closely. Many I've found are obsolete in that range. The voltage yes, however the low current range with the voltage range combined no. The transistor itself can be in that range just for switch on characteristics because of the low current. So I'm leaning toward switching config with high voltage blocking capability when off due to stored energy in the capacitors during shut down conditions when powered off. The part used is a safer use of a part that could handle potential voltage conditions that "may" occur in that board. Questions, are there any other transistors with that numbering or is that the only one? Also is that one resistor green or look like it's been heated and has burnt? It's sort of the only green resistor on the board of blue 1/10nth sized others. :Extra: the only part I've found of yet close, however high on current handling capability by a leap is the KSP43 a Fairchild Semiconductor type the KSP42 handles more voltage by 100 volt at 300 volt max, the KSP43 is 200 volt max. It's just the collector amperage is far greater on these Fairchild types placing them at 500mA half an Amp.

Also thanks for putting up with (if that might be a what am i reading moment) my often running sentences and potential sudden change of direction during topic if and when it occurs.. hmm something to look forward to if hasn't occurred yet....

Click to expand...

Thanks! You definitely are a wealth of knowledge on these parts, designs and goings on in the industry.
I'll search on my computer tomorrow morning to see if I can source the part.
Reguarding the resistor, I'll also look for duplication on any of the boards. I was busy all day today on
Family and interviews and couldn't look at anything. I have removed both resistors and can get close up pics of them to share tomorrow.

Much gratitude for your input!

Trying to figure out where those tracks on the pcb go surrounding that particular 3206 transistor goes. If possible to get an image/photo of the back (circuit traces) power pcb with the same (similar) orientation (that plug still at the top of photo). The image can be of the whole board just like the one above with the two green arrows. By looking at the one then the other can follow the tracks to surrounding components. The top area of the current one is a bit dim, tho the collector appears to go under those resistors then I loose where else it goes on the other side of the board. Thanks
I need to get a form of image structure to be able to post images via url. As the ramped up one (edited) to see the screened tracks on the top turned out quite violet.

AN extra note added, the Fairchild transistor i mentioned has the incorrect pin out to the 3206.
The base on the 3206 is pin 3. The other mentioned pin 2 is the Base. There are bound to be transistors that will swap (plug and play) with close results. An compatible one (double checked the pins) is more close to the 3206 in stature. 2SC1473A Panasonic. I have some issues with preferring any to any site that would have any components as it is viewed to me as a form of advertising for any particular site (use to forums not liking that). However the part number just for a reference outright is 2SC14730RACT-ND.
A USA site would be closer digi tally of coarse.

GromTag said:

Trying to figure out where those tracks on the pcb go surrounding that particular 3206 transistor goes. If possible to get an image/photo of the back (circuit traces) power pcb with the same (similar) orientation (that plug still at the top of photo). The image can be of the whole board just like the one above with the two green arrows. By looking at the one then the other can follow the tracks to surrounding components. The top area of the current one is a bit dim, tho the collector appears to go under those resistors then I loose where else it goes on the other side of the board. Thanks
I need to get a form of image structure to be able to post images via url. As the ramped up one (edited) to see the screened tracks on the top turned out quite violet.

AN extra note added, the Fairchild transistor i mentioned has the incorrect pin out to the 3206.
The base on the 3206 is pin 3. The other mentioned pin 2 is the Base. There are bound to be transistors that will swap (plug and play) with close results. An compatible one (double checked the pins) is more close to the 3206 in stature. 2SC1473A Panasonic. I have some issues with preferring any to any site that would have any components as it is viewed to me as a form of advertising for any particular site (use to forums not liking that). However the part number just for a reference outright is 2SC14730RACT-ND.
A USA site would be closer digi tally of coarse.

Click to expand...

Thanks for the extra note! I was having a bit of difficulty getting to the ordering of the actual component on one site. I'll check out the 2SC1473A Panasonic, 2SC14730RACT-ND.

Absolutely, I took another set of pics.

Two of the Back, the second zoomed up (let me know if It's good enough):




Here are some additional pics (sideways)

Removed bad / gunked up components:



Here's something interesting... When I look back at the original picture of the problem
area with the blown transistor:



And compared the resistors to others nearby (R494 and R481), I have a good feeling that these are the matches
I might be looking for:



Just another pic on the right side...


Hey GromTag, are you a surfer?

Hey GromTag,

I found the Panasonic 2SC14730RACT-ND over at DigiKey here: https://www.digikey.com/product-search/en?keywords=2SC14730RACT-ND

So there might be some hope with this part if it's compatible as you mentioned it might.

Getting 10 of these for 5 dollars, and a few resistors will well be worth the experimentation cost wise..
Before i pull the trigger in ordering anything I'll search a bit more.

Thanks!

Thanks.
The photos do need more light, however now I can see that the two transistors at that point the bad one and the adjacent are tied together. One turns the other on or off. An absolute way to find out what your part is, And I should have mentioned this earlier about testing the leads of the Circuit side of the board for the E pin port on the damaged 3206 with a multi tool. with no power to the amp needed, Volt mode, common pin to GND point on the power pcb and the positive lead on Both of those caps positive from the contact solder point with a highest setting to safely read the capacitors voltage via multi tool. Just looking to see if the caps have any charge in them. They need to have virtually none.

If so it need not exceed a few volts like 1-5 volt, some caps hold power up to a point continuously, If high volt is present, a resistor of at least 200 - 500 Ohms 1-4Watt to 1/8Watt, at least from the + to a common source, or use the - pin at the cap that may still have a low charge even if the system has been powered down for some time, as long as the voltage is not above 18 Volts, if the cap can hold up to or more than that and still has that level of voltage above 18V, reasons an ark can occur via a fast jump across the contact made at cap discharge with an resistor giving a noticeable shock if the contacts are held directly by hand, The current from a cap can jolt into conduct then level out (lower) through the resistor as any voltage drops. Below 18V on avg left over can result in a small ark at resistor lead contact with the rated resistors value range.

Example of 20V avg left over, near 100mA at 200R (Ohm) resistor and about 40mA with a 500R resistor, the 500 is safer over all to use and can deplete a cap holding a potential up to 50V =100mA still remaining, quite rare but not unheard of in a computer PSU power supply. And in actual, a capacitor of at least 50V when having a near complete charge via the safety margin of a cap, typically 10-15V or so above the Volt range feed to the cap being used can be about 20 Amps at that contact ark in an instant even for a 1000uF cap when discharged.
a caps Volt rating on case would typically not be exceeded, 35V max applied power for a 50V Cap per example.

So once the caps are determined safe with Practically no charge,

Multi tool in Ohms mode X1 or standard low value Ohm range, The common probe on the common GND where available on the board, the positive one at the E on the removed 3206 transistors solder point, then check readings
What are the readings at initial start at the E and Common GND point?

The E To board GND result reading.

Next
with the positive probe still on the 3206 E, move the multi tools common probe to the initially tested caps + at the solder point and whats the readings? The E to board Cap + result?
Essentially looking for continuity, the large Capacitor at the right side with the Tianbo Relay can be used.

surf? no I do not, have never really tried. If i did would probably have issues with turning and trying to keep ahead of inertia so the board doesn't go leaving me for a swim, which is the second problem, swimming.

GromTag said:

Thanks.
The photos do need more light, however now I can see that the two transistors at that point the bad one and the adjacent are tied together. One turns the other on or off. An absolute way to find out what your part is, And I should have mentioned this earlier about testing the leads of the Circuit side of the board for the E pin port on the damaged 3206 with a multi tool. with no power to the amp needed, Volt mode, common pin to GND point on the power pcb and the positive lead on Both of those caps positive from the contact solder point with a highest setting to safely read the capacitors voltage via multi tool. Just looking to see if the caps have any charge in them. They need to have virtually none.

If so it need not exceed a few volts like 1-5 volt, some caps hold power up to a point continuously, If high volt is present, a resistor of at least 200 - 500 Ohms 1-4Watt to 1/8Watt, at least from the + to a common source, or use the - pin at the cap that may still have a low charge even if the system has been powered down for some time, as long as the voltage is not above 18 Volts, if the cap can hold up to or more than that and still has that level of voltage above 18V, reasons an ark can occur via a fast jump across the contact made at cap discharge with an resistor giving a noticeable shock if the contacts are held directly by hand, The current from a cap can jolt into conduct then level out (lower) through the resistor as any voltage drops. Below 18V on avg left over can result in a small ark at resistor lead contact with the rated resistors value range.

Example of 20V avg left over, near 100mA at 200R (Ohm) resistor and about 40mA with a 500R resistor, the 500 is safer over all to use and can deplete a cap holding a potential up to 50V =100mA still remaining, quite rare but not unheard of in a computer PSU power supply. And in actual, a capacitor of at least 50V when having a near complete charge via the safety margin of a cap, typically 10-15V or so above the Volt range feed to the cap being used can be about 20 Amps at that contact ark in an instant even for a 1000uF cap when discharged.
a caps Volt rating on case would typically not be exceeded, 35V max applied power for a 50V Cap per example.

So once the caps are determined safe with Practically no charge,

Multi tool in Ohms mode X1 or standard low value Ohm range, The common probe on the common GND where available on the board, the positive one at the E on the removed 3206 transistors solder point, then check readings
What are the readings at initial start at the E and Common GND point?

The E To board GND result reading.

Next
with the positive probe still on the 3206 E, move the multi tools common probe to the initially tested caps + at the solder point and whats the readings? The E to board Cap + result?
Essentially looking for continuity, the large Capacitor at the right side with the Tianbo Relay can be used.

surf? no I do not, have never really tried. If i did would probably have issues with turning and trying to keep ahead of inertia so the board doesn't go leaving me for a swim, which is the second problem, swimming.

Click to expand...

Happy Thanksgiving!

I humbly appreciate your feedback!
I'll post a better pic later after the family gathering.

I can definitely do more measurements and read this in greater detail.

Thanks!

Thank you, and to you, a Happy thanksgiving.

Also I need to momentarily toss some projects here to better focus on yours in assisting, I get mixed up momentarily at times and hence the oops on the Fairchild type as i use Motorola types 2N3904 NPN and 2N3906 PNP practically often more than any other (they have the center pin as Base, it becomes a habit given time when designing any project with the same). So to get the readings on the E on the 3206 E with the resistors isolated on the power pcb is now disconnected from the board essentially. So the test point for that transistors E would be the blue resistors end point at the R501 looking point right at that R on the solder side of the board.

I have managed to enhance the image of the Solder side traces and I see that the top markings state the transistors 3206 emitter goes only to that resistor array, and the Collector goes to Jumper J405, The green resistor acted as a Base Bias from that A970 which may be Toshiba PNP. now that is driving the 3206 Base High (on) The Blue resistor connects that exposed track that passes right beside those two corroded resistors on solder side to the 3206 Emitter. So in thought that A970 turns on the 3206. Exposed tracks are rarely HOT Positive unless directly at the switching Transistors at the edge of that Power PCB board. was just needing to know if that 3206 E channel went to any common connection including the possibility of those two black wires which look like ground connectors. The 3206 looks to enable pull in for the transistor switching components Biasing trim pot for phase offset. that shifts the push and pull banks into close rhythm. Too close the switching fets could ring (it can be audible) and miller effect could occur. However i doubt that adjuster is of any concern to it's current setting. the parts really just looked corroded not burnt out. Just that the 3206 may not had initially been up to the task of operating that control with good survivability. the Panasonic are better made in my opinion. Matsushita Panasonic the [M] logo on some caps. very close logo to motorola also.

A note I'm adding in, On the power pcb components side Those 4 large white resistors, the one at the FET Q443, C terminal, there is a small resistor left of under that glue directly horizontal to that Fet Q443 C terminal. Visually, does it by any chance look to be corroding any at that lead on its right side facing that FET Q443? when enhancing the photos i saw a great amount of bubbling in that glue, it looks like liquid electric tape applied at either during assemble or repairs. that glue Gives me the I dislike that feel.
Some shops I've known over some years that have come and gone, used liquid vinyl electric tape in a can, and the results were bad as it ate away and corroded the components that had voltage flowing through them over time. Removal of this substance usually resulted in damage to transistors film, tearing the film off as a result, so that would not be advised. I'm mentioning this to you as an be aware of.

I just keep adding things don't I? I have found that that green resistor is actually a 1K Ohm 1% tolerance, there are via the other images i have been looking at, editing brighter. The blue is still 68 Ohm 1% tolerance. Near the bad 3206, R494 is the matching Blue, and the R481 is the matching green to the type of resistor values to replace the corroded ones.

GromTag said:

I have managed to enhance the image of the Solder side traces and I see that the top markings state the transistors 3206 emitter goes only to that resistor array, and the Collector goes to Jumper J405, The green resistor acted as a Base Bias from that A970 which may be Toshiba PNP. now that is driving the 3206 Base High (on) The Blue resistor connects that exposed track that passes right beside those two corroded resistors on solder side to the 3206 Emitter. So in thought that A970 turns on the 3206. Exposed tracks are rarely HOT Positive unless directly at the switching Transistors at the edge of that Power PCB board. was just needing to know if that 3206 E channel went to any common connection including the possibility of those two black wires which look like ground connectors. The 3206 looks to enable pull in for the transistor switching components Biasing trim pot for phase offset. that shifts the push and pull banks into close rhythm. Too close the switching fets could ring (it can be audible) and miller effect could occur. However i doubt that adjuster is of any concern to it's current setting. the parts really just looked corroded not burnt out. Just that the 3206 may not had initially been up to the task of operating that control with good survivability. the Panasonic are better made in my opinion. Matsushita Panasonic the [M] logo on some caps. very close logo to motorola also.

Click to expand...

So sorry, I didn't get an email notification that this and the next message at 5:13 arrived.
I was out most of today. I'll look into these and respond with good detail.

Again, so sorry...

GromTag said:

A note I'm adding in, On the power pcb components side Those 4 large white resistors, the one at the FET Q443, C terminal, there is a small resistor left of under that glue directly horizontal to that Fet Q443 C terminal. Visually, does it by any chance look to be corroding any at that lead on its right side facing that FET Q443? when enhancing the photos i saw a great amount of bubbling in that glue, it looks like liquid electric tape applied at either during assemble or repairs. that glue Gives me the I dislike that feel.
Some shops I've known over some years that have come and gone, used liquid vinyl electric tape in a can, and the results were bad as it ate away and corroded the components that had voltage flowing through them over time. Removal of this substance usually resulted in damage to transistors film, tearing the film off as a result, so that would not be advised. I'm mentioning this to you as an be aware of.

Click to expand...

I took 2 pics of the resistor on Q443 up close:




It's definitely got the black glue , tape goo junk there. I noticed that the Resistor itself (white) was a bit loose. I could get it off, and measure it.
Not exactly able to see if one of the posts isn't soldered in well. Know how to get this black junk off easily?

I'll clean it up enough to do a few measurements with the VM.

Did you want me to take more pics here in a little while? Sorry, catching up as quickly as I can
(got a few eggs in the air at the moment and juggling )...

Hey GromTag,

Based on a slower, a bit more thorough pass read of your messages from last night, I'll do another correct reading of the Transistor 3206.
Where there any other pics or steps you'd like me to perform for the analysis?

Thanks!

No need for the removal of that or other white 5 Watt 22 Ohm resistor, they are quite tough on survival. I was just curious about that smaller resistor under that glue next to that White 5 Watt. The lead sticking out from under the glue shows no corrosion. As for removal of that glue, it's not easy to remove. No solvents that I know of will remove it without eating at the components themselves resulting in damage. The main areas that are typically affected by the glue are high voltage areas like the voltage at the 3206 transistor. Just on the boards where the glue is blobbed, I'm looking at the photos for corrosion at other places where I can see in pnoto around the glue. Over all None of those are corroded. as for the white resistors being loose, those leads are frail by design. Quite flexible hence the glue used, just the wrong kind. Manufacturing use at a lower cost glue. Was meant to hold parts in place against vibration moving the parts loosening and soft leads braking.

Also If I mention anything that is a not sure by all means speak frankly. As I have been quite all over the place, each time I'm looking at the board I wind up seeing something different, or I see a mistake I made and after the post rather than editing it with the slight possibility of it not being seen then causing a back and forth I just add in new info instead, bad habit from me to any one that may not fully understand what I'm in my mind comprehending as I am saying (typing) it.

So just to clean up what I think is a possible mess that I have made I'm going to recap with the info gained thus far, Thus far the Transistor that looks very close to a potential replacement is the Panasonic 2SC1473A NPN. only because the leads that I could see on the PCB board for the E from the 3206

(and if I ever call it a 3602 Sorry I am meaning the 3206, I will double check to avoid that. I have at least over 10Gigabytes of transistor and IC components datasheets, you could emagine right?)

continuing, goes to a common ground connection, however I loose the tracks on the backside (solder side) of the PCB near those black wires with ring looms. So "If" the Emitter on that bad 3206 does in fact go to those wire components, then that should be a Ground point as those have to be common connectors, I've not seen what they connect to via the screw used. that aluminum heat sink? of so then those two wires are common Gnd for the sink itself also completing the path to a GND point for the 3206 .

If the track goes else where I cannot be sure with the wires blocking some of the power PCB's view. A photo of that area with those two rings slightly over to the left from the current image all ready posted as a reference to the paths I need to see if in fact the E does go to a common point on the board.

For the P channel I have searched for, looks to be an Toshiba 2SA970 PNP channel, Its collector is driving that 3206 Base on with that Blue acting as a pull down controller to common. In other words when the board switches off that 3206 that resistor is responsible for preventing that transistor from "floating" being on a slight bit resulting in an unstable setting. Small current can reactivate a transistor just like a toggle switch not fully turned on, the contacts on toggles tend to arch. And seeing the voltage on that transistor even with soldered contacts can be no exception due to the voltage. That resistor begins to fail the transistor does not shut down fully/ properly.

As for the Green one, it's a 1K Ohm actually. My first view was of the corroded one, I could only see the brown, black, black stripes. The others over to the left are the same types, Resistor number on the board R481 matches the green as it is seen to be used in many other locations in similar config. The Resistor number R494 to its left from the top (parts) side matches the Blue at 68 Ohms. Both are 1 percent tolerance type resistors. at 1/10 nth wattage size or just 1/10 Watt resistor for internet reference. Decent resistors should be used in those two's places to assure clear operation due to voltage potential slightly heating the resistors changing their resistance values, Colder= slightly higher resistance, lower current flow. Hotter = lower resistance, more current flow.
The Term is PPM parts per million.

A good replacement for Blue 68 Ohm would be RNC50J68R1FSRE6-ND Vishay Dale. for the 25PPM being a bit overkill on current drift but 200Volt max capable. However Digikey is only selling them in droves of minimal orders and have the correct 1/10 size resistors and yet have none in stock... This resistor would be an excellent replacement for the 68 Onm if not for minimum order requirement and stock availability.
https://www.digikey.com/product-detail/en/vishay-dale/RNC50J68R1FSRE6/RNC50J68R1FSRE6-ND/3247484

looking for another shop or a different resistor. Mouser has an 279-LR1F68R 1/8 Watt, that can fit all tho be a bit close on fitting taking all available space for the 1/10 resistors spot. And I'm not fully aware of TE-Connectivity products.
https://www.mouser.com/ProductDetail/TE-Connectivity-Neohm/LR1F68R

A good replacement for Green 1K Ohm (1,000 Ohm) would be from Mouser 279-LR1F1K0 1/8 Watt resistor.
https://www.mouser.com/ProductDetail/TE-Connectivity-Neohm/LR1F1K0
https://www.mouser.com/ProductDetail/TE-Connectivity-Neohm/LR1F1K0
1/8 Watt are typically 3mm in length via the resistor itself. And I often call such small resistors 1/10 out of habit, only using surrounding components to try and gesture their size most of the time.

Sorry, had a browser update, requiring a restart,
Continuing.

As for the transistor, Still for adequate replacement. Panasonic https://www.digikey.com/product-det...-components/2SC14730RA/2SC14730RACT-ND/972412
That are obsolete but still have stock, however thus far the only I have found close. The 1 concern with this is the resistors are from Mouser, and the Transistor is from Digikey. 2 different shipping.

Will continue to search for those TR-connectivity resistors on Digi. Digi does not appear to have the correct ratings and size, larger resistors can easily be applied to the ports via just bending the wire.
However in some to many audio applications the resistor being lifted above the board be an amount can introduce noise into the components. Depending on how they operate. And as to why I'm trying to prefer a matching resistor type in size to be placed right on the board just like the original ones that were removed.

(and of coarse the decision is and has been yours to make if I've sounded directing in any comments, my bad. I just tend to operate reading like the term "stereo instructions" quite often)