Hi CJ,What's next on my task list? LOL
Hi CJ,
By looking at the the image, I don't think you have the resistor wired in correctly. Originally two wires were connected to the speaker. If you can imagine removing one wire from the speaker and connecting that wire to one end of the resistor. Then connecting the other end of the resistor to the vacant terminal on the speaker that would be right.
spec
That is correct. But strictly speaking (sorry for pun) the resistor should go in the high side- if there is one (some amps have a bridge output so there is no high side).It doesn't matter which terminal side correct?
Yes, that is correct. You can forget about the speaker now that you have protected it and tested it. Yes, we will be working on the power amplifier board mainly.I put the speaker back in the cabinet.. Is it safe to assume that I'll have all the parts out of the box for this testing?
That is correct. But strictly speaking (sorry for pun) the resistor should go in the high side- if there is one (some amps have a bridge output so there is no high side).
Yes, that is correct. You can forget about the speaker now that you have protected it and tested it. Yes, we will be working on the power amplifier board mainly.
Bear in mind that mains voltages will be present on the circuit up to the primary of the toroid transformer (big & round) so please take care.
The next test is to set your meter to DC volts and measure the voltage across the speaker terminals. (it should be 0V to +-0.1V).
spec
Sorry, I'm a bit confused.
I currently have the amp board disconnected from anything else, and measured with the MM and it measured at 0V, and the 2nd try 0.1V.
Is this test set up correctly?
Thanks,
cz
Oh I see. I did not realise that the amplifier board was disconnected.
I meant to measure across the speaker terminals with the system fully configured and turned on. Is it possible to do that?
spec
Hi CJ,I think this is possible... I'd need to get the speaker back out of the box..
I'd assemble it back just like it is in this pic:
View attachment 102274
I was doing some noodling in thought on this, and the two or one blown resistor at the bottom (where it says "Bad Resistor) - the white connector goes to the pre-amp pcb (even says it on the board), which kind
of now makes sense to me why no sub woofer output is present, but is fine for the two mains (they're going thru).
View attachment 102275
I do feel the issue is in this neighborhood.
I'll run this next test tomorrow with all the guts on the table.
And of course: I'll Bear in mind that mains voltages will be present on the circuit up to the primary of the toroid transformer (big & round) so please take care.
I'll make it easy for myself to only be near the speaker connectors and away from the transformer...
Then of course afterward, I'll need to shut it down, and let it dissipate for a day before touching it all.
Unless you know of any ways to drain the voltage out quicker?
Hi CJ,
Yes that would be good. What you heed is a completely configured system but with access to all the boards.
You are very wise to be cautious, but you will not need to wait a day before touching the circuit. I would say that, without seeing the schematic that 5 minutes would do. The golden rule is not to touch the system while the mains is plugged in. If you make measurements you normally unplug the system and connect the common lead of your multimeter to zero volts somewhere and then plug the system in and make measurements with a well insulated probe. It is also wise to power the system by a trip that disconnects the power in case of an inbalance between live and neutral currents.
I am wondering, in view of the surprising complexity of of the bass sub, if it would not be better to take it to a repair shop, or even ask a friend who has experience of repairing complex equipment.
spec
Hi CJ,
I hope you didn't mind me suggesting getting help with fixing your bass sub, but what concerned me is that often you can create more havoc trying to repair complex equipment if you don't have all the test equipment and the service manuals. I have done just this.My mate, who services musical gear, tears his hair out when he gets a rig that has been previously 'serviced'.
As I have said many times before, it is a great shame that you are not just down the road, because I could then call around and advise. It is extremely difficult, as many of us have found on ETO, to do remote fault finding.
But we will have a go and see what can be done. I will consider the next move.
About getting components, that is easy, especially as you are in the States and most components on a bass sub are liable to be standard types. DigiKey is one of the most popular component distributes with home makers. But, Mouser, Arrow, RS (Allied), Element 14 (Farnell) (Newark) are good too. There is also a slew of smaller distributors and then there are the budget retailers, ebay being the biggest, followed by Alibaba and then Amazon, I guess.
https://www.digikey.com/
https://www2.mouser.com/?gclid=CjwK...ZUejah5v8ygTisC9ahOSutP6GZ1q1isW4WhoCzI7w_wcB
https://www.arrow.com/
https://www.alliedelec.com/
https://www.newark.com/
As to sleep, I generally hit the hay around 12.30pm and sleep until 7am, if I have been active. But if not, it is 1pm, up at 4am, back to bed at 6am, sleep till 8:30am. But I also tend to fall asleep on the settee around 7pm for half an hour. On the other hand, after a few pints of Butcombe (excellent local real ale) it would be bed at 1am and oblivion until I get a dig in the ribs from the missus, some time the next morning.
Before I retired, sometimes we worked 24Hrs with no sleep, when there was a panic on.
spec
That would be q good idea.I do have a friend who might be able to have a look with me on it.
No probs. As I said you are in te best part of the world for components.Thanks for the resources (links) on parts.
Three terminal components are often transistors either, NBJTs, PBJTs, NMOSFETs or PMOSFETs. The most common for audio amplifiers is NPN Bipolar Transistors (NBJT) and their compliment PNP Bipolar Junction Transistors. Big manufacturers tend to get their parts directly from the manufacturers and have their own custom number marking, so it is often not possible to get a replacement, except from the equipment manufacturer, if they will cooperate- often not. But, having said that, most components are standard and if we can see the circuit diagram we can recommend a standard part, which can often be better than the original where there is a weakness in the design.What is this 3 pronged black component ? I tried identifying it by number on the web, but couldn't find it.
That makes sense. It is important to keep a positive outlook when you are out of work and get as much exercise as possible. I was out of work for six months once, and I know it is not much fun, being retired with a few decent pensions is a different story though. In some parts of the UK being unemployed is a way of life because of the closure of many heavy industries: coal, steel, automobile...Wow, you do have an interesting sleep pattern.. For me, I stay up till about 11 or 12, up at 5am, sometimes 4.
But since I've been un-employed, I'm more erratic.
No probs. As I said you are in te best part of the world for components.
Three terminal components are often transistors either, NBJTs, PBJTs, NMOSFETs or PMOSFETs. The most common for audio amplifiers is NPN Bipolar Transistors (NBJT) and their compliment PNP Bipolar Junction Transistors. Big manufacturers tend to get their parts directly from the manufacturers and have their own custom number marking, so it is often not possible to get a replacement, except from the equipment manufacturer, if they will cooperate- often not. But, having said that, most components are standard and if we can see the circuit diagram we can recommend a standard part, which can often be better than the original where there is a weakness in the design.
May I ask why you are out of work. Is there high unemployment in Jacksonville?
Yes, if it is a normal component it can be tested easily. I will define.Hmm.. Wow, I wonder if this is tough luck on this part... No way of testing it in isolation to ensure it's bad?
No probs- I'm a nosey parker by nature.Actually there's a decent economy here, but demographically speaking it's a city with roughly 1 million residents,
and the industries here are a bit more specific (financial servicing, banking, insurance, transportation/logistics), and
my preferred work is iOS app development - demand isn't so great where it's higher for web developers. Luckily,
I have an impressive history as a tech project manager that I'm starting to ignite again, but I prefer iOS dev.
Shouldn't be too much longer before I get the + money flow again.. Thanks for asking
Yes, if it is a normal component it can be tested easily. I will define.
Awesome!
No probs- I'm a nosey parker by nature.Sounds hopeful, from what you say. Ios is a fairly good area to be in. You no like Win? Or is that a dirty word.
spec
I like Win dev but it's not that exciting - my last gig I did strictly that (a .net WPF - XAML thick client application), kinda cool stuff, but most companies are looking
for .net web apps.
Update: I took the Transistor and the two questionable resistors off.
On YouTube, Learned how to identify and test the Transistor, and it was in fact a PNP Bipolar Junction Transistor, and it was bad.
Couldn't find a replacement, and I'm quite certain I won't be able to get the part from KRK.. SOL as they say.
I'm either going to bring it into to a service center that's authorized depending on the cost, or buy the whole back panel for $180+ from compass (once I get $$)...
Oh well.... I do appreciate ALL of your help on this Spec!
Thanks, CZ...
Hi CJ,
The service center would be the best approach. You can not be sure that replacing one board would cure the fault.
Good luck.
spec
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