- Blog entry posted in 'Teardowns', July 13, 2013.
INTRO
Story started when i got this hifi-system from my friend, it was supposed to be in perfect condition, but however, previous user before my friend always had headphones plug plugged in so headphones jack got wasted....I tried to repair it with forums help, but came in conclusion that this isn't wise to repair, as part should have been ordered from factory, wich would have costed more than 40€'s. Well, i salvaged it for parts then :D.
TEARDOWN
Disassemply was very easy, i found service manual consisting full illustrated disassemply guide. Front panel had all the controls, and back panel had all the connectors: mains, speakers, aux in, and antennae, two types. only connector that was at front panel was headphones jack.
Inside was PCB boards for separate functions: power, amplifier/filter, front board, cd-deck, and tape-deck. All of these were completely modules, as swap-in-place style, no need to find THE part for repair, at least that precisely.
There was plenty of screws, good, no worries to break any essential plastic-clips. All signal/system groundings were connected to base of the case, which was metal. only safety earth was missing, as there wasn't any. Power board had all stuff for power distribution: transformer, PCB fuses, relay, and such.
Amplifier board had all the amplifier/filter parts, along with speaker, antennae and aux connectors. Also, backside had SMD stuff.
Front board had small tactile switches, custom LED screen, and that wrecked jack....backpanel had too SMD parts.
tape-deck had basic stuff for tapes, many, many mechanical slides and gears, along with that ''reading'' device, what is it anyway? surprisingly, there was also one optocoupler too. plus motors.
Cd-deck had control circuits for selecting cd, motors and such
AFTERWORDS
Well, despite the fact that this was cind of waste of my time in terms of repair, i did salvage some good gear, well not that expensive, but still, i'm very pleased with this project!
thanks again for your time! :)
and thanks forum guys who helped with this project, regardless of outcome!
tvtech, July 13, 2013
Hey Fez I don't touch music systems...too many cables and crap everywhere. I suppose I would/could do them but the TV'S keep me 100% busy with my time. Stay good, tvtech
fezder, July 14, 2013
hey there, yeah you're right about cables. I dont do this as a job, yet, so this is basicly my hobby, so time isn't that much issue. Problem is mainly keeping things organized, focus at one device at a time, otherwise ''fault'' gets forgotten and needs to start all over again....of course, there are faults that need pause :D. like currently, i have my previous repairs, like one amp and one monitor still waiting to be repaired. lack of skills i suppose. Man, i'd love to be apprentice/helper in some repair service, but my education is too low currently. well, perhaps that time will come eventually. regarding tv's, i've only tore them apart, i dont have that much acknowledge about them in terms of safety for example. i've read that CRT tubes hold or even generate charge by themselves. electricity is magic indeed....
tvtech, July 14, 2013
Now you be careful now :eek: Listen to me very carefully: If you want to play around with CRT tubes or old Monitor tubes [B]DO THIS FIRST:[/B] 1. Take one of your Meter leads and unplug it from your Meter. You have a lead in your hand now plugged into nothing. 2. Take that lead and push the part that went into your Meter under the thin wire strap at the back of Tube. If you look carefully, you will find it. 3. Once you are sure that the end of your Meter lead is indeed under the strap, making contact and is staying there... 4. Take the sharp end of the lead and force it under that Rubber Cap on the top of the tube. Sometimes you hear a loud spark sound. That means the tube was still charged and could have shocked you...... It is hard to explain. Doing the best I can here from far away. Just do the steps above please. At least then, the CRT cannot belt you anymore when you least expect it. Because it's charge has been terminated. Stay safe tvtech
fezder, July 14, 2013
ahh, i THINK i understood what you meant, by that rubber cap, is it that cap what is coming from HV cable from flyback transformer? see link [url]http://www.electronicrepairguide.com/images/flyback1.jpg[/url]
tvtech, July 14, 2013
[QUOTE=fezder;bt690]ahh, i THINK i understood what you meant, by that rubber cap, is it that cap what is coming from HV cable from flyback transformer? see link [url]http://www.electronicrepairguide.com/images/flyback1.jpg[/url][/QUOTE] Yes Fez You need to discharge the Tube. You need to get it to the same potential as the Aquadag surrounding it (that carbon like material at the back). Fuck, it is hard doing this over the Web. If you were sitting next to me on the bench you would understand within 5 seconds. You understand so far though? Regards, tvtech
fezder, July 14, 2013
yet another term wich i never heard before, aquadag, nice, thanks for info! :) but, you meant like this, at least it shows how to discharge that tube, and the way you described: [url]http://www.riddledtv.com/journal/DischargeCRT/index.html?t=165[/url]
tvtech, July 14, 2013
Bingo...you have got it ;) Hey, I love HV.....but also have LOTS of respect for it. Stay and play well ;) Regards, tvtech
fezder, July 14, 2013
same here, i don't fear electricity, i just respect it so it doesn't ''bite''.... oh, and by the way, what cind of tv's you repair?
tvtech, July 14, 2013
CRT Fez. And the associated SMPS... Some SMPS are good. Some SMPS are bad. I see them all.
fezder, July 14, 2013
ah, i see :) what you mean by others are good, other bad? like build quality or hard to repair?
tvtech, July 20, 2013
Well, for example, just about all Chinese CRT SMPS look the same these days. They all generally blow up the same way and are predictable when repairing. So no sweat.... Then a genius little Chinese guy decides to make a simple, unreliable PSU as above [B]complicated[/B] and add on more bits and pieces...and then it becomes a nightmare to fix. And everything added on is not necessary. It still blows up like its simpler cousins.....but now it cannot be repaired...... I can name the components part for place on the normal Chinese standard CRT PSU. I have fixed thousands of them. As SMPS go though...I have absolutely no respect for them at all. Inefficient Linear anytime for reliability. Period. Unless..and I say unless...the SMPS is built by a company that specializes in the dark art of SMPS design. Like Delta Electronics who make lappie SMPS for major laptop suppliers. If I was young E Engineer, my goal would be to find a way to join them and LEARN. Delta Electronics make SMPS with exceptional reliability. One of the few Companies Worldwide that actually sells millions of units with most people not knowing who or what they do. Most Lappie companies love Delta ;)
fezder, July 20, 2013
ahh, interesting :). inly faults i've heard in SMPS's are caps, and what blows up after bad caps :D. sadly, so far only cad-fault i've repaired was one LCD screen, which caps were bursted....hopefully customers cheapness doesn's bite my ass later on, as she didn't want reliable panasonic caps, instead i replaced old ones with samway, or something. ''I can name the components part for place on the normal Chinese standard CRT PSU. I have fixed thousands of them.'' you mean there are some specific components that blow? or did i understood wrong? :S. i recently bought laptop PSU, wich was made by delta, if i recall right.
tvtech, July 20, 2013
Hi Fez Delta is good to go. Very reliable ;) Till next time tvtech
