Yamaha A-1 Repair and restore: beyond Deoxit

Yes ,we can help if you are very carefull
Always discharge electrolytic capacitors with a resistor NEVER , NEVER with a screw driver like you can see in this video
Here again in this movie we can see all you should not do !
AK is a reliable source , follow experienced members , not the web !
once you did what I recommend you in my last post , come back to us with report

Who will you trust ?
The web or a guy who do repair on all high quality equipments over 40 years with many worldwide customers ?
 
oh i had no doubt thast the video was wonky, i posted it for a laugh (iu thought it was funny that the guy thought that he should spread his wisdom lol). the problem was that when i asked before, ya'll told me to discharge but not how and i kinda rushed over it but connecting a wire to the ground terminal and connecting the other end to the metal legs of my equipment stand and not worry about it anymore until last night. so no doubt that my rushing was the source of error. ofcourse i also made the other error that plugged the unit in to test the lights and forgot to unplug and got a spark when i tried to unscrew the transistor. so that was a separate mistake but the problem with the caps holding a lot of charge is pretty egregious.
 
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Yes use a large watt resistor maybe like 500 ohm to 1000 ohm.

I did the same thing you did and blew the output. and in the same fashion , after I discovered the emitter resistor was bad.

Dont get discouraged. It happens to all of us. Just learn from your mistakes and get better with practice.

Athanasios
 
actually i got so upset with myself exactly because you mentioned it just before i did it hahaha. i was got so frustratyed with myself because i could see that you that you warned me about it like 4 posts above it. well what can i say? we live and we learn.
 
I just skimmed through the whole thread and to add some things which may not have been covered:
  • The capacitors you want to discharge with the 500-1000Ω resistor Nash suggested are the main filter caps (largest ones), do this every time before working on the amp (obviously switched off first) and check across the terminals with your meter in DC V to make sure they're low once done.
  • Most of the Nichicon lineup is good, a safe bet is using either the PW or HE series (UPW / UHE) as they are 105*C rated. It is safe (even beneficial) to go up in voltage rating over stock, but measure the diameter of stock part and check diameter of replacement part to make sure they are similar / will fit. Keep capacitance value same. Note (or mark on board) the polarity of caps you remove, because sometimes there are errors in screenprinting.
  • Did you re-check your output transistors? Because they look to be alive from your previous test.
  • When you've replaced any bad parts and are ready to do live testing of voltages, first it's good to build yourself a dim bulb tester, as it will save your amp if you have made a mistake that causes the output transistors to short (the bulb will glow bright instead). A 60-100W incandescent (old style, not energy saving) bulb will do. You need no load connected for this to work (no 70W resistors, no speakers). You can also have this connected when testing voltages which avionic might ask you to do.
  • Generally if the bulb dims + stays dim and the relay clicks the amp has no major problems, but there may still be minor ones.
  • Get some mini-grabber leads for your multimeter (you press the top and a little spring-loaded hook comes out) so you can clip to parts without shorting before powering up the amp to read the voltages (incl. setting bias / dc offset). Poking around in a live amp with regular tip leads is asking for trouble.
I'm pretty sure most people made the same mistakes you have at some point, don't let it get you down, just try not to repeat them. You do have to be really patient working on these things, work slowly and double check all work before powering up the amp. A small mistake due to rushing can cause many days of extra work.

Best wishes!
 
I use 470 / 15W across the terminals and wait a couple of seconds, always checking the voltage with the meter.
 
Thanks guys pair 8 ohm, 100 watt resistors ordered. Even though im too impatient about putting that emitter resistor , which arrived today, in and firing it up, I am going to be forcing myself to be disciplined and I'm not gonna touch it until I have the resistors and the mini grabbers. I promised myself no more getting shocked myself or zapping any elements lol
 
Good morning fellow AK’rs. I’ve been into audio since I was 13 at 15 in 1978 I started a DJ business. That’s when I bought my first Yami it was a P 2200. It was in my rack until 3 years ago when I got out of the business. I’ve since bought 2 more P 2200’s and one amp came with 2 complete sets of output transistors neatly packed on cardboard to protect contacts. I need a few more pieces to help in completing my vintage system rebuild. Pic slow ’ I need a CD player looking at Tascam 503 and replace my old Sony reel to reel with a newer version not shown. My question is. Does anyone know a good yami guy in Ontario Canada that can give my beloved beauity’s some love’n ? I will be bi amping a set of JBL 3648 cinemas and matching 2446H driver and with the matching JBL 8340 surrounds. Pic of speakers is when I first brought them home. I assembled horn driver at that time to get prospective of size. I’m in the process of putting and Jatoba veneer on the speakers in the coming weeks
Shane
 

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Good morning fellow AK’rs. I’ve been into audio since I was 13 at 15 in 1978 I started a DJ business. That’s when I bought my first Yami it was a P 2200. It was in my rack until 3 years ago when I got out of the business. I’ve since bought 2 more P 2200’s and one amp came with 2 complete sets of output transistors neatly packed on cardboard to protect contacts. I need a few more pieces to help in completing my vintage system rebuild. Pic slow ’ I need a CD player looking at Tascam 503 and replace my old Sony reel to reel with a newer version not shown. My question is. Does anyone know a good yami guy in Ontario Canada that can give my beloved beauity’s some love’n ? I will be bi amping a set of JBL 3648 cinemas and matching 2446H driver and with the matching JBL 8340 surrounds. Pic of speakers is when I first brought them home. I assembled horn driver at that time to get prospective of size. I’m in the process of putting and Jatoba veneer on the speakers in the coming weeks
Shane
What does this have to do with a Yamaha A-1 ? Start a new thread about your 2200.:thumbsup: Look up AK'r Vint age..he may be able to help you out.
 
i just found this :

DYD3GZIl.jpg


the traces in the pcb are domolished and it is right where thhose emitter resistors are.

how can i fix that?
 
Remove the bad trace and any carbon that potentially short one trace to another.
 
working on the trace.

i just want to say that these mini grabbers blew my mind. these are life saving.

before i saw your post i was trting to use a resistor leg to connect them now im trying to use a piece of wire that has insulator
 
done. same problem.

music only from one channel.

this time smoke seemed to come from the power supply (electrolytic board)
this time the transistors heatsinks did not get hot

also when i touch the volume knob the bias values go haywire and when i let it go they go back to close to normal. (i dont mean turning it, i mean just touching it)
 
it looks like that the transistors on the power suply get really hot and the glue on them smokes. because i dont see any sign on burn on an resistors and the one resistor next to the big caps that has signs of burn measures 10 ohm so i think it is the glue on it that is burning.
 
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