For that amount of time and money, you can buy another in working condition.
Unless it is of sentimental value, it is a wasted effort, or not sufficiently rewarding, in my opinion.
You can also change the main board to a populated Class AB or D amplifier board, enough for most users.
Unless it is of sentimental value, it is a wasted effort, or not sufficiently rewarding, in my opinion.
You can also change the main board to a populated Class AB or D amplifier board, enough for most users.
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Do a search, using your power supply volts in search term: '30-0-30V audio amplifier', (for example)...you will get many results. Or try '30W audio amplifier'...
Connections for input, power supply and output are provided.
If needed, get one with a heat sink, they can be hard to find in some countries.
Connections for input, power supply and output are provided.
If needed, get one with a heat sink, they can be hard to find in some countries.
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Don´t worry, the thread is dead anyway.
I wasted time answering in good faith, like many others, but you never ever answered what is the defect you are trying to correct, so....
What part of this are you having a difficult time understanding?
Sorry to be so dense that I would think with these listed issues I should make repairs/replacements.
I sincerely do appreciate everyone's time and interest.
90% of the Electrolytics were outside 20% tolerance
80& of the Transistors were very low HFE, below 50
80% of the Resistors were outside 5% tolerance
Drivers and Outputs are random and not the same, plus low Hfe
Also see post 44 & 46 as an example of the Ceramics Spec is 0.1uf and they measure 0.067uf that appears to be out of spec, my misunderstanding.
Also the Fuse Resistors had been changed out to Carbon Film
In regards to the Symbol Schedules and Parts List, I felt there was a discrepancy but now I see it is just me.
Ok, just one more time.What part of this are you having a difficult time understanding?
Sorry to be so densethat I would think with these listed issues I should make repairs/replacements.
I sincerely do appreciate everyone's time and interest.
90% of the Electrolytics were outside 20% tolerance
80& of the Transistors were very low HFE, below 50
80% of the Resistors were outside 5% tolerance
Drivers and Outputs are random and not the same, plus low Hfe
Also see post 44 & 46 as an example of the Ceramics Spec is 0.1uf and they measure 0.067uf that appears to be out of spec, my misunderstanding.
Also the Fuse Resistors had been changed out to Carbon Film
In regards to the Symbol Schedules and Parts List, I felt there was a discrepancy but now I see it is just me.
1) you-do-not-have-a-problem
Period.
"But ... but ... but ... what about what the list I mention here?"
2) those-are-not-problems.
That is simply the EXPECTED tolerance in a consumer grade product, and to boot, FIFTY YEARS LATER.
3) For your information, and this is first hand knowledge because I WAS BUILDING AND SELLING AMPLIFIERS 50 YEARS AGO (actually since February 1969, do the Math), way back then you could buy over the counter, at any Electronics Components Shop:
* 20% tolerance resistors, no extra colour band indicating that, which were the cheapest.
* 10% tolerance ones, which is what the average builder or hobbyist used, trying to be slightly above average. More expensive, of course. Silver band.
* 5% tolerance, PREMIUM quality, significantly more expensive. Gold band.
So that Yamaha is PERFECT, as far as 70´s consumer grade Electronics go.
Stop OBSESSING over non-problems.
10%, 20% and worse was so much a thing that it was indicated in the official Electronics Industry codes (EIA and all that).
Capacitors were even worse, and don´t start me on Electrolytics.
Want precision satisfying your Peak meter?: buy medium grade (not the absolute cheapest of course) Chinese made equipment, manufactured by any mid sized semi-automated Factory,with modern mass produced parts.
There you will find the precision you want.
Just to end (I hope
), about :it is YOU who quoted me NINE times in less than2 days (same as ringing my doorbell or banging on my door).
I have infinite patience usually giving very detailed Tech answers but this thread went overboard.
Unless you have a real problem, leave as is.
But don´t try to rediscover b the wheel, fire, and cooked foods, that ´s OLD stuff.
So much judgement being handed out here, that is not at all what I was hoping for. I thought I had asked some very simple questions with hopes of simple answers. My big mistake in thinking, has become more of a delusion. I did receive some okay information and I am most appreciative of the assistance.
Same here.
They might be plugged in backwards, in which case that ¨still work, but one telltale sign is p i s s poor Hfe
Plus others, such as Vce Max around 5-7V, etc. but hard to notice when the power supply is:
You're putting too much thought into the documents. Plenty of times changes are made during production because of cost or availability. The best way is visually see what the board has. Metal film resistors for everything until you get above 1 watt then it's usually the white coffin cement kind. Metal film resistors are cheap and pretty standard. Spend $3 and get yourself a bag of 100. Ceramic caps are usually for bypass reasons but I have seen them used in coupling applications. Again nothing here is critical or stressing the caps in any way. Buy whatever is cheapest. Low ESR or FC caps are best used in switching power supplies. You won't see any advantages in audio applications. Lately I've been splurging and buying Nichicon audio grade caps because they are gold colored. Polystyrene and film caps last forever. I'd leave them alone. One time I did see a green dipped film cap with it's guts exploded outward. Someone was pushing their PA amp too hard in church.
So I shouldn't replace them with any Film Cap?
What about MLCC like this: FA26C0G2J103JNU06
What about using the DME for replacements?