Yamaha A-1 Repair and restore: beyond Deoxit

Some of those old boards are getting to the point where desoldering damages the solder pads.
solder pads. thats the term i was looking for.


anyway i checked every component that i soldered or desoldred but nothing. the voltage accross the caps is 53 but the bias voltage that is supposed to be 35 is zero. no relay no nothing. at this point i guess i should put the originbal transistors D476 and B556 back in because before that there was the relay click.
 
no it was not working and i coudnt figure it out. also you didnt post the pictures so that i can take the board out and send it to a professional like you to be repaired so i decided to replace all components that i can in the power supply and see how it turns out. i basically tried to follow the steps of mr., yamaha and repalce almost all compoents that he replaced iun his restoration project of 2010. now i am in deep ooooh la la but ill figure it out.

Hello , Dadbeh , you are right I didnot post pictures because customer who promised me to bring me two A1 for repair never came .....I am sorry about that but many people says things they don't do , "that's the law of the west "

Just one thing : replacing all components do not make a repair , because you don't learn anything , and you have a chance to be unsuccessfull
If your boards are very old and your iron solder too hot , dammaging pcb will be more easy !
 
Mr Clinic Audio

It seems we have to keep reminding you a couple of basic AK rules:

1) You shall not use AK as a commercial billboard for your personal business

2) People come here to learn, not to be lectured. And your behaviour is continuously giving folks one detail, but never the whole story, and thus leaving many AKers in the woods. It seems you like to do this to profile your supposed superior skills and knowledge.

PLEASE: start your own website and threads, and stop abusing other folks' threads as your business billboard and harassing newcomers in this hobby.
 
Mr Clinic Audio

It seems we have to keep reminding you a couple of basic AK rules:

1) You shall not use AK as a commercial billboard for your personal business

2) People come here to learn, not to be lectured. And your behaviour is continuously giving folks one detail, but never the whole story, and thus leaving many AKers in the woods. It seems you like to do this to profile your supposed superior skills and knowledge.

PLEASE: start your own website and threads, and stop abusing other folks' threads as your business billboard and harassing newcomers in this hobby.


That is not the case. Clinic Audio in this thread, is sharing his knowledge and expereince and helping others learn. The tidbit about sending my board to him was just a small part of one post as the last resort when I have tried everything and disn't get results. And was hopeless. I don't thinkthat it was abusing my thread.
 
You shall not use AK as a commercial billboard for your personal business

I am sorry but I did not .

And your behaviour is continuously giving folks one detail, but never the whole story, and thus leaving many AKers in the woods. It seems you like to do this to profile your supposed superior skills and knowledge.

Yes , you put your finger at the right point . My knowledge is uncommon on YAMAHA products and some members that you call "newcomers" will be advised to follow them instead to copy some post made by unable people to refix problem by replacing unnecessary components or all !

I never used AK for any personal business and I am sure that many members I did help , can confirm this .

I do not deserve any award yo refix one YAMAHA A1 , that's my job ( and I can do it within some hours whatever the problem is )
But as Dadbeh precised, I have tried , each time it was possible , to help him to follow a good track to be successfull .

Good luck guys , I have to take care about my customers
 
And how do you call that ?

I call that I am not responsible . I was expecting arrival of these YAMAHA A1 here for repair and delete the main board to show how do to it to Dadbeh .
As I do not have any other A1 here , it is not possible to make these helpfull pictures for Dadbeh
This A1 owner's will maybe change his mind in some days (or week , I don't know ) and I will takes these pictures but to speak clearly I don't think that Dadbeh will wait so long

And you do that frequently.

?? I don't see what you want to say ...This is out of subject here
we are here to help members in troubles nothing else
 
Dadbeh, you need to buy a part tester or learn how to test parts. Ebay has some cheap ones .

Click on pic.





Shot gun replacing parts is NOT how you lear. You know how i know? I did the same stupid shit working on CRT projectors.
So listen to what other say, and ask more questions if not sure how to test parts or measure voltages.

One thing is I always measure parts out of the unit, or at least lift one leg of the part measuring , like a resistor, did, or cap.

Just relax go slow and listen to the advice given.

Did you replace those emitter resistors? And if so then Id check the pre driver transistors to the bad channel.



Athanasios
 
well my problem was that my faulty speaker cable was shorting the + and - speaker outputs causing one particular transistor to go up in flames. it was really bad abd it was a mystery. i finally figured it out in my other restoration thread for CA-2010. then i replaced that transistor with a modern equivaalnet and it started working but I didnt like the sound of either so i sold them both at considerable loss and now i am not much interested in vintage electronics really but i am still playing with vintage TTs and speakers. I prefer the sound of my modern mosfet transistor amps to both of these by a wide margin.
 
I got a Yamaha A-1 integrated amplifier for 40 bucks !

It works save for an issue with the phono stage.


Oddly in disc mode both channels work. However when listening to vinyl while NOT in disc mode, I only get sound out of one channel. Odd, right ? SOMETIMES it works not is disc mode. But mostly does not.


I plan to open it up and dexoit all the switches and potentiometers. Hopefully it's just that. I'll also look for obvious signs of burned components and such.

I have the 47k plugs for the phono stage. They seem to work.

Just wondering if this is a common fault.
 
I got a Yamaha A-1 integrated amplifier for 40 bucks !

It works save for an issue with the phono stage.


Oddly in disc mode both channels work. However when listening to vinyl while NOT in disc mode, I only get sound out of one channel. Odd, right ? SOMETIMES it works not is disc mode. But mostly does not.


I plan to open it up and dexoit all the switches and potentiometers. Hopefully it's just that. I'll also look for obvious signs of burned components and such.

I have the 47k plugs for the phono stage. They seem to work.

Just wondering if this is a common fault.
Also want to add that when not in disc mode both channels work ONLY in mono.
 
I have 3 A-1's to work on. Finally started on 2 of them, they have
been kicking my butt for a few years now. Some tips,
- main caps don't bleed, make a rig (100-1k resistor?) to bleed
- amp has some great test points for voltage measurement via base
- good ESD care required around FETs on driver board
- If you use a variac then the start up voltages at test points eg,outputs
can be a bit scarey but they do normalize when voltage increased.
- I've had problems caused by C524(mylar) breaking down. Recall ivandezande
posting that these yellow caps are problematic. C520 and C512 are
next on my list to investigate. These are polystyrene(!), trying to
track down why the +O pin would go -ve (say -5-8Vdc...)
- I removed the outputs and connected 1N4148's across the b-e's
- previous owner did a refurb and in their wisdom undid some of the wire
wrap (probable cause of my problems)
 
I'd concentrate your effort on the input select switch.. Disassemble and do it right..;) The stereo/mono switch would be 2nd.

There it was! A lot of de-oxit on all the switches did it! Now I get great two channel audio in regular phono mode and disc mode.

I built a re-cap (electrolytic) list visually and from the parts list. I usually re-cap the power/amp stage, phono, and tone control stages. Sometimes the main power caps too, cost permitting.

Question:

Where are the electrolytic capacitors in the phono stage?

Are they one the VR and SW circuit board, pre-amp board, or drive board? I doubt they are in the power or electrolytic board.

Also i seem to recall that in disc mode only a mylar capacitor is in the circuit path between the MM/MC amp and the main amp? I can't find it. I'd probably change that if i am right.

The goal here is to have pristine as good as new or better than new vinyl playback.
 
I have 3 A-1's to work on. Finally started on 2 of them, they have
been kicking my butt for a few years now. Some tips,
- main caps don't bleed, make a rig (100-1k resistor?) to bleed
- amp has some great test points for voltage measurement via base
- good ESD care required around FETs on driver board
- If you use a variac then the start up voltages at test points eg,outputs
can be a bit scarey but they do normalize when voltage increased.
- I've had problems caused by C524(mylar) breaking down. Recall ivandezande
posting that these yellow caps are problematic. C520 and C512 are
next on my list to investigate. These are polystyrene(!), trying to
track down why the +O pin would go -ve (say -5-8Vdc...)
- I removed the outputs and connected 1N4148's across the b-e's
- previous owner did a refurb and in their wisdom undid some of the wire
wrap (probable cause of my problems)

What do you recommend for the two main large caps?

Also i want this to be a headphone amp (god damn it's good at that beats my A-1000) and a vinyl playback only. See my other post i can't figure out where to change the electrolytic capacitors for the MM/MC amp.
 
The VR&SW board has caps for the phono MC stage. The board
also houses the volume pot.

The PRE amp board (NA07043) houses the Phono MM stage. There
are 4 x 1uf/50V caps (C419...422) that appear to be for power rail noise path.
Replace with Nichicon UPW or whatever handy. The board also has 2x1uf/100V
film caps (C415,6) that I did not replace. I would doubt that yamaha would
use mylar in the audio path.

For main caps I opt for united chemi-con KMH or SMH, 22000uf/80V.
 
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