Yamaha A-1020 Needs TLC
- Thread starter Bratwurst7s
- Start date
.. couldn't wait till weekend ...
I put all together and after double-checked (more than double) everything .... dim-bulb tester connected ... POWER ON ..
yes, yes , yes nothing exploded nothing burned, seems to work.
I then read through the service manual how to adjust idling current.
The first measurement showed 1.5 mV (left) and 2 mV (right). I adjusted both channels to 6 mV in non class A.
After turning on auto class A I measured 13.8 mV on the left and 12.1 mV on the right.
What do you think should I do next?
Is it time to connect some cheap speakers and test if it works for more than 20 minutes?
I put all together and after double-checked (more than double) everything .... dim-bulb tester connected ... POWER ON ..
yes, yes , yes nothing exploded nothing burned, seems to work.I then read through the service manual how to adjust idling current.
The first measurement showed 1.5 mV (left) and 2 mV (right). I adjusted both channels to 6 mV in non class A.
After turning on auto class A I measured 13.8 mV on the left and 12.1 mV on the right.
What do you think should I do next?
Is it time to connect some cheap speakers and test if it works for more than 20 minutes?
I would first check the DC offset.
https://audiokarma.org/forums/index.php?threads/amplifier-distortion-dc-offset-and-you.5634/
If that looks good then yes, try it out with some cheap speakers at low volume.
Cheers,
James
https://audiokarma.org/forums/index.php?threads/amplifier-distortion-dc-offset-and-you.5634/
If that looks good then yes, try it out with some cheap speakers at low volume.
Cheers,
James
DC offset: right 11.9 mV / left 19.8 mV
I connected my CD Player and some speakers.
BAD NEWS: no sound, only if I turn up the volume to maximum there is a very quiet sound
I have checked all connections, switches, knobs, ... no success. Operation successful patient dead.
What would you suggest, where to start searching for errors?
I connected my CD Player and some speakers.
BAD NEWS: no sound, only if I turn up the volume to maximum there is a very quiet sound
I have checked all connections, switches, knobs, ... no success. Operation successful patient dead.
What would you suggest, where to start searching for errors?
I would say that no, your amp is not dead, just sleeping. If it was dead you would have a much higher DC offset I think, and the numbers that you measured are quite reasonable.
Questions:
Both channels the same?
Same problem with headphones?
Same problem with the CD player plugged in to Tuner or Aux input?
My first thought is that there is a problem with those driver boards but we are going to have to get some measurements. Also, keep in mind that I am not an expert and it's been 4 years since I have worked on one of these amps. But if I can't help you then we will just respectfully ask one of the experts to step in and lend a hand. Don't worry, your amp is repairable.
If you don't have them I highly recommend that you get some minigrabber leads for your meter. They will be much safer than using an open tip on a test lead.
https://www.mouser.de/ProductDetail/Pomona-Electronics/4176-02?qs=Y53P/oMJqcnZrzevCLoxsQ==
Cheers,
James
Questions:
Both channels the same?
Same problem with headphones?
Same problem with the CD player plugged in to Tuner or Aux input?
My first thought is that there is a problem with those driver boards but we are going to have to get some measurements. Also, keep in mind that I am not an expert and it's been 4 years since I have worked on one of these amps. But if I can't help you then we will just respectfully ask one of the experts to step in and lend a hand. Don't worry, your amp is repairable.
If you don't have them I highly recommend that you get some minigrabber leads for your meter. They will be much safer than using an open tip on a test lead.
https://www.mouser.de/ProductDetail/Pomona-Electronics/4176-02?qs=Y53P/oMJqcnZrzevCLoxsQ==
Cheers,
James
Hello James,
thank you for your reply. I know it is not really dead, let'say it's in deep sleep.
I've already done some measurements, but can't really interpret the results. I'm going to go a little further with the subject of transistors and do some more measurement tomorrow.
Am I correct in assuming that the preamplifier works correctly and the output stage does not?
thank you for your reply. I know it is not really dead, let'say it's in deep sleep.
YES
YES
YES
That's a good starting point. Would be very nice if you could tell me exactly what I should measure.
I've already done some measurements, but can't really interpret the results. I'm going to go a little further with the subject of transistors and do some more measurement tomorrow.
Am I correct in assuming that the preamplifier works correctly and the output stage does not?
OMGCat!
Super Member
Do you hear the click of the speaker relay closing when it's first powered on? If not then the offset measurements you have taken will need to be done at the relay rather than the speaker terminals as they aren't connected to the amplifier if the relay is open.
I agree with James, it's fixable, just being a little bit cranky right now. It's been almost as long since I've been in a 1020 but I've got the manual here and hopefully can give some pointers as we go.
I agree with James, it's fixable, just being a little bit cranky right now. It's been almost as long since I've been in a 1020 but I've got the manual here and hopefully can give some pointers as we go.
Thank you for your input here.
The speaker relay is switching. I replaced the original one with this from Finder.
If it weren't OK, no sound at all would come even when the volume was fully turned up?
Meanwhile I have already read many threads where similar amplifiers (A series) are repaired.
I'm an electronics beginner and I have to translate the englisch technical terms first, so it's often hard for me to understand.
The speaker relay is switching. I replaced the original one with this from Finder.
If it weren't OK, no sound at all would come even when the volume was fully turned up?
Meanwhile I have already read many threads where similar amplifiers (A series) are repaired.
I'm an electronics beginner and I have to translate the englisch technical terms first, so it's often hard for me to understand.
Hello folks,
checked again all the parts i have replaced - OK
checked all transistors - OK
checked all cables - FAULT
The hint from OMGCat! to check the processor jumpers was a very good one!
Not the jumpers were the problem, the connection from accessory receive to the board was broken
I wasted half a day to find the bug.
Finally replaced the cable with one for connecting a CD drive to the sound card in an old pc.
it's alive
, playing for half an hour now
Now I will enjoy listening music with my new (old) Yamaha for a few weeks and hope there will be no more problems turning out.
The next time I get some pocket money from my wife again I will invest it in capacitors and transistors.
Thank you again for supporting me, when we meet some time I will buy you a beer
checked again all the parts i have replaced - OK
checked all transistors - OK
checked all cables - FAULT
The hint from OMGCat! to check the processor jumpers was a very good one!
Not the jumpers were the problem, the connection from accessory receive to the board was broken
I wasted half a day to find the bug.
Finally replaced the cable with one for connecting a CD drive to the sound card in an old pc.
it's alive
, playing for half an hour nowNow I will enjoy listening music with my new (old) Yamaha for a few weeks and hope there will be no more problems turning out.
The next time I get some pocket money from my wife again I will invest it in capacitors and transistors.
Thank you again for supporting me, when we meet some time I will buy you a beer
Very good!
I was thinking about your problem today and in retrospect my thoughts about looking at the driver boards just didn't make sense if the problem is in both channels. That would mean that the exact same problem would have to exist in two different places, unlikely.
On the other hand OMGCat zeroed in on exactly the right places, the protection relay and the equalizer jumpers. Good thinking.
My wife and I get over to Salzburg from time to time. I just might take you up on that bier the next time.
Enjoy that amp and let us know how it goes when you re-cap the rest of it.
Cheers,
James
I was thinking about your problem today and in retrospect my thoughts about looking at the driver boards just didn't make sense if the problem is in both channels. That would mean that the exact same problem would have to exist in two different places, unlikely.
On the other hand OMGCat zeroed in on exactly the right places, the protection relay and the equalizer jumpers. Good thinking.
My wife and I get over to Salzburg from time to time. I just might take you up on that bier the next time.
Enjoy that amp and let us know how it goes when you re-cap the rest of it.
Cheers,
James
I wouldn't have been able to do that without your support.
I have learnt a lot and will certainly start such a project again. These old devices have to be saved!
I'll definitely tell you how the project continues.
Hopefully I can find the missing front panel somewhere.
Happy for now.
I have learnt a lot and will certainly start such a project again. These old devices have to be saved!
I'll definitely tell you how the project continues.
Hopefully I can find the missing front panel somewhere.
Happy for now.
!!
Does that mean that the entire front panel is missing?
If so I'll keep my eyes open and if I see one anywhere I'll let you know.
Have a great weekend,
James
Does that mean that the entire front panel is missing?
If so I'll keep my eyes open and if I see one anywhere I'll let you know.
Have a great weekend,
James
Hi James,
That's great.
Right now it looks like this.
Inside it shines like new , outside there is still some cosmetic necessary.
In the green marked area you can see what is left of the flip cover.
The two sheet metal clamps are still available.
I'd like to get the flip cover and a nicer power switch.
When I have all the parts together I do a complete re-cap and replace the resistors with metal film ones.
The realization of a real source direct circuit would be interesting, i simply don't like sound controls.
have a nice weekend too
That's great.
Right now it looks like this.
Inside it shines like new , outside there is still some cosmetic necessary.
In the green marked area you can see what is left of the flip cover.
The two sheet metal clamps are still available.
I'd like to get the flip cover and a nicer power switch.
When I have all the parts together I do a complete re-cap and replace the resistors with metal film ones.
The realization of a real source direct circuit would be interesting, i simply don't like sound controls.
have a nice weekend too
WOW! Just wow! Very nice work Andreas.
Cheers,
James
Cheers,
James
Thanks for the compliments, not perfect but looking good.
Just noticed there are some different models on the marked.
My A-1020 has the option of 330/390 pF in the MM phono section, others have 220/330 pF like the manual says.
Good news: I get 2 more devices as part carrier so I can put together a second one and have enough spare parts for the future
Just noticed there are some different models on the marked.
My A-1020 has the option of 330/390 pF in the MM phono section, others have 220/330 pF like the manual says.
Good news: I get 2 more devices as part carrier so I can put together a second one and have enough spare parts for the future
