So are we saying at this stage that it is just a phono stage fault ?
What about the drop in level when playing through speakers but not headphones ?
Looking for distortion is definitely scope territory. All you can realistically do without is check that the DC voltages are correct in the phono stage.
What about the drop in level when playing through speakers but not headphones ?
Looking for distortion is definitely scope territory. All you can realistically do without is check that the DC voltages are correct in the phono stage.
The supply will be common to both L and R channels. All you could hope for would be to see a difference in DC voltages when comparing all circuit nodes in the phono section, left vs right. If the DC levels are similar then the distortion is more of a dynamic issue and you need to see what is happening on a scope to make more of an informed decision.
Although I've never used things like a USB scope, they are very cheap and might be adequate for this low frequency kind of work.
Although I've never used things like a USB scope, they are very cheap and might be adequate for this low frequency kind of work.
Well it was all going so well until my mate decided to upgrade the old caps! He reported no sound, I managed to check it today but have no idea what its doing. I knew I should have done it myself but it sounded so good I dont blame him
I checked all the polarity of the caps first of all and its all fine. The issue is
no sound
no bias voltage
dc offset rises very quickly
I did some basic checks but was too scared to test further due to dc rising to more than 1v in a matter of seconds. I'm a little annoyed as it was painful enough to fix in the first place and now this. I very briefly looked at the solder job and it also looked ok before I ran out of time and had to leave.
Any suggestions please? I plan to go back soon but honestly no idea whats causing it and dont have time to waste there. I was told there was no smoke or bangs and the fuses was not blown and lights came on when I checked.
Please help!!!
I checked all the polarity of the caps first of all and its all fine. The issue is
no sound
no bias voltage
dc offset rises very quickly
I did some basic checks but was too scared to test further due to dc rising to more than 1v in a matter of seconds. I'm a little annoyed as it was painful enough to fix in the first place and now this. I very briefly looked at the solder job and it also looked ok before I ran out of time and had to leave.
Any suggestions please? I plan to go back soon but honestly no idea whats causing it and dont have time to waste there. I was told there was no smoke or bangs and the fuses was not blown and lights came on when I checked.
Please help!!!
It might be over 20 years ago, but they sent me a bag of bits to refresh one channel. Some were substitutes. We lost interest in the amp after that. It was ruined. Perhaps had I done both channels the situation would of been better, but not right still.
They deserve a glass stand with a mirror to see underneath. For that casting has real visual appeal
Edit: I recall the offset wouldn't comply. It wasn't something I could set at a potentiometer. It required a bit more skill than I had, and the internet wasn't an option back then. I bet I have the drawings they sent still though.
They deserve a glass stand with a mirror to see underneath. For that casting has real visual appeal
Edit: I recall the offset wouldn't comply. It wasn't something I could set at a potentiometer. It required a bit more skill than I had, and the internet wasn't an option back then. I bet I have the drawings they sent still though.
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Its a case of back to basics I'm afraid. Always check the supplies are correct first though.
It could be anything but if both channels are the same then it suggests a supply issue.
There is a cyrus2 on ebay with broken front, following a drop. Perhaps in London...
1 sec
Leyland in Lancashire
Mission Cyrus Two Amplifier Was Working Spares Or Repairs | eBay
Are they related enough to make a good one from the pair?
1 sec
Leyland in Lancashire
Mission Cyrus Two Amplifier Was Working Spares Or Repairs | eBay
Are they related enough to make a good one from the pair?
No I think it was 30 volts. From the manual I gather he tested after the diode bridge.
From memory both channel s had the same problem. I thought it was power too but after I saw the txt I don't think power is the problem
From memory both channel s had the same problem. I thought it was power too but after I saw the txt I don't think power is the problem
60 volts total. Plus 30 volts with respect to ground and minus 30 with respect to ground. So one of those fuses should have +30 and the other -30 on each end.
You will never believe it after 2 hours on the phone turns out a diode was shorted!!!!!
The main diode bridge (4 main diodes) one was faulty!!
LOL what in hell was he doing?
I followed your advice, there was no voltage on one side, so he swapped main caps over quickly and same problem on one side, tracked it back to find one diode was just dead! not shorted just dead!
His victory cry (opposite to war cry) indicates the amp was working again. Its using an old 4 amp diode original I believe is 3, was a risk as we were both scared something might blow up LOL. I advised to replace all to new just in case.
Job done again LOL!! And thanks again!
The main diode bridge (4 main diodes) one was faulty!!
LOL what in hell was he doing?
I followed your advice, there was no voltage on one side, so he swapped main caps over quickly and same problem on one side, tracked it back to find one diode was just dead! not shorted just dead!
His victory cry (opposite to war cry) indicates the amp was working again. Its using an old 4 amp diode original I believe is 3, was a risk as we were both scared something might blow up LOL. I advised to replace all to new just in case.
Job done again LOL!! And thanks again!
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