Hello all I would like to know if any one has had any good experience trying to get a replacement Transformer (power) for the D70 Classic amp ,. I have contacted Audio Research in the USA and there reply was no 
they do not have parts and they would not give me the VA ratings and turns etc to have another made . Can any one tell me if they know of a drop in replacement. I live in Australia and have contacted about four different companies and they say not really for such a small run of just one
they do not have parts and they would not give me the VA ratings and turns etc to have another made . Can any one tell me if they know of a drop in replacement. I live in Australia and have contacted about four different companies and they say not really for such a small run of just one
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Can you estimate the VA ratings of each secondary ?
You might be able to affect a repair with multiple transformers or a switched mode approach.
You might be able to affect a repair with multiple transformers or a switched mode approach.
The schematic I have found shows a power supply with outputs + and -39V, + and -75V, + and -15V.
Curious thing, the 75V's aren't used anyware 😕
But since the 12V is derived from the 75V you need the windings anyway.
So you need a transformer with two 28V 5A ( or 56V 5A CT) and 210V 200mA CT.
Mona
Curious thing, the 75V's aren't used anyware 😕
But since the 12V is derived from the 75V you need the windings anyway.
So you need a transformer with two 28V 5A ( or 56V 5A CT) and 210V 200mA CT.
Mona
Oh bother I meant D70 classic power amp sorry team
Sorry folks I made a stupid mistake I meant to say D70 and that is the power transformer I would like more information on SORRY
🙄🙄😀😀
Sorry folks I made a stupid mistake I meant to say D70 and that is the power transformer I would like more information on SORRY
🙄🙄😀😀
Woo there, too many emogies... : ) First off you say in your thread title "dead tfmr", in what way is it dead? Are all secondary's no OP? Often tfmrs and speakers have OC windings and it's possible to find a broken wire or turn and either remove one turn and resolder a lead on or fix it in some way.
If that's not an option either rewind it yourself or get a competant tfmr chap to do it. If it's not potted that is.
Andy.
If that's not an option either rewind it yourself or get a competant tfmr chap to do it. If it's not potted that is.
Andy.
Dead primary on power transformer
Ok so I got my amp back from the repairs and suspensions are correct , the power transformer is dead on the primary . I contacted the audio research company like I said but to no avail . I do have all the current ratings off all the secondary taps as per the drawings but no secondary voltages with out load . The only way i can find the voltages out is if someone has a d70 Amp and can disconnect them from the circuit and check the floating voltage with no load . Any Takers otherwise has any one any ideas 🙄🙄
Ok so I got my amp back from the repairs and suspensions are correct , the power transformer is dead on the primary . I contacted the audio research company like I said but to no avail . I do have all the current ratings off all the secondary taps as per the drawings but no secondary voltages with out load . The only way i can find the voltages out is if someone has a d70 Amp and can disconnect them from the circuit and check the floating voltage with no load . Any Takers otherwise has any one any ideas 🙄🙄
Look for CJ on this site or the groupdiy site...he has documentation on many transformers and apparently rewinds defective ones.. With all those secondaries that looks like a custom unit...CJ is in California somewhere...
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Case solved Sherlock
After getting My amp back from the local Electrician who said he had removed all the secondary windings and told me that the transformer had a dead short I decided to try it myself as I felt that as I was not convinced .
Well after checking out the power transformer and pulling it apart myself ,I did what I should have done in the first place . That is remove all secondary taps to the circuit board myself and try the power transformer try again . I found after doing just that that the d9 diode in the bridge to the 24 dc feed was shorted to earth hence the fuses blowing and this was a dead short across the secondary feed to the 24 volt line
So now I repaired the bridge and upgraded the diodes replaced the caps to that feed and slowly reconnected the secondary feeds and it goes again .
thanks to everyone for your help .
I will upgrade the power caps soon but am happy😀😀🙂🙂🙄🙄 to have a working D60
After getting My amp back from the local Electrician who said he had removed all the secondary windings and told me that the transformer had a dead short I decided to try it myself as I felt that as I was not convinced .
Well after checking out the power transformer and pulling it apart myself ,I did what I should have done in the first place . That is remove all secondary taps to the circuit board myself and try the power transformer try again . I found after doing just that that the d9 diode in the bridge to the 24 dc feed was shorted to earth hence the fuses blowing and this was a dead short across the secondary feed to the 24 volt line
So now I repaired the bridge and upgraded the diodes replaced the caps to that feed and slowly reconnected the secondary feeds and it goes again .
thanks to everyone for your help .
I will upgrade the power caps soon but am happy😀😀🙂🙂🙄🙄 to have a working D60
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ok not fixed
Bench testing is always a good thing as today it stopped again while I was listening to it after about 5 hours continue use this time fuses gone . So now I will check the valvess in case any are getting a bit sad . has anyone any idea to why the 24 volt line would blow fuses ??
Bench testing is always a good thing as today it stopped again while I was listening to it after about 5 hours continue use this time fuses gone . So now I will check the valvess in case any are getting a bit sad . has anyone any idea to why the 24 volt line would blow fuses ??
I suppose you have to check that diode again, since the failure of that would be the symptom of the problem and not the problem itself.
Well here we are in 2023 I have resolved my amp issue and have been working on this D70 to get it running smoothly. The problem were the output 6550 tubes were almost dead and I found this out by buying a good cheap valve tester. I got new output tubes and changed some driver tubes and since then I have had no further issues with this amp. Thanks to all for your help
