I recieved this amp in for repair. I replaced all power supply fets and gate resistors. Also replaced some of the outputs so far. If i have all 8 outputs
(SSP45N20's) in the amp it will draw excessive current. If i take 4 of them out for the left channel amp powers up and play's fine. I checked to see if the outputs were shorted or leaking and even replaced them with different ones.
So wondering where i go from this point since i cant seem to find the problem ? If all 8 outputs are in the amp it draws excessive current
(SSP45N20's) in the amp it will draw excessive current. If i take 4 of them out for the left channel amp powers up and play's fine. I checked to see if the outputs were shorted or leaking and even replaced them with different ones.
So wondering where i go from this point since i cant seem to find the problem ? If all 8 outputs are in the amp it draws excessive current
From my experience, I've found that the only transistors that work (properly) with these amp are the original outputs. I've tried a few other parts (including the 45N20B) and was not successful in finding a viable substitute. I've purchased NOS 45N20As and they didn't work either. I've taken outputs out of a working amp and installed them in the amp I was having trouble with and the original outputs worked. I did this simply to confirm that there was no other problem with the amp. There may be outputs that will work in this amp but I haven't found them.
Where did you purchase the output from?
Where did you purchase the output from?
I took them out of a different sony amp that was working 100% (same model)
There was only 2 outputs that were shorted in the amp im repairing So i took the 2 shorted ones out and tryed powering it up and it draws excessive current with 6 out of the 8 outputs in it. Amp works fine with 4 out of the 8 outputs in it
There was only 2 outputs that were shorted in the amp im repairing So i took the 2 shorted ones out and tryed powering it up and it draws excessive current with 6 out of the 8 outputs in it. Amp works fine with 4 out of the 8 outputs in it
It would seem that one or more of the outputs are leaking. With your meter set to ohms, do you read OL when the resistance is measured from the gate led to the other legs (FETs out of the sink)?
When you say it works fine, do you mean it's not drawing excessive current or do you mean that it's producing clean audio to full power (or at least to clipping)?
When you say it works fine, do you mean it's not drawing excessive current or do you mean that it's producing clean audio to full power (or at least to clipping)?
Ok with only 4 outputs in the amp I put my meter leads on the outputs . I get 28.69 volts on the outputs for a split second upon power up the it will slowly go down to 0 volts. Wondering what could cause this? With only 4 outputs in it it produces clen output and doesnt draw excessive current. The amp i took the outputs from was working 100% flawless. So i have 4 old outputs in the amp im repairing and trying to put 4 in from a differnt amp to see if i have any other problems with the amp
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with outputs Fet 17,18,19,20 in the amp it powers up and produces clean output. If i try putting the other 4 in the amp 1 at a time amp will draw excessive current. I have outputs from another amp and they all test fine but when i try to put more then 4 in this amp it draws excessive current.
Wondering where i should go from here?
Wondering where i should go from here?
It can't produce clean audio with only those FETs in the circuit. Did you look at the output on the scope?
If you measure the resistance between the following points, what do you read?
emitter Q23 - emitter Q25
emitter Q27 - emitter Q29
Have you removed and checked Q23, Q25, Q27 and Q29?
If not, remove them and confirm that there is no collector-emitter leakage and that each one shows two good junctions (~0.6v base-emitter and base to collector). Set the meter to ohms for leakage and to diode check when checking the junctions.
If you measure the resistance between the following points, what do you read?
emitter Q23 - emitter Q25
emitter Q27 - emitter Q29
Have you removed and checked Q23, Q25, Q27 and Q29?
If not, remove them and confirm that there is no collector-emitter leakage and that each one shows two good junctions (~0.6v base-emitter and base to collector). Set the meter to ohms for leakage and to diode check when checking the junctions.
It appear that you had the meter set to the wrong range. Try setting it to a higher voltage range.
You stated that they 'appeared' to be fine. Did all 4 drivers read OL on ohms when checking from collector to emitter (checking with the probes one way then reversed)?
A leaking output can cause the outputs to fail and can cause the amp to draw excessive current.
You stated that they 'appeared' to be fine. Did all 4 drivers read OL on ohms when checking from collector to emitter (checking with the probes one way then reversed)?
A leaking output can cause the outputs to fail and can cause the amp to draw excessive current.
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