petehall347
the brandy coffee man
voltages at protect board ?
Pioneer SA-8100 Power Supply Issue? - Help!
- Thread starter forsgren
- Start date
petehall347
the brandy coffee man
and the rest ?
Here is a wrench in the works. I have the AWM-027-D version, the following is the "D" version. I cannot locate a schematic diagram for this.
This is what we have been working on, I don't know if they are the same board or if they are interchangeable?
Here are the other voltages, obviously something is not right.
Pin 6 -12.39v
Pin 16 34.49v
Pin 17 7.5v AC
Pin 14 34.57v (it shows 8v on the schematic but is it the correct voltage for the "D" version). At any rate, the voltages on Q7 are not close, I do see 0.7v at the base fo Q6. I pulled Q7 (sSC1384 and it checked good, I tried replacing it with the KSC2690 and got the same voltages).
At the base of Q5 I get 6.09v, which should be 20.6v.
We are chasing our tails until we can verify if the boards are compatible. I think the Diodes 5,6 and 7 are part of the issue, if you look at the "D" board, these were very close to the pins that shorted out.
This is what we have been working on, I don't know if they are the same board or if they are interchangeable?
Here are the other voltages, obviously something is not right.
Pin 6 -12.39v
Pin 16 34.49v
Pin 17 7.5v AC
Pin 14 34.57v (it shows 8v on the schematic but is it the correct voltage for the "D" version). At any rate, the voltages on Q7 are not close, I do see 0.7v at the base fo Q6. I pulled Q7 (sSC1384 and it checked good, I tried replacing it with the KSC2690 and got the same voltages).
At the base of Q5 I get 6.09v, which should be 20.6v.
We are chasing our tails until we can verify if the boards are compatible. I think the Diodes 5,6 and 7 are part of the issue, if you look at the "D" board, these were very close to the pins that shorted out.
petehall347
the brandy coffee man
pin 14 will drop when q7 is turned on and the relay pulls in .
i need to see the other pin voltages .
i need to see the other pin voltages .
The diodes are the steering controls for the fault detection circuits to trigger the protection mode via Q5.
The voltages shown on the schematic are for the circuit in the normal operation (relay on) of the circuit. IE not in protection.
What are the voltages at pins 2 and 4?
Good evening, here are the fresh voltages, from the top left side:
Pin 9 -29.86v
Pin 10 -29.86v
Pin 12 18.16v
Pin 11 17.16v
Pin 1 -27.98v
Pin 3 17.16v
Pin 2 -29.97v
Pin 4 17-17v
Pin 6 -12.48v
Pin 17 7.5v AC
Pin 7 ground
Pin 14 24.57v
Pin 15 34.63v
Pin 16 34.49v
Thank you.
Pin 9 -29.86v
Pin 10 -29.86v
Pin 12 18.16v
Pin 11 17.16v
Pin 1 -27.98v
Pin 3 17.16v
Pin 2 -29.97v
Pin 4 17-17v
Pin 6 -12.48v
Pin 17 7.5v AC
Pin 7 ground
Pin 14 24.57v
Pin 15 34.63v
Pin 16 34.49v
Thank you.
petehall347
the brandy coffee man
both amps have problems , first check all the output transistors
then get all driver board pin voltages including the ones that are ground .
Last edited:
Well, the trip turned out a little longer than anticipated. I have been busy with a few other things as well.
Looking at the Control Amp Board (AWG-071) nothing looked suspicious
.
Same with the Equalizer Amp (AWF_006-01).
However, the Power Amp Board (AWH-022-A) is really interesting. The output transistors on one channel are 16.6 - 17.06 volts, their corresponding pair are 31.2 - 39.3 volts which is normal. I measured the emitter resistors and did get an unstable reading on the resistor closest to Q18, it did stabilize after a few. I suspect that one or both of these transistors are bad and were affected when things got shorted out. However, before I remove the entire amplifier section to get to these, could there be other possible culprits?
Thank you!
Looking at the Control Amp Board (AWG-071) nothing looked suspicious
.
Same with the Equalizer Amp (AWF_006-01).
However, the Power Amp Board (AWH-022-A) is really interesting. The output transistors on one channel are 16.6 - 17.06 volts, their corresponding pair are 31.2 - 39.3 volts which is normal. I measured the emitter resistors and did get an unstable reading on the resistor closest to Q18, it did stabilize after a few. I suspect that one or both of these transistors are bad and were affected when things got shorted out. However, before I remove the entire amplifier section to get to these, could there be other possible culprits?
Thank you!
Are you sure about the reading at pin 14? That should be at ground potential. Ohm check it to the chassis.
Also pin 8 should not have any voltage on it.
Pin 4, 8, 9, 14, 17, 18 and 22 are all supposed to be going to ground. 8 & 9 and 17 & 18 are connected together on the PCB.
You need to follow those wires back to wherever they are going. Some of them are most likely going to a multiground terminal screwed to the chassis. if nothing is obviously broken off of hanging in mid-air then ohm check the wires.
You need to follow those wires back to wherever they are going. Some of them are most likely going to a multiground terminal screwed to the chassis. if nothing is obviously broken off of hanging in mid-air then ohm check the wires.