Replace 818 and 1628 with KSA1381 and KSC3503. This always, always, always needs to happen. And the input pair.
This should have been done from day one. I have had countless 850/950's with issues from them.
Pioneer SX-950 receiver
- Thread starter Tomcow
- Start date
This should have been done from day one. I have had countless 850/950's with issues from them.
Others can continue as you need single direction, but I find this real strange. Your left channel outputs from the amplifier board and to the protect board are showing -51V rather than 0 volts, or close to 0 volts. And the right channel outputs to the speaker and protection board are showing +42 volts rather than 0 volts or close to 0 volts.
Sort of saying that there is problems on both channels?
or could there be some miswiring from the restoration work? were any wires removed and connected on the amp board or on the power supply board.
I typically find and repair problems before replacing parts, that could cause issues. With problems on both sides such as yours, I would only start by measuring/testing transistors in question, and replace only if they read bad, (with an analog ohm meter or transistor tester. ) yes some transistors including the input pairs, and others can be candidates for replacement, but should be addressed after you have identified and fixed your problem. If the 818 or its pair are bad (open B to E, or shorted) by all means change, but be careful as the pinout for replacements will be different. Replacing lots of parts in a unit that already has multiple problems can add to the issues, making it so much harder to repair. But this is my opinion.
Sort of saying that there is problems on both channels?
or could there be some miswiring from the restoration work? were any wires removed and connected on the amp board or on the power supply board.
I typically find and repair problems before replacing parts, that could cause issues. With problems on both sides such as yours, I would only start by measuring/testing transistors in question, and replace only if they read bad, (with an analog ohm meter or transistor tester. ) yes some transistors including the input pairs, and others can be candidates for replacement, but should be addressed after you have identified and fixed your problem. If the 818 or its pair are bad (open B to E, or shorted) by all means change, but be careful as the pinout for replacements will be different. Replacing lots of parts in a unit that already has multiple problems can add to the issues, making it so much harder to repair. But this is my opinion.
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with -51 v on 1 channel, and +42 on the other, will never allow for the protect circuit to allow relay click. And good thing because it would fry both speakers. As it didn't work, and unknown issues, I would double check everything. Making sure wiring is correct, making sure the outputs are in the proper locations (no swapping of npn and pnp's etc. I would lift out that amp board and look for areas of work, and checking any components to see if the were installed properly after replacement (transistors etc is B E C in the proper places). Is there any damaged foil traces?. Is there any connections that were accidently bridged to other connections. Are there any incorrect transistors installed? (PNP instead of NPN etc)
If I Disconnect one wire on each side of the amp board, which is the right and left speaker outputs,The speaker relay clicks right on. When I touch either wire back on either power output board, The speaker relay immediately kicks out, protection. When I check C 1628,A-818 and even the predrivers,B-536 and D-381, some thing is over driving them, as I read 48 V 48 V and then 41 V,According to the schematic I should be reading 48 V 48 V, and 1.2 V
Verify that the output transistors are installed in the correct locations.
Once that is ascertained, there are some further checks to be performed on the drivers. This will require that the outputs are installed and NO speakers connected, powering the unit through a DBT, and voltage measurements in the main amp circuit.
Once that is ascertained, there are some further checks to be performed on the drivers. This will require that the outputs are installed and NO speakers connected, powering the unit through a DBT, and voltage measurements in the main amp circuit.
Okay.So with the output transistors removed, I checked all the transistors across the output board from left to right:C-3503,-48,-48,-48.A-1381,47,47,47. D-381,46,46,46.B-536,46,41,46.C-3503,-48,-13,-48.A-1381,46,1.0,46.D-381,.47,40,1.0.B-536-.75,-40,-1.3.
Attachments
Check everything again.
Transistor orientation, solder bridges, and for any toasted resistors until the heat tubing.
Why didn’t you replace the trimmers?
Why is the 330uF cap huge?
Why aren’t the 1uF and 2.2uF both Nichicon KL?
The outputs were fine, you’d be blowing a fuse if they were in wrong.
Transistor orientation, solder bridges, and for any toasted resistors until the heat tubing.
Why didn’t you replace the trimmers?
Why is the 330uF cap huge?
Why aren’t the 1uF and 2.2uF both Nichicon KL?
The outputs were fine, you’d be blowing a fuse if they were in wrong.
Sometimes in the Pine-Ears the board artwork is incorrect or misleading. In the case of the AWH-050 board, they got it right. I marked Q8 for the way the transistor leads SHOULD be installed. If that is a KSC3503 (E or F) the lead orientation is E-C-B facing the front (labelled) face of the device. It's difficult to determine from the photo which side of the device is facing the camera.
