I am looking at the diagram here.
Since all the components needed to drive the output are OK, we can test with power.
The Out put transistors are not mounted during the test.
I am only talking about the Bad channel here so all the test points are on ch A. Fuse for ChA should be replaced. No power yet
Be careful...I am not there to see what you are doing.
1. Put the DVM in Resistance mode and see whether if the Negative terminal of the speaker shows 0Ω to the heatsink.. Since all the transistors collectors are grounded (virtual) (symbol P) the sink should have a direct connection to speaker negative terminal. If not check the channel B. If channel B confirm check why the Ch A sink is not grounded. Do not by pass or place any jumpers. Move on if OK if not (do not proceed ) check and post back.
2. Remove Ch B fuse first and then apply power. Wait for a few min to see if any thing smokes or smell around for burning smell. If fumes or smell cut power and post back. If nothing of the sort move on.
3. Place you finger on Q1 and Q2 ( heat sink, the little ones ) one by one. DO NOT PLACE ON BOTH SINK AT ONCE, I dunno if the sink is insulated or not. The sink voltage difference will be 126VDC, enuf to make say things you don't want to around any one and possible burn the fingers. If later you know the thing burning is your skin.
So place your finger on Q1 first and observe the heat. It should be cool to the touch. Then Q2, same as before, cool to touch. Both temp should be same. If reasonably different, there is trouble.
Remember to keep the other hand away from the amp chassis. Use one finger and one finger alone for this. Do not let the finger touch any thing else.
Do this and post back. If you hurry up, I might be here.
Since all the components needed to drive the output are OK, we can test with power.
The Out put transistors are not mounted during the test.
I am only talking about the Bad channel here so all the test points are on ch A. Fuse for ChA should be replaced. No power yet
Be careful...I am not there to see what you are doing.
1. Put the DVM in Resistance mode and see whether if the Negative terminal of the speaker shows 0Ω to the heatsink.. Since all the transistors collectors are grounded (virtual) (symbol P) the sink should have a direct connection to speaker negative terminal. If not check the channel B. If channel B confirm check why the Ch A sink is not grounded. Do not by pass or place any jumpers. Move on if OK if not (do not proceed ) check and post back.
2. Remove Ch B fuse first and then apply power. Wait for a few min to see if any thing smokes or smell around for burning smell. If fumes or smell cut power and post back. If nothing of the sort move on.
3. Place you finger on Q1 and Q2 ( heat sink, the little ones ) one by one. DO NOT PLACE ON BOTH SINK AT ONCE, I dunno if the sink is insulated or not. The sink voltage difference will be 126VDC, enuf to make say things you don't want to around any one and possible burn the fingers. If later you know the thing burning is your skin.
So place your finger on Q1 first and observe the heat. It should be cool to the touch. Then Q2, same as before, cool to touch. Both temp should be same. If reasonably different, there is trouble.
Remember to keep the other hand away from the amp chassis. Use one finger and one finger alone for this. Do not let the finger touch any thing else.
Do this and post back. If you hurry up, I might be here.