Yamaha CA-800 protection relay not working
- Thread starter mikevinci
- Start date
Could this component be a good replacement for these shock absorbers?
I'm installing the second power amplifier board I had pending, and I've run into a problem. I short-circuited the OUT and E pins of the board while taking measurements. The result was smoke, and I quickly shut it down. I found resistor 623 was visually damaged, although it measured fine, so I replaced it.
Now I have a voltage of 45V between OUT and E. Obviously, the relay doesn't activate when I connect this board.
Can you guide me on which component might be damaged? I've measured, but I can't identify which one it could be. Perhaps TR610 and TR611 are the candidates. I've broken them again, but I measured them on diode scale, and they measure correctly.
Oh my god, I have to be more careful. I'm not in this career to repair this unit or to cause problems. 
Now I have a voltage of 45V between OUT and E. Obviously, the relay doesn't activate when I connect this board.
Can you guide me on which component might be damaged? I've measured, but I can't identify which one it could be. Perhaps TR610 and TR611 are the candidates. I've broken them again, but I measured them on diode scale, and they measure correctly.
Oh my god, I have to be more careful. I'm not in this career to repair this unit or to cause problems.
On the other hand, during the power amplifier stage tests,( which only work with one channel),, I tried swapping the input cable from the right channel to the left to verify that the audio output on both channels was working.
Interestingly, I expected both to work, but they didn't; only one output worked. Both outputs measured the same, and I understand that even after swapping these cables (red and white shielded, two wires, live and ground) on the same board, it should have worked, but it didn't. In these tests, one of the stages was always disconnected.
Is this normal behavior? Or is there a problem with the audio on that channel despite both having the same output voltage to the power amplifier?
Is this unit so intelligent that it knows which channel each audio output to the power stage belongs to and doesn't allow them to be swapped?
Interestingly, I expected both to work, but they didn't; only one output worked. Both outputs measured the same, and I understand that even after swapping these cables (red and white shielded, two wires, live and ground) on the same board, it should have worked, but it didn't. In these tests, one of the stages was always disconnected.
Is this normal behavior? Or is there a problem with the audio on that channel despite both having the same output voltage to the power amplifier?
Is this unit so intelligent that it knows which channel each audio output to the power stage belongs to and doesn't allow them to be swapped?
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Did the glass fuses F601 or F602 blow?
Candidates are TR610 and TR611 along with TR608 and TR609
Points to TR609
Some test points
D602 anode/TR608b +1.8Vdc
D607 anode/TR608e +1.2V
D607 cathode +0.6V
We have all done it, use minnigrabbers where possible
No, the unit is dumb, you can move the IN & E wires to the other channel, expect it to work
After connecting it for the first time, the F601 blew, it was replaced, and subsequently, while taking measurements, the OUT and E short circuit occurred
That's right, I don't have any of those. I need to get a game. I used crocodiles.
I have a problem with this channel, and it's obvious that despite having the correct voltage compared to the other channel that was working, there's no audio. It's very strange, isn't it? It should be outputting audio, and I don't understand why
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Please correct me if I'm wrong
One power amp working, audio ok
Other power amp accidental short OUT pin and GND, need to test/identify failed parts.
The following may help identify failed parts
To test the preamp of the failed/short channel you moved the IN/E wires from this channel to the working power amp, you did not get audio, need to troubleshoot.
It would have been easire to switch the rear coupler off then using rca cables connect left pre-out to right main-in, likewise connect right pre-out to left main-in, ie, cross the channels.
Suggest go back to the volume board and check the white(L) and pink(R) wires for audio with your multimeter set to Vac, especially at the yellow wrapped wires to the filter board. The coupler switch has a history of being dirty causing lost channels.
One power amp working, audio ok
Other power amp accidental short OUT pin and GND, need to test/identify failed parts.
The following may help identify failed parts
To test the preamp of the failed/short channel you moved the IN/E wires from this channel to the working power amp, you did not get audio, need to troubleshoot.
It would have been easire to switch the rear coupler off then using rca cables connect left pre-out to right main-in, likewise connect right pre-out to left main-in, ie, cross the channels.
Suggest go back to the volume board and check the white(L) and pink(R) wires for audio with your multimeter set to Vac, especially at the yellow wrapped wires to the filter board. The coupler switch has a history of being dirty causing lost channels.
Please confirm if I have correctly identified the points on the actual plate.
I've measured the candidate and non-candidate transistors, but they don't appear to have any problems. I suppose the fault will only manifest itself when they're under voltage
What bad luck, I practically had it done and now I'm crazy and lost again with this new breakdown.
Attachments
Correct, the tester is low voltage (8-9V??) the component may fail at higher voltages 50Vdc
Point 1,2,3 on schematic (puntos medicion) are correct
Points 2,3 D607 is correct
Point 1 on D602 is incorrect, wanted anode but probably not significant.
Results point to failed TR611 or TR609.
Suggest remove outlet transistors TR610, TR611 then DBT power up and check voltage at the OUT wire
With Tr610 and Tr611 removed, it maintains an output voltage at OUT of -41v with DBT
Does this indicate that Tr609 could be a candidate?
Given my doubts, I decided to replace all the diodes on the board just in case.
Could this test of removing the final transistors indicate that the source of the fault is TR609?
I don't have a 2SA706, and from what I've seen, it will be difficult and expensive to obtain. If this is the cause, would a good replacement be an MJE15033?
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Outside chance it could be TR604 but more likely TR609 since it matches the stressed R623 when OUT was shorted to GND.
Suggest pull TR609 and connect whatever diode you have handy 1N4148 or 1N400x between base and emitter.
Connect anode to emitter and cathode to base solder pads then dbt power up and check OUT voltage. The diode replicates the transistor b-e junction.
I used a 1N4004 anode emitter on TR609 and cathode on the base of TR609, resulting in -40v
So, can I try replacing TR604 and verifying the correct voltage? Can I keep the diode on TR609 for this test?
That's good news.
So outputs still removed, TR609 removed and replaced with 1N4004 between b-e.
Please diode test TR604, looking for c-e short,
Also measure Vdc at each wire A,B,C,S