sx-750 recap goes from bad to worse
- Thread starter ovalhead1
- Start date
Hoping I can hijack this thread with my current sx-750 protection board mystery.
I purchased this unit non-working and it appears someone else has been in here previously.
I have recapped power amp and protection boards testing and replacing transistors as needed - with new outputs standing by until I sort out this issue.
Once work was completed, on dim bulb tester, protection relay was not "clicking" - I tracked down issue to +31.1vdc on in 36 of the power amp board. Traced this back to also +31.1vdc on pin 9 of the same board (good thing I had not installed/plugged in new outputs...)
All components on power amp board seem to check out - I'm now looking at the Power/protection board where I have recapped, and replaced transistors that checked bad. I found this thread and followed it - I seem to have no problems with fuses or filter caps/rectifier - but I could be wrong here)
AWR-099 voltages:
1: 31 vdc
2: 0 - .2 mdc (fluctuates)
3: .3 - .6mdc (fluctuates)
4: 29.1 mdc
5: 6.6 vac
6: 6.6 vac
7: 6.6 vac
8: 31. vdc
9: 0
10: 31.4mdc
11: 0
12: 0
13: 0
14: 0
15: 4.8 AC
16: -41.9 vdc
17: -36.5 vdc
18: 41.2 vdc
19: 0
20: 0
21:0
22: 12.8 vdc
23: 32.4 vdc
24: 32.4 vdc
I certainly see the high voltages on pins 1,8 and 10...I have pulled the yellow wire going to pin 1 knowing that this would cause the relay to go into protection.
One clue is when I pull q6 (now a new c2383) the relay releases but the voltages on pins 8 and 10 remain the same.
Any guidance would be most appreciated.
I purchased this unit non-working and it appears someone else has been in here previously.
I have recapped power amp and protection boards testing and replacing transistors as needed - with new outputs standing by until I sort out this issue.
Once work was completed, on dim bulb tester, protection relay was not "clicking" - I tracked down issue to +31.1vdc on in 36 of the power amp board. Traced this back to also +31.1vdc on pin 9 of the same board (good thing I had not installed/plugged in new outputs...)
All components on power amp board seem to check out - I'm now looking at the Power/protection board where I have recapped, and replaced transistors that checked bad. I found this thread and followed it - I seem to have no problems with fuses or filter caps/rectifier - but I could be wrong here)
AWR-099 voltages:
1: 31 vdc
2: 0 - .2 mdc (fluctuates)
3: .3 - .6mdc (fluctuates)
4: 29.1 mdc
5: 6.6 vac
6: 6.6 vac
7: 6.6 vac
8: 31. vdc
9: 0
10: 31.4mdc
11: 0
12: 0
13: 0
14: 0
15: 4.8 AC
16: -41.9 vdc
17: -36.5 vdc
18: 41.2 vdc
19: 0
20: 0
21:0
22: 12.8 vdc
23: 32.4 vdc
24: 32.4 vdc
I certainly see the high voltages on pins 1,8 and 10...I have pulled the yellow wire going to pin 1 knowing that this would cause the relay to go into protection.
One clue is when I pull q6 (now a new c2383) the relay releases but the voltages on pins 8 and 10 remain the same.
Any guidance would be most appreciated.
Watthour
Electron Rancher - JS3600
I'll commend you on performing your due diligence and researching the problem before posting.
Since your problem is specific, however, it would probably be best if you opened a new thread for your unit. It will likely get more attention and be a "cleaner" thread more directly focused on the issue at hand.
Since your problem is specific, however, it would probably be best if you opened a new thread for your unit. It will likely get more attention and be a "cleaner" thread more directly focused on the issue at hand.
