I am working on a Car Audio Bargain 2000.1. It appears to be TLx94 ps drive IC circuit. The amp flashes in and out of protect as the drive circuit begins to oscillate. i suspected a shorted transformer on the section building high side rail so i lifted that one side of that transformer and the amp powers on with out rectifiers in and the drive square wave looks goods at the FETS and the square wave that would be feeding the rectifiers look good as well. i re-soldered the the transformer in and it still flashes in/out of protection. ill post voltages below and picture of the driver board.
TLx94 (i believe) DC Voltages
1. 0-1.7~ flashing with protection light
2. 2.44-2.55 fluctuating
3. 0-1.3 to 1.8 fluctuating
4. 2.3-4 fluctuating
5. 1.53
6. 3.55
7. 0
8. 12.52
9. bumping very small voltage try to build square wave per scope.
10. bumping very small voltage try to build square wave per scope.
11. 12.57
12. 12.56
13. 5.0
14 5.0
15. 5.0
16. 0
8 pin op-amp on driver board possibly LM358?
1. ~0-2 flashing with protection light
2. 2.57
3. 2.36
4. 0
5. 1.03
6. 2.98
7. 0
8. 12.56
TLx94 (i believe) DC Voltages
1. 0-1.7~ flashing with protection light
2. 2.44-2.55 fluctuating
3. 0-1.3 to 1.8 fluctuating
4. 2.3-4 fluctuating
5. 1.53
6. 3.55
7. 0
8. 12.52
9. bumping very small voltage try to build square wave per scope.
10. bumping very small voltage try to build square wave per scope.
11. 12.57
12. 12.56
13. 5.0
14 5.0
15. 5.0
16. 0
8 pin op-amp on driver board possibly LM358?
1. ~0-2 flashing with protection light
2. 2.57
3. 2.36
4. 0
5. 1.03
6. 2.98
7. 0
8. 12.56
Attachments
From what I can see, it appears that both transformers contribute to both rails.
Your original post was confusing (for me). Each on a separate line, list what you did, in the order that you did it and what was the difference before and after you did each thing. Leave a blank line in-between each step.
Also, precisely which windings did you desolder.
Your original post was confusing (for me). Each on a separate line, list what you did, in the order that you did it and what was the difference before and after you did each thing. Leave a blank line in-between each step.
Also, precisely which windings did you desolder.
1st check: removed all PS FETs. drive wave all good but no green light but not in protect.
2nd check: installed FETs. Removed rectifiers. Now it is flashing in/out of protect.
3rd check: lifted circled winding's on transformer closest to driver board with rectifiers still out. amp powers on and FETs have large square wave on pin 2.
2nd check: installed FETs. Removed rectifiers. Now it is flashing in/out of protect.
3rd check: lifted circled winding's on transformer closest to driver board with rectifiers still out. amp powers on and FETs have large square wave on pin 2.
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I don't see how desoldering the two secondary windings could have done anything considering that they only feed the rectifiers, which were out of the circuit. Are you sure that you didn't do anything differently that changed the way it acted?
If you solder the secondary windings back into the board, does it again go into protect?
If you solder the secondary windings back into the board, does it again go into protect?
Yes I'm sure that's all i did. Yes i have them soldered back in and it still is flashing in and out of protect.
When I remove the 2 FET's that I have in running the transformer in question with the rectifiers still out the amp does not protect. I did this with the secondary winding's soldered in.
When I remove the 2 FET's that I have in running the transformer in question with the rectifiers still out the amp does not protect. I did this with the secondary winding's soldered in.
The windings that you desoldered go to the input of the rectifiers. The caps are on the output of the rectifiers. There is no direct connection between the caps and the windings, is there?
Did you desolder the single-strand windings as well? Their drive comes from the transformer, not the secondary windings. Is that correct?
Did you desolder the single-strand windings as well? Their drive comes from the transformer, not the secondary windings. Is that correct?
I did not desolder the single strands and yes they do not seem to be driven by the secondary winding's.
I've circled in blue where the secondary winding's have continuity to the capacitors on the bottom of the board.
I haven't cleaned up all my solder from winding's but there are no solder bridges that i can find.
I've circled in blue where the secondary winding's have continuity to the capacitors on the bottom of the board.
I haven't cleaned up all my solder from winding's but there are no solder bridges that i can find.
Attachments
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