dude, where did my power go?
- Thread starter Stalemate
- Start date
fullheadofnothing
Moderator
Measure all terminals on the 41-45 strip and post those voltages.
fullheadofnothing
Moderator
Measure 30 and 31.
fullheadofnothing
Moderator
Power down the amp and resolder 44L.
Once you have a nice shiny joint that includes all the resistor leads, re-measure 31 and 32.
Once you have a nice shiny joint that includes all the resistor leads, re-measure 31 and 32.
fullheadofnothing
Moderator
Sorry, I meant 30 and 31.
You have high voltage on one end of those resistors, but not on the other. Since it was on both of them, I assumed a bad connection at 44. Resoldering should have fixed this problem, but your low voltage at 31 shows that it did not. Can you measure the resistance of each of those resistors? Pictures of the area might also be helpful.
You have high voltage on one end of those resistors, but not on the other. Since it was on both of them, I assumed a bad connection at 44. Resoldering should have fixed this problem, but your low voltage at 31 shows that it did not. Can you measure the resistance of each of those resistors? Pictures of the area might also be helpful.
resistance:
44 - 30 - 2.2 mOhm
44 - 31 - 2 mOhm
Voltage
30 - 2.4
31 . 2 .5
The picture shows a right mess - The resistor from 44 to 45 was loose, so I had to desolder 44L, which didn't work out, so it was moved to 44U, after trying, hence the worn look
Are there any particular angles I need to include?
44 - 30 - 2.2 mOhm
44 - 31 - 2 mOhm
Voltage
30 - 2.4
31 . 2 .5
The picture shows a right mess - The resistor from 44 to 45 was loose, so I had to desolder 44L, which didn't work out, so it was moved to 44U, after trying, hence the worn look
Are there any particular angles I need to include?
Attachments
fullheadofnothing
Moderator
You need to replace the resistors. You can try remeasuring them by putting one probe on either side of the resistor body just to make sure it's not a measurement error, but your amplifier will not function without the right value.
First you should make sure that the solder joints are good on both ends of those resistors. Bad soldering could cause them to read very high. Do the resistors look overheated? The possible failure modes are resistors breaking and resistors getting fried from too much current. If they look fried from drawing too much current you will need to find out what is shorted that would cause this, or they will just fry again. If they are just broken from handling you can probably replace them and go from there.
Did you do the power transformer tests starting on page 31?
Hi,
I've ordered replacement parts for the entire area between the 40-45 and 26 - 35 strips. When I desolder and measure the resistors directly I get some very high values, which means they're fried for some reason. I also ordered replacement capacitators while I was at it. Thanks for all the help so far, the parts will arrive next week, so I'll report back then.
br
V
I've ordered replacement parts for the entire area between the 40-45 and 26 - 35 strips. When I desolder and measure the resistors directly I get some very high values, which means they're fried for some reason. I also ordered replacement capacitators while I was at it. Thanks for all the help so far, the parts will arrive next week, so I'll report back then.
br
V
[edit] I measured the ceramic 2K, 3K and 22k 5W resistors, and got all kinds of strange values, so I gather that's the problem, but: can anyone tell me why all my resistors fry like popcorn? how is it possible?
-v
[/edit]
Hi,
I changed both the resistors and capasitator, and now the measurements are good.
However, when I plug it in, I get just clipping noises in the right channel after a few seconds, while the other seems ok. I've checked and resoldered where I saw it necesarry, tried switching the tubes and speakers to eliminate them as sources of the error.
What should I look for?
br
Vegar
-v
[/edit]
Hi,
I changed both the resistors and capasitator, and now the measurements are good.
However, when I plug it in, I get just clipping noises in the right channel after a few seconds, while the other seems ok. I've checked and resoldered where I saw it necesarry, tried switching the tubes and speakers to eliminate them as sources of the error.
What should I look for?
br
Vegar
Hi,
Yes, I mean both tests. I can do a check and post all the results here tomorrow.
I'd describe it as the sound when you disconnect something from a powered up amp - it's like a "pop" which repeats itself. There is no music comming unless I turn the power off, when the amp powers down, I can hear it briefly.
To troubleshoot, I started comparing the measurements on the channel, and found the the wirewound "ceramic" resistors (22, 2k and 3k 5W) on the right channel was very much off, I was not able to get a good reading, but it was way up in the MOhms, while the left, working channel, gave expected results, so I went ahead and ordered replacements, which will arrive tomorrow.
Is the observation of the sound likely to be caused by the faulty resistors?
Yes, I mean both tests. I can do a check and post all the results here tomorrow.
I'd describe it as the sound when you disconnect something from a powered up amp - it's like a "pop" which repeats itself. There is no music comming unless I turn the power off, when the amp powers down, I can hear it briefly.
To troubleshoot, I started comparing the measurements on the channel, and found the the wirewound "ceramic" resistors (22, 2k and 3k 5W) on the right channel was very much off, I was not able to get a good reading, but it was way up in the MOhms, while the left, working channel, gave expected results, so I went ahead and ordered replacements, which will arrive tomorrow.
Is the observation of the sound likely to be caused by the faulty resistors?
I changed the resistors, and suddenly it worked - for a couple of hours, before the right channel died out and started "popping". It has a signal, but it is very weak, I'd have to turn the balance all the way over and volume up to hear it.
The measurements are:
Terminal / Ohm / VDC
1. * - 380
2. * - 409
3. 0 - 0
4. 250K - 0
5. 0 - 0
6. 1.2K - 61
7. * - 178
8. 0 - 0
9. *- *
10. 7.45K - 0
11. 6.98K- 0
12. * - *
13. 0 - 0
14. * - 219
15. 1.2K - 60
16. 0 - 0
17. 249K - 0
18. 0 - 0
19. * - 405
20. * - 377
21. 1.4K - 62
22. 1.2K - 62
23. 0 - 0
24. 1.2K - 62
25. 1.2K - 62
26. 0 - 0
27. * - 406
28. 0 - 0
29. 0 - 0
30. * - 414
31. * - 414
32. 0 -
33. 0 -
34. * - 407
35. 0 - 0
36. 1.2K - 62
37. 1.2K - 62
38. 0 - 0
39. 1.2K - 62
40. 1.4K - 62
41. 0 - 0
42. * - 209
43. 0 - 0
44. * - 417
45. * - 209
I've resoldered the potensiometers, and the PT, what else should I look at?
The measurements are:
Terminal / Ohm / VDC
1. * - 380
2. * - 409
3. 0 - 0
4. 250K - 0
5. 0 - 0
6. 1.2K - 61
7. * - 178
8. 0 - 0
9. *- *
10. 7.45K - 0
11. 6.98K- 0
12. * - *
13. 0 - 0
14. * - 219
15. 1.2K - 60
16. 0 - 0
17. 249K - 0
18. 0 - 0
19. * - 405
20. * - 377
21. 1.4K - 62
22. 1.2K - 62
23. 0 - 0
24. 1.2K - 62
25. 1.2K - 62
26. 0 - 0
27. * - 406
28. 0 - 0
29. 0 - 0
30. * - 414
31. * - 414
32. 0 -
33. 0 -
34. * - 407
35. 0 - 0
36. 1.2K - 62
37. 1.2K - 62
38. 0 - 0
39. 1.2K - 62
40. 1.4K - 62
41. 0 - 0
42. * - 209
43. 0 - 0
44. * - 417
45. * - 209
I've resoldered the potensiometers, and the PT, what else should I look at?
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