Im starting a new thread on this amp since the last thread says it was closed.
I got the amp to power up and stay powerd up now the amp had a blown trace on the output board.
The amp plays But there are a couple of problems.
1ST problem: when listing to the amp it sounds like the music has an echo to it.
2ND problem: I can hear a hum through all speakers connected to the amp with and without volume.
Any ideas?
I got the amp to power up and stay powerd up now the amp had a blown trace on the output board.
The amp plays But there are a couple of problems.
1ST problem: when listing to the amp it sounds like the music has an echo to it.
2ND problem: I can hear a hum through all speakers connected to the amp with and without volume.
Any ideas?
Ok back to this amp.Im going throught the entire amp top to bottom to get it to sound like brand new again.
Not sure what year this amp was made but wondering if it is a good idea to replace the caps in this amp due to age. If so wondering who makes the best caps out there? When i get this amp done i want it to be pure sound quality
Not sure what year this amp was made but wondering if it is a good idea to replace the caps in this amp due to age. If so wondering who makes the best caps out there? When i get this amp done i want it to be pure sound quality
FC series caps are a good choice for power supplies. They can take more abuse than many capacitors. In this amp, there aren't any capacitors that will be under any real stress. Virtually any capacitor within spec will work. Assuming that all caps meet spec, using expensive capacitors or cheap capacitors won't make a difference in the sound quality.
Im working on this amp still while waiting for parts for other amps.
Im almost done rebuilding the power supply section of this amp then its off to the output section.
My question is if 1 of the UPC1270H's are bad in this amp would that cause the humming through the speakers or cause the music to echo??
Im almost done rebuilding the power supply section of this amp then its off to the output section.
My question is if 1 of the UPC1270H's are bad in this amp would that cause the humming through the speakers or cause the music to echo??
mike49504:
When you repaired all the burned traces, did you reflow the solder around all components near the burned area? Did you check all the grounds on the entire PCB as well as check for any cold solders? When the amp is operating, have you tapped it in different spots around the PCB to see if what you are hearing changes state? If not, try any or all of these. If you get changes when you tap it, that points in the direction of a mechanical connection issue.
Next, are you using a 'scope? Have you isolated what stage the fault is in, driver or output? When you say echo, do you mean there is a perception of actual delay to the signal? Or, does the signal sound "fat" instead of clean? If it is the latter, I suspect a bad distortion product. Whether it is a faulty UPC1270H or something in the output stage, signal tracing will nail it.
The PQ20 is a great satellite amp. They ain't great shakes in the bass department but perform nicely when high-passed. I have a PH15 and these amps are definitely worth the effort to restore.
Good Luck!
When you repaired all the burned traces, did you reflow the solder around all components near the burned area? Did you check all the grounds on the entire PCB as well as check for any cold solders? When the amp is operating, have you tapped it in different spots around the PCB to see if what you are hearing changes state? If not, try any or all of these. If you get changes when you tap it, that points in the direction of a mechanical connection issue.
Next, are you using a 'scope? Have you isolated what stage the fault is in, driver or output? When you say echo, do you mean there is a perception of actual delay to the signal? Or, does the signal sound "fat" instead of clean? If it is the latter, I suspect a bad distortion product. Whether it is a faulty UPC1270H or something in the output stage, signal tracing will nail it.
The PQ20 is a great satellite amp. They ain't great shakes in the bass department but perform nicely when high-passed. I have a PH15 and these amps are definitely worth the effort to restore.
Good Luck!
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