I got this amp for next to nothing knowing it would be a repair job. Basically it blows fuses only when you apply the remote turn on lead.
I'm pretty sure that one of the transistors developed a short but when I use my DMM, the all show up as okay however I have not removed them from the board.
The board looks spotless with no burn marks anywhere and does not have that acrid burn smell that most burned electronics have.
I hooked it up to my car and did have speakers hooked up to it. I have not tested it without speakers (didn't think to). It was hooked up the same way my Rockford amp is hooked up.
The 2 20 amp fuses on the amp do not blow until you apply the remote turn on lead then both of the fuses snap.
Any suggestions? I'm a newbie when it comes to full blown diagnostics but I am not afraid of using a soldering gun when someone points me in the right direction. Done a lot of computer cap replacing and board level repairs on laptops.
Thanks in advance!
I'm pretty sure that one of the transistors developed a short but when I use my DMM, the all show up as okay however I have not removed them from the board.
The board looks spotless with no burn marks anywhere and does not have that acrid burn smell that most burned electronics have.
I hooked it up to my car and did have speakers hooked up to it. I have not tested it without speakers (didn't think to). It was hooked up the same way my Rockford amp is hooked up.
The 2 20 amp fuses on the amp do not blow until you apply the remote turn on lead then both of the fuses snap.
Any suggestions? I'm a newbie when it comes to full blown diagnostics but I am not afraid of using a soldering gun when someone points me in the right direction. Done a lot of computer cap replacing and board level repairs on laptops.
Thanks in advance!
I'm not familiar with this amp but kenwood amps have problems with broken solder connections on the bias transistors. They are typically small transistors clamped to the heatsink in-between the large transistors.
Do not power up the amp unless all of the transistors are clamped to the sink. I'd recommend that you insert a 10 amp fuse in the B+ line before you apply power again. This will protect the power supply transistors better than the two 20 amp on-board fuses.
Do not power up the amp unless all of the transistors are clamped to the sink. I'd recommend that you insert a 10 amp fuse in the B+ line before you apply power again. This will protect the power supply transistors better than the two 20 amp on-board fuses.
Sorry, I missed the other question. In most amps, you can use a single fuse but there are a few that require multiple fuses to operate. Since I don't know every amplifier that needs more than one fuse, I recommend inserting a 10 amp fuse (or 15 amp for larger amplifiers) in the B+ line feeding the amp. That prevents having possible problems with an amp that won't operate properly on one fuse.
Okay, I went and took all the screws off the mainboard and removed it. Well what do you think I found?
I found a bunch of water damage by the power circuits and fuses. What is the next plan of action? Obviously, I'm going to clean it as best as I can using electrical cleaner. I didn't see any cold solder joints but I'm going to reflow them anyway just in case. I'm also going to check the small transistors by the power circuit that have corrosion by them.
But in a nutshell, can corrosion cause dead shorts and be repaired easily just by cleaning it all off or does the corrosion usually cause other parts on the board to fail?
Thanks for everyones help here. This is my first amp repair and I hope to have more in the future.
I found a bunch of water damage by the power circuits and fuses. What is the next plan of action? Obviously, I'm going to clean it as best as I can using electrical cleaner. I didn't see any cold solder joints but I'm going to reflow them anyway just in case. I'm also going to check the small transistors by the power circuit that have corrosion by them.
But in a nutshell, can corrosion cause dead shorts and be repaired easily just by cleaning it all off or does the corrosion usually cause other parts on the board to fail?
Thanks for everyones help here. This is my first amp repair and I hope to have more in the future.
You would insert it in the B+ line feeding the amp. It would allow you to power up the amp with limited current. Then you would measure the voltage at several points. The first you would measure is the voltage drop across each of the emitter resistors. The voltage across them should be very near 0.000v DC. If the voltage across one resistor (or across all of the emitter resistors in one channel) was significantly more, it would mean that the problem was likely in that channel. If none had any significant voltage across them, the problem would likely be in the power supply.
If this amp has bias pots, you should try setting them to the full counter-clockwise position. Someone could have set them too high which could cause excessive current draw.
Is there any evidence that the amp has been repaired previously?
If this amp has bias pots, you should try setting them to the full counter-clockwise position. Someone could have set them too high which could cause excessive current draw.
Is there any evidence that the amp has been repaired previously?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.