Hello, I have a PPI a600.2 amplifier that recently has had some issues. I believe that I ran too much power, causing a channel to blow. The amplifier still plays one of the subs at a very low volume, but there doesn’t appear to be any hissing. I’ve read that the cards go bad on these amplifiers, however I don’t have any experience working on amplifiers.
I’m attaching pictures of the board to see if anybody can help point me in the right direction. A few of the transistors seem to be replaced, meaning the board was worked on, however I’m not sure what could have went wrong this time.
If anybody could help it would be much appreciated!
I’m attaching pictures of the board to see if anybody can help point me in the right direction. A few of the transistors seem to be replaced, meaning the board was worked on, however I’m not sure what could have went wrong this time.
If anybody could help it would be much appreciated!
If you have no experience repairing amps, I'd recommend that you read the following page.
http://www.bcae1.com/repairbasicsforbcae1/repairbasics.htm
Are you sure that the speaker isn't blown? Did you check the resistance across its terminals?
http://www.bcae1.com/repairbasicsforbcae1/repairbasics.htm
Are you sure that the speaker isn't blown? Did you check the resistance across its terminals?
An expert with the schematic and other service manual data may be able to revive your amplifier in a day or two. But assuming he makes $50 an hour, that's about $800. These things are amazingly cheap so I don't think it's worth it. And then, you have an amplifier which you know is not reliable and will fail again.
I know I can buy another amp, but the goal is to keep this one running. Is there any schematics online of this amplifier? I’ve only found the owners manual, nothing about the board.
I don't have a diagram for this amp but the attached should be somewhat similar.
You have to be VERY careful if you power the amp up without having the semiconductors tightly clamped down.
If you do power it up out of the sink, you need to check all heatsink mounted components to see if any are heating up. If they are, disconnect power. Post which components are heating up.
You have to be VERY careful if you power the amp up without having the semiconductors tightly clamped down.
If you do power it up out of the sink, you need to check all heatsink mounted components to see if any are heating up. If they are, disconnect power. Post which components are heating up.
If my channel is blown, what should I be looking to replace on the schematic? Would powering it up to see what heats up tell me what to fix?
If you didn't find any defective transistors, it's going to take some troubleshooting.
For these amps, the bottom cover clamps the components to the heatsink. If you don't build clamps (see attached), you'll have to watch the temperature of the components very closely. You'll likely have to power up for a few seconds at a time, make a few measurements and then quickly power down.
For these amps, the bottom cover clamps the components to the heatsink. If you don't build clamps (see attached), you'll have to watch the temperature of the components very closely. You'll likely have to power up for a few seconds at a time, make a few measurements and then quickly power down.
Attachments
What resistance should the transistors be reading? or is it different for each one?
You should not read anything near 0 ohms between any of the legs of any individual transistor.
You can compare the readings between the corresponding transistors on each side of the amp.
You can compare the readings between the corresponding transistors on each side of the amp.
There's an awful lot of heat sink compound on those TO-220's -- I'd be suspicious of the previous repair attempt just for that. 😉
The measurements of each of the 5 or 6 transistors within one bank should be fairly similar (providing their 'type' is the same -- not a bipolar driver and MOSFET's being driven). Use the Diode range on your multimeter -- trying to measure Ohms is more likely to mislead you (unless they're MOSFET's, which the power supply is very likely to be) -- although dead shorts will turn up just as well either way.
Pics are pretty decent, by the way. But would be better if we could read the device type on the heat-sunk components. Maybe you could mark those up using PBrush or similar.
You'll also want to check that the 'replacement' devices aren't thicker than the originals. The single clamp approach works great if all the parts are on Sil-pads and within a few thousandths of the same thickness. If you're using mica insulators, the thickness of the individual parts must be much more closely matched. (Somebody much smarter than me can probably tell you how closely . .)
What exactly is the output configuration of this beast? A bridged sub and two channels to make stereo? What are the rails? Are they solid?
No offense, please, but I'm a little concerned that you seem to have an over-simplified view of this piece. High-power car amps are NOT a good starting point for someone with 'no amp repair experience'. 😉
Cheers
The measurements of each of the 5 or 6 transistors within one bank should be fairly similar (providing their 'type' is the same -- not a bipolar driver and MOSFET's being driven). Use the Diode range on your multimeter -- trying to measure Ohms is more likely to mislead you (unless they're MOSFET's, which the power supply is very likely to be) -- although dead shorts will turn up just as well either way.
Pics are pretty decent, by the way. But would be better if we could read the device type on the heat-sunk components. Maybe you could mark those up using PBrush or similar.
You'll also want to check that the 'replacement' devices aren't thicker than the originals. The single clamp approach works great if all the parts are on Sil-pads and within a few thousandths of the same thickness. If you're using mica insulators, the thickness of the individual parts must be much more closely matched. (Somebody much smarter than me can probably tell you how closely . .)
What exactly is the output configuration of this beast? A bridged sub and two channels to make stereo? What are the rails? Are they solid?
No offense, please, but I'm a little concerned that you seem to have an over-simplified view of this piece. High-power car amps are NOT a good starting point for someone with 'no amp repair experience'. 😉
Cheers
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