Hi I am trying to fix my Alpine 1507 and when I got it it didn't work but turned on but no audio so far I have replaced all of the output transistors on the signal board now I went and wired it up and as soon as I turned it on the power board mosfets started to burn up one at time like as if something with shorted out my question is what would have happened to make the mosfets start shorting out please let me know so that I can find what I need to to get this thing working thanks again I've been following this website for a while now and I know you guys know what you're talking about thanks again for your help
Frank
Frank
You may have bitten off too much. Replacing transistors isn't like changing spark plugs. You have to check the driver transistors, sometimes the protection transistors short, resistors may be burned even tho they look OK. A schematic is essential to dertermine what needs to be checked, but can you read it? Alpine used to be good about selling service manuals, but they may not be so helpful these days. Pacific Coast Parts may sell you one.
I checked my schematic, and there are gate resistors(33 ohm), drain(ceramic) resistors and driver transistors that have to be checked. 2SC1220 is the + side driver.
Yes I made sure they were all clamped down before attempting to turn it on but as soon as I connected the ground the first fet started to burn up as. I've pulled all the power board side fets all 12 of themy and replaced them with new ones. If I didn't check another resistor would that allow it to take out the rest down the line?
When working on amplifiers, you need to control the current that can flow to the amp until you're sure that everything is OK. You can do this by inserting a current limiter in the B+ line or using a low rated fuse (15 amp is generally safe if all of the semiconductors are clamped down.
Are you sure that all insulators were in place under the transistors?
For most power supplies, when one FET fails, it shorts from drain to gate. This drives 12v to the gate which drives 12v to all of the other gates for that bank and that causes the rest of the FETs to fail if there is no protection (limiter or low rated fuse).
Did you use the same exact part number (IRFZ48N) as replacements?
Are you sure that all insulators were in place under the transistors?
For most power supplies, when one FET fails, it shorts from drain to gate. This drives 12v to the gate which drives 12v to all of the other gates for that bank and that causes the rest of the FETs to fail if there is no protection (limiter or low rated fuse).
Did you use the same exact part number (IRFZ48N) as replacements?
When you are talking about insulators do you mean the thin plastic piece between the heat sink and the transistors.cause I did for the new ones but the other old ones I didn't check so that could be why they are shorting out.
What are the part #s for the power board power transistors locations #s Q613 Q609 Q605 Q614 Q610 Q606 Q616 Q612 Q608 Q615 Q611 Q607. And where can you purchase these online. Thanks again
IRFZ48N
Try arrow. No eBay.
https://octopart.com/search?q=irfz48n
Before ordering parts, I'd suggest removing all of the power supply FETs and confirming that the drive signal is OK.
Try arrow. No eBay.
https://octopart.com/search?q=irfz48n
Before ordering parts, I'd suggest removing all of the power supply FETs and confirming that the drive signal is OK.
How do I check it? cause i mean I have no scope. But I have taken them all off and tried to power it up and it actually does with the protection light is green and the music is green but the power is blinking red.
The best you can do is to measure the gate drive voltage for each of the power supply FETs. Meter set to DC voltage. Black meter probe on the solder pad for leg 3 of the FET. Red probe on leg 1. The power supply board has to be powered up for this. All FET locations should read very nearly the same voltage.
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