I installed the 330 ohm resistors just like you said, and I went to test the amp, the amp powered up but I heard something give and there is no sound output. I teared the amp appart again and around the area of the resistors it is darkened, something is shorted there.
Generally, when the regulators fail, they destroy most of the op-amps. Sometimes, the damaged op-amps can load the regulators and cause them to fail. Repairing the regulators is generally only about 1/4 of the work to get the amp back running.
With the amp powered up, you need to measure the voltage on the op-amps to confirm that the regulators are producing ±18v. If so, you would then need to find what's loading the regulators.
Many times, the defective op-amps will run much hotter than normal. Rarely, an op-amp will become a dead short and won't allow the regulators to produce any voltage. Those can be more difficult to find because they don't run hot.
Are the resistors you used 1/2w or larger?
With the amp powered up, you need to measure the voltage on the op-amps to confirm that the regulators are producing ±18v. If so, you would then need to find what's loading the regulators.
Many times, the defective op-amps will run much hotter than normal. Rarely, an op-amp will become a dead short and won't allow the regulators to produce any voltage. Those can be more difficult to find because they don't run hot.
Are the resistors you used 1/2w or larger?
The replacement that digikey superceded the ssp45n20a fet drivers is wrong and I had to put back the original ones, and replaced again those Q transistors and now it all works fine. So the 500D is done. My other 500D that I fixed before has some major capacitor leaking, the whole board is wet. Whats going on
What would be a good replacement for SSP45N20A?
What would be a good replacement for SSP45N20A?
Are the tops of them swollen?
Are you sure it's coming from the caps?
Excessive ripple current or excessive voltage would be two possible reasons for them to fail.
Are you sure it's coming from the caps?
Excessive ripple current or excessive voltage would be two possible reasons for them to fail.
the amp works fine, caps have this plastic cover and it looks swollen and you can press with finger on the plastic and it goes down a bit.
Anyway, can you help me with the MTX 152, I can't seem the find what resistors are the ones that burned up
Anyway, can you help me with the MTX 152, I can't seem the find what resistors are the ones that burned up
I have no information on the 152. I've never had one in the shop.
Did you try to get the values of the components from the other channel? They should be identical. R3xx should be the same as 2xx in the other channel.
If the tops are not swollen, it's unlikely that the liquid came from the capacitors.
Did you try to get the values of the components from the other channel? They should be identical. R3xx should be the same as 2xx in the other channel.
If the tops are not swollen, it's unlikely that the liquid came from the capacitors.
For short term testing, yes but the 640s are rated for significantly less current so they're not a suitable permanent replacement.
I got it put together the best I can and it powerd up and I can hear the speakers but barely, with gain all the way up as well as the gain on the player all the way up I can barely get it to produce sound. I guess I did not put the correct resistors where they should be. I will have to wait until I get one good 152 then see what resistors they are. Or I can use this for parts.
Do you have positive and negative 18v on the power supply pins of the op-amps?
Do you have positive and negative rail voltage on the output transistors?
Why couldn't you get the value of the burned components from the other channel?
Do you have positive and negative rail voltage on the output transistors?
Why couldn't you get the value of the burned components from the other channel?
because the burned resistors burned the labeling on the board so I don't know which ones they are. So the best thing I can do is to wait until I find another 152 or if someone can post hi-def photo of the good board. I replaced the op amps, socketed the board so thats no problem. Am glad that I fixed the other amps.
Use the surrounding parts as a guide. They may be grouped the same in both channels.
If you simply don't want to repair this one, let me know. I realize that it may not be worth the effort.
If you simply don't want to repair this one, let me know. I realize that it may not be worth the effort.
I want to fix it but wuthout proper information I hate to guess what goes there, so until I get proper picture of this amp I might be able to fix it. other chanell is not grouped the same, resistors are totaly at different positions and not grouped the same. So I will wait until I get proper information on the amp and go from there.
Perry, I found another MTX 152 that works now I can see what components are there to fix my other MTX 152. However this amps has problems too, it works fine at low gain, soon as you turn the volume up or gain on the amp up, the output distorts badly, it sends nasty noise to speakers. What could it be? op-amps.? On the board I can't see anything that is overheated, it looks ok.
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