Fried my car amp the other day, there's four resistors that are toast. I'm having a problem figuring out what these are, in order to purchase/order some.
To me, the lines almost look like: brown (or deep red), green, green, metallic brown.
The band that's usually gold or silver, looks metallic brown. Amp is a PPI Pro-Mos 425 (4 channel amp).
In sunlight, with a magnifying glass, they look:
Silver, black, black, brown (10 ohm, 10%)
Gold, black, black, brown (10 ohm, 5%)
Thanks in advance,
Tim
To me, the lines almost look like: brown (or deep red), green, green, metallic brown.
The band that's usually gold or silver, looks metallic brown. Amp is a PPI Pro-Mos 425 (4 channel amp).
In sunlight, with a magnifying glass, they look:
Silver, black, black, brown (10 ohm, 10%)
Gold, black, black, brown (10 ohm, 5%)
Thanks in advance,
Tim
An externally hosted image should be here but it was not working when we last tested it.
Thanks! The two in picture in particular, got hot enough to burn the casing of a wire that was above it, wire appears in tact still though. Resistors off, they both read (meter set at 200) 11.4 or so.
Only 4 of these in the board, and all four look burnt/discoloured, nothing else on board looks bad. Maybe I'll solder them back on, and power it up (just power) and see. I shut off ignition when realized there was something not right, put ignition on again after a few minutes to see if power light on amp, and there was no longer.
Tim
Only 4 of these in the board, and all four look burnt/discoloured, nothing else on board looks bad. Maybe I'll solder them back on, and power it up (just power) and see. I shut off ignition when realized there was something not right, put ignition on again after a few minutes to see if power light on amp, and there was no longer.
Tim
Good news and bad news. Good news, the amp still works, and still powers speakers.
Bad news, for some reason power light stays on after turning off ignition, the ignition/accessory wire is connected using same feed as my second amp, and the second amp powers off.
Get a bit of a "pop" when the radio/ignition comes on basically, didn't experience this before. Sound is not quite the best, but this install is with a different car from were I had it installed before.
One of my front components crackles a lot when volume increased. (unsure if now just a bad speaker, and not the amp causing this)
Tim
P.S, Perry, how can I test the capacitors for a short? The green components next to these resistors correct?
Bad news, for some reason power light stays on after turning off ignition, the ignition/accessory wire is connected using same feed as my second amp, and the second amp powers off.
Get a bit of a "pop" when the radio/ignition comes on basically, didn't experience this before. Sound is not quite the best, but this install is with a different car from were I had it installed before.
One of my front components crackles a lot when volume increased. (unsure if now just a bad speaker, and not the amp causing this)
Tim
P.S, Perry, how can I test the capacitors for a short? The green components next to these resistors correct?
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Thank you. Well, I think I put the amp further in its grave. Everything initially seemed fine, then lots of crackle in the speakers, and more smoke from the amp.
The only thing different in this whole scenario is the car. But I probably damaged the amp when I had it hooked up wrong (bad ground, wired to what I thought was the speaker wire at the radio, but those were wires fed to the factory amp). I think that started the damage.
Hooked it up correctly last night, wired to the speaker wires exiting the factory amp (that go direct to the speakers), had sound. Apart from the amp staying powered on (symptom of having damaged in first place?) I had sound, but like I said now, driving this morning crackling got worse so I stopped and the amp was hot and starting to smoke.
Tim
The only thing different in this whole scenario is the car. But I probably damaged the amp when I had it hooked up wrong (bad ground, wired to what I thought was the speaker wire at the radio, but those were wires fed to the factory amp). I think that started the damage.
Hooked it up correctly last night, wired to the speaker wires exiting the factory amp (that go direct to the speakers), had sound. Apart from the amp staying powered on (symptom of having damaged in first place?) I had sound, but like I said now, driving this morning crackling got worse so I stopped and the amp was hot and starting to smoke.
Tim
Resistors appear to be still ok, reading what they should be, just that they were the components heating up quite badly.
The first set of capacitors are dead I think, on board one gives a quick reading then "0" or nothing, second one does not show any reading. The other two across on the board near the same set of resistors, both capacitors read around 700
Tim
The first set of capacitors are dead I think, on board one gives a quick reading then "0" or nothing, second one does not show any reading. The other two across on the board near the same set of resistors, both capacitors read around 700
Tim
You'll need to check the capacitors out of the board and replace the ones that are defective before you can do any more troubleshooting.
What smoked in the amp? That type of resistor generally doesn't smoke much when it burns and you wouldn't be able to tell it was burning if the cover was on the amp.
What smoked in the amp? That type of resistor generally doesn't smoke much when it burns and you wouldn't be able to tell it was burning if the cover was on the amp.
I replaced the capacitors just in case. Yes, those two resistors got really hot, burned/melted the casing on a wire that was close to it, so that was what actually was burning.
As this is a 4 channel amp, the resistors that appear to be the main problem are closest to the front/rear output plugs.
The board is almost like a mirror image, each half set up per front/rear, so ohm meter on the capacitors on the "not so bad" side read around 690.
Ohm meter on the "bad" capacitors (even the new replaced ones) while in the board, show a quick reading (1.690, but I'm not used to this meter) and then the reading goes blank.
Tim
As this is a 4 channel amp, the resistors that appear to be the main problem are closest to the front/rear output plugs.
The board is almost like a mirror image, each half set up per front/rear, so ohm meter on the capacitors on the "not so bad" side read around 690.
Ohm meter on the "bad" capacitors (even the new replaced ones) while in the board, show a quick reading (1.690, but I'm not used to this meter) and then the reading goes blank.
Tim
The 10 ohm, 1~2 W resistors in the Zobel network should not get hot. If the capacitor in series with them is good (measures high impedance with an ohmmeter), I bet the amp is oscillating at a ultrasonic frequency. You need an oscilloscope to find out if this is the case.
~Tom
Itching to test it, I put power to it, only for a short while (realized something I have to do first), and power light not coming/staying on when ignition off. Hoping that is a good sign.
The one thing I forgot, which I'm thinking caused the problem, the car's factory amp is still plugged into the car harness. I am thinking somehow it putting power out to the speakers, even if not hooked to the factory radio, may have been putting power reverse onto my amp. Does that make sense for the resistors for heating up like they did?
Test is, I have to completely disconnect the factory amp and see if things are good.
Tim
The one thing I forgot, which I'm thinking caused the problem, the car's factory amp is still plugged into the car harness. I am thinking somehow it putting power out to the speakers, even if not hooked to the factory radio, may have been putting power reverse onto my amp. Does that make sense for the resistors for heating up like they did?
Test is, I have to completely disconnect the factory amp and see if things are good.
Tim
Slowly but surely, getting somewhere with this. Ok, amp appears fine now, except now maybe a bad ground somewhere, maybe my deck. I get this buzzing sound in all speakers, even the subs, so that makes me think I need to be looking at the deck for problem source.
Amp is not getting hot, and what sound is in the speakers is normal, apart from this buzz I have now. All speakers make a "pop" sound when car turned on or A/C kicks in, hoping a bad ground?
Tim
Amp is not getting hot, and what sound is in the speakers is normal, apart from this buzz I have now. All speakers make a "pop" sound when car turned on or A/C kicks in, hoping a bad ground?
Tim
Grounds are good, this darn car, I ran the RCA cables on passenger side, opposite to power run on driver side, but used the channel in the car to keep it neat and there's part of the car harness that runs down each side. RCAs must be getting interference with some power in other wires. My only other option is down the centre under the centre console, but looks a bit tricky.
Thanks everyone for your assistance on troubleshooting the amp, if it's not one thing, it is another. Now to re-run my RCAs and should be good.
Tim
Thanks everyone for your assistance on troubleshooting the amp, if it's not one thing, it is another. Now to re-run my RCAs and should be good.
Tim
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