EDIT: Check post 8. My posts before 8 were not even looking at the circuit correct, so its all invalid.
I can't for the life of me remember what they are "called" when they are mounted where they are, so googling/searching the forum hasn't got me anywhere yet...
Anyways.. Got a cheap old 2 channel amp (around 200w rms) I was repairing, and I noticed one of the resistors burned open on the speaker output.
It's a resistor that connects the batteries ground coming into the amp, directly to the middle speaker connections. (both channels share the center output). Anyways, the resistor was burned, and I can't tell its markings. Its a 1/4 watt size is all I know. It also had a small capacitor making the same connection (0.1µF) that is a open circuit that I already have a replacement for.
What would be a ball park value to replace it with? I'm under the impression that this isn't a critical component, I just have no idea the ball park range I should be going for. few dozen ohm for few hundred k ohm?!
I can't for the life of me remember what they are "called" when they are mounted where they are, so googling/searching the forum hasn't got me anywhere yet...
Anyways.. Got a cheap old 2 channel amp (around 200w rms) I was repairing, and I noticed one of the resistors burned open on the speaker output.
It's a resistor that connects the batteries ground coming into the amp, directly to the middle speaker connections. (both channels share the center output). Anyways, the resistor was burned, and I can't tell its markings. Its a 1/4 watt size is all I know. It also had a small capacitor making the same connection (0.1µF) that is a open circuit that I already have a replacement for.
What would be a ball park value to replace it with? I'm under the impression that this isn't a critical component, I just have no idea the ball park range I should be going for. few dozen ohm for few hundred k ohm?!
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Are the R and C in series? Sounds like an outout Zobel.
If so, the resistor is usually 10 ohms, around 1W or more.
A capacitor normally measures open on an ohm meter, so
it may be fine.
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I forgot to add that part, no they are parallel.
Both of them jumping straight from the ground input to the middle speaker outputs (the non bridgeable outputs)
It's definitely a 1/4w resistor
Also might as well add, its your typical 2ohm per channel stable, 4ohm bridged stable amp.
American Legacy LA590, lol... Another freebee to mess with, without fear of being responsible for not fixing it.
both the capacitor, and the resistor, both have their own connection to ground. They aren't "daisy chained" like a series.
Also, there isn't any capacitor/resistor anywhere that I can find on the board connecting the two other speaker outputs to ground/anything else.
I'll upload a photo just as soon as I can find my phone around my garage lol...
I would be interested in finding out why the resistor burned.
It could indicate a fault elsewhere or just that the amp was grossly over driven.
Don't run class d without a speaker connected.
It could indicate a fault elsewhere or just that the amp was grossly over driven.
Don't run class d without a speaker connected.
I could be completely way off here, I was thinking that a long time ago I had read about like "filter resistors" or something or other on the outputs of some amps, and that they could blow from something easy (someone touching a power to the chassis of amp, or crossing a speaker wire idk) and that it wasn't CRUCIAL to have this in there. BUT that is something that after I found it today, and spent entirely too long googling before making this post, I haven't found anything that fills in the gaps in my memory, so I might have just made all that up.......
I'm pretty sure my friend just shorted it out. I wish he could just "recall what happened". I think he's ashamed he killed two amps in the same day (claims he has no idea how it happened, I already repaired the other one lol)... anyways
upon pulling it apart, found the remote's trace on the board was burnt, a couple bulging caps, fixed those. Checked the power sides mosfets, the rectifiers. Haven't got to the audio side's transistors.
I had intended on powering it up with a 20w limiter after repairing what I had, so I could then proceed.
Since the remote trace fried, I suspect the OP-amp it leads to is also going to be dead.
I am extremely far from an expert. I spend more time reading than I do probing with my meter. I also have no ties to this amp, I couldn't care less about the amp itself, just using it as another freebee to learn on without the fear that i've had on more expensive amps i've repaired over the last couple years.
Everything I said last night, disregard. I don't know what I Was thinking, I'll blame it on the alcohol, lol..
I made a quick schematic to show exactly what I'm working with.
I need to figure out what to put in R1.
Also, D1 is a larger diode that I haven't pulled from the borad, so I don't have its specs. I'm not sure if it is bad or not.
Now that I've fully seen how its setup, I'm guessing the resistor value isn't super important? Get it in the ball park? If so, what ould the ball park be? lol..
Also, would it be safe to assume that Diode 1 is still fine, since it's a very large diode, and the 1/4w resistor is completely burnt. Or should I go ahead and lift a leg and test it?
I made a quick schematic to show exactly what I'm working with.
I need to figure out what to put in R1.
Also, D1 is a larger diode that I haven't pulled from the borad, so I don't have its specs. I'm not sure if it is bad or not.
Now that I've fully seen how its setup, I'm guessing the resistor value isn't super important? Get it in the ball park? If so, what ould the ball park be? lol..
Also, would it be safe to assume that Diode 1 is still fine, since it's a very large diode, and the 1/4w resistor is completely burnt. Or should I go ahead and lift a leg and test it?
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