Update of what I did today and a bit of context that may/may not be helpful, hopefully it might be. Will still try removing the resistor tomorrow
Not sure if I mentioned that the previous owner said they had it in storage a few years prior to selling the amp to me, said it was working when they put it in storage
The board is pretty filthy so today I ended up cleaning as much of the board as I can without giving it an isopropyl alcohol bath (if that would be a good idea), nothing changed functionally
This coil still seems a bit sketchy to me as there is quite a bit of oxidation around the contacts, is there any way to test to see if its still functional? (image attached)
Amp only goes into half protect when headunit volume is raised to 30 (max volume is 34) with signal, gain is at minimum on the amp
Amp will go into half protect when relays engage only with a speaker connected (4 ohm)
It takes 3 restarts to turn on properly (restart as in remote turned on then off, B+ constant) from leaving the amp unplugged overnight or for a while
First start when relays engage there is a weird sound
Second start, goes into half protect when relays engage
Third start is when it goes into power normally and will not go into half protect until headunit volume is increased with signal
Not sure if I mentioned that the previous owner said they had it in storage a few years prior to selling the amp to me, said it was working when they put it in storage
The board is pretty filthy so today I ended up cleaning as much of the board as I can without giving it an isopropyl alcohol bath (if that would be a good idea), nothing changed functionally
This coil still seems a bit sketchy to me as there is quite a bit of oxidation around the contacts, is there any way to test to see if its still functional? (image attached)
Amp only goes into half protect when headunit volume is raised to 30 (max volume is 34) with signal, gain is at minimum on the amp
Amp will go into half protect when relays engage only with a speaker connected (4 ohm)
It takes 3 restarts to turn on properly (restart as in remote turned on then off, B+ constant) from leaving the amp unplugged overnight or for a while
First start when relays engage there is a weird sound
Second start, goes into half protect when relays engage
Third start is when it goes into power normally and will not go into half protect until headunit volume is increased with signal
Attachments
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Isopropyl alcohol won't do any harm but if you use 70% or 91% alcohol, they contain water so you must make sure that all of the water has evaporated before applying power.
It's odd that those are even in the circuit. This amp (and clones of it) are the only ones I know of that have inductors in that part of the circuit. As long as you read 0 ohms between the drain terminal of M6 and the rest of the inductors in the output filter, it's OK.
It's odd that those are even in the circuit. This amp (and clones of it) are the only ones I know of that have inductors in that part of the circuit. As long as you read 0 ohms between the drain terminal of M6 and the rest of the inductors in the output filter, it's OK.
Inductors show 0 ohms
Removed R7, Still goes into half protect on first or second start like it did previously, but when in normal power when I raise the headunit volume it does not go into half protect as it did.
I will test the small speaker on it tomorrow to see if it still goes into half protect, but there is still no speaker terminal output (besides some noise) on the scope when in normal power
Normal power as in power led, no protect led
Removed R7, Still goes into half protect on first or second start like it did previously, but when in normal power when I raise the headunit volume it does not go into half protect as it did.
I will test the small speaker on it tomorrow to see if it still goes into half protect, but there is still no speaker terminal output (besides some noise) on the scope when in normal power
Normal power as in power led, no protect led
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I just did, it seems to be “working”
With a speaker, there is now good output and it plays a lot louder than it did (enough power that I believe it is working fine, current actually changes with gain/headunit volume increase/decrease now)
With that being said the protect light is still half lit and it idles around 5amps. Is that idle normal for these amps? Also what does removing that resistor do? Should I keep it out?
Power supply fets also seem to be getting a bit warm but that also may be normal?
(Photo is with speaker attached on 1x probe, scope at 5v 5ms)
With a speaker, there is now good output and it plays a lot louder than it did (enough power that I believe it is working fine, current actually changes with gain/headunit volume increase/decrease now)
With that being said the protect light is still half lit and it idles around 5amps. Is that idle normal for these amps? Also what does removing that resistor do? Should I keep it out?
Power supply fets also seem to be getting a bit warm but that also may be normal?
(Photo is with speaker attached on 1x probe, scope at 5v 5ms)
Attachments
The resistor disables the relays. We have to troubleshoot the protection circuit.
Are the FETs heating at idle?
What's the rail voltage (measured at the output of the rectifiers with a multimeter)?
DCV on pins 15 and 16 of US1? If it's easier, you can measure this on pins 10 and 11 of the PS Driver board header.
Are the FETs heating at idle?
What's the rail voltage (measured at the output of the rectifiers with a multimeter)?
DCV on pins 15 and 16 of US1? If it's easier, you can measure this on pins 10 and 11 of the PS Driver board header.