I replaced all the outputs and drivers in that channel. I powered the amp and it was drawing 40 amps current. 3 of the IRF540 FETS were getting hot. I removed those 3 and re powered the amp and it powered up fine.
I re-installed them and it powered up and blew the fuses for that channel.
I removed the D41D8 and powered the amp and the 10uf 50v cap next to it exploded. I replaced the cap and the driver and repowered the amp.
The 75 ohm resistor next to the D41D8 instantly smoked. I replaced it and repowered the amp. Then the 75 ohm resistor next to the D40D8 instantly smoked.
I am not sure what is going on here. It is hard to follow the schematic, as there is no silk screen markings on the board.
Some of the fuse holders have 14 vdc going to them when just power and ground are hooked up and some dont, is this right? When the amp is powered they have rail obviously.
I am at a stand still, unsure where to go next. I dont want to keep blowing parts.
I re-installed them and it powered up and blew the fuses for that channel.
I removed the D41D8 and powered the amp and the 10uf 50v cap next to it exploded. I replaced the cap and the driver and repowered the amp.
The 75 ohm resistor next to the D41D8 instantly smoked. I replaced it and repowered the amp. Then the 75 ohm resistor next to the D40D8 instantly smoked.
I am not sure what is going on here. It is hard to follow the schematic, as there is no silk screen markings on the board.
Some of the fuse holders have 14 vdc going to them when just power and ground are hooked up and some dont, is this right? When the amp is powered they have rail obviously.
I am at a stand still, unsure where to go next. I dont want to keep blowing parts.
The bias pot is fully counter clock wise.
You want me to measure across the bases of the D40 and D41? Red probe on one base and black probe on the other base?
The amp will not power up through a current limiter with the fuses installed. If both fuses are in with a current limiter just hooking up power and ground makes the amp draw current and when the remote is applied it will not power.
If I remove the 2 fuses for that channel the amp will power up, but I dont think I can get an accurate reading across the bases of the 2 transistors you need without the fuses installed can I?
Something in that channel has to be shorted or something???
If I remove the 2 fuses for that channel the amp will power up, but I dont think I can get an accurate reading across the bases of the 2 transistors you need without the fuses installed can I?
Something in that channel has to be shorted or something???
Are you sure that all transistors are in the correct locations and installed with the proper orientation?
I replaced all RFP18N10 with IRF540
I replaced all RFP12P10 with IRF9540
A56's drive IRF540's
A06's drive IRF9540's
I put everything back as it was just different outputs. The other channel with the new outputs and drivers works fine. Its just this one channel.
If the 2 fuses for that channel are not in it powers fine and nothing heats up.
The rail voltage to the channel is causing the issue.
Im lost?
I replaced all RFP18N10 with IRF540
I replaced all RFP12P10 with IRF9540
A56's drive IRF540's
A06's drive IRF9540's
I put everything back as it was just different outputs. The other channel with the new outputs and drivers works fine. Its just this one channel.
If the 2 fuses for that channel are not in it powers fine and nothing heats up.
The rail voltage to the channel is causing the issue.
Im lost?
I compared it to the other 4 Power650's I have and they are all exactly the same locations.
I couldnt answer the second question because the amp will not power up through a limiter with the fuses for that channel installed.
It will only power up through the limiter if the fuses are not installed for that channel.
All the rest of the channels seem fine with their fuses installed. Maybe when the 10uf 50v cap blew or some of the resistors burned it damaged the drivers?
Maybe I should try and replace them again?
These boards are so sensitive to heat I dont like changing parts multiple times you know?
I am not sure what to do next.
I couldnt answer the second question because the amp will not power up through a limiter with the fuses for that channel installed.
It will only power up through the limiter if the fuses are not installed for that channel.
All the rest of the channels seem fine with their fuses installed. Maybe when the 10uf 50v cap blew or some of the resistors burned it damaged the drivers?
Maybe I should try and replace them again?
These boards are so sensitive to heat I dont like changing parts multiple times you know?
I am not sure what to do next.
Please read #35 and #36.
I replaced the output and now the amp will power through the limiter. Nothing seems to be getting warm.
Wierd thing is........I always have battery voltage on the brown wire from that channel, even with the remote unhooked???
When I power the amp it drops to about 10.50 vdc. None of the other channels have this problem.
What could be letting battery voltage to the brown wire of that channel?
I replaced the output and now the amp will power through the limiter. Nothing seems to be getting warm.
Wierd thing is........I always have battery voltage on the brown wire from that channel, even with the remote unhooked???
When I power the amp it drops to about 10.50 vdc. None of the other channels have this problem.
What could be letting battery voltage to the brown wire of that channel?
OK I figured it out.
1st was the shorted output, replaced that.
Still had the B+ voltage on the brown wire.
Replaced the 10uf 50v cap way out of tolerance.
Still had the B+ on the brown wire.
Started testing all of the legs of of the outputs in that channel.
The only thing that makes any connection with the brown wire is the drains of those 6 outputs.
So obviously it had to becoming from a leaky or shorted FET right?
Wrong!! I found a little itty bitty solder bridge from the source to drain on one of the IRF9540's.
I only saw it through a powerful magifying glass.
It was my own dumb *** mistake. I am so mad at myself.
The amp idles stable, has no DC on the bridging wires, and produces clean audio.
1st was the shorted output, replaced that.
Still had the B+ voltage on the brown wire.
Replaced the 10uf 50v cap way out of tolerance.
Still had the B+ on the brown wire.
Started testing all of the legs of of the outputs in that channel.
The only thing that makes any connection with the brown wire is the drains of those 6 outputs.
So obviously it had to becoming from a leaky or shorted FET right?
Wrong!! I found a little itty bitty solder bridge from the source to drain on one of the IRF9540's.
I only saw it through a powerful magifying glass.
It was my own dumb *** mistake. I am so mad at myself.
The amp idles stable, has no DC on the bridging wires, and produces clean audio.
If you didnt read post #39 please do.
This amp was extremely noisy through the speakers until the bias was set. Once I set the bias it was very clear and crisp.
Why so noisy like feedback and static without the bias set?
How many mv on the source resistors should I set this amp at to be perfect?
I just eye balled it watching my amp meter on the supply for testing purposes.
This amp was extremely noisy through the speakers until the bias was set. Once I set the bias it was very clear and crisp.
Why so noisy like feedback and static without the bias set?
How many mv on the source resistors should I set this amp at to be perfect?
I just eye balled it watching my amp meter on the supply for testing purposes.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.