Leave it on for as long as it was taking to lose audio. To the voltages there change more than a tiny fraction of a volt?
If you remove C821, does the 2.34v change?
I'm assuming that you still have the 21844s disabled.
I'm assuming that you still have the 21844s disabled.
Post the DC voltage on all terminals of U5 on the driver board with the black meter probe on the negative rail.
Last edited:
U5 LM293 Overcurrent protection
1 0,067V
2 10,50V
3 6,044V
4 0,001V
5 0,356V
6 0,006V
7 12,14V
8 12,15V
Without Remote all Pins have around 0,4V
1 0,067V
2 10,50V
3 6,044V
4 0,001V
5 0,356V
6 0,006V
7 12,14V
8 12,15V
Without Remote all Pins have around 0,4V
Those look OK.
Are the 21844s original?
Do you have a way to keep them cooler? Temporary heatsink?
Are the 21844s original?
Do you have a way to keep them cooler? Temporary heatsink?
I put in new ones from Mouser.
I can fit some heatsink on them from a 8000D I think. Should I try then again with enabled output?
This week new FET's should arrive, i will try then again with freshly baked Drivers.
I can fit some heatsink on them from a 8000D I think. Should I try then again with enabled output?
This week new FET's should arrive, i will try then again with freshly baked Drivers.
Did the originals fail?
When the heatsinks are added, enable the ICs and see if audio shuts off after the same time.
Does the IC that's driving only 2 FETs heat at the same rate?
If you enable only one at a time (assuming that they heat at the same rate), does the amp lose audio at the same point in time as when both are enabled?
When the heatsinks are added, enable the ICs and see if audio shuts off after the same time.
Does the IC that's driving only 2 FETs heat at the same rate?
If you enable only one at a time (assuming that they heat at the same rate), does the amp lose audio at the same point in time as when both are enabled?
Fet's were ok.
Heatsink doesn't change the time of shutdown.
With 2 Fets it heats less i think.
If 1 or 3 are driven doesnt really change the time of shutdown.
Most drivers are getting hot, there are no Buffer Transistors in this circuit so that isn't rly the Problem i think.
The waveform isn't starting to distort, it just disappears from the driver ic's.
Heatsink doesn't change the time of shutdown.
With 2 Fets it heats less i think.
If 1 or 3 are driven doesnt really change the time of shutdown.
Most drivers are getting hot, there are no Buffer Transistors in this circuit so that isn't rly the Problem i think.
The waveform isn't starting to distort, it just disappears from the driver ic's.
When I measure the voltage, black probe at - Rail, red at the Right pin of the Q52 muting tranistor, the amp shuts off. Is that part of the circuit so jumpy or could that be something to check again ?
I wouldn't expect a multimeter to shut the amp down when measuring the voltage on the base of Q52.
Monitoring the voltage on pin 2 of the PS driver board, do you see a pulse of voltage as the remote voltage is applied to the amp?
Does the protect LED light up briefly when the amp powers up or powers down?
Monitoring the voltage on pin 2 of the PS driver board, do you see a pulse of voltage as the remote voltage is applied to the amp?
Does the protect LED light up briefly when the amp powers up or powers down?