OK. So the 25 volts is confirmed as good.
That means that you must be seeing around 34 volts DC across the caps. If that voltage is climbing slowly during the time the 25 volts is good then you have to look to the rectifiers and caps. If something was "pulling the voltage down" on the cap side then there is no doubt whatever that the diodes would literally be on fire.
It doesn't add up what is happening. You have to look at the rectifiers.
A definitive test is to scope across the DC rail and see what is happening. That would show excess ripple due to a cap problem. If there is no ripple then the rectifiers aren't passing the current (and as such they have to be faulty).
I suppose there could be a wiring error or construction error but I'm assuming not. Something like the amp circuitry "in series" with the supply somehow but that would be a bizzarre error.
That means that you must be seeing around 34 volts DC across the caps. If that voltage is climbing slowly during the time the 25 volts is good then you have to look to the rectifiers and caps. If something was "pulling the voltage down" on the cap side then there is no doubt whatever that the diodes would literally be on fire.
It doesn't add up what is happening. You have to look at the rectifiers.
A definitive test is to scope across the DC rail and see what is happening. That would show excess ripple due to a cap problem. If there is no ripple then the rectifiers aren't passing the current (and as such they have to be faulty).
I suppose there could be a wiring error or construction error but I'm assuming not. Something like the amp circuitry "in series" with the supply somehow but that would be a bizzarre error.
All the resistor across X3 and X4 is doing is acting as part of a CRC filter to reduce ripple slightly.
For testing you can just add a shorting link in place of X3 and another in place of X4.
Once you are happy it is working you can consider what value of resistor you would like to try in those positions.
The current I am referring to is the DC current drawn by the amplifiers from the secondary side of the supply.
For testing you can just add a shorting link in place of X3 and another in place of X4.
Once you are happy it is working you can consider what value of resistor you would like to try in those positions.
The current I am referring to is the DC current drawn by the amplifiers from the secondary side of the supply.
Just as a starting point, once the amplifiers are stable and you can measure the DC current being drawn from the power supply.
You might be looking to drop approximately 1V across the X3 and X4 resistor.
If the two amps are drawing a combined current of say 3A.
R = E / I.........so R would be 1 / 3 Ohms = 0R33
P = I ^^2 x R.......so it would need to be at least 3W ...... 5W would be better.
You might be looking to drop approximately 1V across the X3 and X4 resistor.
If the two amps are drawing a combined current of say 3A.
R = E / I.........so R would be 1 / 3 Ohms = 0R33
P = I ^^2 x R.......so it would need to be at least 3W ...... 5W would be better.
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