Anyone know of a good replacement for the FB31N20’s ?
Also does this amp use both fb31n20’s and 9640’s?
Someone was inside this amp and it has all mismatched outputs in it
Also does this amp use both fb31n20’s and 9640’s?
Someone was inside this amp and it has all mismatched outputs in it
Attachments
Here are the drive signals for the power supply fets .
With all outputs out of circuit the amp still draws excessive current.
I have a 0.1 uf cap connected between gate and source .
Scope settings are 10us 1volt/div
Do these appear ok or is there a drive problem
To the fets ?
With all outputs out of circuit the amp still draws excessive current.
I have a 0.1 uf cap connected between gate and source .
Scope settings are 10us 1volt/div
Do these appear ok or is there a drive problem
To the fets ?
Attachments
Those don't look like there is a capacitor connected. When a capacitor is gate-source, you'd expect the same curve on both the top and bottom of the waveform.
Should I replace the drivers again ?
I double checked my connections and they are solid connection on the 0.1 cap between gate and source
I double checked my connections and they are solid connection on the 0.1 cap between gate and source
Replaced all of the transistors on the power supply driver board .
Same issue the drive signals doesn’t change .
Any ideas ?
Same issue the drive signals doesn’t change .
Any ideas ?
Could i possibly have a bad 494 ?
Or any ideas on what to check ?
Not sure why this is happening either but the amp will draw excessive current and fets get hot within 2 secs
Or any ideas on what to check ?
Not sure why this is happening either but the amp will draw excessive current and fets get hot within 2 secs
Do you have a meter to confirm that the 0.1uF capacitor is within tolerance?
Did you try twisting the transformer to see if that made a difference?
I'm assuming that you removed the rectifiers to isolate the supply.
Did you try twisting the transformer to see if that made a difference?
I'm assuming that you removed the rectifiers to isolate the supply.
That looks OK. What does the other bank look like?
The scope may be at 1v/div but the probe is on 10x, correct?
The scope may be at 1v/div but the probe is on 10x, correct?
Here is the other bank .
The scope is set to 10us 1volt/div
The probe is set at 1x not 10x
2nd pic is of another bank of fets . This is the bank I’m having the most issues with .
Here is what I get on the scope with 1 fet installed in the bank .
The scope is set to 10us 1volt/div
The probe is set at 1x not 10x
2nd pic is of another bank of fets . This is the bank I’m having the most issues with .
Here is what I get on the scope with 1 fet installed in the bank .
Attachments
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I found that one of the transformers was shorted .
Without any outputs in the amp right now I get -45 volts of rail but +65 volts of rail .
Should I put the outputs back in circuit and see if that changes anything ?
Without any outputs in the amp right now I get -45 volts of rail but +65 volts of rail .
Should I put the outputs back in circuit and see if that changes anything ?