The audio drivers on this amp are shorted . They are 2N4403,4401
Wondering if any other drivers will work ?
I know the originals are available but trying to wrap this amp up ..
Wondering if any other drivers will work ?
I know the originals are available but trying to wrap this amp up ..
Attachments
I will just replace them with the original part numbers .
When the outputs fail in this type of amp I usually replace the outputs and drivers .
Wondering if I should order anything else that’s common on this design that fails when the outputs short
When the outputs fail in this type of amp I usually replace the outputs and drivers .
Wondering if I should order anything else that’s common on this design that fails when the outputs short
The optocouplers typically prevent any damage beyond their location in the circuit. Check everything between them and the outputs.
I find that the drive is best tested with the outputs in the amp but the rectifiers removed.
I find that the drive is best tested with the outputs in the amp but the rectifiers removed.
Replaced the outputs and drivers .
Also replaced a few gate resistors .
When I power the amp up I get about 1 volt measured directly across the speaker terminals and the voltage slowly drops to 0.00 then climbs back up to about half a volt . It continues to do this over and over .
Could 1 of the optocouplers be at fault ?
Or any ideas ?
Also replaced a few gate resistors .
When I power the amp up I get about 1 volt measured directly across the speaker terminals and the voltage slowly drops to 0.00 then climbs back up to about half a volt . It continues to do this over and over .
Could 1 of the optocouplers be at fault ?
Or any ideas ?
The rectifiers were in circuit .
With the rectifiers removed I get 7 volts measured directly across the speaker terminals
With the rectifiers removed I get 7 volts measured directly across the speaker terminals
Last edited:
If you connect a load across the speaker terminals, does the amp draw more current or does the voltage simply drain off?
I replaced the optocouplers just to rule them out .
With the rectifiers out of circuit I get 1 volt measured directly across the speaker terminals .
When I connect a 4 ohm load across the speaker terminals the voltage drains off .
With the rectifiers out of circuit I get 1 volt measured directly across the speaker terminals .
When I connect a 4 ohm load across the speaker terminals the voltage drains off .
Post the images of the high and low-side waveforms on the gate legs of the output transistors.
Do the same for the output terminals of the optocouplers.
Do the same for the output terminals of the optocouplers.
First 2 images are of the high and low side drive on the gates of the outputs .
3rd pic is pin 6 of the optocoupler (U2)
4th pic is pin 6 of the other optocoupler (U1)
Scope set to 2us 5 volts div
A couple of the images appear blurry but when I look at the drive signals that’s what my scope does I tried adjusting it same results
3rd pic is pin 6 of the optocoupler (U2)
4th pic is pin 6 of the other optocoupler (U1)
Scope set to 2us 5 volts div
A couple of the images appear blurry but when I look at the drive signals that’s what my scope does I tried adjusting it same results
Attachments
Connect a signal source and set the level to the minimum (no output).
Do you still see the signal as blurry (being modulated)? No need to post images.
Set the output significantly higher. Do you see significantly more modulation?
Does it remain modulated or does it show intermittent modulation?
Did you check to see if audio ever passed through the amp when it was pulsing the output (when the rectifiers were in the circuit)?
Do you still see the signal as blurry (being modulated)? No need to post images.
Set the output significantly higher. Do you see significantly more modulation?
Does it remain modulated or does it show intermittent modulation?
Did you check to see if audio ever passed through the amp when it was pulsing the output (when the rectifiers were in the circuit)?