So I have this rockford punch 200ix that I am working on. Some of the SMD caps started leaking near the crossover module.
I changed out all those caps, touched up some broken solder joints here and there with the Zobel network, etc....
The amp works fine UNTIL you turn the treble control. soon as you bump the treble control from the 0 position, the Left channel starts drawing a ton of current and oscillating. Its roasting the Zobel network too. if you turn it up more, it'll start pulsing in and out of oscillation.
This happens regardless if a speaker is attached, or the RCAs are hooked up.
I have never seen this behavior before, has anyone else?
I changed out all those caps, touched up some broken solder joints here and there with the Zobel network, etc....
The amp works fine UNTIL you turn the treble control. soon as you bump the treble control from the 0 position, the Left channel starts drawing a ton of current and oscillating. Its roasting the Zobel network too. if you turn it up more, it'll start pulsing in and out of oscillation.
This happens regardless if a speaker is attached, or the RCAs are hooked up.
I have never seen this behavior before, has anyone else?
Seankane may have a fix but I've never seen one (from Rockford). It generally only happens with the gain at or near the maximum setting.
You may be able to reduce the gain or the boost for the treble (by altering values) to prevent it happening.
For most amps, keeping the gain no higher than about about 50%, will prevent oscillating but it varies by amp.
You may be able to reduce the gain or the boost for the treble (by altering values) to prevent it happening.
For most amps, keeping the gain no higher than about about 50%, will prevent oscillating but it varies by amp.
Ah, thanks for the info... Yeah the gains are all the way up (how I got it). I will turn it down some. Seems everyone wants to turn the gains all the way up. each time I see an amp for repair, 9 times out of 10, the gains are all the way up. (people wonder why they blow)
This is the first time I have ever encountered the amplifier doing this. I am looking at the schematic, but i don't see any feedback from the amplifier stage to the pre-amp stage so I am having a hard time figuring out why it oscillates.
This is the first time I have ever encountered the amplifier doing this. I am looking at the schematic, but i don't see any feedback from the amplifier stage to the pre-amp stage so I am having a hard time figuring out why it oscillates.
Increasing the value of C129/C229 may help. Confirm that it doesn't cause too much roll-off at the high frequency end of the spectrum.
There isn't any feedback from the output to preamp stage (not before the differential amps, anyway).
There isn't any feedback from the output to preamp stage (not before the differential amps, anyway).
I have only seen this a few times and it was due to a defective treble pot. I can't say for sure if this is your problem, have you at least cleaned the pot?