i finally received the 1n5366 diode from mouser.com, replaced it, and the noise is still there (it needed replacing anyway, though. that eliminates that problem). upon closer inspection, the capacitors look like they have leaked in the past. you can see discoloration like some sort of liquid seeped between the translucent plastic covering and its metal case. do these caps commonly go out/leak in this model of amplifier?
I believe one or more of the allen screws on the edge of the board tightens on a board trace that connects power ground. This makes the amp heatsink ground to keep the rf inside. Otherwise I would think your power and ground wires are radiating due to the amp having an internal problem in the power supply section.
Actually the screw that grounds to the sink may not be on the edge, I just found a pic of a 200dsm. Its been a while since I've seen the inside of a dsm.
Actually the screw that grounds to the sink may not be on the edge, I just found a pic of a 200dsm. Its been a while since I've seen the inside of a dsm.
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i dont see anywhere where the allen screws could ground any traces on this model. all of the screw holes on the pcb have no traces to touch the case.
Use an ohmmeter to check continuity between the heatsink and the power ground terminal on the amp, it needs to be connected for noise shielding. The trace may be on the bottom of the board surrounding a screw hole. Be sure there is not paint or anything keeping the trace from conducting to the sink.
Some of the older punch amps used a small jumper that connected the ground trace on the board to the heatsink
Some of the older punch amps used a small jumper that connected the ground trace on the board to the heatsink
my ohmmeter doesnt show any continuity. if there are any jumpers, was it one that physically screwed on to the heatsink on one end and a ground trace on the other? other than that, i dont see anywhere where the jumper/wire/etc could have attached to the pcb (either the bottom or the top of the board), since none of the screw holes are surrounded by any traces to connect to the case.
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i have the board out and there are no traces around the 4 screw holes that attach the board to the case.
on the punch 40dsm i am working on, none of the holes have any copper at all, but i am going to try to use a wire like you are saying. why doesnt rockford ground the heatsink on their amps? i replaced the cr7 diode that was burnt with a 1n5366, and the noise was still there. i looked at the filter capacitors c9 and c10 and i notice some corrosion/discoloration, especially with the orange c9 cap (like electrolyte seeped between the plastic cover and the metal case).
okay, i have grounded the heatsink/case by soldering a wire that connects the heatsink to the ground terminal (there is no copper/metal around the holes, thats why i had to use the ground terminal) but it still does it. that leads me to those caps or other internal issues; i'll keep plugging at it until i get this goin': I'm a fighter! thanks for all the help guys; im glad to make this forum home.
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okay, i have grounded the heatsink/case by soldering a wire that connects the heatsink to where the ground terminal connects to the board (there is no copper/metal around the holes; light shines through it, thats why i had to use the ground terminal) but it still does it. that leads me to those caps or other internal issues; i'll keep plugging at it until i get this goin': I'm a fighter! thanks for all the help guys; im glad to make this forum home.
i've already ordered them; they're on their way as i type. is this a common problem for these amplifiers?
p.s. i downloaded the electronics tutorial sites you host. theres a lot of good stuff on them!
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You seem to be already deep into this, but did you try just moving the amp to a different location? Maybe by reorienting it you might detect a change in the interference? (I realize a small car limits mounting options.) The first step in squelching interference is to determine its source. Shotgunning can work also.
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