25 to life power 1000 sub channel problems

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mikep28

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#1
Power 1000 25 to life very gently used bought it day 1 Amplifier has always exhibited a very light humm that changes in frequency with or without signal applied. The other day when volume on head unit get about 1/8 way only channel 5, sub channel would cut out. On the way out of town on business trip the amp decided to smoke my 10 inch subs. Quickly got out and flip the breaker off. When I got home I removed the amp and put it on the bench extremely clean inside no fire. No smoke. Nothing appears burnt. Power the amp up no DC offset on any channel and the 4 IRFP3415 's do not read shorted. Amp doesn't show protect or anything. Also if I push gently around the input circuitry the humming the amp has always done ceases.

Any idea what tried to barbecue my speakers?
 
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#2
Were you using a completely non-conductive probe when you were pushing on the board?

Some of the Rockford amps would oscillate if you touched the shields with no RCAs plugged in. Maybe something similar could happen if there was a problem with the RCA inputs. For the amps that I've seen do this, connecting a 1000pf capacitor from the shield to the center conductor at the RCA jacks eliminated that problem. Those same amps would sometimes produce a loud thump when you touched the shields with no RCAs plugged in. Connecting a 27k resistor (not critical, what I used the first time and continued to use) between the shield and the closest ground that I could find stopped the thumping.

The metal shield part of the input RCA jack sometimes gets loose and has to be soldered.
 
#6
For some amps, problems with the preamp shield ground can cause the amplifier to oscillate which can be inaudible but still drive full power to the speaker. I don't know if that's possible with this amp.

If the inductor is shorted (possibly intermittently), that could allow the class D carrier to be driven to the speakers. This can cause the amp to blow speakers.
 
#7
Perry Babin said:
For some amps, problems with the preamp shield ground can cause the amplifier to oscillate which can be inaudible but still drive full power to the speaker. I don't know if that's possible with this amp.

If the inductor is shorted (possibly intermittently), that could allow the class D carrier to be driven to the speakers. This can cause the amp to blow speakers.
Click to expand...

Ok I understand. Well I guess I got the RCA input too hot soldering on it. I guess I melted the inside of terminal. Rca is very very difficult to plug in. Are these a common part I can order? Mouser? Digikey etc?
 
#9
The center pin on the RCA is broken for the RH sub RCA input. I've tried PM'ing seankane for other items and he never PM's me back.. The part number and description from a bill of materials for a T40001bd I have is: J101 1040-52316-01 CONN-TH~RCA~2 POS~VERTICAL~FEMALE~NICKEL~PUNCH / POWER

I'll contact Rockford and see how 'proud' of these $2 connectors they are 🙂 ... Might drop Jason at freeman's a email and see if he has any.
 
#10
Sorry I didn't post this earlier but it may help someone else.

Sand the bell and the frame of the RCA jack with fine abrasive. 400 grit sandpaper will work. I use a fiberglass scratch brush but those aren't very common.

Apply flux to the area to be soldered if you have it. If you use a cotton swab to apply the flux, it will also clean away any residue left from sanding.

Heat the frame first. When the frame starts to accept the solder readily, move the soldering iron to heat the frame, the molten solder and the shield bell. The solder should flow readily onto the bell. The solder doesn't need to flow all around the shield. 1/2 of the way around is more than enough.

It's important that you use a hot iron with a relatively wide tip and do this quickly. If the area to be soldered was properly prepped and the iron hot, it shouldn't take more than about 20-30 seconds after the heat is applied initially.
 
#11
Thanks perry. Great information. I just got off the phone with Rockford tech support. He confirms I have the proper part number but the part girl doesn't show the part listed. No idea what to do from here. We all know that these were used in a crapload of amplifiers. I found some stuff on switchcraft's website but I'll have to look later, I'm out of time today.

Perry I got the schematic and bill of materials for this amp if you want it.
 
#16
I just soldered the RCA back together. I found the RCA connectors like used in older a2,a4 etc amps. I decided to just repair this one. I decided to reinstall this amplifier in my car. It plays fantastic. More I keep thinking about it, I believe the previous problem might have been the loose fan shield inside the amplifier. It didn't look like it fell far when i disassembled the amp but that's the another thing I think could have caused the previous previous problem. Just glad my subs sound like they survived but I bet they took a beating from the DC voltage. They smelt pretty bad.
 
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