Richard Rice
From:
Illinois, USA
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Posted 21 Jun 2012 4:22 am |
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Well, I worked on this amp for three solid days, and finally called in my friend for some help. I got the Normal channel going, but couldn't manage to get the lead channel talking or any reverb.
We spent 12 straight hours on it yesterday, tracing, testing, and measuring components. This was my fourth day, but it sure helps to have smart, stubborn friends. My buddy managed to get the lead channel working, the reverb was just a very frustrating thing we couldn't find for the longest time. As it turned out, the foot switch jack had been miswired- acting as a permanent defeat. Once he clipped a jumper on the jack, the reverb kicked right in.. Go figure. We replaced all the IC chips, swapping between the Burr Brown chips and the originals, then back again, then reverting to the originals. It appears there were some mods done to the circuitry, but not the "standard" tone enhancement mod.
Reversing what we could see had been changed, going back to the original chips, reflowing the entire PCB, removing, cleaning, and replacing some broken pots, cleaning and retensioning the Molex connectors, replacing inferior wire with high quality wire, the list goes on and on..
By the time it seemed to be working as expected, it got really late. I reassembled the amp, finishing around 12:30 AM this morning. So I have not been able to test it yet, but it was all working when it was in pieces, jumpered together all over the bench and the floor..
Once I had everything back together in the cabinet, I fired it up to make sure I didn't do anything stupid, and it seems OK so far. I noticed a bit of growl when turning up the reverb, even without anything plugged into the amp. I've seen this same thing happen on other amps when the reverb pan was too close to the transformer, and remedied it bt flipping the pan around- not sure if that will work (or if it's even a problem) with this amp. I'll check it out this morning, once my family is out of the house.
Since I haven't played these amps before, I don't know if this growl is normal, or if I need to be concerned about it. I don't remember noticing it when the amp was on the bench, which leads me to believe it may be an inherent characteristic of the amp. Any guidance appreciated. The growl goes away as I decrease the reverb, and is nonexistent when the pot is rolled completely down.
I will need to acquire a couple of replacement ganged pots, as these are damaged- but-working. Hopefully these are still available through Peavey.. Peavey has failed to respond to my email, and their forum software has failed to send me activation codes. I plan on calling then on the phone this morning, as nothing else seems to be working. Disappointing.
I plugged a regular guitar through the amp during the repair process, and when it finally got to working, it is incredibly loud and clear.
I also found it interesting that the amp didn't work with the Burr Brown chips. As I'm not an expert, I now wonder if it was coincidence, or if it had to do with having swapped the chips into the amp without having replaced the resistors and capacitors per the mod recommendation. It seems to me that the newer values would tend to increase the gain,thus drive the replacement chips harder. If one of you smart guys has an opinion, I'm all ears. I may opt for the upgrade in the future, but want to finish the repairs and see how the amp is before changing it.
All in all, it is on the right track, and I'll know more in an hour or so. Pretty cool amp from what I have heard thus far. 
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'84 Marlen Custom D-10, 8X4
Oahu Tonemaster 6 string lap steel
Rice Custom 6 string lap steel
Republic Squareneck Tricone
Homebrew 6 string reso
10 string Melobar- Rice modified
Rice Custom 8 string reso (under construction)
Hohner 6 string lap guitar (acoustic)
Kustom K-500 tuck & roll
Peavey Century
Peavey Vegas 400
Peavey CS-800
Bag End custom 1X12 & 1X15 cabs w.EV drivers
Steelin' thru a '72 Vibrosonic Reverb and a '69 Dual Showman Reverb (Stereo) |
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Richard Rice
From:
Illinois, USA
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Posted 21 Jun 2012 5:37 am Brief update
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Upon plugging my PSG into the amp, the lead channel was barely working, the reverb was distorting badly, and cutting in and out intermittently. Having reflected on it, I removed and reinstalled the reverb Molex connector, and it seems to be working for the moment. I now recall noticing that if I flexed the PCB in either direction the signal would go from quiet and distorted to loud and clear. My friend retensioned all the Molex connectors after I noticed the weird cutting in-and-out, and the problem seemed to be solved. Obviously, I had to disconnect them when I reassembled the amp, and upon removing/reattaching the reverb connector it seems to be working again. Until I can get a couple of replacement pots I won't know if it is fully cured, but it's a fun amp for now. I don't trust it yet, though. It's close, but not gig ready just yet..
_________________
'84 Marlen Custom D-10, 8X4
Oahu Tonemaster 6 string lap steel
Rice Custom 6 string lap steel
Republic Squareneck Tricone
Homebrew 6 string reso
10 string Melobar- Rice modified
Rice Custom 8 string reso (under construction)
Hohner 6 string lap guitar (acoustic)
Kustom K-500 tuck & roll
Peavey Century
Peavey Vegas 400
Peavey CS-800
Bag End custom 1X12 & 1X15 cabs w.EV drivers
Steelin' thru a '72 Vibrosonic Reverb and a '69 Dual Showman Reverb (Stereo) |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 22 Jun 2012 12:23 pm
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| Everyone should have some of that Caig's Pro-Gold (and De-Oxit as well)... this is magic for things like pots and connectors. Guitar Center sells it, IIRC. Spray a tiny amount on one side of the connector, mate them, then work them in and out a litte. Good for all electronic connections... if you want to do hi-temp (like tube pins) you need their special hi-temp formula (non-spray). |
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