Members Belva Posted September 23, 2011 Members Share Posted September 23, 2011 OK so this Hohner Marlin I just built a new cab for and put in some Eminence 1058's sounds so damn great it's hard to believe. Harmonics from heaven and some natural breakup. I've seen tube amps without the flavor of this SS thing. It has a great 'verb and a chorus that can be dialed in to just make the amp sound big, if that makes any sense. It also has an OD that sounds really good. But there is a problem with that part. It has individual jacks for OD, 'verb and chorus. I tried an tuna can footswitch that I know works properly in the OD and it automatically goes to full/cranked OD regardless of where the OD knob is. Am I possibly looking at a bad pot or loose solder connection at the pot? I did spray all the pots with DeOxit while it was out and I have no more scratchy from any of them.Also, this thing is prolly 30 years old. Do SS amps require a cap change? I'd really like to keep this one working for as long as I can. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted September 23, 2011 Members Share Posted September 23, 2011 I could only find one pic of a marlin on line so I cants make out an accurate config. Questions. Does the footswitch need to be plugged in for the overdrive to work? Have you looked at the overdrive jack inside the cassis to be sure its isnt a stereo TRS jack and therefore needs a dual switch. Have you tried a momentary switch? Some amps have an onboard relay for switching and an spst will lock it up. Was the deoxint dry when it was powered up? If the overdrive works without the switch, do the other tone controls work too. I'm guessing this is a single channel amp? In a single channel amp with drive with drive switching, what the switch "Might Do" is take the gain pot down to zero and leave the clean channel running. Maybe if you hold the amp closer to the phone I can see it (Ha Ha) Since I cant see the config, all I can do is suggest you trace out whats going on. I dont want to assume a component has failed at this point without more details so I can tie the problem down logically and use some deductive reasoning to narrow down the possibilities.A cheap amp may not have the gain control on the amp in operation and may rely on a pot in the remote switch. If the jack had three wires, its possible the footswitch had a gain knob on it to work the gain remotely. You never know with some oddball amps. They would try anything to get themselves sold. In any case If the drive works unpluggedthen I'd say the switch config is wrong first. Its either taking down the wrong side of the gain pot or theres something else there you're overlooking. Its possible you shorted a leg of the pot or board rehousing it. Any shielding like foil should have an insulator layer over it where it spans the components and only make contactwith the chassis. Link to comment Share on other sites More sharing options...
Members Mr.Grumpy Posted September 23, 2011 Members Share Posted September 23, 2011 SS amps work at much lower voltages than tube amps, so in general the caps last a lot longer. But they still don't last forever. It's one of those "if it ain't broke, don't fix it" type things to me, if you're not hearing AC hum from the amp at idle, your filter caps are probably OK. On the other hand, lower voltage electrolytics caps are cheap and easily available, so as long as you've got the thing apart you might as well throw ten dollars worth of caps in it for peace of mind. I bought a big Acoustic bass combo amp last year, one of the original 70's ones. 1 x 15" in a horn loaded cab. It worked but the volume was very low - turned out that at least one of the electrolytic caps had failed, it had popped open. I replaced the electros and the thing works great now. Link to comment Share on other sites More sharing options...
Members Belva Posted September 23, 2011 Author Members Share Posted September 23, 2011 The overdrive doesn't need the footswitch to work and the knob controls the overdrive fine. When the footswitch is plugged in is when it goes full drive. But the footswitch will turn it on and off. It isn't a TRS type jack. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted September 23, 2011 Members Share Posted September 23, 2011 Humm, Try putting a pot in line with the footswitch and adjust your level there. You could adjust the amount of boost you want at the pedal. Link to comment Share on other sites More sharing options...
Members tedmich Posted September 23, 2011 Members Share Posted September 23, 2011 I always recap amps older than 10yrs; you can often fit 50-100% more filtering in the same package and its cheap insurance also the noise floor drops a bit and bass usually improves too. Most SS maintenance I do is the "defur" procedure with a paintbrush, and vacuum... Link to comment Share on other sites More sharing options...
Members Belva Posted September 23, 2011 Author Members Share Posted September 23, 2011 Humm, Try putting a pot in line with the footswitch and adjust your level there. You could adjust the amount of boost you want at the pedal. That's win. I'll have to look to see what the pot value is for the OD on the amp. I'm guessing this would be similar to a guitar volume pot where you ground the right lug to the pot case, run the + to the center lug and the ground wire to the pot case? Naturally the footswitch would be in the line. That would give me what I want. I'd like to use the OD just to give me a bit of fat for leads. I could also maybe just run a push/push pot. Link to comment Share on other sites More sharing options...
Members Belva Posted September 23, 2011 Author Members Share Posted September 23, 2011 BTW I did pull the main PCB as well as the small ones for the OD, 'verb and chorus just to see if I noticed any cold solder joints or obvious breaks in the traces on the boards. I had to do this in order to spray the pots. I also did the "defur" mentioned by Tedmich. And yes, this condition existed before I pulled the amp out of it's original cab.At this point the amp is dead quiet at idle and I get zero feedback with the vol & master cranked and the guitar, with vol cranked, leaning string side against the amp. EQ's were in the middle when I did that.There is potential in this one. Link to comment Share on other sites More sharing options...
Members Belva Posted September 23, 2011 Author Members Share Posted September 23, 2011 http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=1hum_1volOK so I wasn't thinking. Use this diagram subbing the wire for the output jack and the switch for the pup. Will that get me close to what WRG is suggesting? Link to comment Share on other sites More sharing options...
Members WRGKMC Posted September 23, 2011 Members Share Posted September 23, 2011 The switch for the overdrive simply shorts the tip and ring right?Put a pot in series with the switch and see what happens, just lift the hot side of the cable coming into the switch, connect it to the middle lead of the pot, then connect an outside lead to the switch. Youll need to try different pots to see which one might work, or if it will work at all. My thought is if a dead short brings the amp to full gain, what about half a short? Half gain? Just gotta mess with it and see. you may need a 1M, 500K, 250K 10K or 1k or 100ohm pot. Just cant tell you for sure without taking a look. Its easy to figure out. Just use a one ended guitar cord, plug it into the boost jack and try different resistors or pots till you find something in the right range. If you have a 250K pot and wind up needing something lower because it goes from zero to full on too quick, you could use a resistor over the pot to bring the value down. The setup is tip of plug > through cable > Center leg of pot > outer leg of pot > Switch leg1 >Switch leg 2 > Ground of cable > Through cable > Ring of plug. Simple Link to comment Share on other sites More sharing options...
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