Peavey Practice Amp Problems

lunchmeat

I would fix it. First, simply try tightening the nut on the outside. Or, if you can get to it, try bending the contacts slightly. If that doesn't work you can pick a new input jack up for less than $5. Try Radio Shack.

You can pick them up online.

http://www.universaljems.com/cart/jack.htm

Since it's been sitting in a closet for a long time, maybe get some contact cleaner and clean the input jack. My brand new Fender Bassman 100 combo started cutting out the day before a gig. I panicked, then wiggled the speaker cord - dirty contact. Input jack and speaker jack - those are open air, so would probably be the first things to get corroded.

Tried tightening the nut...I think it probably did some good but the problem persists; that was my first idea. I usually check for loose stuff, but no beans.

I can't really get to the pin inside...I know it's making contact because I get a signal, but it will cut out if it's in the wrong place. I thought maybe something needed resoldering, or maybe something was shorting? I'll try cleaning the input (how do I do that now?) and if that doesn't work, I can try going for a new input jack - but how would I get the old one out and get the new one in without taking apart the preamp?

You can get electrical contact cleaner at radio supply stores, like Radio Shack. If you can, get some Caig cleaner - it's the best on the market.

Oh, looks like Guitar Center carries it now.

http://www.guitarcenter.com/shop/navigation/caig?N=100005+202573&g=home&src ="4WWRWXX"

Deoxit rocks!

Pricey, but it works.

Try spraying the contact cleaner on a Q-Tip and see if you can clean the contacts inside the jack.

You may not have to replace the jack, just very gently bend the contacts inward with needle-nosed pliers.

And always be careful whenever working inside an amp. You can get electrocuted even if the amp is off and unplugged. If you are not familiar with electronics, take your amp to a reputable technician. Call your local music shop and ask what repair rates are.

I was afraid you'd say that.

I know voltages are potentially lethal in tube amps, since they hold electricity or whatever (I don't know how it works) but is it the same with solid-state? I suppose so.

While we're at it, how would I modify the thing to have a line-out jack, so I could hook it to, say, a 2x12? I want to do this with my Peavey Audition 110 (my guitar amp) and the Microbass, at least until I get new amplifiers.

I was afraid you'd say that.

I know voltages are potentially lethal in tube amps, since they hold electricity or whatever (I don't know how it works) but is it the same with solid-state? I suppose so.

While we're at it, how would I modify the thing to have a line-out jack, so I could hook it to, say, a 2x12? I want to do this with my Peavey Audition 110 (my guitar amp) and the Microbass, at least until I get new amplifiers.

Try the contact cleaner first.

If you want to hook up an extension cabinet (2x12), then it wouldn't be a line-out jack you'd need; it would be a second speaker-out, if you will. Different voltages. But if you were wanting to connect a second guitar/bass combo (with its own amp), then yes, you'd want a line-out. In which case you'd have to take the amp out anyhow, and you could fix/replace the original jack really easily.

Two work arounds though: If you want to add a second speaker cab without taking the thing apart, you could get a 1male-2female mono 1/4" Y-adapter for the speaker out; plug the plug into the existing speaker out, then the internal speaker gets one side of the Y, and the extension gets the other, using a second speaker cable. You'd have to find the correct impedence either way - the imp. of the internal and external speaker combined. You can find the formula here and elsewhere on the net.

And if you want to add a second amp/speaker combo, you could still use the Y-adapter; plug it into the input jack of the amp, plug the guitar into one side, and an extension cable into the other which goes to the input of the second combo amp. Or if that doesn't work, plug the male side of the Y into the guitar/bass, and run two guitar-cables out from there, to the two amps.

Ok if you haven't found out already, here's your problem. You didn't specify the exact amp model, you said it was a Peavey "bass amp." Then about the last post you made you say it is a MICROBASS amp. I suspected it might be a Microbass when you said you pulled UP on the plug and it worked. What is happening when you pull UP on the plug the plug is acting as a lever to push DOWN on the jack casing, causing it to make contact with the circuit board where the solder joint has broken.

You can spray contact cleaner in this thing for an hour and it won't get any better. It probably needs professional help. Sorry.

The reason this is happening? The MICROBASS amps I've seen don't have normal input jacks that are attached to the control panel with a hex nut and then connected by shielded cable to the circuit board. Instead they used the dreaded "soldered directly to the circuit board" plastic case jack. (I don't think you'll find one at Radio Shack either.) These jacks are notorious for causing problems. Shoving in and jerking out plugs is certainly to be avoided with these things as is pulling the cable at odd angles. Even NORMAL use will break the solder connection eventually no matter how careful you are. I was surprised that a company that otherwise makes great gear and has a long standing reputation for building reliable gear would use these el-cheapo jacks as it is just asking for trouble and they had to know this. It is not a case of IF they fail, it is only a question of WHEN they fail.

SADLY, the same is true of the volume and tone controls on this model which do not even have nuts behind the knobs to hold them steady. The volume and tone knobs wiggle so much they feel like they are going to come off any second. This is not true of any other bass amp Peavey makes as far as I know. While these amps sound great for their size, these cheap pots and jack soldered directly to the circuit board are multiple failures just waiting to happen.

These MicroBass amps have been discontinued. Oddly the next step up in the old line, the Minx (a great little practice amp & also discontinued), didn't have these problems. Peavey isn't the only company that used this technology. I've also seen these same plastic case circuit board mounted input jacks used on some solid state Fender guitar amps like the Fender Champion 30 and Champion 110. (The MicroBass, Minx and Basic USA made Peavey amps have been discontinued and replaced with the Asian made MAX combos. As cheaply made as the MicroBass was, it still sounded good for its size when it worked...and the new Asian amps are...well, Asian amps. They are not half the amps that the old Microbass, Minx & Basic were and are so cheaply built they are pretty much disposable.)

If you want it fixed you need to take it to a service tech. Any decent TV shop guy should be able to fix it quick if there is no Peavey dealer around. Any Peavey dealer will be familiar with this issue. All the Microbass amps get it eventually.

If you decide to fix it, there is no need to pay a tech to fix it more than once. The service charge will be about the same to eliminate the problem for good by installing a traditional Switchcraft jack instead of just soldering the old one back to the circuit board because sooner or later the old one is going to mess up again...even after you fix it this time. To fix it, solder a shielded cable from the new Switchcraft phone jack to the circuit board where the old jack was soldered directly to the circuit board and you'll never have this particular problem again.

On the multiple cabinet question. MOST Peavey combos will go to 4 ohms. Peavey combos have an 8 ohm speaker built-in. The extension cabinet must be a MINIMUM of 8 ohms. You can only use one 8 ohm extension cabinet. You could use two 16 ohm extension cabinets. I don't know of anyone making 16 ohm 4X12 extenstion cabs. To go lower than 4 ohms total is how these amps get blown. 8 ohms plus 8 ohms equals 4 ohms.

Sorry about your little bass amp. They sound good.

Hmm, I missed this...I hadn't logged on in a while.

Thanks for the info, brotherdave - it's good info, and very useful. I hadn't been really having problems with the amp until I read your post (but perhaps that's because I wrap the cable around the handle? I've gotten so used to doing it that I don't notice anymore, so I don't know if I stopped doing that or not) and yeah, it still seems to have the same issues. No sound unless I pull up on the jack.

The knobs, however, seem to be fine - the gain knob is a bit scratchy but it's in working condition. A question - this soldering job, can it be a DIY job? I'm not all that great at soldering, but with practice I could probably get the job done, but should I really be opening up my amp to do this or should I just do it somewhere else? There's a Peavey dealer where I am, but the guy said I'd be better off getting a new amp; I, however, didn't see anything I liked (considering I got this amp for free). Should I try fixing it myself, or should I find someone to do it for me?

And finally, yes, as you said, it's rated for 4 ohms. That's what's printed on the back (although I'm not sure if the "4 ohms, 9V RMS, 20 watts" is for the speaker or for the amp.) The speaker is probably dying, as it seems to fart around a bit at lower registers (but that might just be the jack). Would it be feasible to uninstall the amp itself and use it separately with, say, a 2x12? All I'd really have to do is take out the amp itself, unhook the existing speaker, and wire it to a cab with the same ohmage...right? *sweat* Just a pet idea of mine, until I win the lottery and can buy a Kustom 8x10. :D

First to anyone else who might come along with one of the Micro/Minx/112 amps, one word of advice. Keep your jack nuts, (the little nuts around the jack holes) tight. They can work loose and this will let the jack wiggle more than it should each time you insert or remove a phone plug. Just keep them finger tight. This eliminates wiggle which breaks the solder joint. On the other hand, over-tightening would also be bad because on some models they are made of plastic and will strip easily.

Yes you can do it yourself. I am NOT a professional tech but I have fixed mine. Just this past Sunday I had to resolder something in my Minx. The little external speaker jack pc board developed a broken solder joint where the internal speaker wires come off this little board and then go to the internal speaker. I looked around trying to figure out how I'd fix an input or output jack should it wiggle a solder connection loose. So, I figured out how I'd go about it on a Minx.

I DO NOT GUARANTEE THIS WILL FIX YOUR AMP. Your jack may in fact have an internal problem. But you can at least eliminate that the problem if it is a broken solder joint.

My fix was much easier than yours will be though. I could easily get to the bottom of the little circuit board, which on the Minx is actually held by the speaker jack itself, without removing the main circuit board. There is nothing else securing that little circuit board, I just removed the jack nut and I could remove the little pc board. Piece of cake.

However, you will probably have to remove the main circuit board to get to the bottom of it which is where the soldering needs to be done for the input jack. I've never actually had to do this on a Microbass.

The logical steps should be to remove the volume and tone knobs. The plastic nuts holding the jacks, if any. The plastic nuts holding the volume tone pots, if any. The nuts will probably turn with your bare hand. While they may look like black metal, they may actually be plastic so don't use pliers or anything like that forcefully on the nuts or they'll scar all up. Next remove the screws holding the amp section in the cabinet. It will then slide out. (Be careful here not to put too much force on it. it should slide out either from the front or the back. Usually the back. If it does not slide out freely or seems hung, the speaker wire could be kinked or caught. If the speaker wire seems kinked or hung and you keep forcing it you could pull the speaker wire loose from the circuit board. To get around this, lie the amp flat on its back. remove the grill, the screws holding in the speaker and then remove the speaker. (Use care with the screwdriver around the paper cone of course.) Slowly lift the speaker until you can get to the speaker lugs. Note which colored wires go to which posts on the speaker and make a note of it. Then pull the lugs off the speaker terminals. They should slide off using finger force if you can and needle nose pliers if you have to, then completely remove the speaker and set it safely aside (avoid putting any pressure at all on the paper cone.) Once the speaker is out see if the speaker wire is caught or snagged. Sometimes pulling on the speaker wire from inside the speaker cabinet will help unkink it. The amp should now slide out freely.

Once the amp is out. You'll be able to see the circuit board. Look for how it is attached to the chassis. If there are any capacitors, (large cylindrical objects that look like batteries or such, )avoid them as you might get a shock. I've not been inside a Micro, but there were no big potent looking caps in the Minx. Once you figure out how the board is secured to the chassis (screw, plastic clips, whatever, remove them and slip the chassis back so the volume and tone pots slide out of the amp facing. There will be electrical connectors and possibly some transformer wires, power cables and so forth that will prevent you from lifting the front of the circuit board so you can see the bottom. If there are plastic connectors for these wires you can pull them apart and reconnect them when you are done. You may be able to lift the board straight up from the front without undoing any wires to see the bottom of the circuit board where the jack is soldered to the circuit board. While looking at the bottom of the printed circuit board, where the solder joints are, try wiggling the instrument input jack just a little and see if you can visibly see movement on any of the pins that extend from the jack into the circuit board. If you do, then that is the culprit one. There are two or maybe three pins from the input jack, I can't remember exactly. The jack may not wiggle at all if 2 of the pins are solidly connected, but a visual inspection might show you which pins seems to move or which joints look suspect. Even if you don't see anything suspect just CAREFULLY apply one bead of solder to each pin so that it contacts the pin and the circuit board and does not extend beyond the obvious contact point on the board for each pin. Overkill here would be a bad thing. Once all the jack pins are resoldered, let it cool for a minute. Take advantage of this minute to unplug and move the soldering iron during this time to a safe location away from the immediate area you are working in.

Now reassemble the amp in the reverse order in which you disassembled it. Cross your fingers. Fire it up. Plug in your axe. Give it a try. If you see smoke. Call 911. And the secretary will disavow any knowledge of my actions....

(If this doesn't work you might actually have a bad jack. Maybe a Peavey dealer will sell you one for a few bucks. OR you could buy one of the new MAX series amps. They sound pretty good and certainly are cheap. It would probably be better to by a new Max than pay someone $75 to fix yours if resoldering the jack or installing a new jack doesn't work.)

I really hope that helps you. I fixed mine. I think you can fix yours. Good luck Jim.

And finally, yes, as you said, it's rated for 4 ohms. That's what's printed on the back (although I'm not sure if the "4 ohms, 9V RMS, 20 watts" is for the speaker or for the amp.) The speaker is probably dying, as it seems to fart around a bit at lower registers (but that might just be the jack). Would it be feasible to uninstall the amp itself and use it separately with, say, a 2x12? All I'd really have to do is take out the amp itself, unhook the existing speaker, and wire it to a cab with the same ohmage...right? *sweat* Just a pet idea of mine, until I win the lottery and can buy a Kustom 8x10. :D

OK that rating label is for the AMP.

I'd fix the instrument jack before going any further. Anything beyond that right now is pretty much wasted time. Without a good input signal amps do all kinds of wacky stuff which could explain the unusual sounds.

The amp in the Micro is too small to push a bunch of speakers anyway and whatever you do don't go lower than 4 ohms. Actually TOO LITTLE wattage can damage otherwise good speakers by rubbing a spot in the voice coil. FURTHER IMPORTANT NOTICE: Once you remove the internal speaker you can NOT turn on the amp without having a cab connected or you could blow the amp. Also once you start drilling or otherwise customizing the amp it might make it more difficult to sell or trade later if you ever wanted to do so.

Yeah you could take the amp part out, but a better option for safety's sake would be to leave it in the cabinet and disconnect the internal speaker as I described in the speaker removal instructions in my previous post. Get a switchcraft jack, cut the lugs off the speaker wire, strip a quarter inch of insulation off the end of both speaker wires and solder the speaker wires to the jack with the POSITIVE connected to the tip contact lug on the jack, drill a hole large enough for the jack in the back of the speaker cab area or VERY carefully drill a hole on the back of the amp chassis. All these modifications are kinda time consuming and you risk doing something wrong and trashing the amp. Then mount the jack wherever you put the hole. Depending on the cab thickness, a jack may not mount on the back and you'll have to use a jack mounting plate. You can make one with a metal lid off a coffee can painted black. See how complicated this could get? It will be way easier to drill the cab than to drill the chassis. But the jack will mount easier on the chassis. Once you get your jack mounted you can then plug in a cab...but the combo's internal speaker will not work of course. A Micro isn't going to move a lot of air though even if you hook it up to some big speakers.

If I could make a suggestion, If what you want is a head, sometimes you can get a very reliable old Peavey head like my CENTURY 200 (100 watts @ 4 ohms) on eBay for under $50, plus shipping on eBay. Or at a pawn shop. I love my old Century. I've had it about 30 years. Wouldn't sell it either. You'll never move much air no matter how many speakers you connect to a MicroBass amp circuit. It is a practice amp, not a performance amp. It isn't meant to be real loud, just usable for home practice. I know you don't have much money, but you can't make a silk purse out of a sow's ear and I think that is what you might be after. It ain't happening brother.

Suggestion 2. IF (and that is a mighty BIG "IF") resoldering the input jack does FIX the input problem and the amp sounds way better, then take it to the lcoal Peavey dealer and see if he'll let you trade it in on a new Peavey or larger used Peavey. Or sell it on eBay. At any rate it sounds like the Microbass isn't what you want or need and you need to find some way to get a more versatile and more powerful bass amp.

There are good buys out there. With Christmas coming you'll see all kinds of used gear for sale real cheap on eBay as guys struggle to get money to impress girls with lavish gifts only to have the girls dump them later anyway and they'll be wishing they had their gear back!

Good luck....but based on what you are asking I think even if you get it working perfectly...you are still going to want a bigger amp. If you want a bigger amp, I'd buy a bigger amp. You can't Frankenstein this thing into a Firebass.

Regards,
Dave

Indeed, I suppose you're right.

I like this thing...I just want it to be louder than it is, if I ever play with a drummer. The last time I tried, it was pretty much all drums and a bit of guitar. No real bass, not when the drums got loud.

Any suggestions for the gain knob? I thought it was only scratchy, but it doesn't seem to actually be changing the sound at all. Is this a usual problem as well?

I'll check out the christmas deals on Ebay, that sounds like a good idea.

Indeed, I suppose you're right.

I like this thing...I just want it to be louder than it is, if I ever play with a drummer. The last time I tried, it was pretty much all drums and a bit of guitar. No real bass, not when the drums got loud.

Any suggestions for the gain knob? I thought it was only scratchy, but it doesn't seem to actually be changing the sound at all. Is this a usual problem as well?

I'll check out the christmas deals on Ebay, that sounds like a good idea.

Wow you like it that much? Ok, put a microphone in front of it. Run the microphone into the PA. It will be louder.

If you like the Micro, you'll love a good old (and usually pretty cheap) Century 200 head into a good 4 ohm cab or into two 8 ohm cabs. At about half volume you'll be heard just fine at rehearsal & you'll forget all about the Micro in about five seconds. They might ask you to turn it down.

MicroBass is a home practice amp. Home practice means no drummer, no guitarist, unless it is someone on bongos and an acoustic guitar. You could also mic one up to record. I've heard of people recording with them and with the Minx. You are trying to use your Micro for a rehearsal amp. That won't work unless you put a mic in front of it and feed it through the PA. I've tried the larger Minx-II for a rehearsal and it wasn't really adequate with our maniac drummer and the Minx-II has 50% more power and a bigger speaker than your Micro. I like the way my Minx sounds for home practice but it is not up to rehearsals.
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Second issue is the volume/gain control on your Micro. One or more of three things could be going on. The pot could be dirty. Or again, a bad input connection can cause all kinds of problems and could be the reason the gain isn't working and when you fix the input everything will be fine. I don't know that for sure, but it is possible. A third possibility is that the same stresses that cause the input jack problems can also happen to the volume/tone controls because they are mounted to the circuit board the same way as the input jack. While you have the circuit board flipped over put a bead on the gain pot pins just like the input jack pins. Make sure no solder leaves the obvious contact area where it should go. Stray solder is not a good thing.

Touching up these connections correctly while you have the amp open won't hurt. I mean really, it sounds like your Micro is at death's door right now anyway. The WORST that will happen is that you finish it off. If this doesn't work it is time to either put it out of its misery or take it to a real tech....who will charge you more that it is worth to fix.

This idea might be a longshot, but if there are any ELECTRONICS CLASSSES at a nearby high school, college or trade school they'll sometimes take items in for repair and only charge you for parts. The work is done by students under the supervision of an instructor who grades them on their repair "project." It helps to know someone at that school. I got a TV fixed like that once years ago. Just thought I'd mention it since you are low on dough. It will take time though and there is no telling when you'll get it back so don't be in a hurry.

Again, no guarantees. I'm basing this info on experience. If you or any of your IMF force should be caught or killed. The secretary will disavow any knowledge of your actions. Good luck!