A wierd high pitched squeal. - PLEASE CLOSE

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

I have a Nashville 400, and I was getting a high pitched squeal when I turned up the reverb. I changed the cable, that I got from another forum member, that goes from the tank to the chassis. No difference. The problem started when I tried to solder the wires to the pins in the chassis like people suggest, to get rid of the Molex plug. I accidently dripped some solder on the PC board. I was able to scrape all the solder off the board.

So, I just unplugged the tank and use the RP155 I have in the front effects loop for reverb. In response to a thread about a NV400 turning on and off by itself, I pulled my chassis to take some pics for the author. I did the unplug/re-plug all wires with connectors and put it back in. So, I plug the tank back in, and to my surprise, there was no high pitched squeal unless you turned the reverb up way past what someone would probably turn it. I was a happy camper. Now I can use the RP for other effects, and put it on the floor next to my volume pedal. I know I can still do that, but I prefer the reverb in the effects loop.

So, I go to my gig on Friday night. After I set up, I turn my amp on to check things out before the gig. The bartender chick and a few other guys start complaining of an obnoxious high pitched squealing noise. I am about 12 inched from my speaker at this gig, and I hear no squeal. I turn off the amp and they can't hear it any longer. I turn it back on, and they complain again. Turning the volume and post gain all the way down helps, but doesn't totally get rid of it. I have my bass player and the singer in the band stick their ears to the grill cloth on the amp. There was also a guy in the crowd that was an engineer, with a specialty in sound engineering. He couldn't hear anything but the usual buzz that we get at certain venues. They hear nothing. So, I turn the verb all the way down and put the RP in the effects loop.

How can they hear something that others can't hear?

Now, I am going to pull the spring completely out of my amp and try to mount the RP onto the floor of the amp, and mount a small power strip or a "Y" power connector to have one plug power both the amp and RP. Does anyone see any problem with doing this?
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

Bo Borland · From: South Jersey -

I had a similar issue Friday night. It was the reverb pan connectors in my NV112.

It started as a buzz that got.louder when I unplugged my cable to.the input, when I turned up the reverb it squealed like a pig. A little manipulation of the reverb bag and moped plugs and it went away. For now

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

The sound was not audible from the speaker. Myself and three others confirmed that.
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

Two runs at the test. 13,281 and 13,526 with Senn heiser headphones.
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

And, back before I had to stop using the reverb, I could hear the sqeal just fine. It seems to only squeal a really, really high frequency now.

The girl singer in the band is 26. She couldn't hear it with her ear on the grill cloth. One of the guys that could hear it is in his 60's and a rock musician. One of the true wonders of the world.
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

Peter Harris · From: South Australia, Australia

I get a high-pitched squeal like that everytime I come home with a new piece of musical equipment..

...lately I've taken to bringing them in from the car after dark.. that seems to have fixed it! Laughing

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If my wife is reading this, I don't have much stuff....really!

Ken Fox · From: Nashville GA USA

We had that problem a few times in mods we did using the Burr Brown chips in the reverb drive/ recovery stages. One chip has two op amps and does both functions in that position. I finally quit using the BB chips in the reverb section all together. The older Opa2604 was more prone to do that than the Opa2134.
The chip actually goes into oscillation at a frequency above 10K Hz at full output. It was rare but did happen. If you still have an old chip you can try it in the reverb circuit and see if that solves it.
As you said it was very high pitched and at a very low volume.
Also a loose ground to the input side of the tank will cause it to squel like spit, too. That is why the Molex connecter must be have a tight fit

Ken Fox · From: Nashville GA USA

Here is a copy of the original Peavey mod using the same OPA2604 chips in the reverb drive, just as I was doing back then. I circled the reverb chip for you

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

I upgraded all chips to the 2134's. And that was when I tried the soldering of the reverb wires and when the squealing problem appeared.
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

Ken Fox · From: Nashville GA USA

Did you get a kit from me? My kit only has 5 chips now. There was a time when I included one for the reverb but stopped that a while back.

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

You did the original mod. After you recommended the the 2134 chips, I bought some and replaced them. I think their were 6 or 7 of them. Should I change the reverb chip to the one you did in the mod, or the one that Peavey had in there originally?
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

Ken Fox · From: Nashville GA USA

Use the original Peavey chip for reverb.

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

What is the number for the original chip. I have moved twice since you did the mod, and I can't find the bag of old parts you sent me.
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

Ken Fox · From: Nashville GA USA

4558.

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

Thanks Ken.
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

Michael Brebes · From: Northridge CA

I've run into situations where equipment was emitting a 20KHz whine and no one could hear it but me. Would only last a couple minutes before I had to leave! Some people can hear those frequencies and some people can't. They thought I was nuts until we put a spectrum analyzer in the room and found out the approximate frequency. Some of it has to do with age, but there are some people, like me that can hear things over 20KHz, and I'm almost 63.
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Michael Brebes
Instrument/amp/ pickup repair
MSA D10 Classic/Rickenbacher B6/
Dickerson MOTS/Dobro D32 Hawaiian/
Goldtone Paul Beard Reso

Mesa Boogie Studio Pre/Hafler 3000
RP1/MPX100

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

What really puzzles me is, I could hear the high ptiched squeal prior to me re-plugging all connectors in the inside of the chassis prior to plugging the reverb back in. That squeal disappeared. I assumed it was fixed, but maybe it was also emmiting that squeal they were hearing that I, my bass player, and girl singer (who is 26, making the age aspect a little flawed) couldn't hear.

I will replace the op amp to the one that was originally in the amp and see if that works. Of course, I won't know unless someone who can hear it tells me.
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

John Billings · From: Ohio, USA

Donny,
I blitzed out at 3400. Pitiful! But I have terrible Tinnitus.
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'91 Tele with 60's Maple neck
Dozen more guitars!
Dozens of amps, but SF Quad reverb, Rick Johnson cabs. JBL 15, '64 Vibroverb for at home.
'52 and '56 Pro Amps

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

Still not fixed

I installed a new 4558 opamp in U5 (reverb), and it actually got worse. Now, even with the reverb control all the way down, and the pregain all the way down, it squeals when I start to turn the postgain control up. It stops when I take the reverb spring out of the circuit. I have tightened up the female pins in the Molex plug. The RCA connectors at the pan are clean and look good.

Any more ideas?
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

Lane Gray · From: Topeka, KS

Send it to Mike Brown. You've been futzing with it long enough. Pull chassis and pan.
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2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects

Ken Fox · From: Nashville GA USA

Pull terh tank out and make sure it is floating freely on the 4 suspension springs. I have seen the pan get stuck on top of one of the two metal post and it will squeal like a pig,

Other than that try another tank

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

Ken... It moves freely.

Well, I decided to get my meter out and this is what I got. This is with the tank removed from the amp. I have no clue as to how the tank works. I don't know how they number they prongs in a Molex plug, so I will name them 1 through 5, with 1 being at the arrow part of the plug.

With the pan disconnected, with neither of the RCA plugs plugged in:

On the input side (cable not plugged in): I get no continuity between the black wire lug and the tank cover. I get continuity between both the black and green wire lugs.

No continuity between the black wire lugs on both jacks. No continuity between the green wire lugs on both jacks.

On the output side (cable not plugged in): I get continuity between the ground lug (black) and the cover. Also get the half second beep between the black and green lugs on the jack, and also between green and the cover. I also get the half second beep between either the black or green lugs to all 3 springs.

With just the output RCA plug inserted: I get continuity from the ground lug on the jack to the cover. I get continuity between the ground (black) and hot (green) on the jack for maybe half a second. Constant continuity between the black lug and anything in the tank.

With just the input RCA plug inserted: No continuity between the black wire lug and anything metal in the pan.Constant continuity between black and green lugs on the jack. No continuity between the green lug and anything metal, including the springs.

With both plugs inserted:Continuity between the black lug on the output jack to anything metal. Half second Continuity between black lug on output jack to pin 4 in molex. Constant Continuity between green lug on output jack to pin 5. Half second Continuity between pins 4 and 5 on molex. HAlf second Continuity between green lug on output jack to anything metal.

The cable by itself: Continuity between pin 1 in plug to center pin on input RCA plug. Continuity between pin 2 and the outside of the input RCA plug. Continuity between pin 4 in plug to center pin on output RCA plug. Continuity between pin 5 and the outside of the output RCA plug.

Damn. I think it's nap time.

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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

Forgot to mention, the reverb does work, but it has that squeal.
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting.

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

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