Converted Peavey Deuce issues

[beasleybodyshop]

There is light at the end of this tunnel!
I have swapped the OT wires, those are good now. both channels are not affected by the Treble/Middle/Bass however. Moving those knobs around doesnt change the tone in any way. Channel one still works, however only when i have channel 2 past 8 o'clock. if i have channel two turned completely down no sound comes out of channel 1.

another weird thing about channel 2: as i am turning it down, right before it gets to 7 o"clock (all the way off) it makes a loud pop. Channel one volumes only work after i get channel 2 volumes above this "popping" sound. What does this mean?

when i disconnect the NFB, it just makes the amp go into screamo mode. Im going to try to connect it to the 16 ohm tap.

[Leo_Gnardo]

I'd expect a jump in gain with the NFB disconnected but not into screamo mode... sounds out of control.

Are you using new potentiometers or ones you rescued from the old Peavey?

[beasleybodyshop]

using new potentiometers. I found my eq issue - middle lug of the midrange wasnt connected

also, when I kick standby on and off, after a slight delay I hear a few loud pops.

I feel that issue with channel 2 lies in a dodgy connection between the ch. 2 input jacks and where the signals for both channels join back into one - gonna check that in the morning.

[Leo_Gnardo]

using new potentiometers. I found my eq issue - middle lug of the midrange wasnt connected[

That would do it. Also would act as an EQ bypass = more gain (Like MkI Boogie)

also, when I kick standby on and off, after a slight delay I hear a few loud pops.

Not too unusual. Caps charging is the usual explication. Snap crackle pop, let's rock.

I feel that issue with channel 2 lies in a dodgy connection between the ch. 2 input jacks and where the signals for both channels join back into one - gonna check that in the morning.

The # of problems is reducing. What troubleshooting is all about. Good work.

[beasleybodyshop]

I have triple checked all connections coming from channel 2 to where it joins back into ch. 1. The only thing i can conclude is the pot for volume 2 is bad - i can't really explain why turning volume 2 up kills the signal for channel 1.

Also i have discovered a connection between the treble control and presence - if i have treble turned down, and turn up the presence it doesn't squeal. If i turn the treble up and start cranking up the presence, then it starts to squeal. What does this mean? I checked my output with an RTA app i have, the presence squeal is around 13Khz.

Getting there!

[beasleybodyshop]

Ok, a little update. I have studied up on parasitic oscillation - sounds like that is my squealing issue. I have tried prodding and moving my signal wires around while the amp is on and oscillating, but i dont think im getting much difference. Here is a gut shot, could someone tell me where the problem lies?

[M Fowler]

The output is too close to the input.

That impedance selector and wires need to go near the speaker jacks nice short run.

[Leo_Gnardo]

Ok, a little update. I have studied up on parasitic oscillation - sounds like that is my squealing issue. I have tried prodding and moving my signal wires around while the amp is on and oscillating, but i dont think im getting much difference. Here is a gut shot, could someone tell me where the problem lies?

Looks like your signal flow is right to left, right? What's that big round thing just off to the right of the board? Looks like a big pot or switch. If that's the output impedance selector, it's mighty close to the input circuitry - there's a setup for ultrasonic oscillation. And that's what could be causing your signal shutdown, not a defective pot. When the amp starts turning out dog & bat frequencies, there goes your audio.

If it is the output selector try moving it to the back panel, get a couple inches between it, and all wiring to/from the OT, away from the input preamps.

- - - - - - - - - -

Now that I see the big pic, looks like the OT wires pop up thru the chassis, right under the preamp. Yikes! Join Mr. Fargen - I had to fix his #007 that had much the same. Here's what I did, and it worked:

Sandwich a piece of copper foil or sheet between 2 layers of fishpaper. Make it big enough so none of the pre circuitry can "see" the OT wiring thru your copper sandwich. (Imagine you're Superman, xray vision but can't see thru lead. Like that.) Solder a wire to the copper so you can ground it. Slip the copper sanny under the circus board, between the OT wires sprouting up, and the bottom of the board. Run ground wire to a convenient ground location, AWAY from the pre circuitry. Dress any other exposed OT wiring as far away from input as possible. Stir mix enjoy. Hope this does it for you.

[cbass]

The output is too close to the input.

That impedance selector and wires need to go near the speaker jacks nice short run.

YUP and you didn't follow the grounding scheme I showed you.Also try to get your wiring down against chassis as soon as it leaves its terminal. Your output wiring is running right against the plate for V1 that can;t help

[Reeltarded]

using new potentiometers. I found my eq issue - middle lug of the midrange wasnt connected

You might want to check that the middle lug of the midrange control is connected.

[beasleybodyshop]

The output is too close to the input.

That impedance selector and wires need to go near the speaker jacks nice short run.

YUP and you didn't follow the grounding scheme I showed you.Also try to get your wiring down against chassis as soon as it leaves its terminal. Your output wiring is running right against the plate for V1 that can;t help

I had completely forgot you had given me that grounding scheme, sorry. Once I move everything else around I will give it another go. It it the same as the "larry grounding" thing ive seen over at the metroamp forum?

[cbass]

yup thats it.Larry STudy that.First get them output wires away from yer preamp

[cbass]

You might try just hard wiring the speaker jack you need for now

[beasleybodyshop]

You might try just hard wiring the speaker jack you need for now

This. I think that's what I'm going to do once my speakers come in. The selector switch I bought is too bulky for most of the back panel; I can't seem to get any space between it and the sockets, which is why I stuck it in an unused reverb jack hole lol.

[beasleybodyshop]

Update: I have sandwiched the copper foil under the circuit board, and ran my OT wires underneath it. I have grounded the foil, far away from the preamp. I still get 13Khz squeal when i crank up both my treble and NFB. also when i play high notes it will squeal subtly as well.


What am I missing here? I even replaced the 47K NFB resistor. When I have it soldered into the board, it reads 4.5K, but when I take it off and its by itself, it reads 47K. what gives?