Need help trouble shooting peavey xl-500 mix amp

[Jazz P Bass]

Lots of knobs

Sounds like a Mackie board that I worked on.
Divided by 2.
312 knobs. 180 nuts.
All to fix a bad capacitor.

[captainlee]

Master board update #4

Hi Enzo,

Yes I still have the hum hooked up to another amp from the main on the master board and the volume will increase the hum.

So I switched out the new parts ( we have been working on)power board to another xr-500 and all works fine so the power board is fine yea yea. cause I had a great instructor.
So I'm going to trouble shoot that master board and all its components
over the next couple of weeks and i'll tell you any new news.
so Thanks for now and I'll be talking to you later for sure!!!

Thanks Cap.

[Enzo]

Look at the schematic. There is darn litle in the master main circuit.

[captainlee]

Master update #5

Hi Enzo,


The problem is in the effects section as I turn up the effects volume, on the master board, I get white noise mixed with the reverb not real bad but still there.??
any ideas

getting much closer. Cap.

[Enzo]

The Master stage is the one little IC. There are other things on its input, like FX return, so if THEY are noisy, then it will comeout the master. But those circuits are also tiny. SO if the reverb return is noisy, replace its chip.

Or even this: FInd the reverb IC and pull it from its socket. Now turn up the master, is hte noise gone?

[captainlee]

8 legged spider on master board?

Hello again , Enzo Hope you are feeling better.

So are we talking about the small 8 legged IC chip on the master board yes??
there is only one, and if so do you have a part number for allied or mouser I would prefer to buy from them. U1=7942--5532 PV part #. Thanks...Cap if this the right chip Ill test it on Monday morning and let you know.

[Jazz P Bass]

NJM5532 dual opamp

Link:NJM5532D NJR Op Amps
Here is a nice search site. It queries the major distributors.
Link:FindChips.com Search

[captainlee]

Serch for ic chips

Wow Thanks thats just what the captain needed!!!! and that's a mighty fine guitar you got there too. Cap.

[captainlee]

Broken leg

Hello all,


Yea, I broke the leg off of the IC so I'll have to order another one. It will be a week or so before I can get another one. I check back then thanks for now.
Cap.

[captainlee]

Peavey xr-500

Should be getting the parts tue or wed. Cap

[captainlee]

Peavey xr-500 back on line.

Hello Enzo,

So I put in the new part 5332 and it works good, plenty of volume sounds strong,
However the same problem with the effects volume control humming as it is turned up on the master board only. how shall I search for the problem.
Thanks for getting me this far. Cap.

p.s. both of my xr-500 have this same hum effects problem.

[Enzo]

There are two cables to the reverb pan, and they end at a white Molex plug where they connect to the main board. Disconnect that molex plug. is the hum still there?

[captainlee]

Peavey xr-500 back on line.

Hi Enzo,

Yes after disconnecting the cable from the master board , the molex plug., the hum is still there. So I have a small amount of hum mixed with reverb. Cap.

[Enzo]

Lets regroup.

With the channel board disconnected froom the master board, turning the MASter up increases hum. But turning the reverb down stops the hum? Hum is onl;y present with reverb up?


Not sure what a little hum with reverb means when the reverb is unplugged. You mean turning up the reverb control brings up some hum? Can't have any actual reverb when the reverb is unplugged, after all.

The reverb recovery is just the one op amp stage. If it hums a little, it may be a normal amount.

[captainlee]

Peavey xr-500 back on line.

Good evening Enzo, nice to hear from you.

There is a small amount of hum from the amp itself but when you turn up the effects volume it gets louder and is mixed with the reverb when all connector are plugged in. when you unplug the reverb cable the hum still increases it is the same minus the reverb. The hum is loud enought to muffle the reverb.

So it must be in the main amp board.
i have replaced most of the parts on that board.??