Quote from: crane on October 25, 2010, 02:14:02 PM
Thanx for your replies!
Sometimes pulling out tubes is not an option (in case of a stubborn guitar player - not me)
My main need is to get a nice tone for playing gigs.

OK,, Rock or Metal?

If Rock/Blues ,,,, then you are missing out on something great. 8|
Pull the 2 tubes as JMF mentioned,,, or better still install a switch allowing you to switch them on and off at will. (just find and old Mesa circuit to see how simple it is to do)

This mismatches the OT and really helps to thicken the tone.
(Should be standard on ALL 100 Watt Heads)
IME the Amp looses little SPL by doing this but does enhance the tone.
You will get a much fatter sound.
You can also install a Dana Voltage Reg Kit along with the above.
This will give you SPL control so the amp stays in the magic zone without deafening the crowds. (You do have thousands of Fans I hope? Winky)

you can hunt down King TUT's Power scaling circuit (very similar to Dana idea)
Google *LondonPower Kevin O'Conner* you will soon catch on.

As to Metal,, never really was interested in playing power chords or blinding fast riffs that make no music melody,, (shrugg) but hey it's a free world.
If that your bag then Others here will have plenty of ideas for you I'm sure.
Phil.

Hi,
   In that case your clean is not being switched to ground.
The likely culprit is the Foot Sw is faulty,, or whatever part does the switching.
Phil.

Well spotted Joe cool,, Good to know someone is awake.
Yep I once wrote out a 10 page answer to a 2 year old posting.   
Phil.

Hi,
    You will find weber mass Attenuator schematics here:
http://www.freestompboxes.org/viewtopic.php?f=2&t=2287

*First posting on the page ,,3 schemos :tu:

AFAIK, you don't need to log in to view the links or whatever you call um?

100 Watts      oh you poor soul, 
It will make your job so much easier by doing this with small amps.
Hint.

As long as you understand the down side to these things and are prepaired to work with less than ideal sonic reproduction then yep it might work for you.
It depends greatly on what exactly you want to achieve with Attenuation.
i.e. Bedroom practice/ Recording/ Live use.
Have fun, Phil.

Whoops,, Laney,, Peavy,, darn they sound the same.
Yep pot's can be a nightmare to get the same ones.
Phil.

 Continuity test on the guitar or just Check the hum with another guitar.
I'd seriously consider establishing whats wrong before outlaying money on gear that may not solve the problem.
Phil.

kin0,
I quote from your first post:
""I think I will be able to build a head if I'll take it slowly.""
Good advice, Winky.

Then; ""Any suggestions what to do or to build?""

It's already been said.

Concentrate on the preamp first,, and try *ever so hard* to keep it simple.
RodE's site has already been mentioned and there is tons of stuff you need to know on that site.
Read Teemu's Free PDF book downloadable here.

Sorry chum but you give the impression that you just have to ask the right people and it will all fall into place.
Some of your ideas would take weeks for even the hardened hobby chap to pull together.
For a novice that will likely convert to years of effort.
That said it can be very rewarding if you are very pa-pa-patient.
If you consider time an enemy,, then just purchase something already made or search these pages as I'm sure a few here have already done what you ask and a lot of research has gone into it.
It's up to you to find these postings and ask them for advice. Hey man they are not going to come to you. So Time to go dig
Cheers, Phil.

Guys a couple of points,

1/ Is that a *circuit-braker* on the top corner?
If so, Whatzit there for? Headscratch??

2/ The solder pad that CT's the 2 main Caps,, looks like it has let go.

cheers, Phil.

While you have the glowing bulb,,,,
Measure the Voltage on the speaker terminals.

And Both voltage rails while you are there.
Your in good hands with Mr Fahey :tu:
Phil.

Ouch,, Yep I'm not suprised,, I did that with a Fender Performer.
Welcome to the world of cheap plastic crap

you can get them back together but it's delicate work.
you have to re punch the end again to spead it tight into the plastic holder.

If I remember correctly you are in Australia?
The Alpha Pots sold by DickSmith and Jaycar will fit into a lot of peavey Amps but they are metric and Peavy use Imperial shafts and knobs and such won't fit so you will need to adapt stuff.

The One thing I hate the most is trying to fix or replace pots.
I wish the world used standard stuff it would make life so much simpler.
Phil.

I'd be finding out if the pots are available *Before* Attempting any ressurection.

The Peavy stuff I've worked on have imperial pots (Not Metric) and fancy brackets soldered to the board. I can't get replacements for them where I live.

They are often a pain to get out/off the PCB so if you break one,,what then? cry.
A scratchy pot at least still works :tu:
Just my thoughts on it

Nice recondition job BTW,
Phil.

Just MO,,
But I'm yet to hear a good convincing ZOOM efx unit.
But then I don't use EFX units.

I find Analog stuff much more real world. 8|

I did have a Zoom 9020 with floor pedal = Crap Fruitloop lolipop machine and friggin noisy.  :trouble Long gone Thank God.

Also had (and still Have) A Quadraverb GT.

The Zoom was A toy and the Quad was at least a stunning piece of equipment that although a pian in the ass to use sounded real.
The Quad is now used in a small PA rig where it's fantastic reverbs are put to use on Vocals.
Phil.

Quote from: EDWARDEFFECT1 on September 24, 2010, 03:24:34 PM
i replaced the tank with a good working tank and the amp still hums.i tested the rca leads with an ohm meter and all four leads test @ .2 ohms.do you have any other ideas...thanks for your help.if i ground the input tip to sleeve the hum goes away...if that helps.....thanks....ed!!

Hi Ed-fect,
               Reverb tank next to transformer :loco
Don't ya just love the professionalism shown in there design and layout of commponents. :lmao:

Anyone Armed with only half a drunk brain cell knows how prone Reverb tanks are to picking up hum.
Sadly this is not uncommon in even big name equipment.
yes you See *Hartke* and you assume they know the basics,,, obviously not!!

Get that tank as far away from the transformer as possible, Rewire it all if need be.

Make darn sure the Metal Case is grounded correctly.
mostly they are grounded at one (And only ONE) Point.
More often than not the pickup End also Grounds the Reverb Case.
Never ground both input and output commons,, one common has to float.
Pull the tank out completely disconnect it then with a DMM establish which common is connected to the Case.
One of the 2 ground Lugs will be directly connected to the tank Case.
If none (or Both) then you just found part of the problem.

Also be aware that Most Rev Tanks have no bottom and often the PU end just picks up all and sundry noise floating around,,
(you need to point the open end AWAY from any RFI)
Don't think by bolting a big sheet of metal on the bottom will fix hum issues because you will create a resonant chamber which will probably start to feedback and squeal at the most critical moment.

The Tank is open for very good reason,, they need to be acoustically DEAD. An open bottom is the most obvious way to do such things.
I notice Accutronics now use a cheap piece of cardboard as a bottom plate.
It matters little in Fender type Amps because they are mostly mounted inside a big vinyl bag anyway which offers enough protection when screwed to bottom panel.

If the tank is one of those small cheapies like some amp builders who just screw them to the Cabinet board with rubber grommets being the only shock absorber.
This is just plain stupid and shows Zero understanding of how it should be done.

The other part of the issue is quite hard to get your head around but I'll give it a go.

I Quote you here;

"if I ground the input tip to sleeve the hum goes away...if that helps.....thanks....ed!!

I'll assume you refer to the Reverb PU return cable?
Likely culprit is to much gain on the PU circuit.

Most Amp circuits rely heavily on BIG Gains at the PU end to capture the reverb effect. This saves them a lot in parts count (Read As $Profit Margin$) as the Driver end is where it all should be done but harder to do.$$$

If the Driver end is strong (Most are not) then you only need a small amount of gain (hence less noise) at the PU end for a strong Convincing Reverb.

The result of Hi gain return path is as you have described here,, when you turn up the reverb you get a lot of noise/hiss/hummm introduced back into the Audio path.

Sadly (more often than not) there is no easy fix or work around.
All I can offer you is to Disconnect the Reverb unit (Perminantly) and go get a seperate Rev unit.

After many years of frustration I Built my own Reverb unit and except for the slightest rise in hiss (mainly transistor noise or boltzmans resistor noise)
It's Dead quite,,, even when Reverb is on TEN.
(I will quite glady put it up against the BEST Spring Reverb units Ever built, including the Bottle powered units, Not claiming it's BETTER but just as good.  )

Which proves that If a humble hobby nerd like me can build a stunning reverb circuit with only limited ability and electronic Skills,,,,
Then one can only assume that Big Brand names does not mean the best brains are working on your beloved Amp circuit.

As to the channel switching issues,, well I'll leave that to the chaps who are better qualified to pass comment.
Hope you get it sorted soon.
Cheers, Phil.

Quote from: christopherrgerhardt on September 21, 2010, 05:30:59 PM

Quote from: phatt on September 20, 2010, 04:52:07 AM
Hi Chris xyz, (not even gonna try to spell it)

If knocking the tank produces sound then the pickup end is working but the driver end will likely need work.

Now that's helpful!

The change-out is fine, it's a match. How would you go about finding and testing the drivers?

I test them by wiring a small speaker (i.e. small computer spk) to the *Driver end*.
If sound comes out that small speaker then the driver part is at least functioning,,, how well is a little harder to write about.
Judging from Enzo's comments,, i.e. if it is indeed a peizo unit then Hard to know as I've not played around with one of those.

I need more info:
Try looking at the transducer (inside the rev Tank/tube)
Does it have a small magnet passing through an iron core?
Magnetic units look like a very small transformer and a small magnet sits inside the iron core.
The spring wire passes through the centre of this tiny magnet.

Enzo has already explained the peizo concept for you.
So you really need to establish what the hell we are all talking about before we can be of much use.
Cheers, Phil.

Hi Chris xyz, (not even gonna try to spell it)

If knocking the tank produces sound then the pickup end is working but the driver end will likely need work.

If you have changed the tank then there maybe a complete mismatch,,, Reverb tanks can be quite different and more often than not a simple swap does not work.

I have no idea what this *Cardboard tank* contains as I've never heard of such a thing.
At a guess it's a very different drive unit.
You might start by measuring the DC resistance of the *Driver coil*,, or Transducer,, note the reading,, then check the new tank *Drive coil*

If they are very different in Ohms reading then you may have found the problem.
A Driver transducer that reads 2,000 Ohms  will not work in a circuit that needs 4 Ohms.
Phil.