Quote from: SurreyNick on March 09, 2018, 04:12:19 PM
I'm confused.  I want to build Brian Wampler's modified MXR Distortion Plus but the board layout I have found produced by storyboardist on the Effects Layouts blog (http://effectslayouts.blogspot.co.uk/2015/07/wampler-distortion-plus-mods.html) differs from the schematic I found which is apparently the one produced by Brian Wampler and which appeared in the article in Premier Guitar.  They both claim to be from the same source though.  Are there two different Wampler mods to the MXR?

Both versions (see attached) have distortion, tone and volume pots, plus switches for smooth, bass and compression but the version on the Effects Layouts blog has 9 diodes instead of 8, has 7 resistors instead of 4, and has 9 capacitors instead of 7.  Some of the values are different too.

Am I going mad, and which of these two versions should I build?

The first schematic does not show the power supply filtering and reverse polarity diode protection.

That would account for some of the differences...

I didn't minutely compare both... try drawing a schematic for the second one and compare then...

Cool! 
Glad to read you guys got it fixed. 

Hey JM, you got some of that Magic Dust for sale?  :lmao:

I want/need some!   :loco

I've done this quite a bit... that is...drawing schematics from circuit boards.

Post #45 in this thread https://www.ssguitar.com/index.php?topic=3850.msg34578#msg34578

I describe the method I use to get a schematic from a circuit board.

Edit; it can be quite tedious... but if you really want a schematic... have at it.

Check the threads I have started in this section (Schematics and Layouts) of the forum.

Most of them have schematics I created using this method.

Quote from: lapsteelman on January 13, 2018, 11:42:55 PM
Haven't posted in awhile, just wanted to chime in and say a guitar player I was playing with got his hands on one of these.. I think he put a couple different speakers in the cabinet... but it sounded fantastic! REALLY great surf tone..

Nice!
Ya, they are cool amps.
I have no doubt it sounds better with different speakers. 

I started a project custom cabinet for mine and I need to get back at it.
Life stuff got in the way.... 

Pics...

Cool looking amp! 

Are those 12" speakers?

Quote from: lotus1 on December 20, 2017, 09:36:49 AM
Effected repairs, Had to use a 1ohm resistor instead of .5...It's alive!! Workd again and that very cool sound is being heard again, Once again, Thanks for all. Will try to post pics soon.M

Good to hear you got it working!
Looking forward to the pics. 

Almost "any" 50K pot with a rotary switch will work.

The differences will be in the mounting and knob spline (or lack thereof).
Check also the mounting hole size, although you can always open the hole if needed.

A quick google search found this...

http://www.goldmine-elec-products.com/prodinfo.asp?number=G20953

Use a knob with a set screw. It won't match the other knobs, but who cares...

Or google search images for "50K pot with switch"

https://www.google.ca/search?q=50k+pot+with+switch&rlz=1C1ASUC_enCA634CA634&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiM9N2byJHYAhVD4WMKHQmcBsEQ_AUICigB&biw=1920&bih=949

Look thru images and find one that's close.

You can always run wires from the pot to the board, no need to have the pot mounted directly to the board.

Edit; Or, just mount any old 50K pot and find a place for a separate toggle switch for distortion on/off.

Lots of ways to go with this, if you are not fussy about keeping it "original".

Quote from: lotus1 on December 16, 2017, 10:09:19 PM
1/2? Thanks.  Was told the transistors went bad, they were replaced but, resistors, no.and yes, he was lazy... Haven't gone in myself as without a schematic, I don't touch...or help. I will rectify both the resistors and shoddy wiring, will report back. Oh, and the amp was only used with the cabinet it came with, a 2x12...haven't measured cabinet Z yet, so...It does look like the original cabinet. Will post more pics in the morning,Thanks.<

Likely won't ever find a schematic, and that means you will have to draw it yourself.

The main board doesn't look very complicated, should be fairly easy.

What I do...

Take good pics of where everything hooks up to the board AND hand draw a picture of where every wire attaches.
Label accordingly. The more detailed you make this, the less chance for mistakes when re-installing the board.

Remove the board from the amp and scan the copper side.
Import the scan into a graphics program (I use paint.net).
Flip the image so you have a component side orientation, as if an X-ray from the top component side.
Print that, and hand draw the parts right on the picture.
Now you have a layout diagram.

Draw schematic from that.
I use Express PCB which is a free program and comes with Express SCH schematic drawing program.
You could also draw it by hand.
Several of my first attempts at drawing a schematic I did by hand.

HTH

Glad it was some help. 

Amp sound quite good. 

Nice Strat! I like natural finish on those. Was it always natural or did someone strip it?
Great playing/demo too.   :tu:

Oh ya, we'd be interested in seeing the schematics.  :dbtu:

Edit; I'll keep an eye out for those knobs.
I'm often browsing for vintage 70's amp stuff.

Cool amp! 

Agree with Enzo, those boards would be super easy to trace.

I remove the board from the amp and scan the copper side.
Then manipulate the image in a graphics program, (I use paint.net).
Print it off so the traces are seen as if looking xray view from the top (component side) of the board
and then hand draw the components right on the page.
Now I have a layout and an easy picture to draw a schematic.

Also, I've had 70's vintage SS amps that were hissy.
Usually changing preamp transistors to modern low(er) noise types helped greatly.
Seems like the front end is where most of the hiss usually originates.

I've seen knobs like that somewhere.... let me check... I'll be back...

Hmmm, faulty memory on the knobs...

I thought this guy had some   http://www.surplussales.com/shafthardware/Knobs/Index.html

but I don't see them in his list.
Still, you may want to scan through what he has, or maybe shoot him an email.
Maybe he can help?

I've bought stuff from him before, no issues, good vendor.

Got pics of the amp? 

Is the circuit board so complex that it would be difficult to trace/draw schematic?

Thanks for the pics!   :tu:

Looks like the reverb tank is "upside down" compared to both of the other ones.

I agree, all those iterations are a bit puzzling/amusing! 

Why? Who knows.    Different factory, different production run etc.

I too like the look of Fender knobs, but on these amps my personal preference is for the original knobs.
To each his own. 

Thanks again for sharing!  :tu:

Thanks for the pics. 

Interesting layout compared to the others.

Can you do a overall shot that shows the whole chassis.
Thanks!