Green Russian BMP V1 PCB

[modusmongo]

Hi everybody. I have done the true-bypass and AC adapter mods for my BMP and would like to go further - starting with a tone stack bypass foot switch. I have all the advice I can handle as far as what to do, but I can not find a photo of my PCB which tells me which component corresponds to which section of the BMP's design. I suppose now would be a good time to admit that I can not read a schematic - I'm willing to learn, but it's a slow process and I'm old ;D

For example, the tone bypass mods talk about "C1" and "R1". I can find plenty of photos for those sections for a NYC reissue, but I can not find them for my PCB (bm-1-01.00.000 green russian muff V1).

I imagine that there are others looking for this info as this PCB is tha same for the civil war and early green russians, so what I propose is that I create such a document with the help of someone here who has the time to match the 43 caps resistors and transistors in MY BMP to the BMP jargon used by everyone who talks about the pedal.

Here is an example of what I'd like to create:



And here is my PCB with all the components numbered.



Would some kind soul like to help me convert the numbers on my photo to the BMP component names? I sure would appreciate it. I've spent days searching the internet and I'm fed up ;-)

If you need a bigger pic of my PCB, its here.

Thanks!

[newey]

mm-

First off, I appreciate that you wanted to make the photos big, but they're so large they spill off the side horizontally and force horizontal scrolling. Please downsize those a bit.

Your PCB layout appears pretty similar to the other one you posted, it looks like a few minor differences at best. "R1" and "C1", for example, correspond to your nos. 16 and 17. Of course, we can't know that for sure without getting into the question of what connects to what- which means turning the PCB over and examining the traces, and then correlating those to the components.

Your 4 transistors, corresponding to Q1-Q4, are 14,15,29, and 43. The orange oval thingees are the capacitors, like 10 and 17, as well as the square ones like 5. There are a couple of oddball ones- your No. 39, and No. 34. 34 corresponds to C15 and is an electrolytic cap (meaning it has a + and - connection, it is polarized).

Everything that's not a capacitor or a transistor is a resistor. Some of the Russian resistors don't carry the std color striped coding, making it tougher to know what values those are. Also note that the example you posted doesn't number all of the resistors- there are several small ones that aren't numbered, for example between C5 and C6.

Your layout seems to roughly follow the other one, except around that area, C5 and C6, where your components are mounted vertically rather than horizontally. That may just represent a difference in the layout and not in the wiring, but again, we'd have to examine the PCB traces to know for sure.

Although you were unable to find a diagram of the Russian BMP, do you have a schematic of one? If we had a schematic (assuming it was known to be valid) it would be easier to match things up with your photo. I'd also suspect that someone probably published a comparison of the 2 schematics, noting any differences between the 2 versions.

[cynical1]

Well, I found a tracing of the PCB.



A very interesting history on the Russian Muffs...

...and a small catalog of schematics for the Russian Muffs...

However, I have no idea if any of this applies directly to your board.

But hey, I'm not the electronics guru...I'm just the Google-Fu guy...

Happy Trails

Cynical One

EDIT: The cheap and dirty way to resize an image is to click on MODIFY, then change the first tag to , with the "x" being your new pixel sizes. Finally, just click on Modify Post and your image will be resized without having to mess around with actually doing any real work...

[modusmongo]

Hi Newey and Cynical1. Thanks for your responses. I have resized the larger pic so you won't have to Hscroll ;-)

Here are 2 shots from the back, and from the front with good light showing through.




I appologise to the soldering gods for the disasters at C1 and R2. The pins were bent over prior to soldering and I couldn't figure out how to get them out delicately (any suggestions?)...

the tone stack bypass mod I want to do is here. The reason I got so ruffled was that I assumed that C1 and R1 corresponded to 17 and 16 respectively (in my pic above). I don't see either of these going directly to ground. I would love to simply grab the output of each one and run it to ground using a DPDT to cut the ground link and therefore bypass the circuit. I think that I am FAR from understanding this!

Cynical, Yes, the kitrae site is wonderful. It was there that i figured out that I had the early green with the civil war PCB. ps. I'm building an electric and have some woodworking questions for you! I'll post them over in Lutherie and Repair...

[modusmongo]

AND... Cynical, the PCB you found is indeed mine. I superimposed it over the pic of mine: I love Photoshop!

[sumgai]

newey,

mm's example was made my someone else. Those un-numbered thingies are diodes.


modus,

I need to see a correct schematic for your unit. Please post it here, or at least a link to it. Hopefully it's something that's easy to read!


sumgai

[newey]

mm's example was made my someone else. Those un-numbered thingies are diodes.

Ouch. That's what I get for posting before my first cup o' coffee. I did realize the example was from elsewhere.

[modusmongo]

Hi Sumgai, I found the "verified" schematics for all versions here. The schem I believe to be mine is this one.

According to the Kitrae site, My BMP is a V1 early Green Russian (schematic V7). It has the same PCB as the civil war muff, but a few component changes.

Noobie question: Can I get accurate resistance readings by testing the resistors while they are on the PCB? In other words, do I need to take them out (and disassociate them from the rest of the circuit) to find out what value they are? It'd be really helpful to at least know the resistor values. I see that most of them are color coded, so I could spend a few hours at the code color calculator site, but I imagine I could read all of them in 5 minutes if I could simply test them with the multimeter...

As far as my labeling project goes. I suppose that simply identifying the differences between my numbered PCB and the sample I found (both pics in my original post) would do the trick. What I'd like to have in the end is a definitive labeled version of my PCB showing all the BMP terminology "R1" "C1" etc.

Thanks to all for your help!

[ijustwannastrat]

I don't believe you'll be able to read them while they are on the board. However, it may be good experience to get used to reading the color values. It's not fun, but you'll start to remember the code. And there's no blue ones, so you don't even have to mess with multiple codes!

[modusmongo]

Hi IJWS. Yea, I'm finding that values on the PCB are different than values when pulled out. However, if one side of the resistor is direct to ground, the value seems to be okay on the PCB.

I'll learn to read them ;-)

That's a lovely body in your avatar! Did you carve that yourself? I'm working on something similar right now, but I'm not ready to present it (I'm a little embarrassed). My first guitar project...

[ijustwannastrat]

the value's aren't the same because there are parallel paths for electrons to move on.

Thank you very much about the body in my avatar! I bought the guitar from Warmoth (censored). I did actually carve a huge chunk out of the front side, though, for a piezo system. And I sanded the finish off, because the brown faded to red. But enough hijacking, that's just my "boredom" project....

[ashcatlt]

Apr 13, 2011 2:31:08 GMT -5 modusmongo said:

Hi IJWS. Yea, I'm finding that values on the PCB are different than values when pulled out. However, if one side of the resistor is direct to ground, the value seems to be okay on the PCB. .

That's only accidental, and probably because there's a cap or two around it. Don't rely on this.

You can get accurate readings by disconnecting one end of the resistor from the board. You don't have to take it all the way out.

[modusmongo]

WOW! Success! Inspired by our god of metal, I set to reading the schematic this morning and slowly tracing the input signal to the tone circuit. I found the 22k resistor going to ground and the 0.01 cap also going to ground. I cut the trace between the cap and ground because it was isolated. I then desoldered the ground end of the resistor and soldered the freed end to the ground end of the cap. I soldered a wire to the cap/resistor ground end and and ran it to a simple on/off stomp switch. I ran the return from the switch to the hole left where I desoldered the ground end of the resistor. ET VOILA! I have my nice crunchy BMP sound for rhythm, and when I step on the newly installed switch, it lifts the ground for the tone section and I get 6db of gain plus a good dose of 1k mids!

Lesson learned: I CAN read a schematic, if slowly.

ijustwannastrat: this would have been impossible if I couldn't read the resistor color codes. Thanks for your help!

[ijustwannastrat]

>.> you welcome. But, you figured out the code yourself. You took advice and ran with it.

Also, I may need to try this on my BMP. Sounds tasty.

[newey]

MM-glad you worked it out.

And from the tone of this thread, I'm half-expecting to hear a chorus of "Kumbaiyah" ;D ;D ;D

[cynical1]

Glad it worked out. So...when do we get to hear this mysterious little device?

HTC1