Boss PH-1r

[R.G.]

I recently ran into the need to fix one of these more quickly than I can trace it out. The owner's a friend and is only going to be here for one day.

Anyone have a pointer to the schematic for the Boss PH-1r? I have almost every other Boss schemo, but not this one or the PH-1.

[Ry]

There isn't a schematic of the PH-1r floating around that I've ever seen, but I emailed you the PH-1.  I have a PH-1r that I can double check against the one you have if it would help.  Mine distorts a little, though.

Ry

[R.G.]

Thanks, Ry! Any checking would be great!

[Ry]

Okay, I cracked mine open.  Let me know if you want any measurements to compare against in the morning.

[Mark Hammer]

You may likely want more information than this, but as near as I can tell, the PH-1r is simply a PH-1 with a regen control, and the variable feedback path that implies.

Or is there some sort of major design shift between the two?

[R.G.]

Problem is, I don't know. I won't see it for a few days. For once, I'm trying to get ahead of the curve.

[slideman82]

I recently ran into the need to fix one of these more quickly than I can trace it out. The owner's a friend and is only going to be here for one day.

Anyone have a pointer to the schematic for the Boss PH-1r? I have almost every other Boss schemo, but not this one or the PH-1.

Hi RG! Well, I posted about the SYB3 bass synth schemo, does it exist?

[Ry]

Search is my friend:

http://www.diystompboxes.com/smfforum/index.php?topic=56852.0

Has the PH-1 schematic and board layout.  The thread also has a link to top and bottom side of the PH-1r board.  They are both 4-stage phasers.  The PH-1r model uses three dual op-amps for the signal path and a TL022 for the oscillator, the PH-1 has two quad op amps for everything.  The idea should be generally the same, though.

This link has a much better shot of the top side of the board:

http://www.diystompboxes.com/smfforum/index.php?topic=63098.0

This thread has some more info:

http://www.diystompboxes.com/smfforum/index.php?topic=28758.0

[R.G.]

Hi RG! Well, I posted about the SYB3 bass synth schemo, does it exist?

I've never seen it, or don't remember it by that name.

[R.G.]

Search is my friend:

Well, don't I feel like a yo-yo! 

I usually remember all the schemos that cross this board, didn't remember that one, and so I didn't go do the due-dilligence search - in spite of pounding google into powder.

Thanks!

Given a top and a bottom, how far away can a schematic be? 

R.G.

[Ry]

Given a top and a bottom, how far away can a schematic be?

If anyone is having a go at tracing it out for a schematic, I have mine open and ready to check component values and connections.  I just don't have the time to draw it up myself right now.   

[R.G.]

I'm reversing the schematic from the two photos you left pointers to. Unfortunately, almost none of the parts values can be read from those photos, so I may ask you to write component values into a parts layout if you're willing.

A refresher on tracing for people who have not seen it before.

1. Obtain high res pictures of top and bottom side of the PCB. The higher the res, the better.
2. Using a photo retouching program, crop both to just the PCB outline. Mirror the bottom picture once so it's like you're looking through the PCB at the traces.
3. In the photo program, put the bottom picture on one layer. Stretch/shrink/distort it to get the best possible flat-PCB image. While you're at it, make it big enough to cover most of a letter sized sheet of paper.
4. Add another layer on top of that. In this layer, draw in lines of something like light gray wherever there's a trace. Make the lines about as wide as the traces. Draw an outline of the PCB.
5. Add another layer; on this one draw in filled circles for pads. Make these the same color as the traces. It's easier to tell where the traces go if you draw them first.
6. Add another layer. On this one, import the picture of the top/components. Stack the traces layer on top of this one, then stretch/shrink/distort the picture of the component side to fit the outline of the bottom side.
7. Add another layer. On this layer, draw PCB-style parts outlines of the parts IN THEIR PROPER POSITIONS.
8. Make the bottom and top side photos invisible. What you're left with is the PCB pads, the traces, and the component positions. The will not all match perfectly. Go make them do that, turning on the photo layers as needed.
9. When you have a PCB layout, start drawing the schematic from it. You know from the wiring where the input comes in, the output goes out, where the battery comes in , where ground is, etc. You can figure the rest out.
10. Either as you go along or all at once at the end, figure out parts values and  annotate the schematic.

I'm in step 9 in the PH-1r. I will not be able to do step 10 from these photos because they are not detailed enough. In fact parts of the schematic will have to be handwaved because I can't fully figure out where the traces go. But I'll get enough.

As it turns out, the PH-1r is different from the PH-1; the JFET phase stages use the drain-feedback method of linearization of the JFETs as well as a regen control.

[Ry]

Sure thing, I'll start drawing something up.

[R.G.]

Wait! Don't do that. Let me send you the parts layout so you don't have to draw. I'll email it to you.