HELP with my MXR PHASE 90 MODS. PLEASE!!

[brokenstarguitar]

Im new to the modding world nd I cant read schematics yet but im doing pretty good modding some things. I do need some help with this though. Now, I did the script mod, no toggle yet nd waiting for the 1m pot to arrive to R20. My question is, theres a mod to replace R27 for a 250k resistor but I cant find one in the local stores, the closest are 220k and 330k. Would it b ok to replace R27 with the 220k instead of the recommended 250k? Nd what would the difference b? Also if someone can post pictures of the pulsing light mod (atm its easier to see pictures than read schematics) thatd b great. Any and all recommendations would b great. Thanks in advance.

[Mark Hammer]

One can always replace a resistor that's NOT in your parts bin with a "McDonald's arch" of two other values that you DO have, which sum up to the same value as the one you're missing.

[brokenstarguitar]

So 2 125ks will do? Nd what u mean by arch? Like just put the 2 in as if they were glued together?

[Mark Hammer]

Solder two ends together, a few mm from the body of the resistor, bend them over to fit in the same space on the board as a single resistor, and solder them into place.  100k + 150k makes for 250k exactly, and uses two standard values.

Of course, I have no idea what's in your parts bin.

[Blitz Krieg]

Nobody has the same pedal as you so pictures aren't going to help with the pulsing LED mod.

[brokenstarguitar]

Ok sorry ppl but im new to the mod thing so pls bare with me. Im in the middle of the Script mod, ive removed R28, C11, nd C12. Replaced C4 nd C2 with .047uf caps. Put jumpers on R30 nd R 34 in each others place nd put a 1m pot on R20 nd im not getting a signal when the pedal is on. What could I have done wrong? Heres a pic of the work. Ive tried the wires from R20 in different ways as well.


http://s23.photobucket.com/user/myssinwally/media/Mobile%20Uploads/20140611_225336.jpg.html?sort=3&o=0

[armdnrdy]

The image of the board could be a bit more clear but....I believe that your board is double sided...which means that you have to solder the pads on both sides of the board.



If you look at the red arrow that I drew...you'll see the jumper that you installed with a trace going to an IC. That connection isn't being made because you didn't solder the top pad.

You have to go through the board and solder all of the top pads for all of the components that you changed.

[brokenstarguitar]

Sorry to b so dumb but pads? Is that another word for the pot? Nd I uploaded a few more pics in that album. Just scroll through it. Thank yous so much. I just want this working again lol.

[armdnrdy]

The pads are the round areas on the board with the holes that the resistors, capacitors, wire, etc. go through.

They're called solder pads. My red arrow is pointing to one. You need to solder the pads on both sides on a double sided board. Connections are made from one side of the board to the other through these solder joints.

[brokenstarguitar]

Oh ok. I resoldered them on top nd bottom but still nothing. I get a clean signal when its off though.

[armdnrdy]

ive removed R28, C11, nd C12. Replaced C4 nd C2 with .047uf caps. Put jumpers on R30 nd R 34 in each others place nd put a 1m pot on R20

Did you solder all of the above (including the pot wires) on both sides of the board?

The resistor and capacitor leads that you removed may be making a connection between both sides of the board.

Since I can't see the complete board routing in the photo...it is best if you go through and solder a small piece of wire in each pad of the components that you removed on both sides of the board.

[armdnrdy]

This is what a double sided board looks like from the side. The component leads can connect parts of the circuit from one side to the other.



Do you see the image that says two free vias? Then something about homemade wire? That's what you need to do to the components that you removed. Put a small piece of wire in the hole and solder it on both sides.

[brokenstarguitar]

It was working fine with the new caps. This issue started when I took off R20, R30 nd R34 to add the pot. Ill take them all off nd put them back on but the solder looks good nd isnt touching anything else. Ill update when finished. Thank you.

[armdnrdy]

It was working fine with the new caps. This issue started when I took off R20, R30 nd R34 to add the pot. Ill take them all off nd put them back on but the solder looks good nd isnt touching anything else. Ill update when finished. Thank you.

You need to solder the pot wires on both sides of the board.

[armdnrdy]

the solder looks good nd isnt touching anything else.

I think you misunderstood one of my statements.

The resistor and capacitor leads that you removed may be making a connection between both sides of the board.


That should read: The resistor and capacitor leads that you removed may need to make a connection between both sides of the board.

[brokenstarguitar]

Im totally gonna set this thing on fire. I took everything off nd resoldered it all back on nd still nothing. I really dont get this. All thus to add a depth control. Smh.

[bluebunny]

That's a very handy diagram, Larry.  And a useful reminder that not all the boards we play with are plated through.  Needs a sticky all of its own.

[armdnrdy]

If your P90 isn't a smoldering pile of ash...and you want to take another stab at getting it going again....you're going to have to be patient and wrap your head around what I've been trying to explain to you.

I found this on another site:
Then locate R28 (right above the output jack) and clip one end off. You can clip the resistor out at both ends if you like, or just cut one end and raise it enough to break the connection.
Do not desolder the resistor! I can't stress this enough – one of the through-plated holes also serve as a pathway between the two sides of the circuit board, and it is very easy to damage it (leaving you with a dead pedal). A pair of small cutting pliers is all you need, and will keep the pedal safe and working fine.

This is what I have been talking about. By removing components on this double sided board you have broken the circuit. You now have to complete the circuit from one side of the board to the other. Take some time and study the image of the double sided board that I posted. The green is the fiberglass board and the red is the copper traces. You'll see some of the red area jumping from one side of the board to the other via the resistor lead.

[brokenstarguitar]

oh. ok i understand. Now, how do i find the schematic for my board? (well for the R16, R20, R30, R31, R34) Ive looked through the ones i have and google but can seem to find them....