still have an mxr phase 90 problem

Started by sgmodel, October 12, 2006, 04:45:48 PM

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sgmodel

i have posted my problem with the mxr phase 90, i been trying to figure out the debugging page and i have n idea where to start really i have my volt meter and I'm trying to trace the back of my board but i don't have a good enough schem and I'm just clueless the problem was its a completley dead unit it did work but unforuntaly its dead and it was just out of nowhere

boogietube

Here's a schematic at tonepad the layout is different but the schem is probably similar (pdf file)
http://www.tonepad.com/getFileInfo.asp?id=42
Pedals Built- Morley ABC Box, Fultone A/B Box, DIY Stompboxes True Bypass box, GGG Drop in Wah, AMZ Mosfet Boost, ROG Flipster, ROG Tonemender, Tonepad Big Muff Pi.
On the bench:  Rebote 2.5,  Dr Boogie, TS808

sgmodel

that isn't really gonna help me, what I'm faced with right now I'm not getting any power from the input jack from what i see theres 3 pins on the back side of the board for the AC jack one pin leads to the battery positive side and the other two are just grid.
i really don't want to bring this to someone and pay for them to fix it plus i like the pride factor when actually get something working correctly

R.G.

Quotei really don't want to bring this to someone and pay for them to fix it plus i like the pride factor when actually get something working correctly
Cool. Good motivation.

Here's what you need to do.
1. Get that schematic from Tonepad, Aron's schematics, General Guitar Gadgets, maybe other places. The schematic tells you the electrical connections of the parts.
2. Learn enough to be able to find a part on the board by referring to the schematic and tracking it down on the board. It would be helpful to you if the parts placement diagram for your board existed so you could tell just by looking at the diagram where R23 is; unfortunately, to the best of my knowledge it's not available. Does the board have notations of which part is which? If not, either you or someone else is going to have to be able to get a part name from the schematic, then go find it on the board. This may take some effort.
3. After that, you can start on measuring voltages on the pins of certain parts on the board and we can point you to what to measure and what's probably wrong.
4. You can then be really proud because you're a whole step better at electronics than you were.

It might work to take detailed pictures of the top and bottom of the board so someone else could find parts for you to measure. But it will be slow that way.

There is one possible short cut. Since it happened quickly, it is possible it was plugged into a wrong-polarity power supply and that incident popped the power protection diode. If so, test that diode for shorted. This happens a lot. Without seeing the board I can't point you to where it is.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

Jay Doyle

Or, continuing on R.G.'s theme, if you don't use a power supply, check the battery connections, and all other off board wires to make sure that none of them broke or slipped.

If it worked and then all of a sudden didn't, most likely it is one of the things that can wear out or break.

sgmodel

alright i can sorta get an idea on what I'm doing but I'm far from figuring anything out,  if you take a look at this http://aronnelson.com/gallery/albums/Schematics-etc/phase_90_board.sized.jpg  and find R15 right above that is the power supply thingy mabober (great word isn't it) i could take pictures but i have no idea how to upload them and post them but anyways  that is my board down to the T direguard the script mod and the rest of the things on the page the only thing i want to do is find out why power isn't going past the input  for my 9 volt supply when i plug a battery in to the unit i can probe and get a voltage on the pins for the wired supply but when i plug in my 9 volt and probe the pins for that i get a big fat zero on my DVOM    :icon_cry: