Pork Barrel NOW FIXED AND WORKING (FAULTY MN3007 CHIP)

[thorpy6]

Hi sorry my first post is a help thread but hey i post a lot on BYOC and this is my first time here so hello everyone.

Problem is as follows:

Bypass signal good. Led lights on switch engagement. those are the positives.

here is the problem: i cannot get any effected signal to come through, its entirely quiet as if i have a short somewhere.

I have tried the following.

Checked wiring off board, was all good (now cut for checking and will redo come boxing up time)
checked resistor values
checked capacitor values,
checked polarity on caps,
checked 2n 5088 transistors are all fitted in the right orientation and all are 2n5088
checked diode direction.
checked for solder bridges and shorts using magnifying glass and shining a torch behind and on top of board.
changed mn3101 just in case.,
changed jrc4558 just in case.
changed power supply,
tried new battery

I am now stuck and seek help please. FYI the MN3007 was bought from banzaieffects, a reputable place as far as i am concerned. but i have another in the post just in case it turns out to be bad. Here are the pics of the board:











thanks in advance for your help, all the best adrian

[gtr2]

Did you test the board before boxing it up?

[eniacmike]

did you adjust the trim pot? usually when I build up a pork barrell it doesn't work until I adjust the trim pot into the sweet spot.

you can post some voltages for Vd and Vb

[jkokura]

If everything you checked is fine, I suspect the chips. Keep looking. Try walking away for a while and see if anything changes next time you try to debug.

Jacob

[thorpy6]

If everything you checked is fine, I suspect the chips. Keep looking. Try walking away for a while and see if anything changes next time you try to debug.

Jacob

yeah i thought it might come to this!! ah well i have another mn3007 on the way.

i forgot to say, tested in and out of box, trimmer does nothing and thats about it really. vd and vb where are these?

[eniacmike]

Vb is on pin 5 of the jrc4558, Vd is on pin 1 of the MN3101 and also pin 1 of the MN3007.
To measure set your multimeter to DC voltage and connect the black test lead to ground and the red test lead to the pin you want to measure.

Hopefully it's not a dead MN3007. I got mine off ebay and got lucky I guess.

http://shop.ebay.com/sharpseller2000/m.html?_nkw=mn3007&_sacat=0&_odkw=&_osacat=0&_trksid=p3911.c0.m270.l1313

[thorpy6]

I was desperately hoping it was the chip, id tried everything else. Anyway turns out it was. Pedal sounds greta now, pics to follow. Many thanks for all who offered their advice and guidance. Modulation is my nemesis!!

[thorpy6]

Finished product!! sounds really great, not as insane a chorus as i was expecting somehow but nice anyway.

[CRBMoA]

Diggin' the battery retainer, Thorpy!

[thorpy6]

Diggin' the battery retainer, Thorpy!

cheap and cheerful but it actually works really well

[eniacmike]

glad it is working. your build was too clean to not work. did you really order 1/8 watt resistors for all those slots? thats impressive most of us just bend 1/4 watt resistors to fit.

[thorpy6]

glad it is working. your build was too clean to not work. did you really order 1/8 watt resistors for all those slots? thats impressive most of us just bend 1/4 watt resistors to fit.

Thank you very much!! yeah i was bemused as to why it wouldn't work i rarely get any problems (aside from stupidity which can be spotted after a time out) these days. As for the 1/8 resistors

they're really cheap so i bought a load for some sunkings i was going to build which have just gone out of stock Grrr