HEEEELP - Tonepad's Maestro FSH don't work!

[gigimarga]

hello,

after a long fight i got a lm13700...so i've built what i want from a long time ago...maestro fsh...i used the tonepad's version (http://www.tonepad.com/getFile.asp?id=96)

the only serious mod that i've done was that i've replaced the 2.2M resonance pot with a 3M one (the only value greater than 1M that i had...)

but after a couple of hours of working i had a big surprise: didn't working...didn't matter if it was on filer or on s/h...the only thing that i've noticed was a huge volume drop (with the resonance pot maximized...otherwise - almost no sound) and the sound passed without any modification!!!

i've rotated both trimpots...the only effect was that i found some points where the volume was higher...but no effect too!
how must to be ajusted these trimpots?
what affects?


with a very well regulated power supply at 8.88V, i measured the following voltages (both trimpots at half - s/h mod):

ICL7660 (instead of MAX1044) 1: 8.88 2: 4.45 3: 0 4: -4.12 5: 8.43 6: NC 7: NC 8: -8.43

IC1 - LM13700   1: -6.42   2: NC   3: 1.59   4: -0.17   5: 0   6: -7.69   7: NC   8: NC   9: -1.10 10: 0 11: 8.39 12: 8.59 13: -0.18 14: 0 15: NC 16: -6.43

IC2 - 4558 1: -0.10 2: 0 3: 0 4: 8.46 5: 0.56 6: 0.28 7: 0.30 8: -8.92

IC3 - 4558 1: -0.18 2: 0 3: 0 4: -8.47 5: -4.84 6: 0 7: -7.12 8: 8.92

Q1 - 2N3904 E: -0.27 B: NC C: -8.47

Q2 - BF245A D: -6.25 S: 8.39 G: 7.61

Q3 - 2N3906 E: 0.61 B: 0 C: -1.76

Q5 - BF245A D: 8.12 S: 7.33 G: 7.33

Q6 - BF245A D: 8.92 S: 8.12 G: 8.12

thx a lot all and please give me a little help...i want very much to make it alive!!

[Nitefly182]

This sounds like your charge pump is dead . I had that happen on an FSH1 once.

[gigimarga]

Thx for your answer...what do you mean by "charge pump" (sorry, but english isn't my native tongue  )...i tested ICL7660 before using it in another stompbox and it was working...but now i remeber that when i turned a trimpot i saw a little spark on it...but after that it disappear...

[gigimarga]

 

[gigimarga]

nobody have built it with success???

[slacker]

Here's a couple of things to check just from looking at your voltages.

Pin 12 of the LM13700 has 8.89 volts and pin 3 has 1.59. These 2 pins are connected together so they should have the same voltage on both of them, so something is wrong there. Pin 12 might be shorted to pin 11 which would explain why it has 8 volts on it.

The pin 4 and 8 voltages of IC2 are reversed. Maybe you just wrote them down wrong, if not there's something wrong there.

[gigimarga]

Thx a lot slacker...you're right on both...pin 12 was shorted to pin 11 ...on IC2 i wrote them wrong...but no effect yet

[gigimarga]

i retested all...seems ok now...but no effect

[Morocotopo]

gigimarga, I built it. It worked fine, but I could never get rid of ticking noise in the S/H mode (in filter mode it works OK. A bit fiddly to set the controls). I boxed it anyway, since it´s such a unique FX. There´s a thread around here somewhere about it...

Morocotopo

[gigimarga]

thx a lot for your support...but where is that thread about FSH ?

i searched the entire the forum and i didn't anything that can help me ...

my mainly sorrow is that it don't work in filter mode...in s/h mode i've red that i need to tweak the noise transistor...but in the filter mode i undestood that i don't have to tweak anything

what i must to do for you to send me your voltages  to compare them ?

thx again!

[gigimarga]

Heeeeeeeeeeeeeeeeeeeelp!

[gigimarga]

In the filter mod i must to tweak the trimpots or no?

[gigimarga]

 

[Eb7+9]

notice your FETs are slammed into the positive rail ... check the 10k trimmer leading to the first jFET ... there might be an open there

[slacker]

It might be useful to post your voltages now the LM13700s output isn't shorted to the supply.

[gigimarga]

Thx all!!!

My new voltages, using a 9V battery, on LM13700 are (filter mode):

IC1 - LM13700

  1: -7.26
  2: NC
  3: 7.65
  4: -0.14
  5: 8.14
  6: -8.37
  7: NC
  8: NC
  9: -1.13
10: 0
11: 8.77
12: 7.65
13: -0.20
14: 0
15: NC
16: -7.16

Thx again!

[gigimarga]

Another headache: when i've turned the 10k trimpot to one extremity a nice flame and some smoke arise from it
I replaced it with a new one and i had the same problem
Why?
The trimpots must to be at some wattage?

[gigimarga]

 

[MikeH]

There's no doubt- you have a solder bridge somewhere or an incorrect component.  I know it sucks, but you have to check every component and check every solder pad against a printout of the pcb.  That's the only way you'll find it.

[gigimarga]

Thx....i will recheck all