Conn Multi-vider (Silverbox)

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Conn Multi-vider (Silverbox)

Postby JD0x0 » 28 Aug 2017, 00:43

I recently bought a Multivider from a famous musician. The unit works fairly well except some issues.

The 'soprano' circuit doesn't seem to work. If I turn it up I get a slight increase in hiss. If I mix the signal so it's only soprano I get a nasty weak, gated sound from the instrument. I'm told it's supposed to be a fuzz, not an octave up, but it doesn't sound like a (working) fuzz.. Also, I'm not sure what the knob does in the top left corner. It doesn't seem to effect the signal much except when at '0' the octave no longer works. Is this the 'effect level' control?

The third possible issue, is I noticed with the 'bass' or first octave down, sometimes when I hit notes it'll seem to jump UP an octave. At one point I thought it was the soprano circuit functioning intermittently but it doesn't seem to be affected based on where the 'soprano' switch or level control is set

The unit was repaired in 1976 from a sticker on it. That may have been the last service.

I opened the unit and noticed some electrolytics, and also what looked like some transistors.. I'm assuming germanium?? My guess is they went bad which is causing the malfunction(s) but does anyonewith more experience know what's up?
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Re: Conn Multi-vider (Silverbox)

Postby Nocentelli » 28 Aug 2017, 16:51

The bass and sub-bass on many analog octaves jumps around, e.g. even boss OC-2 which is fairly well regarded us not immune.

Could you take some close up pictures of the board? It may provide some hints as to the soprano problem, and maybe even a trace could be attempted.
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Re: Conn Multi-vider (Silverbox)

Postby JD0x0 » 28 Aug 2017, 17:06

Nocentelli wrote:The bass and sub-bass on many analog octaves jumps around, e.g. even boss OC-2 which is fairly well regarded us not immune.

Could you take some close up pictures of the board? It may provide some hints as to the soprano problem, and maybe even a trace could be attempted.

Sure, I'll just have to find my good camera.

One thing I did notice, was some nasty green corrosion on one small area of the PCB. I carefully cleaned it to expose the traces, but I couldn't tell what would cause that one spot to corrode so heavily. (I assumed it was an e-lytic cap that leaked, at first, but couldn't find evidence...no other areas were like this in the pedal) There's also some old black foam stuck to the PCB in some spots, which I will need to clean better. I gave it a quick cleaning and touched up some joints to see if it would affect the issue(s) I was having, but it looks like I'll have to pull this apart a bit more so I can inspect the actual components better.

Thanks for the input!
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Re: Conn Multi-vider (Silverbox)

Postby JD0x0 » 26 Sep 2017, 01:06

What's the preferred filehosting site for this website? I can't directly upload pictures because the file size is too large.
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Re: Conn Multi-vider (Silverbox)

Postby bajaman » 26 Sep 2017, 05:41

reduce the file size of any pictures to 1Mbyte or less and you are good to go :wink:
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Re: Conn Multi-vider (Silverbox)

Postby JD0x0 » 26 Sep 2017, 08:45

bajaman wrote:reduce the file size of any pictures to 1Mbyte or less and you are good to go :wink:

That kills the precious resolution. I'll give it a shot, though
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Re: Conn Multi-vider (Silverbox)

Postby JD0x0 » 26 Sep 2017, 08:56

20170925_1950341.jpg

20170925_194953__1506412378_108_41_203_159.jpg

20170925_194946__1506412321_108_41_203_159.jpg
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Re: Conn Multi-vider (Silverbox)

Postby bajaman » 26 Sep 2017, 09:42

if you are using a digital camera make sure you set it to macro for close up pictures - my eyes are hurting after trying to view these images :(
Nowadays i find that most smartphones especially iphone 5 onward take the best pictures :wink:
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Re: Conn Multi-vider (Silverbox)

Postby bajaman » 26 Sep 2017, 11:31

some pictures o the other side of the board are good to help anyone wishing to trace the circuit too :thumbsup
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Re: Conn Multi-vider (Silverbox)

Postby pinkjimiphoton » 22 Oct 2017, 00:55

these were designed for brass... there was a pickup and preamp (i think) assembly before the multivider.

the soprano is indeed an octave up and should be fairly farty sounding. its basically like a division down organ, it fuzzes and gives ya various octaves.

always wanted to fuck around with one of these. its likely not broken.

first thing i'd do would be replace every single electro and tant cap on the board.
then it will probably work.
if not, use an audio probe and multimeter. the ge q's don't just go bad, and i think these were using silicon by the time they got this far
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