The Synth Thread...

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Re: The Synth Thread...

Post by OffYourFace » Fri Dec 14, 2018 12:04 am

StevenO wrote:
Thu Dec 13, 2018 1:49 pm
I'll give it the Office Space treatment.
Check the attenuator switch on the back (output level; low medium high). It’s always an issue. We usually mod them so they’re always in the high mode.

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Re: The Synth Thread...

Post by oid » Fri Dec 14, 2018 12:39 am

OffYourFace wrote:
Fri Dec 14, 2018 12:04 am
Check the attenuator switch on the back (output level; low medium high). It’s always an issue. We usually mod them so they’re always in the high mode.
That would not account for the high output when the chorus is on, most likely the chorus switches or associated circuitry.
Logic gates based on billiard-ball computer designs have also been made to operate using live soldier crabs of the species Mictyris guinotae in place of the billiard balls.

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Re: The Synth Thread...

Post by OffYourFace » Fri Dec 14, 2018 2:44 am

oid wrote:
Fri Dec 14, 2018 12:39 am
OffYourFace wrote:
Fri Dec 14, 2018 12:04 am
Check the attenuator switch on the back (output level; low medium high). It’s always an issue. We usually mod them so they’re always in the high mode.
That would not account for the high output when the chorus is on, most likely the chorus switches or associated circuitry.
Sick.

It’s just a suggestion. We can take guesses all day until our typing fingers bleed but you and I aren’t there in person so it’s a waste of time. He just moved it to another room. My instinct says output switch or output jacks, especially if he’s running it in stereo.

I’ve worked on over a hundred Juno 106s in the last two years. It’s always the same shit.... unless your intern blows up the psu with his shaky hands.

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Re: The Synth Thread...

Post by oid » Fri Dec 14, 2018 3:48 am

OffYourFace wrote:
Fri Dec 14, 2018 2:44 am
oid wrote:
Fri Dec 14, 2018 12:39 am
OffYourFace wrote:
Fri Dec 14, 2018 12:04 am
Check the attenuator switch on the back (output level; low medium high). It’s always an issue. We usually mod them so they’re always in the high mode.
That would not account for the high output when the chorus is on, most likely the chorus switches or associated circuitry.
Sick.

It’s just a suggestion. We can take guesses all day until our typing fingers bleed but you and I aren’t there in person so it’s a waste of time. He just moved it to another room. My instinct says output switch or output jacks, especially if he’s running it in stereo.

I’ve worked on over a hundred Juno 106s in the last two years. It’s always the same shit.... unless your intern blows up the psu with his shaky hands.
Sorry.

EDIT: Fuck diplomacy, if you have been in over 100 of these than you know the circuit. Explain to me, in the full technical sense, how either the output jacks or level switch can account for the output being quiet except when the chorus is engaged.

There is a slim chance the jacks could cause such an issue, it has been awhile since I have looked at the schematic, but I doubt it, it is certainly not the level switch, unless physics are what broke when he moved it.

EDIT: Checked the schematic, jacks can not cause this either, chorus and clean signals are summed by opamp IC6 before the level switch or output jacks, there is no interaction, they affect both chorus and clean equal in all possible modes of failure.
Last edited by oid on Fri Dec 14, 2018 4:47 am, edited 2 times in total.
Logic gates based on billiard-ball computer designs have also been made to operate using live soldier crabs of the species Mictyris guinotae in place of the billiard balls.

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Re: The Synth Thread...

Post by oid » Fri Dec 14, 2018 4:38 am

Time to offer something constructive after that little rant.

My guess would be that the FET transistors which disengage the chorus are at fault and they are actually shorting some of the signal to ground when the chorus is off, it is unlikely that both of these transistors failed at the same time so would lean towards something conductive is loose in there creating a short, a common culprit when all that changed between working and not working is the synth was moved.

If running stereo, does one channel work as it should?

Does chorus mode affect it at all?

Edit: to many edits tonight! I admittedly get a little off when people give experience as proof of anything other than their experience, sorry for the previous post.
Logic gates based on billiard-ball computer designs have also been made to operate using live soldier crabs of the species Mictyris guinotae in place of the billiard balls.

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Re: The Synth Thread...

Post by StevenO » Fri Dec 14, 2018 4:51 am

Easy fellas, we're all friends here.

But yeah, not the output Jacks or the attenuation switch as far as I can tell as it operates the same way regardless of position. Google tells me the chorus needs rebiasing, which is a possibility, though it's strange that something would have gone funky just from moving it to the next room.

I'll try cleaning the switches and jacks again, even though I have them a thorough cleaning a few months ago.

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Re: The Synth Thread...

Post by eggwheat » Fri Dec 14, 2018 4:58 am

yeh start with switches and jacks...move to wobbling, reseating cleaning internal connectors...after that it's schematic time :)

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Re: The Synth Thread...

Post by oid » Fri Dec 14, 2018 5:06 am

StevenO wrote:
Fri Dec 14, 2018 4:51 am
Easy fellas, we're all friends here.
I said sorry and admitted my fault :blush: :)

It is not the switches, the switch circuitry, could be.

The bias would have no effect on the clean signal and it is very unlikely that the bias would go off on both channels.

Knowing if stereo is the same in both channels would help. If both channels are affected it is the buffer before the chorus, if just one it is the switch circuitry.
Logic gates based on billiard-ball computer designs have also been made to operate using live soldier crabs of the species Mictyris guinotae in place of the billiard balls.

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Re: The Synth Thread...

Post by StevenO » Fri Dec 14, 2018 5:39 am

Stereo is indeed the same in both channels, from what I can tell when I tested it last night. So I'm guessing it's the buffer?

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Re: The Synth Thread...

Post by oid » Fri Dec 14, 2018 4:30 pm

I would say it is 50/50 between the two, mostly due to my having let my theory slide. Slight chance of a failure in the digital control side, but fairly certain that would require two separate unrelated circuits to fail instead of just one.

The buffer and the switching circuitry are the only things the two signals have in common, safe bet and certainly the place to start. This is all general purpose transistors and the like, most of it is out of the signal path, so no worries of expensive hard to get parts or the synth ending up sounding different. Should be cheap and simple, for an old poly.
Logic gates based on billiard-ball computer designs have also been made to operate using live soldier crabs of the species Mictyris guinotae in place of the billiard balls.

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Re: The Synth Thread...

Post by eggwheat » Sat Dec 15, 2018 4:30 am

Wiggle the nternal leads first...you moved it..it’s old..it’s a Juno. Nothing surprising here ;)

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Re: The Synth Thread...

Post by eggwheat » Sat Dec 15, 2018 4:40 am

Did a short tour working for New Young Pony club who were pretty unique* at the time for using a Juno 60 live.

We had iirc two spare..always opening them up and redoing the connectors..it was almost routine like.

*pre every man and his dog jumping on the retro synth wagon. Even Gary Barlow bought a Prophet from me!

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Re: The Synth Thread...

Post by eggwheat » Sat Dec 15, 2018 5:45 am

Also NYPC are worth checking out...they were great..Sarah Jones the drummer is just brilliant :-*

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Re: The Synth Thread...

Post by shadowplay » Sat Dec 15, 2018 6:31 am

eggwheat wrote:
Sat Dec 15, 2018 5:45 am
Also NYPC are worth checking out...they were great..Sarah Jones the drummer is just brilliant :-*
I really liked when they cooled into more of a post punk thing on that Optimist album, especially Before the Light (whih is kinda Siouxsie via Fra Lippo Lippi. The early stuff was nice and saucy too but I think that album was pretty good.

D
Are you loathsome tonight?

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Re: The Synth Thread...

Post by StevenO » Sat Dec 15, 2018 8:06 am

I'll try and find a day when I can open it up and wiggle some things around.

As much as I love vintage synths, I'm annoyed by finicky they can be. Right now, my Prodigys pitch feel needs callibrating, my SH-2000 is toast, and my Juno is on the fritz. Sometimes I feel like the only cure is to buy more synths!

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