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EdisonRex
Site Admin
Joined: Mar 07, 2007 Posts: 4579 Location: London, UK
Audio files: 172
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Posted: Tue Apr 24, 2012 10:40 am Post subject:
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Oh wait. it's a JX-3P. I have one of those. But it's in the USA. I fired it up last September and it still sort of works. _________________ Garret: It's so retro.
EGM: What does retro mean to you?
Parker: Like, old and outdated.
Home,My Studio,and another view |
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DrJustice
Joined: Sep 13, 2004 Posts: 2114 Location: Morokulien
Audio files: 4
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Posted: Tue Apr 24, 2012 3:08 pm Post subject:
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Uncle Krunkus wrote: | I did the test and found that the vibrato effect is on board positions 4, 5 and 6. I rotated all the modules around, and still, it's on 4, 5, and 6.
So, straight away, I've removed the faulty 80017 and made the empty position 6. That gives it the best playability it's had for a long time, 3 steady notes!
Now I have to work out what is creating this vibrato on the main board. |
What's the nature of the vibrato - is it a steady 'real' vibrato, or is it erratic?
The separate Osc1 and Osc 2 clock generators for the DCO counters are common for all voices, so if it made the vibrato it should happen for all voice slots.
It looks like position 4, 5 and 6 get their square wave's from IC 32 (Osc 1 out) and IC 34 (Osc 2 out and sync in). So if the vibrato is is only for 4, 5 and 6, I'd check the connections between the offending voices and IC 32/34.
Are both Osc 1 and Osc 2 affected? If it was only Osc2 it could perhaps be related to the sync.
DJ
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Scott Stites
Janitor
Joined: Dec 23, 2005 Posts: 4127 Location: Mount Hope, KS USA
Audio files: 96
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Posted: Sun Apr 29, 2012 2:57 pm Post subject:
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Wow, Uncle K, you've got more guts than me. I've always been timid around actual, real vintage synthesizers. Seems to me that someone had designed a surface mount/PCB replacement for the 80017, or am I mistaken? Hmmm...
A sound sample of the vibrato might help to figger out where the vibrato is coming from. Maybe....
Cheerio,
Scott _________________ My Site |
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Uncle Krunkus
Moderator
Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
Audio files: 52
G2 patch files: 1
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Posted: Sun Apr 29, 2012 4:21 pm Post subject:
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Thanks for the cred Scott,
Looks like you've been a busy boy too!
Yeah, I might try doing a recording so you can hear what it's like.
I still need to track down a calibrating procedure, there are 4 trimmers per 80017, which all got mixed up in the acetone bath!
That would help with the overall sound by heaps, but I'm unsure where to start.
I still haven't given up on the dead 80017 either, just not sure how to work on these little ceramic boards, or if I even can. _________________ What makes a space ours, is what we put there, and what we do there. |
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Uncle Krunkus
Moderator
Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
Audio files: 52
G2 patch files: 1
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Posted: Fri May 04, 2012 1:09 am Post subject:
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EdisonRex wrote: | Oh wait. it's a JX-3P. I have one of those. But it's in the USA. I fired it up last September and it still sort of works. |
Yeah, but the JX3P doesn't use the A80017 hybrid chips. It uses the same SMD chips separately on the main board, with associated, through hole, passives to create the same VCF/VCA module.
The hybrids are a kinda ceramic substrata, with the SMD OTAs and OP-AMPs soldered onto them. The caps and resistors are layer built onto the ceramic substrata. And,...... the traces are thin, and hard to solder to. Has anyone worked on these chips? _________________ What makes a space ours, is what we put there, and what we do there. |
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EdisonRex
Site Admin
Joined: Mar 07, 2007 Posts: 4579 Location: London, UK
Audio files: 172
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Posted: Fri May 04, 2012 1:26 am Post subject:
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Yeah I read more from this site which I'm sure you're familiar with.
I'd imagine the traces need to be deoxidised and fluxed in order to get anything to stick to them. It all looks really fiddly. _________________ Garret: It's so retro.
EGM: What does retro mean to you?
Parker: Like, old and outdated.
Home,My Studio,and another view |
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infindebula
Joined: Sep 29, 2011 Posts: 29 Location: Canada
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Posted: Tue Aug 14, 2012 6:26 am Post subject:
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As far as calibrating the voices, I suggest you look at (closely) at the Juno-106 service manual which offers detailed info about how to calibrate the 80017s. Basically with the 4 trimmers you are tuning the VCFs to track the keyboard and adjusting the resonance so they all match.
The Juno 106 has test points for this. If you look at the schematic you'll probably find similar points in the MKS-30. |
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infindebula
Joined: Sep 29, 2011 Posts: 29 Location: Canada
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Posted: Tue Aug 14, 2012 10:46 am Post subject:
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Just after I posted, I found the full MKS-30 Service Notes including calibration instructions at http://www.synfo.nl/pages/servicemanuals.html
Very nice site there - strongly consider donating if you find it useful! |
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Uncle Krunkus
Moderator
Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
Audio files: 52
G2 patch files: 1
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Posted: Wed Aug 15, 2012 2:02 am Post subject:
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That link is dead. _________________ What makes a space ours, is what we put there, and what we do there. |
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320
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Posted: Wed Aug 15, 2012 2:59 am Post subject:
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Uncle Krunkus wrote: | That link is dead. :cry: |
Hmm, that mks-30- thing? not dead here ... _________________ Jan
also .. could someone please turn down the thermostat a bit.
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Zodiak
Joined: May 20, 2007 Posts: 249 Location: Gillingham, Kent UK
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Posted: Wed Aug 22, 2012 12:05 pm Post subject:
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thanks for the diary, I have a very early JX-3P which doesn't know it yet but will be going through the same process very soon.
I had no idea about the VCA chips being a problem, but they are now on my list.
I mainly use turned pin sockets because I have found them to be slightly more robust, but also because it is possible to solder them to both sides of a PCB making the repair of damaged tracks much easier.
The IC I have removed does not go back into this socket, but I solder it into an identical one, or an IC header and plug that in instead. This reduces one tricky job to two simple ones and you only have to heat up the IC leg for a very short time. _________________ Stephen
www.Rainsbury.Net |
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MusicMan11712
Joined: Aug 08, 2009 Posts: 1082 Location: Out scouting . . .
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Posted: Thu Aug 23, 2012 1:44 pm Post subject:
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infindebula wrote: | Just after I posted, I found the full MKS-30 Service Notes including calibration instructions at http://www.synfo.nl/pages/servicemanuals.html
Very nice site there - strongly consider donating if you find it useful! | Thanks for the link!!!!! It looks like a super nice resource. Two years ago I gave up trying to find the MKS-10 Service Notes on-line and paid approx. $25 for a paper copy. I posted a link to the site in the thread from 3 years ago where people were looking for the MKS-10 service notes.
Steve |
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