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by Synthfool
Sat Oct 05, 2013 2:20 am
Forum: Jupiter-8
Topic: Could anyone provide photos of the Jupiter 8 VCO board?
Replies: 1
Views: 1643

If you still need photos, I can take some.
Write me at synthfool a.t. synthfool.com
by Synthfool
Thu Feb 28, 2013 9:29 pm
Forum: Jupiter-8
Topic: TSP102J replacement?
Replies: 2
Views: 2952

TSP102J replacement?

Does anyone know of (or have) any TSP102J posistors as used in the JP8 VCO?
I believe it's a PTC (positive temperature coefficient) type and know it's 1K, but I can't find any sales sources or how many ppm/K the original is rated at.

Any info or sources would be appreciated.
by Synthfool
Fri Dec 28, 2012 1:58 pm
Forum: Jupiter-8
Topic: JP8 restored but pitch bend problem over midi, encore midi
Replies: 8
Views: 6660

Also I have a problem with the original Pitch bender since the installation of the MK. The lever itself works by bending the sound. But the 2 VCOs don't follow the bender in the same amount. 1 VCO pitches more than the other, resulting in a weird detuned sound, when the lever is full right. Anybody...
by Synthfool
Sat Nov 24, 2012 1:01 am
Forum: Jupiter-6
Topic: Unknown trace cuts on voice boards?
Replies: 3
Views: 3760

I have a feeling that if you pulled one of those boards and looked on the opposite side, you might find there are jumper wires in place of those traces.
I can't be certain of course, but you might take a look.
by Synthfool
Thu Nov 08, 2012 7:21 am
Forum: Jupiter-8
Topic: Hanging notes/VCO bleed and wiring/connectors
Replies: 14
Views: 7705

Is this of any help?

http://www.synthfool.com/docs/Roland/Roland_Jupiter8/

(last 3 bulletins)
by Synthfool
Sun Sep 30, 2012 8:41 am
Forum: Jupiter-8
Topic: JP8 Eprom sets
Replies: 0
Views: 3546

JP8 Eprom sets

Just a quick note that I have some sets of Jupiter 8 EPROMS version 3.4 for sale.
All 4 roms (A,B,C,D)

$40 plus shipping.
synthfool@synthfool.com
by Synthfool
Wed Feb 15, 2012 11:55 pm
Forum: Jupiter-8
Topic: Help! Who is the best Jupiter 8 tech in San Francisco area?
Replies: 1
Views: 2736

What's wrong with it?
by Synthfool
Tue Dec 08, 2009 12:25 pm
Forum: Jupiter-8
Topic: Can you help me test something please?
Replies: 23
Views: 9911

Some JP8's intentionally have the 3rd prong missing from the AC power lead. This because they could suffer bad damage if caught in a ground loop. But removal of this ground allows more digital noise on the audio outs. So, if I was you, I'd make sure it's grounded well. Check to see if that 3rd prong...
by Synthfool
Wed Oct 21, 2009 8:52 am
Forum: Jupiter-8
Topic: Can´t load from Tape memory Backup !
Replies: 7
Views: 5087

Both the computune and cassette reading circuitry is located on the CPU board.
I'd start there.
by Synthfool
Mon Aug 31, 2009 9:00 pm
Forum: Jupiter-6
Topic: JP 6 not working except the LFO board !!
Replies: 37
Views: 28977

No 1 problem I've seen is NOT parts, but cracked soldering. Have you guys checked the soldering on your PCB's, especially the power supply? Short true story: Person contacts me that's trying to fix his Minimoog. Doesn't know much about electronics, but wants to try fixing it himself. He replaced man...
by Synthfool
Sun Aug 30, 2009 11:25 am
Forum: Jupiter-8
Topic: Increasing Jupiter 8 battery life length ?
Replies: 3
Views: 3738

Sitting unpowered should have no effect on the battery. It's a lithium and unlike the stock nicad batteries found in the JP4, don't need any charging to stay fresh. A bad diode may well be the problem, as mentioned. Also, I've installed about a dozen Encore kits and of them, 2 or 3 had problems. Don...
by Synthfool
Sun Aug 30, 2009 11:14 am
Forum: Jupiter-8
Topic: New JP8 mod help needed
Replies: 7
Views: 4159

I don't recommend a fan. If a DC fan, it will take power from the JP8's supply and actually increase heat and stress, not to mention the possibility of inducing noise into the electronics of the instrument. An AC fan is possible, but still not necessary under normal circumstances. (Ie: moderate temp...
by Synthfool
Mon Jun 01, 2009 5:03 pm
Forum: Jupiter-8
Topic: How properly to calibrate Jupiter 8?
Replies: 7
Views: 6441

I checked out the attached spreadsheet. (interesting! Thanks.) It suggests it was tuned to A442, but that autotune is working well. I have two methods to allow tuning to A440: 1. Set the tuning knob slightly higher before performing calibration. An exact setting can be obtained by using a tuner or f...
by Synthfool
Sat May 30, 2009 6:01 pm
Forum: Jupiter-6
Topic: Jupiter-6 circuit bend?
Replies: 2
Views: 2504

Lots of work repeated for each vco, then no easy way to control unless the operating system was also modified to allow the buttons to choose.
In short: a good idea that probably won't happen. :(
by Synthfool
Sat May 30, 2009 5:54 pm
Forum: Jupiter-8
Topic: How properly to calibrate Jupiter 8?
Replies: 7
Views: 6441

I've calibrated many JP8s. Here's my guesses: The tech didn't have the tuning knob centered during calibration. The temperature was considerably different when / where the tech calibrated it. The tech didn't allow enough warm-up time before starting calibration. Various possible other reasons: the t...

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