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Re: Synth Defects - Ticking Time Bombs

Posted: Mon Feb 23, 2015 7:04 pm
by rschnier
ARP Omni / Omni-2. Power supply throws voltage spikes when powered up, causing damage over time to the many tantalum (decoupling) capacitors connected across the power supply rails throughout the synth, eventually causing one or more to dead-short. Since the power supply rails are not fused, when the dead short happens it takes the power supply and other components down with it.

Re: Synth Defects - Ticking Time Bombs

Posted: Mon Feb 23, 2015 7:16 pm
by coastalscrub
fh991586 wrote:
coastalscrub wrote:- Roland Juno 106 / MKS-70 / HS-60 - the voice chips have an epoxy coating that eventually short the chips resulting in dead voices.
The MKS-70 is fine on this subject: you got it mixed with the MKS-7 & MKS-30, which share the save epoxy chip as the Juno 106.
Thanks for catching that. I edited the OP.

What about synths that use regular removable batteries, either for main power or for memory storage? Last month, I discovered that the batteries in one of my portable turntables were leaking heavily. I caught it in time but I can imagine someone putting a SH-101 or a TB-303 in a closet and not taking the batteries out and discovering the same thing. If you're lucky, the battery acid is contained in the battery compartment and just eats away at the contacts and springs. Which of these kind of synths are most at risk of real damage from a battery leak?

Re: Synth Defects - Ticking Time Bombs

Posted: Mon Feb 23, 2015 9:42 pm
by Swayze
I hear a lot about battery leakage in the Polysix. The Mono/Poly was part of the same family from Korg, but I have never heard of any issues, batteries or otherwise. Did Korg fix this problem on the Mono/Poly, just get lucky, or should I still be concerned? I better open 'er up today and have a look.

Edit: Just remembered that batteries are needed for patch storage, which the Mono/Poly doesn't have...what a relief.

Re: Synth Defects - Ticking Time Bombs

Posted: Mon Feb 23, 2015 10:00 pm
by super_doraemon
The foam inside of the Realistic/Moog Concertmate MG-1 decays into a tar-like paste.

Re: Synth Defects - Ticking Time Bombs

Posted: Mon Feb 23, 2015 10:02 pm
by desmond
Earlier Wavestations and even the A/D Racks can have power supply issues - it seems that the original power supplies were somewhat under specced and can cause the rather lovely "click of death" - the WS randomly hangs and emits a repeated series of clicks to the audio output - I still have a recording of this ;)

The solution is usually to get a replacement power supply.

Also, another common one, not just for the Wavestation but for a lot of synths of that generation is of course fading backlights in displays - both my Wavestation and my CZ-1 have backlights that are so dim they barely shine in the dark.

Re: Synth Defects - Ticking Time Bombs

Posted: Mon Feb 23, 2015 10:40 pm
by tomorrowstops
super_doraemon wrote:The foam inside of the Realistic/Moog Concertmate MG-1 decays into a tar-like paste.
Moog Opus 3 does the same!

Re: Synth Defects - Ticking Time Bombs

Posted: Mon Feb 23, 2015 10:57 pm
by meatballfulton
The analog output stage FETs in the Alesis Ion and Micron go south regularly. Probably also true of the Akai Miniak.

The LED display of the Roland MC505 starts losing pixels over time.

The effects selector on the Korg EM-1 uses a detented pot rather than a physical switch, the part is no longer available if the original wears out.

Re: Synth Defects - Ticking Time Bombs

Posted: Tue Feb 24, 2015 1:01 am
by ppg_wavecomputer
rschnier wrote:ARP Omni / Omni-2. Power supply throws voltage spikes when powered up, causing damage over time to the many tantalum (decoupling) capacitors connected across the power supply rails throughout the synth, eventually causing one or more to dead-short. Since the power supply rails are not fused, when the dead short happens it takes the power supply and other components down with it.
Oh, right... thanks for reminding me why I sold my ARP Omni back in 1997.
Swayze wrote:I hear a lot about battery leakage in the Polysix. The Mono/Poly was part of the same family from Korg, but I have never heard of any issues, batteries or otherwise. Did Korg fix this problem on the Mono/Poly, just get lucky, or should I still be concerned? I better open 'er up today and have a look.

Edit: Just remembered that batteries are needed for patch storage, which the Mono/Poly doesn't have...what a relief.
Glad you found out the answer for yourself.

Stephen

Re: Synth Defects - Ticking Time Bombs

Posted: Tue Feb 24, 2015 1:22 am
by coastalscrub
Some minor defects:

Roland JX-8P - the aftertouch stops working when the metal strip inside gets oxidized

Oberheim Matrix-1000 (black units only?) - humming power supply transformer

Aren't there some synths that have humming or buzzing backlit displays?

Re: Synth Defects - Ticking Time Bombs

Posted: Tue Feb 24, 2015 1:40 am
by max badwan
coastalscrub wrote:Aren't there some synths that have humming or buzzing backlit displays?
Korg M/T series
Roland D70/MV30
Kawai K5000

That's just in my arsenal.

Re: Synth Defects - Ticking Time Bombs

Posted: Tue Feb 24, 2015 3:40 am
by Percivale
Lots of Roland TR-626s have this "burnt" LCD.

Image

Re: Synth Defects - Ticking Time Bombs

Posted: Tue Feb 24, 2015 4:08 am
by mmp
Rhodes Chroma: backup battery leakage & bad power supply design. Road case foam rot ruins exterior finish.

Re: Synth Defects - Ticking Time Bombs

Posted: Tue Feb 24, 2015 6:30 am
by baz99
coastalscrub wrote:Oberheim Matrix-1000 (black units only?) - humming power supply transformer
Nope, white units are just as likely to be affected. They use the exact same transformer after all.

Fortunately the hum is actually only a physical vibration caused by the transformer, it does not propagate to the audio signal path.

Re: Synth Defects - Ticking Time Bombs

Posted: Tue Feb 24, 2015 8:58 am
by Europanaut
rschnier wrote:ARP Omni / Omni-2. Power supply throws voltage spikes when powered up, causing damage over time to the many tantalum (decoupling) capacitors connected across the power supply rails throughout the synth, eventually causing one or more to dead-short. Since the power supply rails are not fused, when the dead short happens it takes the power supply and other components down with it.
And the official Arp "fix" ensures that the 18v spike stays on, so your synth fries immediately. I just had my Omni's psu upgraded. Nice and safe now. (I also had the filter mod done, and it really sounds good.)

Re: Synth Defects - Ticking Time Bombs

Posted: Tue Feb 24, 2015 2:24 pm
by ppg_wavecomputer
max badwan wrote:
coastalscrub wrote:Aren't there some synths that have humming or buzzing backlit displays?
Korg M/T series
Roland D70/MV30
Kawai K5000

That's just in my arsenal.
Korg Wavestation (EX) -- high-pitched whine from the display.

The WS keyboard reportedly might become sticky due to deteriorating component parts -- haven't experienced this myself but I've seen two or three examples with that issue (early DX-7 models seem to suffer from the same disease)

Stephen