[sdiy] Polysix Repair - Panel/Ground Electrified!?

[Ian Michael Ferguson]

Appreciate the follow-ups.

I checked all three voltages at the test points, and they were all very
close to spec. +15, -15, and +5, so no worries there.

So I've discovered you can make limited synth sounds in Manual mode, but
it's not quite right. All controls don't do what you'd expect, if anything.
All sound also stops if Resonance is much past 8 o'clock on the knob.
Probably a bad pot(?) Once I happened to turn that knob full
counter-clockwise I started getting sound.
Switching to preset modes still gets stuck in a drone sound though that
might be because there's no data there from losing the battery(?)

I'm thinking I'll replace the two SN74LS08N chips that were in the battery
damaged area, but otherwise looked OK, just in case, since they are readily
available and I've already socketed them.
Going to check on that Resonance pot and maybe look into reloading the
factory presets...


When it was "shocking" me it was a dull, unpleasant, shock, sort of like
licking a used 9V battery.
You could hold your finger on it, but you wouldn't want to, to be sure.
Certainly not full mains voltage.
The chassis has not been charged in this way in the last several days of me
turning it on, and I've not been able to reproduce it.
So I'm *not* confident it will never come back, but I will have to get an
RCD to do those tests.

-Ian

On Mon, Jul 24, 2017 at 2:01 PM, ASSI <Stromeko at nexgo.de> wrote:

> On Thursday, July 20, 2017 4:49:44 AM CEST Ian Michael Ferguson wrote:
> > While prodding around I then noticed the panel and all grounds were
> > electrified (because they shocked me)!
>
> When you say you got shocked, what exactly does that mean?  You say you've
> tried different places so I'm guessing that it wasn't a very hard shock
> that
> made you throw everything away.  But please do no further experiments
> without
> using an RCD (30mA trip point or less)!  Make sure you are isolated from
> earth, put one hand in your pocket and keep it there.  Then (using your
> other
> hand), measure the voltage of the chassis against some known-good earth
> potential and then measure it again across some not-too-small resistance
> (~33kOhm) you put between chassis and earth (while the power is
> disconnected!).  Chances are that there is a leaky input filter (look for
> Y-
> or X-capacitors) or improperly connected electrostatic shield in the
> transformer.  Otherwise you're probably having an isolation fail in the
> transformer (which will most likely trip the RCD when you connect the
> resistor
> to earth), which you'd need to replace immediately in that case.
>
>
> Regards,
> Achim.
> --
> +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+
>
> Wavetables for the Waldorf Blofeld:
> http://Synth.Stromeko.net/Downloads.html#BlofeldUserWavetables
>
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