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CGS66 Power Supply Hint

CGS66 Power Supply Hint

2014-09-23 by soon.wazoo

Hello everyone! I've just assembled a PSU66 and have followed this exact components' layout: http://cgs.synth.net/modules/pic/pcb_cgs66_psu.gif .

The problem is: leds do light up normally but I'm measuring around 7.3V at the +12V pointing the negative tip at one of the 15V inputs, and above 19V still at the +12V tip pointing the negative sound of my multimeter at the bridge which interconnects both sockets' rows, right after the two leds.

Also trimmers seem to have no effect on voltage values. What's happening?


Could it be somehow useful: I had mounted bacwards the 2 diodes around the LM337 but I'm still getting same measurements even after having corrected the mistake.

http://cgs.synth.net/modules/pic/pcb_cgs66_psu.gif
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Re: CGS66 Power Supply Hint

2014-09-23 by soon.wazoo

(That's going to be extremely noob but :D ) you mean pointing the negative tip of the multimeter at the -12V tip and the positive at the +12?

Should this be even more helpful: I tried connecting a VCO module to one of the sockets and feeding my soundcard directly with a square: nothing but a lo-frequency noise came out AND the LED of the +12V section ceased working (whilst the other one still lit up).

Re: CGS66 Power Supply Hint

2014-09-23 by cg_synth

Black tip goes to 0V. Red tip goes to +12 (will read +12 on the meter).

Black tip goes to 0V. Red tip goes to -12 (will read -12 on the meter).

Re: CGS66 Power Supply Hint

2014-09-23 by soon.wazoo

(Sorry again for having shown such a lack of experience) It reads -8.8V and +11.08V , the PSU's being fed by a 220V/15V toroidal Talema trafo and by now both leds light up normally.

Re: CGS66 Power Supply Hint

2014-09-23 by soon.wazoo

Yep, but that's the strange part of it: best I can get is +9.80V or -9.80V. Might there be something strange goin' on at Graetz bridge or might it have something to do with the trafo (this one: Talema TRT30215 :: Talema Transformers :: Transformers :: Passive Components :: Electronic Parts :: Banzai Music GmbH ) ?



Talema TRT30215 :: Talema Transformers :: Transformer...
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Re: CGS66 Power Supply Hint

2014-09-23 by Ken Stone

measure the voltage across the large capacitors if it is above 15V on each, that is not your problem.
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On Wed, Sep 24, 2014 at 10:44 AM, soon.wazoo@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

Yep, but that's the strange part of it: best I can get is +9.80V or -9.80V. Might there be something strange goin' on at Graetz bridge or might it have something to do with the trafo (this one: Talema TRT30215 :: Talema Transformers :: Transformers :: Passive Components :: Electronic Parts :: Banzai Music GmbH ) ?




Talema TRT30215 :: Talema Transformers :: Transformer...
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Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS66 Power Supply Hint

2014-09-24 by cg_synth

For a 15V transformer, it should be much higher than that. I'd expect to see at least 18 volts across each.

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