Yahoo Groups archive

Cgs synth

Index last updated: 2026-04-28 23:16 UTC

Message

Re: CGS88 and TPS

2015-06-03 by Ken Stone

I really don't know what is going on. The voltages you show are indicative of the divider doing what it should.

Are you controlling the LED board 4007s from the 4013 on the voltage switching board? You should be. Does each board have it's own LM3900, or are you sharing the PSU?

For the LEDs, use high brightness types if you can. No driver is needed with them. The input of the switches D should be taken to pin 14 of the lm3900 via a 10k. The switch outputs go to the LED anodes. The LED cathodes go to pin 7 of the LM3900.

Didi you use static handling precautions for the 4007?

Ken





On Wed, Jun 3, 2015 at 5:00 AM, oeiols@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

The links are ok. I have desoldered the board for the leds too. Nothing.

Before I did that the leds blinking when I moved my hand under the board?
I have tried to measure while steping and have got those results.
LM3900 pin 5: 5,8V alternating -6,8V
4013 pin 11: 7,6V alt -6,9V
4013 pin 13: 7,6v or 5,8v or -6,8v
4007 u4 and u5 pin 3 (sw): alternating 7,6v, 5,8v and -6,8v.
Please help :-)
The vertical mode sort of working but cv from the other pots are bleeding.
And with the leds I didnt use drivers.





--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Attachments

Move to quarantaine

This moves the raw source file on disk only. The archive index is not changed automatically, so you still need to run a manual refresh afterward.