Synth-DIY Yahoo! Groups Archives

Manual and Write stopped working

2017-01-21 by ellsounds@verizon.net

Hello all,

A few days ago my Polysix wouldn't turn on. I stupidly left her on under her dust cover for several hours (never done that before). I saw Old Crow's comment somewhere about first checking the fuses. Aha! One had burned out. I got some exact replacements (1 A, 250 V) and popped them in and it booted right up.

Oddly however, now the Manual and Write buttons don't work. The Tape Enable switch does seem to work (light goes on and bank lights go out). So I can't save any edits (I hardly ever used Manual mode so no biggie there).

Also the #8 Program light always stays lit even when I select other programs/banks. All the sounds are fine, all other parameters seem to work as well as the keyboard modes and Arp. My Kenton MIDI retrofit is working fine as well as I can control the P6 from my UF7.

Problem with the KLM 371 board? I'm not much into electronic repair so I'd have to take it in to a tech. If anyone has any ideas, great. It's not a huge deal breaker to not be able to store patches; I programmed most of what's in there now and I use her in my studio and do any edits needed and record her to audio most of the time. But I would like to be able to store edits.

Too bad the Kenton kit doesn't have the sysex storage ability as then I could get around this.

Thanks in advance for any ideas.

Ells

Re: [PolySix] Manual and Write stopped working

2017-01-21 by Florian Anwander

Stupid standardquestion the battery is replaced? Did the synth ever suffer battery leakage before?

On 21.01.17 19:36 , ellsounds@verizon.net [PolySix] wrote:

Oddly however, now the Manual and Write buttons don't work. The Tape Enable switch does seem to work (light goes on and bank lights go out). So I can't save any edits (I hardly ever used Manual mode so no biggie there).

Also the #8 Program light always stays lit even when I select other programs/banks.

Re: [PolySix] Manual and Write stopped working

2017-01-22 by ellsounds@verizon.net

Not a stupid question at all; I should have been more specific about the board's history.

Yes, the battery was replaced almost 18 years ago with a lithium one. There were some traces that were repaired about 11 years ago and it's been working perfectly up until a few days ago.

Re: [PolySix] Manual and Write stopped working

2017-01-22 by Florian Anwander

Hello Ells,

good. Then:
The common part between Manual/Write and LED#8 is the Databus D07. This
signal is provided by IC30 on the CPU Board (KLM367). I can imagine,
that the Modulation assignment (MG to VCF or VCA) won't work too or
works wrong, but you will not recognize if you are working with presets
mosttimes.

I would check the signal on IC30 pin8 with an oscilloscope and compare
it with IC30 pin 6.

If it is always high or always low, then replace IC30.

If there is a changing signal, the check pin 12 on the connector CN10 on
KLM367, then pin 12 at the connector on the KLM371, and finally at the
switches and at pin7 at IC5 on the KLM371.

Florian

Re: [PolySix] Manual and Write stopped working

2017-01-23 by ellsounds@verizon.net

Thanks so much Florian. The MG actually works fine in all modes (VCO, VCF and VCA) which is good I suppose. Would that make any difference?

Great to know how to narrow down the problem to the IC30 on the KLM367 board. I don't have an oscilloscope to test the IC30 though unless there's a osc probe to PC soundcard adapter and something like PicoScope software?

They always had computer/ham radio fests near me with used oscilloscopes; too bad I never got one. May try online.

At the very least you narrowed it down for me and I can see about getting a hold of an oscilloscope and if your diagnosis plays out replace the IC30 myself. I'm not much of a tech but I've built computers and such so this wouldn't be much of a stretch.

Thanks again!!!

Ells

Re: [PolySix] Manual and Write stopped working

2017-01-23 by ellsounds@verizon.net

Also where can I order an IC30? I see many others at Syntaur but not the IC30 (unless there's a replacement designation I'm not aware of).

Thanks once more!

Ells

Re: [PolySix] Manual and Write stopped working

2017-01-23 by Florian Anwander

IC30 is a "74LS08". It is a standard TTL IC and every elektronik shop like mouser.com, digikey.com, jameco.com, etc. will be able to deliver.

On 23.01.17 18:20 , ellsounds@verizon.net [PolySix] wrote:

Also where can I order an IC30? I see many others at Syntaur but not the IC30 (unless there's a replacement designation I'm not aware of).

Re: [PolySix] Manual and Write stopped working

2017-01-24 by ellsounds@verizon.net

Great, thanks. Looks like a bit of desoldering and resoldering but after I test to check the IC30, if the issue pans out I'll order the part and have my tech put it in. My soldering skills are not very good.