Synth-DIY Yahoo! Groups Archives

poly mode inaccessible?

2017-04-28 by jw_dewdney@yahoo.com

hey guys - okay i've got one for you ... this problem just popped up tonight after messing around a bit with the chord function - I couldnt' seem to get back out of the chord mode (except by hitting unison) but there was NO going back to poly mode. Switching the P6 off and back on again gave me poly mode but not once i go into unison mode. There's no going back without power cycling the unit.

Any idea what might be askew? or is there some known bug with this? (i dont' remember ever having such a problem before)

Re: poly mode inaccessible?

2017-06-12 by jw_dewdney@yahoo.com

i was kind of hoping by now someone might have a suggestion to try ... i'm a bit lost as to where to start ... anyone? thanks

Re: poly mode inaccessible?

2017-08-05 by jw_dewdney@yahoo.com

a 'good scan' of the 371 board layout showing the traces clearly would be a great start if anyone has one.

Re: poly mode inaccessible?

2017-08-05 by jw_dewdney@yahoo.com

I'm getting back into this issue now and starting to read through the schmatics in the service manual ... unfortunately the scan of the KLM371 board isn't showing much in terms of the trace routing for the unison or poly switches... and I can't seem to find any obvious connection to them in the schematics.

can someone give me a hint here? I would really appreciate it ... I"m assuming a bad chip or diode somewhere

Re: poly mode inaccessible?

2017-08-05 by tlule@gmx.de

Hi,

I attach the schema that I found on the web. Then, through carefully comparing this with the PCB, I found that the switches SW4, SW8, SW7, SW6, SW5 in the bottom left corner, are the tactile switches for ARP, POLY, UNI, CHORD, HOLD respectively.

From there should be able to see that e.g. the POLY switch pulls down the net P14 through D13, whenever net P20 is pulled down by the CPU. So you need to trigger your scope on the falling edge of P20, to then monitor if the state of P14 changes to LOW while you press the switch.

Good luck.

Re: poly mode inaccessible?

2017-08-08 by jw_dewdney@yahoo.com

thanks so much! i guess it just needed fresh eyes... i spent about four hours looking through my service manual and know i probably spent at least 15 minutes looking at that very page -but somehow i missed it. That makes lots of sense - and esp. that it's on the KLM366 ... should be pretty easy to track down now... thanks again!

Weird cross modulation

2017-08-27 by Frank Carvalho

Fired up my P6 today, as it has been too quiet for too long, but found
that it had a strange kind of background noise. After opening the filter
entirely, no resonance, bypassing the FX, setting the VCO to PW, pulse
around 4, it is very obvious, that two keys pressed produce a sort of
ghost note, that sounds like a multiple of the frequency difference
between the two keys, like a sort of cross-modulation. If I press E6 and
F#6, I can also hear an E3. The ghost note is also there using a saw
wave, just not so prominent.

I don't think it's suppose to do this. What could be the reason for
this, and how do I fix it?

Thanks

Frank

Re: [PolySix] Weird cross modulation

2017-08-27 by Frank Carvalho

I have attached a sample of what it sounds like. Maybe it can help.

/Frank

On 08/27/2017 05:15 PM, Frank Carvalho dko4342@vip.cybercity.dk [PolySix] wrote:

Fired up my P6 today, as it has been too quiet for too long, but found
that it had a strange kind of background noise. After opening the filter
entirely, no resonance, bypassing the FX, setting the VCO to PW, pulse
around 4, it is very obvious, that two keys pressed produce a sort of
ghost note, that sounds like a multiple of the frequency difference
between the two keys, like a sort of cross-modulation. If I press E6 and
F#6, I can also hear an E3. The ghost note is also there using a saw
wave, just not so prominent.

I don't think it's suppose to do this. What could be the reason for
this, and how do I fix it?

Thanks

Frank