Vintage Synth Explorer Forums

Hybrid88 wrote:

cornutt wrote:My only other guess at this point is that it has something to do with the keyboard interface circuitry.

Yes, well I was kinda thinking that but then why would OSC2 not work at all?

When I wrote that, I was thinking that the MS20 had a duophonic keyboard. I've since realized that it doesn't. Sorry about that.

oooooh that would be awesome

I see MS-20's come in all the time with VCO 2 dead or intermittent due to patch bay contacts. Also, sometimes it is not that the VCO is dead, but that due to a CV issue it is running fine, but above or below audible frequency range.

Steve Jones wrote:I see MS-20's come in all the time with VCO 2 dead or intermittent due to patch bay contacts. Also, sometimes it is not that the VCO is dead, but that due to a CV issue it is running fine, but above or below audible frequency range.

Hey steve, could you explain further, what do you mean by dirty contacts? How would that affect the signal? What are the points to clean?

In any case, could you say either way if you will be able to look at it? Like I say I'm not in any great rush so to speak, but I really do need to know if you can look at it at some point so I know whether to get ready to send it soon or not. It doesn't have to be straight away but a time frame would be good. I've also got other synths that I'd like to send to your shop so I need to get onto that at least this year for sure.

Thanks mate.

The little normaling contacts in the patchbay sockets can get dirty and intermittent, usually VCO 2 starts getting erratic and then cuts out. I can take a look for you but I have some big polysynths to restore first so I can't take new jobs until I have cleared them out... it could take 4-6 weeks.

Steve Jones wrote:The little normaling contacts in the patchbay sockets can get dirty and intermittent, usually VCO 2 starts getting erratic and then cuts out. I can take a look for you but I have some big polysynths to restore first so I can't take new jobs until I have cleared them out... it could take 4-6 weeks.

Ok, thanks Steve. Consider me on the waiting list for some jobs then, I'll get back to you in about a month or so and see how things are then.

Cheers.

If it's a bad jack contact that could be a pretty simple fix once you get the thing open.

Yeah, I'll try one last time to see what I can do I don't really know how to "fix" a bad contact, apart from cleaning it I suppose - if it doesn't work I'll be sending it to Steve.

Cheers.

hmm... if it's a bad contact in the patchpanel, what happens if you plug "kbd cv out" to "osc cv in" (or whatever it's called, the "normal" hz/v input...)?

pflosi wrote:hmm... if it's a bad contact in the patchpanel, what happens if you plug "kbd cv out" to "osc cv in" (or whatever it's called, the "normal" hz/v input...)?

An image to make things clearer (not mine),


Well, I did patch an audio signal (just to see what happened) into the "VCO 1+2 CV In" and "VCO 2 CV In" under the volume knob, and while the other Osc1 waveforms suddenly worked, OSC2 was still dead even when trying it with both the inputs I mentioned above.

I'll have to try it with the MS's internal keyboard patched to CV in's when I get the bottom back, it's in bits at the moment so it's not really possible now.

I'll post back later when I've tried it out.