Moog Music Forum

I'm getting readings on U6, both the comparator line and the MUX line. Just for giggles I pulled the chip and fired it up, and sure enough I get no front panel leds (except for the octave switch on the mod wheel). I tried replacing the chip with a TL082 and it made no difference (though I don't know...

I also just realized I was probing the Z80CTC, not the CPU - Glad I looked at the schematics! I want to recheck that tonight and make sure things look right. I still feel like the problem is at the DMUX somewhere. If I probe something and it goes high on the scope to the point of disappearing, shoul...

Markyboard wrote:Also does pushing the autotune button do anything or is it locked as well?

Locked up as well. Unless I remove U5, then I can hit it and it works for about 10 seconds until it all locks up again.

I probed around on the DAC and the surrounding circuitry. I'm not getting a super good reading on the scope but as I increased the V I could see the DAC was moving in a continuous way, so I'll presume that it's good... Interestingly, I checked the voltage at pin 16 on the 4051s and it's supposed to ...

MB,
I'm good with troubleshooting here unless anyone else is opposed. Someone may find it and learn something someday.

I'll take a look at the DAC and the surrounding components along with the 4051s... fortunately these ICs are pretty common.

My first name is Mike :) Ok - so, yes, I do have the schematics and have been using them so far to try tracing out my issue. For as 'noob' a tech as I make myself out to be, that's purely based on knowledge of complicated digital electronics. I do have fairly good equipment, in fact I just bought a ...

I found the test point (P49, empty 3-pin connector) but am I supposed to short all 3 together? It doesn't really indicate any of this in the manual.. I found it by looking at the schematic (based on the one empty connector I saw) EDIT- Ok, I ground the 3 leads together just figuring what else would ...

https://live.staticflickr.com/65535/47837180011_16ed60028e_z.jpg That's what I did with the power supply transistors... see the red wire tubing over the solder joints... **NOTE: please ignore that radial 1000uf cap! I thought I had axials and turned out I didn't so I didn't order them :oops: so I'l...

Hey MB! Well I read your overhaul thread in triplicate just trying to get an idea where I’d stand getting this thing worked out. So on the DMUX board is where I was getting the hot resistor and transistor. I first identified it with my thermal gun and saw that area of the board was over 115 degrees!...

Apologies for starting a second thread, but I needed to focus on the actual issuer. I'm in a bit of a fix - I'm hoping it's something simple but I need some guidance. Back story: Memorymoog purchased 2 weeks ago, with the understanding it would crash after 2-3 minutes. I pulled the power supply and ...

Broke it again... slipped with my DVM checking voltages at the DMUX board and shorted something... was 5 minutes into a calibration when I did that ...

Disregard- I got it working. Shunt resistor solder joint was cracked.

Now on to the fun parts...

Before I ask complicated repair questions, does anyone here repair or work on the Memorymoog that could offer some power supply troubleshooting tips (original supply)? I have some questions and trying to get some clarification on what I think is wrong. I picked up a very nice early MM the other day ...

Eh, Nevermind... I messed around with the attenuation and also let the FreqBox warm up for a bit and I was able to get it to track the second oscillator! Pretty wild...

I see this has been discussed before and I've watched the vimeo video: https://vimeo.com/3823169 I guess my question is, after following along with these instructions, am I supposed to be able to track the entire keyboard in tune with the VCO on the FreqBox? Has anyone successfully gotten this to wo...