Moog Schematics/Service Manual

Hey Guys, its been a loooooong time since I've posted last (got married/settled in, etc.) anyway, I have a plea for help.

Does anybody have or know of a Moog Satellite service manual that I could get my hands on? I've scoured the net and I can't find anything except for patent records. I know that its not that great a synth compared to the greats like the minimoog but I still think its fun (when it works).

If anybody could point me in the right direction super grateful!

Thanks,

-Mike

I have the service manual, if you tell me the problem I may be able to direct you to the part of the circuit that you need to look at.

http://www.groupdiy.com/index.php?topic=12639&highlight=moog

may be here? :roll:
http://home.no.net/eifi/Gear/DIYLinks/SynthDIYLinks.html

[quote author="Steve Jones"]I have the service manual, if you tell me the problem I may be able to direct you to the part of the circuit that you need to look at.[/quote]

Yes, it powers on fine but I'm not getting any audio. Any ideas?

Thanks,

-Mike

[quote author="Xopek"]may be here? :roll:
http://home.no.net/eifi/Gear/DIYLinks/SynthDIYLinks.html[/quote]

Thanks for the suggestions but from what I can tell, this thing isn't too popular in the Moog relm. When it worked I thought it had a pretty fun sound and I got it for free so I can't complain.

Try checking the power supply first, it is +/- 18 volts into the regulators, and +/- 9 volts at the outputs of the regulators which are the rails that run the machine. if you ground the negative terminal of your meter and probe with the positive terminal you should see + 9 volts on one side of the "contour" slider and minus 9 volts on the other side.

[quote author="Steve Jones"]Try checking the power supply first, it is +/- 18 volts into the regulators, and +/- 9 volts at the outputs of the regulators which are the rails that run the machine. if you ground the negative terminal of your meter and probe with the positive terminal you should see + 9 volts on one side of the "contour" slider and minus 9 volts on the other side.[/quote]


Steve,

Yeah, I'm getting the 9v.

If you have a scope, take a look on pin 6 of IC 3 and play the keys to see of there is a key control voltage there, and pin 6 of IC's 5 and 6 for gate signals.

The oscillator is IC's 8, 11,12 and 21, see if there is a waveform on any of the pins of transistor Q46.

csonics said:

[quote author="Steve Jones"]Try checking the power supply first, it is +/- 18 volts into the regulators, and +/- 9 volts at the outputs of the regulators which are the rails that run the machine. if you ground the negative terminal of your meter and probe with the positive terminal you should see + 9 volts on one side of the "contour" slider and minus 9 volts on the other side.

Click to expand...

Actually, after remeasuring, i'm getting +9 on one side and +1.2v on the other. I'm using the main board ground rail for ground. Does that sound right?

Well, it looks like either one side of your power supply has failed, or else something in the circuit is dragging it down.

The minus 9 Volt side is IC2 controlling transistor Q1, taking it's reference from the +supply which is IC1. It looks like IC2 is a plain old 741, so maybe it has failed. Pin 6 of IC 2 controls the base of Q1 which supplies the -ve rail.

Also, look and see if there are ANY tantalum capacitors in the machine, and replace them with new ones, these are likely to be short circuited.

Thanks Steve! I owe you a beer or 3. I'll test that and see what I get.

[quote author="Steve Jones"]Well, it looks like either one side of your power supply has failed, or else something in the circuit is dragging it down.

The minus 9 Volt side is IC2 controlling transistor Q1, taking it's reference from the +supply which is IC1. It looks like IC2 is a plain old 741, so maybe it has failed. Pin 6 of IC 2 controls the base of Q1 which supplies the -ve rail.

Also, look and see if there are ANY tantalum capacitors in the machine, and replace them with new ones, these are likely to be short circuited.[/quote]

Hey Steve,

Pardon my ignorance but a 741 is just an opamp right? I'm trying to find a good replacment to start with but there are quite a few variations of it on mouser. Thanks man!

The parts list on the diagram says that it is a 741, but have a look on the top of the chip and let me know what is written there. They should be available pretty much anywhere.

I replaced both ic1 and ic2 and nothing changed. Same voltage. Any thing else I can try?

There may be a component in the unit that is shorted and dragging down the negative rail? Just to be sure, look at the voltage at the junction if R7 and C2, this is the output from the -ve supply. If this is not -9V then there could be a bad op amp in there somewhere pulling too much current, or perhaps a shorted tantalum capacitor. Do any of the chips in the machine get hot?

Alternately, transistor Q1 if faulty would also kill the negative rail.

[quote author="Steve Jones"]There may be a component in the unit that is shorted and dragging down the negative rail? Just to be sure, look at the voltage at the junction if R7 and C2, this is the output from the -ve supply. If this is not -9V then there could be a bad op amp in there somewhere pulling too much current, or perhaps a shorted tantalum capacitor. Do any of the chips in the machine get hot?

Alternately, transistor Q1 if faulty would also kill the negative rail.[/quote]

Yeah, I'm definitely not getting -9V. I'm going to try to replace Q1 and then move on from there. I can't seem to find any tantalum caps on it though, they all look like polypros or ceramics. I haven't noticed any warm ics but I'll turn it on for a while and check them all.

Thanks again so much for your help!!!!

Hey Steve,

Does your manual say what kind of transistor Q1 is? It doesn't have any markings on it.

Thanks,

mike

According to the parts list it is a TIS 93 (PNP). Might be better to take it out and test it before substituting it as the wrong sub could put the voltage beyond the circuit's tolerence.

I have made a scan of the PSU circuit, but I have no idea how to display it on the page here...