Korg monopoly problems.

sam · Post by **sam** » Mon Oct 16, 2006 7:47 am

Symtoms....
No output..
Effects light stuck on.
Lfo lights not working.

Has anyone had these problems..?
I also need some schematics.

Advice appreciated...

sam · Post by **sam** » Mon Oct 16, 2006 7:56 am

I have found the schematics....
So any ideas

Analog Freak · Post by **Analog Freak** » Mon Oct 16, 2006 8:01 am

I've never seen the guts of one of those before but I know that they are very similar to the Korg Polysix. If it has a Nickel-Cadnium battery inside like the Polysix does, odds are it has leaked battery acid and corroded the circuit board around it. If that is the case it is going to be an expensive fix for a tech or a DIY project from h**l, as my Polysix was.

sam · Post by **sam** » Mon Oct 16, 2006 8:10 am

Analog Freak wrote:I've never seen the guts of one of those before but I know that they are very similar to the Korg Polysix. If it has a Nickel-Cadnium battery inside like the Polysix does, odds are it has leaked battery acid and corroded the circuit board around it. If that is the case it is going to be an expensive fix for a tech or a DIY project from h**l, as my Polysix was.

I have fixed many poly sixes but it's my first time inside a monopoly.
It has no memory battery to worry about...
What I need is input from other users/repairers to see if there are common faults to look for.

I like to get as much info before I dive in.

dougt · Post by **dougt** » Mon Oct 16, 2006 9:36 am

First thing I would check is the power supply voltages...

Here's the service manual -

http://machines.hyperreal.org/manufactu ... Manual.zip

shendo · Post by **shendo** » Mon Oct 16, 2006 3:25 pm

I opened up my Monopoly recently because I am having problems too. Not problems like what you had mentioned.
I did not see a LI battery in the Monopoly so I imagine that's not the case.

Forgive me if I tack on to your post.
If anyone has some ideas:
I have noticed a lot of little things wrong with mine, which I understand because its a vintage synth, but if someone knows:

1) The tuning scale of the first VCO is off quite a bit in the lower octave of the keys.
2) It seems to make a lot of static in the 2-3 khz frequency range.
3) Some pots dont seem to do anything at all or have a very limited range of control (maybe I need to replace those pots). Filter Decay, Sustain and Release for example.

sam · Post by **sam** » Wed Oct 18, 2006 4:17 pm

No output..
Effects light stuck on.
Lfo lights not working.

Has anyone had these problems..?
Advice appreciated...

[/quote]

Voltages check out ok...I wonder if the 2044 filter chip needs changing...?

sam · Post by **sam** » Wed Oct 18, 2006 5:35 pm

SO..the vcf chip in the monopoly reads...ssm t 2044 (8245)

Is this the same as a polysix ssm 2044 (8209)

dougt · Post by **dougt** » Wed Oct 18, 2006 9:54 pm

Analog Freak · Post by **Analog Freak** » Wed Oct 18, 2006 10:47 pm

Yeah those other four digit numbers represent the date the chips were produced.

sam · Post by **sam** » Thu Oct 19, 2006 12:39 pm

I tried another vcf chip but no difference...
Effects light stuck on / Lfo's not blinking / Dead as a dodo .....What's going on here..?

Post by **Maschinengeist** » Thu Oct 19, 2006 2:45 pm

For some reason, I missed that thread. I come back to you on this.

Post by **Maschinengeist** » Fri Oct 20, 2006 1:33 am

No output > Have checked for the solder joints / loose wires?

Effects light stuck on> Have you taken a reading of the resistors? The NPN transistor could be defective. BUT most likely it's the switch that's defective.

Lfo lights not working. Most likely a dead LED

Hope that helps

sam · Post by **sam** » Sat Oct 21, 2006 12:49 pm

Update....All wires check out and solder joints ect...Still no output.
If I had a scope it would be easier but I don't have one yet.
Still searching...Any ideas...

Post by **Maschinengeist** » Sat Oct 21, 2006 2:21 pm

Ok, let's dig deeper then.

Do you have access to a digital multimeter? If so, check if there is juice flowing to the output (test different points from the PCB to the socket and the socket itself). If there's activity, the socket might be defective (it happens) and need to be replaced.

Have you checked the quality of the solder with a magnifying glass? Sometimes a solder joint look great to the naked eye but is problematic when closely inspected at a bigger (and clearer) scale.

If that fails too, we'll go up the pathway.

Korg monopoly problems.

Different Monopoly problems.

Re: Korg monopoly problems.