RS-09 restoration gone wrong

Synth Repair
1

Hello! Amateur tinkerer here. Long time lurker, etc… looking for a little advice on what’s gone wrong :laughing:

Recently I decided my RS-09 needed some love, and I have a bit of time on my hands, so I decided to do a recap on all but the GATE board (too many for now!) and a clean up of the keys, etc. Here’s the service manual in case you want to know what I’m referencing.

I’ve now recapped the electrolytics on Control 1 and Output boards. I thought I’d plug it all back in before I go any further to check that it’s working, and… it’s stuffed. The power LED doesn’t go on, and there is a loud white noise being output regardless of whether it is on or off.

I’ve checked for continuity in all of the solder joints I made and they all seem fine. I’ve been careful to replace them all with suitable caps.

The only thing I can think of is that I have slightly damaged a ceramic 241k capacitor, crushing it under one of the connectors. Could that cause this problem?

Any other thoughts? My intuition tells me it seems like a PSU problem, but I haven’t touched it yet, so I’m not sure how I might have damaged it.

If you need any more info to help, let me know!

Any advice is much appreciated!!

[As an aside, I don’t seem to be able to find a replacement 241K ceramic cap, and there’s no info about voltage on it - any thoughts on an appropriate replacement?]

2

It sounds to me like something may have been connected incorrectly during reassembly. Make sure all cables are going to the correct place, that none were put on backwards, and that you didn’t accidentally transpose the connector over a pin while connecting.

Since there’s noise at the output regardless of the synth being on means that something is wrong with the grounding. I’d definitely check all cables running between the PSU and other boards. You can use a multimeter set to continuity or resistance testing to help you determine where the ground connection is making it to. Judging by that the power LED isn’t lighting up then perhaps the PSU itself isn’t grounded properly. Does the synth have a three prong or two prong power cable? And is there a connection from ground of the PSU to the synth chassis present?

Also be careful, grounding problems can lead to electric shock if the synth chassis isn’t properly grounded. If this is a synth with a two-prong plug be especially careful because there’s no escape to ground for accumulated charge except through you. Only ever handle stuff in and around the PSU after the synth is unplugged from the wall.