Symetrix 528E design error that causes power supply short.
I have received several Symetrix 528E mic processors that have had intermittent shorts pop up. After a little tracing I was able to find the culprit. On the LED display board there are 4 black screws. They are all the same and they all have captured lock washers. Three of these screws are fine but there is one left center that will give you fits if you do not know about it. In the picture below you can see where the screw goes and how close the traces are to the hole. When you screw down the thing the lock washer will eventually bite into the traces and short out the 15 volt supply.
On some of the newer versions there is a plastic screw in this hole but most of the time there is just a normal metal screw. I have been putting a fiber washer under the screw and have not had any problems or returns since. I don’t crank down on this screw since there are 3 more holding the board down and it does not need it to be too tight.
Just a quick tip for you to keep in mind if you ever get to work on one of these.
I am interested in sending you some 528’s for repair. Are you interested in the work? If so what is your fee?
Thank you
Hi Mark. Sorry I took so long to get back to you. I am sorry to say that I have had to shut down my little business. I took on a job with a radio reading service putting in all new studios. It is quite a job. Plus I was volunteered to take over the quartermaster position at my VFW and that has proven to be a real challenge.
Hi,
Having an issue with my 528E where the output is just noise and the output LEDs are all on (Same with the De-Ess, expander and limiter if they’re turned on). This is the case whether Line or Mic is selected. Have you seen this problem before? Thanks.
It definitely needs new caps all around and probably some new switches. All the through hole and surface mount 4.7uf bipolar caps.