Ensoniq EPS Noise and Other Glitches

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Ensoniq EPS Noise and Other Glitches

Post by Ahow77 » Mon Aug 31, 2020 4:50 am

Hey All,

I've got an EPS that's acting funny. The most bothersome issue is a noisier than desired audio output. It produces a slight high pitched whine that changes slightly when buttons or keys are pressed; and I can hear through the outputs when the floppy drive or SCSI interface is being accessed.

I was thinking that the first thing I might try would be to recap the psu, and when I was inspecting it I noticed what looked like some dried fluid, or some other kind of corrosion below one of the voltage regulators. Do voltage regulators contain fluid that can leak out?

Here's a pic of the voltage regulator (you have to click on the pic to see the whole thing - aka the "leaky" part):


Other glitches include: sometimes after being on for a while it will stop producing sound which is remedied by restarting it, if there's a sound in slot 1 it will automatically be layered onto sounds in the other slots (even if the light for slot 1 isn't lit), the "amp" button isn't responding, which I was hoping could be fixed with contact cleaner, but maybe it's related?

I checked all of the internal connections and they seem to be nice and snug. This is otherwise a really clean EPS. I got it for $75 (yay!) and it looks like it's hardly been used. I upgraded it with v2.40 firmware and a 4X memory expander with SCSI that I took off another EPS that wasn't as clean. I've had it for almost a couple of years now but have only recently really started using it. I'm pretty sure these issues are new though. Any thoughts and/or advice is appreciated!

Here's a pic of the mainboard with rev#, etc if that's helpful..


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Re: Ensoniq EPS Noise and Other Glitches

Post by Hyde » Wed Sep 02, 2020 11:34 pm

I have 2 EPS keyboards. I had to change the main board in one, resolder links to the keyboard contact boards together on the other. I talked to in guy in Seattle who said he had 7 backup EPS machines for parts, because they were unreliable. The EPS is my favorite sampler. Such a great machine. thesoniq.com is the best source for repairs. As values continue to rise, outside repairs will make more sense. I fix what I can. When it's over my head(which is often), I go from trying to fix parts to replacing circuit boards. A hood lift often cost $100, plus parts & labor. At this point it's almost cheaper to replace the whole machine. but, things seem to be changing, fast.

I hope you figure out the issue. If you ever want to sell the 4x expander, I'm always looking.

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Re: Ensoniq EPS Noise and Other Glitches

Post by blueknob » Sat Sep 05, 2020 7:26 am

Yeh I think everyone who see that PSU pik will say, rebuilt it. Clean off all goop, replace the canned caps. I've found tants die, usually with smoke and a bang. I don't think the PSU had any but check. One thing I have noticed with ensoniq, they used good quality PCB/components. That mainboard PCB layout is really something in 1987, PCB CAD was just emerging.
Suggestion: there are a lot of suspect electrolytic caps about, try and buy from reputable dealer rather then cheapest from ebay.

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