Ensoniq DP/4+ REPAIR (cap leakage, corrosion)

[Whoops]

Finally I was brave enough to open my DP/4+ unit.

It turns On fine, "Battery is Low" message which is normal after being left in storage for many years.
"OS version 2.05" message and then straight to the presets.

I've tested it and it works perfectly.

Unit is dated December 1996.
Digital PCB is : REV B 1995
Analog board says: Part No 4001025101 REV B

I've carefully visually inspected the Lytic caps, tracks and all the boards and it looks perfectly fine.
No signs of corrosion or any leakage, traces look brand new.

Or I was lucky, and the unit can still be recapped before any leakage, or there were some different batches of Lytic caps used by Ensoniq over the years in these units, and some older batches leaked and newer batches don't leak.
The Lytic caps in my unit don't seem to be the same as the ones showed in the photo in the first post of this thread, the numbering written into it are different.
I'm saying this also because the units showed here that show corrosion/leakage seem to be from 1995 and before.
It's just a possibility, but that might explain why my unit doesn't manifest any problems after almost 30 years.

Or not... and it was just pure luck (until now) and it can start to leak anything soon, we don't know at this point

here are the photos:

 

[Whoops]

The only issue is a noise coming from the power supply, but it's not in the signal path, its a noise that can be heard coming from the unit itself. I've taken some pictures and all the caps look fine. Any suggestions would be greatly appreciated.

That noise is just acoustic noise from the Power Transformer vibrating.
My transformer is doing exactly the same.

It's not an uncommon problem with older units, the transformer starts to vibrate over the years and make that noise. And I think the noise is amplified also because it's mounted directly on the metal case and there's some metal cover on top of it, so all of those vibrate in sympathy with the transformer and make the party louder.

The solution I see would be to remove the transformer, and dip it in warmed and thinned transformer varnish 2 to 3 times, let it dry very well.
And when installing it again a thin vibration dampening material should be installed between the transformer and the metal parts it attached to.
Something like rubber, or high density (but thin) foam, rubber washers on the screws and so on.
If for some reason I keep my unit I would do all this to the Power transformer for sure as I really don't like that transformer acoustic noise.

 

[Script]

I've tested it and it works perfectly.

Happy to hear !

What a good start into the New Year

 

[Whoops]

Happy to hear !

Thanks my friend.
If I keep the unit I will change all the Lytic caps for sure, just to be safe. I don't like to work with SMD (neither I'm good at it) so I might pay someone to do it.

But if I sell the unit, which is what I'm inclined to, I will sell it stock and just let know the buyer that he might want to service and re-cap the unit in the future.