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Fixing an Ensoniq DP/2 (recapping the power supply)
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Fixing an Ensoniq DP/2 (recapping the power supply)
nangu
One of my Ensoniq DP/2s had bad caps in the power supply. It's an easy fix if you know what to look for- kind of a sneaky problem, though. The unit powered up and looked fine- it just wouldn't pass anything but dry signal.

The DSP chip needs a different voltage than the rest of the system. If the line-lump power supply fails to provide that particular voltage, then the unit seems to boot up normally- you just can't get anything other than dry signal out of it. tIB said he had one that would "crackle horribly on power up for a couple of minutes and then settle into working fine" - that may have been the same problem, just not quite advanced enough to make the DSP chip shut down completely.

I replaced two caps- Mouser part number 667-EEU-FR1E102L. They're 1000uF, rated for 25V. These are taller than the original part, but there's plenty of room for them. I circled them in yellow on the pic below. The power supply on the right is unmodified, but I expect that I'll also need to fix it someday..

Ignore the polarity shown on the PCB!! My PCB had the polarity marked wrong for one cap. The negative side goes toward the other cap in the pair. You can see in my pic that the stripes on the caps both point towards the center:

ringstone
Mine had a nasty buzzing sound in the output signal that got worse until that's all I got. Bad caps in the power supply as well...

Cheers
Blair
stk
Awesome, thanks so much for this.
Mine has been following me around in unworking condition for twelve years, no techs would touch it.
bentley
Many thanks for the info!

My symptoms were a steady noise in the outputs along with a steady red ight on Input 1 with no signal present. Replacing those 2 caps in the power supply fixed it right up!
stk
Hmm, I finally got around to digging my DP/2 out of storage and replacing these caps.

Unfortunately, nothing has fixed :( Unit powers on, input indicators light up when being sent signal, but output is completely silent (ditto headphone out).

Does anyone know the pin configuration of the power plug, so I can check for the correct voltages on the correct pins?
Do you think it's worth replacing the other caps?

Cheers!
stk
Just noticed the pinout is printed on the back of the unit hihi

I'm getting nonsense reading tho, probably down to my electronics ineptitude. Think I might need to get someone with more than a passing knowledge of this stuff to take a look.
Jcsveth
Must be the weather - I just replaced those caps a couple of weeks ago. Unfortunately, unit powers up correctly now (it was showing full input with nothing plugged in) but now I get no output even though the input indicator is now working correctly. cry
Looks to be the same issue as you stk. If I find anything else, I'll post it.
stk
Jcsveth wrote:
Must be the weather - I just replaced those caps a couple of weeks ago. Unfortunately, unit powers up correctly now (it was showing full input with nothing plugged in) but now I get no output even though the input indicator is now working correctly. cry
Looks to be the same issue as you stk. If I find anything else, I'll post it.


Thanks, will do also. I think I might have to send my PSU to a tech to troubleshoot.
Spleet
I had exactly the same problem as Bentley did. Continuous humming in the outputs along with a steady red light on input 1, even without anything being connected.

Two fresh 1000µF, 25V caps later and the front input works fine now. The rear inputs, however, are very, very silent, input 2 even more so than input 1. In order for anything to be heard the input knobs have to be turned to 100%, and even then the input leds only just reach a solid green. If I do go into the red ever so slightly, by cranking up a mixer send to extreme levels, or when using the front input, the DP2 produces harsh digital-like artefacts. As if the unit can't handle an overloaded signal without immediately starting to clip.

I replaced the other caps (3x 10µF, 16V; 1x 3300µF, 16V), just to make sure, but that didn't change my DP2's meek pose.

Does any of the above make sense to anyone? Isn't it strange that rear input 1 behaves so differently from the front input? After all, they are the same, aren't they?
stk
Yeah, .i think there is more to it than just the OP's solution. I haven't got around to taking my unit to a tech yet.
leeski
jus done this cap change/replace and now have sound coming out of the headphones but nothing out the back outputs d'oh!
All inputs inputting, applause

many thanks nangu thumbs up
Roh
I am having issues with my DP 2 being stuck in a "loop" on startup sequence - cant get into the programs - after "Ready", it tries to restart constantly...

Anyone seen this issue before?

Any ideas?

Thanks!!
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