Roland D-5 Power Issues

[marVelo]

Hey everyone, I'm new here and really hope you can help me out.

As of last night my Roland D-5 synth will no longer power on.
When I bought it (For $80) it had a loose solder connection on the PSU input which I fixed in a second. For the past year it has worked great for me and never had an issue.

Last night I went to turn it on to mess around and no power. Tried different 9v adapters and no luck. It is dead. A brick.

The only thing I could imagine that might have hurt it was that I tried to see if one of my other adapters would work with it earlier in the day (It didn't work, didnt even brighten the LCD)

Could this have fried it seeing that it was a 1A 9v adapter instead of the usual 800mA 9v? If it did what is the best way for me to diagnose and fix whatever problem it caused? Will it ever work again? I'd really rather not have to send it to a Roland shop as it will cost well over twice what I paid for it.

Thanks in advance,
Tom.

[blue hell]

[marVelo]

How would I go about checking the internal power?

[blue hell]

Hmm ... if you have to ask maybe it would be better to have it fixed ... maybe not by Roland ... anyway if you want to go on it would be helpful to have schematics or a service manual ... things like that ... it's very hard to give guidelines here without actually knowing the device ... well .. maybe someone else here knows it.

[Wendy48088]

It may be the reverse power protection diode is shorted. If you reverse the polarity of the power supply into the unit (the Roland D-5 is a NEGATIVE CENTER PIN) it will cause a protection diode inside the unit to short out, and then this diode must be replaced for the unit to power on again.

I just got done replacing one on a D-5. Pictures here:





















Wendy

[blue hell]

Wendy, great entry here!

[Wendy48088]

Thanks!

I took pictures in case I had a blond moment (even us brunettes get them - I think it's the estrogen...) and forgot how something I took apart a short while ago went together. Also to document to show other people, so I was glad to find this in my search for info on the Roland D-5...

Using the wrong power supply - one with a reverse polarity from what the unit is designed for - is probably a pretty common mistake.

They all look pretty much alike - it's easy to grab one and if it's the wrong one... Oops...

I mark all my power supply units with a silver Pilot / Sharpie marker as to what equipment it goes to.

In this case it also took out the 9 Volt 1 Amp power supply. I suppose it caused a fusible link to go out inside the wall transformer / power supply. I didn't open it up to try to fix that - I just used another 9 V power supply rated for about the same current - 800 mA.

Checking the diode with a Digital test meter on the diode test scale it was indeed shorted both ways. The good one was infinite resistance (open circuit) one way and 600-700 ohms the other.

Not a bad fix if you have a couple of hours, a cross-tip head screwdriver, a soldering iron, some solder wick, some solder, and a long nose pliers. Oh, and also a diode rated to at least 50 V and 1 Amp.

Since the protection diode is in parallel and not in series with the input power rail, it would work again if the protection diode was simply cut out of the circuit. However, if one is fixing it in the first place, that's the perfect argument to not skip out on replacing the protection diode...

I should also note that the power input jack does seem to be a loose fit, which bothered me and I vowed to fix it. But I could not bend the metal tab on the bottom inside the power jack to tighten it very much.

I then checked with a meter set to continuity and iwas a bit surprised to find that it is a positive electrical contact that doesn't drop out if you move it a bit. Probably a tighter fit would break more easily if the power connector plugged into the jack got bumped. After all, it is in the back where you plug it in and then shove the whole unit back without any further thought...

Just don't ask me to repair a couple of keys that don't fire. I tried to fix a friend's Roland U-20 with two bad black keys. Between the rubber membranes and the contact buttons and a flex ribbon electrical connector which I stupidly removed to be able to turn the keys around and over without (I thought) risking damaging the flex ribbon cable, only half the keys now work.

I bought the D-5 from someone selling it on CraigList for $60 and gambled I could fix it. And I lucked out.

So now the Roland D-5 is going to be used as a MIDI controller keyboard for the U-20 (MIDI output of D-5 to MIDI input of the U-20). Works great that way. So at least my story had a happy ending...



Glad to share...

Wendy

[Antimon]

Yeah, that's a massive entry! Surely helpful to someone - Wendy! Is it just me, or are these circuit boards often beautiful?

/Stefan

[samrayvsr]

[quote="Wendy48088"]Thanks!

Just don't ask me to repair a couple of keys that don't fire. I tried to fix a friend's Roland U-20 with two bad black keys. Between the rubber membranes and the contact buttons and a flex ribbon electrical connector which I stupidly removed to be able to turn the keys around and over without (I thought) risking damaging the flex ribbon cable, only half the keys now work.



Your post has been very helpful. Thanks.

I would like to know if you were able to fix the problem regarding the Roland U-20 flexible ribbon cable. I encountered same problem with my D-5. I removed the clip holding the flex ribbon to fix/clean the contacts under the rubber membrane, due to some bad keys, when it accidentally peeled off.

I tried using lead pencils but it didn't fix the problem. Now I would like to try using a conductive pen but I’m afraid to damage it further.

Maybe someone out there have tried the same or is familiar with those types of flexible ribbon cables would like to share their experience.

Sam