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Roland Juno-1 failure. Magic smoke

Posted: Wed Feb 13, 2019 7:32 pm
by hudkins
Warning, noob question follows:

I have a Roland Juno-1. I plugged it in and turned it on and there was this tremendous burning smell. I unplugged it as quickly as I could but before I took off the power I saw the display backlight still worked but there was no text. I don't know anything else at this point.

My electronics knowledge is pretty basic but I want to try and tackle the repair. I haven't opened it up yet to look for physical damage. I'd really appreciate some hints as far as what to look for. Also, if I'm able to repair it, I'm thinking re-capping it and I'm wondering if it would be worth it.

I do have the service manual.

Re: Roland Juno-1 failure. Magic smoke

Posted: Thu Feb 14, 2019 12:13 am
by Mooger5
Well, there is only one fuse inside and the display is still working, so the fuse is OK. It´s most likely a blown capacitor in the Power Supply board. The one labeled C14 probably. You really have to open up the unit and have a look inside. Don´t forget to unplug it from the mains.

Re: Roland Juno-1 failure. Magic smoke

Posted: Thu Feb 14, 2019 11:12 am
by Kentronix
My first step would be to go looking for blown capacitors around the PSU too. I dont know my way around the inside of a Juno-1 but wanted to post a picture of what a blown/vented capacitor looks like, they will either be completely obvious or have the tops vented as per this pic :-

Image

Re: Roland Juno-1 failure. Magic smoke

Posted: Thu Feb 14, 2019 4:03 pm
by hudkins
Thanks both of you :) I looked and there was a blown cap in the power supply, as you both indicated. I've decided to go ahead and recap the whole thing for future proofing and they're in the mail.

Thanks!