Roland D550 Synthesizer PSU re-capping question - Page 1
Forum section: electronics / beginners

author: DiegoMax
author_rank: Newbie
timestamp: February 26, 2017, 09:19:39 am
content: Hello everyone, long time follower of the youtube channel, but first time posting on this forum.Im by no means an electronics engineer or anything like that, i would consider myself a hobbist, and that would be a very generous way to call it. In any case, I own a Roland D-550 rack mount synthesizer from 1987, which works fantastic, however, the LCD backlight died about 5 years ago (its the old EL type fluorescent 2x40 HD44780 compatible type). So i finally decided to replace the LCD display with a new led backlit one, and that went smoothly.The question is, since this unit is almost 30 years old, i thought it would be a good idea to replace all the capacitors on the PSU and i wanted to ask the experienced people here how would i go with it:should i replace every single cap with new ones ?are there some very specific ones that i would definitely replace ?should i just ignore the fact that they are 30 years old and keep using the unit without worrying ?I attach here a schematic of the PSU of this unit, and maybe you guys can give me some advise regarding this. Thanks in advance!!!// Diego

author: The Soulman
author_rank: Super Contributor
timestamp: February 26, 2017, 09:47:30 am
content: It depends..The caps could last for another couple of decades or one could blow up next week, no way of telling.If one of the below fits your situation by all means replace them all:1) The device is going to be used/powered on quite a lot.2) The device needs to be as close to be 100% reliable (i.e. used in a live show).3) The device is planned to be passed on to a next generation.4) A beginner want's to enhance basic soldering skills.5) Just for peace of mind.Are the small values capacitors (such as c15 and c16) drop shaped?

author: DiegoMax
author_rank: Newbie
timestamp: February 26, 2017, 09:56:12 am
content: Hi The Soulman, thanks for your reply.I guess that from your list, only item 5 would apply.And yes, c15 and c16 are cyan color and drop shaped.They are the ones barely visible below the black and white cables on the attached picture. Im sorry dont have a better picture right now, but they are definitely drop shaped.(Sorry cant take a picture right now, but the attached picture is from the d-50 which is the keyboard version (as opposed to rackmount), the board is a bit different due to space constraints, but the components and design are exactly the same and i recall from memory too, that the capacitors on mine are the exact same cyan drop shaped ones)

author: SingedFingers
author_rank: Frequent Contributor
timestamp: February 26, 2017, 10:08:20 am
content: Sensible approach based on the fact that higher ESR and therefore bad capacitors dissipate power.1. Power it up for an hour.2. Power it down and disconnect the line cord.3. Feel the can and try and sniff each capacitor. If it feels hot and/or smells of burning plastic, replace it.4. Inspect around the base and top of all the capacitors and look for bulging or corrosion.It's probably likely to do more damage just replacing them blindly unless you have decent temperature controlled soldering iron, braid, solder etc.

author: Kjelt
author_rank: Super Contributor
timestamp: February 26, 2017, 06:33:07 pm
content: If you are not short on money i would just replace the caps, what are we talking about $10 max. A no brainer if you ask me.

author: DiegoMax
author_rank: Newbie
timestamp: February 27, 2017, 06:54:24 am
content: Thanks all for your replies, i guess i will just recap it fully for peace of mind.Cheers!