FIXED - Roland S-550 Flashing LEDs of Death

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Werecow
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FIXED - Roland S-550 Flashing LEDs of Death

Post by Werecow » Sat May 14, 2016 3:00 pm

Just sharing this because I've run across several references to the S-550 and the dreaded FLoD (Flashing LEDs of Death) elsewhere on the internet, but none with any solutions. My experience might help someone else in the future.

Last week during my constant eBay trolling for broken stuff to fix, I ran across this unit that wouldn't power up, for repair, sold as-is. And really cheap. So it met all my criteria :) I'll spare you the troubleshooting details, but in this case, the root of the problem was a bad floppy drive, which took out the 4A fuse in the 5.2V supply. Replacing the fuse and removing the drive brought back the 5.2V supply, but left the front panel LEDs flashing, with no display. Repairing the drive and reinstalling it brought the unit back to normal operation.

So apparently, part of the boot initialization is a floppy drive test. If the drive is damaged, missing or incorrectly configured, the initialization halts with all the LEDs flashing and no "Insert Sys Disk" prompt, just a blank display. I'm sure a bad drive isn't the only cause of FLoD, but it's certainly one of them.

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Yekuku
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Re: FIXED - Roland S-550 Flashing LEDs of Death

Post by Yekuku » Sat May 14, 2016 11:03 pm

Just out of curiosity , which component was shorted on the floppy ?
Thanks for sharing!
It is all about sharing...

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Werecow
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Re: FIXED - Roland S-550 Flashing LEDs of Death

Post by Werecow » Sun May 15, 2016 12:24 am

The problem component was C1, one of two low-profile electrolytic caps on the top side of the PC board, just above the connector for the head positioning servo. You have to disconnect 5 connectors and remove 2 screws to pull the board and get to it. I believe it used to be a 22µF 35V cap (now more like a low-Ω resistor), but I'll verify and edit on Monday because it's at my shop, and I'm not.

BTW, this is a Toshiba ND-352S-A drive. Roland probably used the same model in all the S-550s, but YMMV.

p.s. I wouldn't ordinarily put effort into repairing a floppy drive, but I don't have any others with black front panels, or ones that could have the original black panel transplanted onto them. ;)

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Re: FIXED - Roland S-550 Flashing LEDs of Death

Post by blueknob » Sun May 15, 2016 7:07 am

Werecow wrote:Last week during my constant eBay trolling for broken stuff to fix, I ran across this unit that wouldn't power up, for repair, sold as-is. And really cheap. So it met all my criteria :)
I do this too, it's a winner all round, it's great feeling when we get the item fully working and usually in my case, once I've "played" with it for a week or so I lose interest. Although my lastest "faulty" buy turns out to be a fantastic item.

I'm not in it for money more the challenge, so my best solution is to fix for other people which is another good thing, anyway thanks for spreading the news of a solution.

I have noticed that more kit seems to be going faulty, duff caps and chips expiring seem to be the main culprits. I have stuff from the 1990s that are falling over, stuff from the 1950s are usually a total rebuild requiring replacement transformers and all.

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Re: FIXED - Roland S-550 Flashing LEDs of Death

Post by Werecow » Sun May 15, 2016 8:41 pm

@blueknob: I have to agree about doing it for the challenge. I hate to see older equipment end up in a rubbish bin or cannibalized for parts, when only a bit of knowledge, time and effort are required make it completely usable again. Granted, it's not bleeding-edge technology, but it works. And once all the dry caps and old, fragile CMOS are replaced, I'd even venture to say that it will outlast modern gear.

Keep up the good fight. If you can't save the planet, save the kit. :)

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Re: FIXED - Roland S-550 Flashing LEDs of Death

Post by danielortizdecaracas » Mon Jul 08, 2019 6:10 pm

hi everyone please my roland S550 blinking leds too, no booting at startup, just only blinking all leds no any system message on display, any fix for this? display replacement? floppy replacement? floppy USB emulator? any idea please? thanks a lot in advance

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Re: FIXED - Roland S-550 Flashing LEDs of Death

Post by fh991586 » Wed Jul 10, 2019 8:12 pm

There are many ideas listed in the previous posts. Have you checked any of them?
Considering parting away from:
-Roland TR707
-DSI Mopho

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