VOGONS

I pillaged parts from my Chinon FR-506

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First post, by eesz34

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Story time.

When I took my Chinon 5.25 drive out of service perhaps 25 years ago, it went into my scrap box. It was working, but by that time they were considered nearly useless. I tossed all the 3M 5.25 floppies I had too. I took the top metal shield off and probably cut it up for some thing I was building. I stole a few surface mount capacitors from it. Luckily, that was all I did. Who would have thought I'd want to resurrect it now? I'd imagine there's similar stories out there about computers, cars, etc.

I can't find a schematic for the FR-506. FZ-506, yes, but not this one. The FZ-506 schematic has some general similarities, but there's a lot different. So, does anyone have this drive and willing to put a capacitance meter on the footprints boxed in red? I realize in-circuit measurements aren't perfect, but I'm not going to expect anyone to de-solder parts on their drive!

Or, if anyone has a schematic that would be awesome.

Reply 1 of 6, by eesz34

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Let's try another angle at this. I cannot find a datasheet for the controller on this drive. It's branded CHINON and part# is T8745F, made in Japan early 1992.

Maybe this is a custom Chinon part, or maybe it's rebranded. This part must have all the floppy drive functions in it because the only other chip, other than the spindle motor controller, is an 8 channel driver for the stepper driven by this chip.

Long shot: anyone know of a floppy controller that's an 80 pin QFP, 24 pins along two sides and 16 pins along the other? It's an odd configuration because I haven't been able to find any floppy controllers that's 80 pins.

Reply 2 of 6, by weedeewee

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in circuit measurement, ( if any other responder whines or complains about it, they'll be put on santa's naughty list), using a metrix mx54.
C21 108µF
C10 20 or 100 nF * ( depending on which range is selected on the mm)
C20 200nF
C17 40, 90 or 200nF *
C14 15nF
C9 40, 86 or 200nF *

fluke 12b on auto
c21 228µF
c10 ol
c20 96nF
c17 82nF
c14 ol
c9 76nF

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !
https://www.vogonswiki.com/index.php/Serial_port

Reply 3 of 6, by eesz34

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weedeewee wrote on 2022-11-10, 17:36:
in circuit measurement, ( if any other responder whines or complains about it, they'll be put on santa's naughty list), using a […]
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in circuit measurement, ( if any other responder whines or complains about it, they'll be put on santa's naughty list), using a metrix mx54.
C21 108µF
C10 20 or 100 nF * ( depending on which range is selected on the mm)
C20 200nF
C17 40, 90 or 200nF *
C14 15nF
C9 40, 86 or 200nF *

fluke 12b on auto
c21 228µF
c10 ol
c20 96nF
c17 82nF
c14 ol
c9 76nF

Thank you so much! Could you also get the two on the motor board? Those should be easier. I think the one that's missing should be around 4.7uF according to a datasheet for a similar chip, and the other I measure almost nothing so there could be some parasitics affecting it.

Frustrating that the only chip I can find a datasheet for is the boring line driver for the stepper. Chinon apparently didn't want anyone looking these up 😉

Reply 4 of 6, by weedeewee

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eesz34 wrote on 2022-11-10, 18:12:

Thank you so much! Could you also get the two on the motor board? Those should be easier. I think the one that's missing should be around 4.7uF according to a datasheet for a similar chip, and the other I measure almost nothing so there could be some parasitics affecting it.

Frustrating that the only chip I can find a datasheet for is the boring line driver for the stepper. Chinon apparently didn't want anyone looking these up 😉

Oops, missed that.
...
looking at the motor board on mine right now and it looks nothing like the one on your photo...
Your chip is an M51784P, mine is an M56635FP and there's no C11. No idea what the other's id is.

my FR-508 is rev B, top pcb label ends on EY, bottom pcb has id M33901 (delta) YG.FI.(mirrored)RL

also, I'm missing the lever. I'll have to print one.

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !
https://www.vogonswiki.com/index.php/Serial_port

Reply 5 of 6, by eesz34

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weedeewee wrote on 2022-11-10, 18:30:
Oops, missed that. ... looking at the motor board on mine right now and it looks nothing like the one on your photo... Your chip […]
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eesz34 wrote on 2022-11-10, 18:12:

Thank you so much! Could you also get the two on the motor board? Those should be easier. I think the one that's missing should be around 4.7uF according to a datasheet for a similar chip, and the other I measure almost nothing so there could be some parasitics affecting it.

Frustrating that the only chip I can find a datasheet for is the boring line driver for the stepper. Chinon apparently didn't want anyone looking these up 😉

Oops, missed that.
...
looking at the motor board on mine right now and it looks nothing like the one on your photo...
Your chip is an M51784P, mine is an M56635FP and there's no C11. No idea what the other's id is.

my FR-508 is rev B, top pcb label ends on EY, bottom pcb has id M33901 (delta) YG.FI.(mirrored)RL

also, I'm missing the lever. I'll have to print one.

Fair enough. I have a better handle on that board because at least I can find a similar datasheet for that chip. The main board, though, thanks again, because there is no information at all for that one.

Reply 6 of 6, by Datatr

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I am looking for the integrated chip M56635FP without success. If anyone has it for sale, I would appreciate it if you contact me.

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