How to modify a Chinon FB354 floppy drive to enable the disk activity LED.

[DavidQ]

I found this information last year on how to get an Amiga 500 Chinon FB-354 floppy drive with a functioning disk activity LED working in my Amiga 1000 and produced this set of instructions on how to do it. Although I have posted it elsewhere I thought folks here might find it helpful too (do this at your own risk).

Steps to follow...

1) Solder a 2200 ohm (2K2) surface mounted (SMD) resistor to the Chinon FB-354 floppy drive motherboard at location R13 to enable power for the disk activity LED locations A & K on the front of the motherboard.

2) Solder an LED to locations A & K being careful to attach the LED anode to location A and the cathode to location K.

I have uploaded a diagram (JPEG) with this post showing the relevant locations.

Credits for original mod information.

Jan Beta's YouTube video...
"Amiga Internal Disk Drive in External A1010 Case".
(The video contains Chinon FB-354 LED activity resistor mod info at 10 Minutes 40 Seconds in).
[ Show youtube player ]

Jan refers to the mod information originating from...

Stephan Ricken at the brotkastenblog.
https://brotkasten.blog

[deimos]

I wish I'd known that 30 odd years ago when I ended up with a 500 drive in my 1000 after Commodore couldn't get the original to read past disk 2 of Dragon's Lair.

[DavidQ]

Well, I know everything comes to he who waits but 30+ years might break a record of some sort.

[JHKrueger]

Even in 2022 this information still made my day, as I finally got that silly LED to work. Thanks a million.

[DavidQ]

Glad it helped.

[Jope]

There are a few variants of the drive, but the footprint for the resistor is always found roughly around the same place. You can use your multi meter to trace it from the LED backwards, if your drive is different to the illustration.

[DavidQ]

That's interesting information, thanks Jope. It would be good to have photos of the variants posted here. I'll do so if I ever see any of them.

[JHKrueger]

My drive looked exactly like the one in the photograph.

[JHKrueger]

Hello everyone,

Now I encountered Chinon drive with a different board layout. It does have R13 in place, but that seems to have another purpose. I checked the connections to the LED (which so far does not work), and "K" is connected to ground, whereas "A" routes to R19 (which is not populated). I added a 2,2 kOhm resistor, but that did not help. Any suggestions?

Cheers,
Jens

[JHKrueger]

I just realized I uploaded the wrong picture in my previous message. I thought both drives with the different layouts were similar, but curiously the one in the picture has R19 populated. Here is the one with R19 empty. On neither of the two boards, just adding an LED worked.

Cheers,
Jens

[Jope]

Trace the signal backwards from the LED, perhaps it's a missing transistor on this board or the location number for the resistor is different.

[madmungo]

I have this same drive. When tracing out the LED cct I found R19 & Q1 missing. Anyone know what transistor to put there?

[jurassicman]

Would it be possible to do the same with a Chinon fz-354 (the usual floppy drive inside A600/A1200)?
If so, could someone give the step by step instructions to achieve that?

UPDATE:
I've just opened an specific thread for it

[Nikoh77]

Hello guys, I added a 2200 resistor and now I have 12v on A and K, is it correct? I need a 12V led?
@DavidQ @jurassicman @madmungo @Jope @JHKrueger @deimos

[DavidQ]

I'm not able to check my A K voltage at present but I used a Kingbright L-153IDT LED which is available on eBay UK in packs of 5 for between £3 and £5.

Kingbright L-153IDT 2.3mm x 7mm x 8mm Rectangular Red Solid LED Lamp Through Hole.

Info and photo...
https://uk.farnell.com/kingbright/l-...red/dp/2001790

PDF Datasheet...
https://www.farnell.com/datasheets/1446115.pdf

Hope that helps.

[Nikoh77]

ok i checked everything again, i changed resistor twice but A-K always gives me 12.2 volts always on, constant, nothing to suggest floppy activity....
My pcb is like that on first photo in this discussion that DavidQ as posted

[braunaudio]

Originally Posted by madmungo

I have this same drive. When tracing out the LED cct I found R19 & Q1 missing. Anyone know what transistor to put there?

Found the same on my FB354 and put in a 2.7k in R19 (didn't have any 2.2k's on hand) and a MMBT3904-TP (Bipolar Transistor) into Q1 and found that to work in my drive.

Mouser Link for Transistor:
https://au.mouser.com/ProductDetail/...DjIayULQ%3D%3D

[madmungo]

Originally Posted by braunaudio

Found the same on my FB354 and put in a 2.7k in R19 (didn't have any 2.2k's on hand) and a MMBT3904-TP (Bipolar Transistor) into Q1 and found that to work in my drive.

Mouser Link for Transistor:
https://au.mouser.com/ProductDetail/...DjIayULQ%3D%3D

Thanks for the info. Will give it a go and see if it works.