Chinon FR-506 - flippy?

All questions about how to use KryoFlux go here.
aaronr
Posts: 6
Joined: Sun Oct 28, 2018 7:53 pm

Chinon FR-506 - flippy?

Post by aaronr » Mon Oct 29, 2018 12:58 am

Hi all, I recently got a Kryoflux board and a Chinon FR-506 drive for the purposes of ripping all my old Apple 2 disks from my youth. Works great so far!

However, I want to be able to read the backside of the disks and do the flippy mod. Couple of questions though, has anyone done the flippy mod with this particular drive? Looks like there's a couple millimeters back from track 0, so I'm hoping I don't have to make any physical modifications.

Secondly, the track 0 sensor appears to go LOW when it's at track 0 and the phototransistor is blocked. Does this seem correct? I ask because the transistor circuit posted to youtube uses an NPN which I'm assuming brings that line low to defeat the track 00 sensor and allow it to go past 0. Is it safe to assume that, given the fact that the sensor on my drive goes low, I'd want a circuit that pulls it HIGH (+5V) with pin 33 is high?

Thanks in advance for any insight you can provide.

ivandiaz
Posts: 18
Joined: Wed Sep 05, 2018 12:47 pm

Re: Chinon FR-506 - flippy?

Post by ivandiaz » Mon Oct 29, 2018 10:52 am

Hi:
I did the Panasonic transistor mod with a Chinon FZ-506, which I am no sure works the same as yours, it works and goes to -8 without having to dremel anything, BUT:

* The assembly didn't cross the track 0 limit by itself, I had to push it manually backwards to the end stop, once there it locked itself without problem to -8 and read correctly. If the head is not pushed it acts as if the mod wasn't there.

* I don't know if it was my unit or having to push the assembly, but the upper head got misaligned frequently, and I had to manually adjust it, which is very fiddly and not recommended, but possible if you have enough patience. The bottom head didn't have this problem.

I submitted some dumps from it, and it seems the alignemnt isn't good enough (altought the guided format and the emulator checks out), so I will sell it (it works perfectly as a normal drive) and get one of my Panasonics modded.

aaronr
Posts: 6
Joined: Sun Oct 28, 2018 7:53 pm

Re: Chinon FR-506 - flippy?

Post by aaronr » Tue Oct 30, 2018 1:32 am

The fact that you say it "acts as if the mod wasn't there", seems to confirm my suspicions. Did you connect the collector end of the transistor to the output of the photosensor? Because if so, it basically would act like that, by already trying to pull the line low when it's low (which it is when the sensor is covered).

ivandiaz
Posts: 18
Joined: Wed Sep 05, 2018 12:47 pm

Re: Chinon FR-506 - flippy?

Post by ivandiaz » Tue Oct 30, 2018 9:59 am

Hi:
I don't think so, for the Chinon FZ-506 you can find good schematics and info on the Commodore PC-40 III service manuals at:
http://www.retroisle.com/commodore/pcs/ ... 9_Mar).pdf

If you look at Appendix B, page 29, you can see the value of the sensor at TP8 (which is were I put the collector) goes to less that 0.5v at track 0 (there is some histeresis too, and the high value isn't reached until track 3, which I find confusing). I think my problems had more to do with electronics that are "too smart" and count tracks.

I don't know if there are similar information for the FR-506, but perhaps if you search for service manuals for PCs that had one in their configuration you could get schematics.

aaronr
Posts: 6
Joined: Sun Oct 28, 2018 7:53 pm

Re: Chinon FR-506 - flippy?

Post by aaronr » Wed Oct 31, 2018 1:52 am

I could very well be misunderstanding, but isn't the flippy mod supposed to override the track 0 sensor to make the drive think that it hasn't hit track 0 yet? If that's true, then wouldn't you want to prevent the sensor from outputting a low signal as it approaches home?

I thought I read somewhere else on this board that the mod assumes that the sensor for a given drive goes high when track 0 is hit.. which would tell me that I'd want to reverse the logic for the drive I have.

Again, i could be totally mistaken about this though..

ivandiaz
Posts: 18
Joined: Wed Sep 05, 2018 12:47 pm

Re: Chinon FR-506 - flippy?

Post by ivandiaz » Wed Oct 31, 2018 1:49 pm

Yes, thinking it over, I think you are right, but then the drive can be made to go to -8 and read all side 1 without a mod, only pushing it past track 0. It would explain some of my problems at least.

ivandiaz
Posts: 18
Joined: Wed Sep 05, 2018 12:47 pm

Re: Chinon FR-506 - flippy?

Post by ivandiaz » Wed Oct 31, 2018 1:51 pm

Nevertheless, there are people which modified a Chinon moving the track 0 sensor back (you only have to loose a screw and slide it back) and using -b-8 to assign logical -8 to the 0 track. I tried this, but the problem is that the electronics in the drive count the number of tracks and you can't reach track 83, it stops at 78, which it is not enough for 40 logical track formats-

aaronr
Posts: 6
Joined: Sun Oct 28, 2018 7:53 pm

Re: Chinon FR-506 - flippy?

Post by aaronr » Wed Oct 31, 2018 2:31 pm

That may be ok for me, since I’ll be ripping mostly 35 track Apple 2 disks. I’ll try the mod with it flipping it high instead of low when activated and I’ll let you know how it goes.

Thanks!

aaronr
Posts: 6
Joined: Sun Oct 28, 2018 7:53 pm

Re: Chinon FR-506 - flippy?

Post by aaronr » Sun Nov 04, 2018 10:27 pm

Well, I was able to create a circuit using an NPN and PNP transistor to fool the track 0 sensor, but the heads can't go back far enough without some physical modification. It can go back about -5 before it bumps into the hard stop.

User avatar
mr.vince
Posts: 2101
Joined: Tue Oct 05, 2010 5:48 pm

Re: Chinon FR-506 - flippy?

Post by mr.vince » Tue Nov 06, 2018 8:29 pm

Hence our video. Happy dremeling!

Post Reply