Floppy drives restoration advice

[Xanxi]

So i was about to test those caps with my multimeter and a spare PSU to avoid using the whole A4000, but i had an intuition which made me test other enclosures first.

And it happens the MITSUMI drive does work with moving heads, can read and write everything, though not my best drive because of the noise it makes when spinning.
I had only 4 enclosures still available, and one of them (unbranded, unlabeled) works with that drive and others, while my second TECHNOPLUS enclosure i was using so far causes any drive to not move heads at all, and the two others i have marked as RF302C only gives DFx:?? with any drive.

Now i know that the TECHNOPLUS enclosure can work with MITSUMI drives since i have another one working with a similar drive. About the RF302C, i have no clue for now, perhaps they are proprietary to one type of drive.

So, since the beginning of my restoring project, i have cleaned and fixed 8 drives but i have only 6 working enclosures, while i still have 10 drives to work out including 3 CHINON A2000 type FB354 and 2 of their HD counterparts FB357A, 2 internal PANASONIC for A1200 and a few others. Probably again some others buried somewhere in my storage room.

I need to fix my enclosures first and will start looking closely at their adapter boards in the next days.

 

[Xanxi]

Here are the pics of the board from the Technoplus enclosure (providing of course that the top case matches the lower case, i can't be 100% sure after 25 to 30 years).
I could not remove the board without force to take a picture of the bottom side, so i let it go to avoid breaking it for good.

Any idea what's preventing the heads to move with that board?

 

[Xanxi]

Stupid me, i couldn't remove it, because there was a third screw!

So he is the other side of the board.


With my very limited electronic knowledge and my multimeter, i have noticed that continuity does not check between the legs of that resistor or even between the points there are soldered too. Don't know if that is normal, but perhaps that resistor could be dead?
I have also tested the Omega mode which is believe is related to resistors and i get a fluctuating value but my hands might be too shaky for this small stuff.

EDIT : and i understand now that all these wires are a modification by Sébastien to allow that board to use other drives than the original Citizen with belt which was inside before.

Remise en état du lecteur TechnoPlus

Yet something here is amiss.

 

[darefail]

This enclosure accepts unmodified pc drives. Have you tried with one?

 

[Xanxi]

Ok i will try one tonight.
I only have available one of these slim floppy drive combined with USB memory cards reader but it has a 34 pin header so will try that.

About the continuity around a resistor, as i know nothing, i have asked Gemeni IA and it says there should be continuity with a multimeter. Does that mean the resistor is bad?

 

[darefail]

Why there should be continuity?
What is the purpose of that resistor if there was continuity?

 

[darefail]

According to the colors of the resistor, it should be 200KOhm. No way of continuity.
You mean the resistor on your last photo which is between 2 legs of the chip, right?

 

[Xanxi]

I don't know, i have asked the IA and it seems as clueless as i am.

Yes that one.

 

[darefail]

It depends on what you have asked..

 

[Xanxi]

I hope the future of mankind won't rely on AI.

"If I measure the continuity of an electrical circuit on either side of a resistor, what is the expected result?

Show suggestions

Continuity measure on both sides of a resistor: expected result
If you are measuring the continuity of an electrical circuit on either side of a resistor, you should get a continuity signal."

 

[darefail]

It is correct to ask "if i measure for continuity". When you say "the continuity" it is like you are sure there is continuity, so maybe you burnt the circuitry of the AI

I just did exactly the same question like you, in my ChatGPT AI and it gave me the correct answer

Almost all multimeters do the beep sound when the resistance is in the range of 0-50 ohms.
So generally don't hear the sound but look at the value to be sure. Ideally it should be < 1 ohm

 

[Xanxi]

Well it seems Gemini car learn something from ChatGPT.

I used Gemini a few days ago for professional advices and it gave me some apprently good sense comments but nothing practical really.

 

[darefail]

All these AI applications are very very good but they have a limit.
The most difficult thing is to know this limit. So never trust it in a subject that you are not familiar.

 

[Xanxi]

Unfortunately, my available PC drive doesn't work at all in the Technoplus enclosure. Not even the head moving even if it does click on boot up. On the other hand, i don't know if that NOS drive works at all in a PC.

But good news, the old Mistumi drive i did the soldering on has finally decided to work in one of my Roctec RF302C enclosures. Now it is screwed inside for good before it changes its mind.

That leaves me for the next adventures with another RF302C and still the second Technoplus.
I think i should first get somewhere a few working PC drives in good shape and use them from there. They don't seem to be available new anywhere by now.

 

[darefail]

If it clicks on boot up, it is not totally dead and as long as it is NOS it should be working.

You can find NOS drives on eBay for sure and not too expensive.

 

[Xanxi]

Yes i am looking into what Ebay has to offer right now.

In the meantime, here is the board from the last enclosure not working apart from the Technoplus. This one is Roctec RF302C. All drive tested with this one gives DFx:??? without any floppy disk.
Under artificial light, i thought that some pins of the HD7438P chip might lack solder but continuity check (again!) seems good with my multimeter.

Any idea what might be the problem here?

 

[solarmon]

Check the continuity of the switch to make sure it is working as expected. The switch normally enable/disable the drive.

I would recommend using Amiga Test Kit to help troubleshoot and diagnose floppy disk drive issues.

 

[Xanxi]

Yeah i will do that soon.
For now, i have paused my tinkering of the drives and stored the remaining ones until i receive some new stuff.

But i have started working on the disks themselves.
I have a 3D printed kit to be able to clean them with the alcohol but i have net started yet.
It seems most of my old floppy disks are fine to read and write with my restored drives.
Some have bad cylinders, more often HD disks formatted as DD, and i have tried the trick to pass them several times under a big magnet and reformat afterwards. It seems to solve the issue most of the time, especially when reformatting with my Drawbridge USB drive.
Some still let me hear a small click click when the heads move on portions of the disks. I have known that dreadful sound for decades but would like to understand why and how it is made mecanically. Is it from the heads or from the disk?

Concerning Amiga Test kit and similar softwares, i don't know why they have never ever worked on my A4000 and would like to solve the problem. I can't boot from such a disk (issue with my Deneb flashROM maybe) and from the WB the computer freezes instantly. It would certainly help to be able to count on it.
That's why i am also working on my spare plain A600 to have a simple small wedge Amiga to work on my drives and disks.

I can say that those floppy disks finally seems to be an excellent storage media. In the 90's i though they were made for 5 years at most and started to trust CD. I couldn't be more wrong when CD/DVD are totally unreliable, both burnt ones or industrial pressed ones, while floppy disks seem mostly ok more than 30 years later.

 

[darefail]

Beware with magnets because a strong magnet can easily kill the disk and make it unusabl, instead of erase it.
About the click sound.. Tik, tok, click, clack are similar sounds and this is difficult to explain. Maybe a video with sound would be more helpful.
Have you tried a different version of ATK? Maybe 1.18?
Indeed, magnetic storage media, either floppy disks or VCR and audio tapes, are more reliable compared to cd's.

 

[Xanxi]

There are old devices available from Ebay called bulk tape erasers which seem to do the job of restoring floppy disks to new, but i can only find them from the USA (expensive shipping cost + customs and only 110V US power outlet). So i have seen someone on a Youtube video replacing these erasers with this magnet.

Amazon.fr

I have ordered one from Amazon and i am waiting for it to be delivered. In the meantime, i have used a smaller magnet which was on my fridge door to keep messages in sight.

I'm going to record the clicking sound of the bad cylinders with my phone.