[Repair] disk drive 6128+ troubleshoot

jbaudrand · 19:37, 25 September 22

Hello, After successfully repair the power switch of 6128+ thanks to you, we try to repair the disk drive: we changed the belt, but it still doesn't work properly. We have read other threads, and frankly we hope it's just the drive and not MB issue. Before buying a gotek for nothing, could you just watch the video and tell us your feeling about it, any idea is welcome, the weird thing is that once we had try a CAT command, the motor drive is keep turning forever, and moreover when we switch the cpc ON and before we type CAT the motor continue to turn.
(sorry for any english mistakes, I'm french)

jbaudrand · 14:27, 08 October 22

we are trying to check if it's a rpm problem. In order to check this I'm trying to create a cpr of RPM.dsk program because we have only c4cpc, no gotek. I'm trying to use nocart 1.9 with no luck. I'm sure I'm part of the problem but I don't know what's wrong, any idea?

Bryce · 15:59, 08 October 22

There's a ROM version of dsktest available here if that's any use: https://www.cpcwiki.eu/forum/applications/dsktest-v0-1b/msg98206/#msg98206

Bryce.

jbaudrand · 18:03, 08 October 22

Thanks Bryce, It's just that I haven't any clue how to use a rom version with c4cpc... it only accept .cpr or .bin file

eto · 20:10, 08 October 22

Quote from: jbaudrand on 18:03, 08 October 22Thanks Bryce, It's just that I haven't any clue how to use a rom version with c4cpc... it only accept .cpr or .bin file

I guess .rom is .bin . just rename it.

Bryce · 10:55, 09 October 22

Yup, you just need to change the file extension to bin.

Bryce.

jbaudrand · 17:51, 22 October 22

OOk we progress slowly, I managed to create a cartridge version of dsktest. I put a cpm/plus disk from amsoft in it. I can switch the drive on off, I can check the rpm 292, but I don't understand what does the others functionnality of the software, I've launch a found sector 193 and it return no. so I'm asking again help, is there a 193 sector on this disc? Is it the head motor that is blocked? I know this sound pretty dumb, but all I've ever did was changing belt, and electronic repairing is not my skill, have you got any clues?

jbaudrand · 10:40, 04 November 22

after I put some oil on head axis and motor axis, now I can read most of my cracked disk, but not a single original disk worked. for example Gryzor does'nt work at all (it worked on my other cpc) and if I try a dsktest speed with gryzor disk it says: 1400 RPM Do you any hint why original disk don't work?

Animalgril987 · 21:18, 04 November 22

I believe that the disk speed should be 300 rpm with a small leeway either side, so either dsktest is reporting the speed as over 4 times as fast as it actually is, or something is very wrong with the drive.

jbaudrand · 21:26, 04 November 22

I got another cpc 6218+ and dsktest show 292 RPM on it too and every disk works. Not this one, so I have no clue what is the pb on this one, I don't have the skill and the tools like Noel to dismount the motor of the head to see if it's perfectly align. Maybe somebody already had this kind of pb and have an easy solution, if not I will remove disk and put a gotek, but frankly I want to save my floppy drive.

Bryce · 13:20, 05 November 22

Quote from: jbaudrand on 10:40, 04 November 22Gryzor does'nt work at all

Hey @Gryzor : He's on to you! You just spin a lot, but don't actually do anything!

@jbaudrand : The rpm software sometimes gives impossible results if the connector to the drive has dry joints.

Bryce.

Gryzor · 13:30, 05 November 22

Goddammit, my ruse had been revealed.

jbaudrand · 21:23, 05 November 22

thanks bryce: I wil check the connectors and put some 3in1 for electric connections. But it's weird: why cracked disk not original disk.

jbaudrand · 15:40, 07 November 22

I give up, still not working. Does one of you still make hardware repair service from France? maybe it's not worth it... I don't know..

Bryce · 15:43, 07 November 22

Maybe the original disk really is damaged?

You can send the drive to me (in Germany) if you like and I can check it out?

Bryce.

jbaudrand · 20:46, 07 November 22

The gryzor disk works perfectly on my old 6128, and the 6128+ of my bros, so the disk is 100% not faulty. I appreciate your offer. contact via mp.

Bryce · 13:18, 27 November 22

Sooo... Drive fixed, so what was the problem? The drive belt was too wide and a little too loose. It was rubbing against the metal frame and "stiffer" disks such as original titles usually are, were causing the RPM's to drop below the acceptable level.

Now reading even the most temperamental test disks I have.

That 1mm extra width and slightly thinner rubber was enough to mess up your day unfortunately (proper belt in foreground, jbaudrand's belt behind).

Bryce.

jbaudrand · 20:16, 27 November 22

I'm happy you succeed to fix it

:/ well the belt came from a french website... maybe it will worth to add only reliable shop or exact belt' specification in cpcwiki (I haven't checked if it's written somewhere)

eto · 14:34, 28 November 22

Quote from: jbaudrand on 20:16, 27 November 22exact belt' specification in cpcwiki (I haven't checked if it's written somewhere)

it is ;-)

https://www.cpcwiki.eu/index.php/Changing_the_drive_belt

JankyComps · 14:58, 27 February 23

Blimmin drive belts! I've just finished changing out 4 on different machines recently. 🤪

When the belt turns out to NOT be the problem however...

I'm troubleshooting a problem with my 6128 disc drive.
Pretty sure something is wrong with the 12v supply, possibly at the monitors end.
If that turns out to be the case, I have some solutions lined up.

But if that isn't the case, I'm planning on taking my multimeter over and tracing the route of the 12v supply from the monitor output across the board to the drive.

Has anyone seen a diagram of the route the 12v supply takes from the monitor to the disc drive? Trying to work out good points to place the probes.

It's at my parents, so I'm working on it sporadically.
Luckily my 464 is behaving perfectly and has a DDI5 on the way. So I'm not rushing

Bryce · 15:44, 27 February 23

There are only two components inside the 6128 that can cause a lack of 12V to the drive. These are the two transistors directly behind the 5V power socket. If the monitor is supplying 12V, but no voltage is getting to the drive, then (assuming no wires are broken) one or both of these transistors is the most likely cause.

Bryce.

JankyComps · 20:38, 16 March 23

I'm relieved to say that it wasn't the transistors! I hate soldering on PCBs and they hate me trying

But thanks to the advice from Bryce, I was looking around in the right area.
Turned out there was a break in the grey 12v cable that comes out of the 6128.

I had limited supplies and I wasn't sure of the type of JST (?) Amstrad used.
So I cut down the original cable until I had gotten past the break. It was inside the blimmin gland!

I had just enough cable connected to the JST plug to still use the gland. Then I spliced in another cable with a 2.5 5.5 end.

It worked!

Turned on and heard a lovely familiar "chunk" sound from the drive.
Roland in Time ran perfectly!

I've got a heavier duty CCTV cable coming with the DC plug already on.
If anyone knows the type of JST plug I need to find, please let me know. It looks larger than the ones I've seen before.

Failing that, I can see a lot of soldering and heat shrink in my very near future

Thanks Again!

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[Repair] disk drive 6128+ troubleshoot