Amstrad CPC 6128 Repair & Upgrade Part 1

[@GadgetUK164]

Part 2 - kzbin.info/www/bejne/r2bJp6KKo96EiqM EDIT: skonkfactory and TrollingAround pointed out that the infra red sensor there isn't for rotation timing, but used to detect the start of sector 0 when formatting. This should allow tracks to remain in sync with each other on the disk, ie. all starting sector 0 at the correct point. Link to Noel's Retro Lab video - please check it out, and his channel! - kzbin.info/www/bejne/jXyTgqKMg7uCaNk I had to re-upload this- someone pointed out I messed the credits up!!!

[@SimonZerafa]

Springs to Mind? 🤣🤷‍♂️

[@neilobusk]

yep subbed to our man Noel... he must be good because he has somewere to hang his tools ::)

[@NoelsRetroLab]

Great video. Yes, that particular model of drive seems to fail like that very consistently. I definitely liked your low-tech fix. It's effective and it'll probably last for a long time. Sometimes the simplest fixes are the best fixes 😃👍

[@GadgetUK164]

Thanks! 👍 Yes, it's low tech! But I think the metal part will continue to bend over time in any case. It would be cool if someone 3D printed something that fits as a cap over that point on the back.

[@mrsoggs1350]

@@GadgetUK164 im a technologic simpleton, but could you not run some solder on the tab to strengthen the metal?

[@GadgetUK164]

@@mrsoggs1350 That's not a bad idea actually!!! The problem would be soldering onto it - the motor is probably Zinc (or something) plated - but you could scratch off that coating, rough up the shiny plated steel flexible part and solder a blob over the lot. If the scratching is good enough and the flux and solder bite, it might do the job and be more fixed in place.

[@GadgetUK164]

One problem - it might be too rigid then. Which could cause damage to the part that slides up and down the worm (over time). it needs some flexibility I think to act as a strain relief when the head goes all the way to the far end (I think).

[@MrFlint51]

The CPC monitor has a socket for the power cable to go into, and a cable to go into the socket on the CPC. Amstrad joysticks have a socket for the second joystick. The wiring routes the common line on J2 to the common2 line inside the CPC. I got a CPC the week they went on sale in 1985, and used it regularly until 1996.

[@nickolasgaspar9660]

I had a nonworking Amstrad drive for years. I cleaned it and I replaced the belt but it refused to work. Yesterday I change all the caps and it was the first time I got a dir from a floppy. It turn out bad caps on these floppies are a common issue.

[@missionpassed4584]

aaah brings back the memory of when I upgraded my CPC 464 to the CPC 6128 and gained quick loading hard disks and a few extra colours in game, then had to buy a compatible tape cassette player to play my non disk games to boot!

[@discoHR]

14:33 Nice pet (top right corner of the screen). :)

[@GadgetUK164]

LOL! I never spotted that!

[@spankysmp]

Great video and handy. I got given one of these with monitor and disks for 'my collection' last year. I did change the belt as you did (bought from the same place!) and the DD still failed so it was consigned to a box for sometime in the future. I might dig it out this weekend and give your fix a go. Cheers.

[@ncbrady]

Interesting fix, by the way that fdd you had is not the same in all CPC 6128's, only some shipped with that particular brand and particular failure, I liked how you explained that the hole in the disc inside the fdd was for the rotation speed, i'll keep that in mind when i program a tool to test alignment/speed for the cpc 6128 later this year. Oh, one final thing, Noel's name is pronounced the same was as 'the first noel...' christmas song (as in 'no el'), and not as the Irish/English pronounce it. Thanks for your video !

[@GadgetUK164]

Thanks! I stand corrected regards to the hole - some drives (PC ones - not 3") may use that for rotation timing, but it seems that majority of older drives that have a hole like that use the hole to find sector 0! That's evident in the 6128 Service Manual which I looked at yesterday. From what I understand they use that pulse so they know precisely where sector 0 is (presumed only when they are on track 0, looking for sector 0). Some people have suggested that sensor is only used when formatting and a read will work without it. I don't quite get that tbh, because you would think that the drive would be able to find sector 0 by just reading the contents of the track and looking for an index pulse or something similar. Maybe it didn't write anything like that, just the raw data.... And when formating, does it really matter where you start writting sector 0?!?! I would think not, unless there's some underlying low level format done at manufacture and the position where you write is more critical than I thought?!?! EDIT: Just made a correction to what I just typed. There is a TRACK00 sensor, but that I believe is the normal track 0 sensor, not the IR one. Others have suggested the RPM is constant 300 rpm and not adjusted / controlled on these drives. I am not sure that's true of all the drives because the service manual describes adjusting it.

[@alanclarke4646]

Hi. The hole nearest the label is the Sector Zero sensor hole.

[@GadgetUK164]

Thanks - shocked at that! I had no idea! It seems its only needed for formatting (and presumably writting)!

[@skonkfactory]

@@GadgetUK164 Nope, writing just uses the sector mark bytes to figure out where it's at.

[@JoystickDivision]

Another great video. Good thing you didn't lose that pin! The Sega SF-7000 uses a very similar 3" floppy disk drive. I had to repair mine with a new belt and a bit of cleaning of the head. Thankfully the belt is the same one that the CPC 6128 uses. I have a video on my channel about cleaning and repairing it as well as an SC-3000H, which was fun.

[@Uncover2295]

Excellent video! I have recently purchased one of these machines as it was the first computer I owned as a child. I have been inspired by various youtube channels to dive into retro gaming and relive my youth. Fingers crossed I can get my machine fixed up by following this and other super helpful videos. I wonder what you do for a living, i work in I.T and know my way around modern machines but am learning all the time about the CPC 6128 thanks to channels like this 👍

[@GadgetUK164]

Thanks =D

[@Nick_R_]

Excellent video. Thank you.

[@IanSlothieRolfe]

I think when the drives were originally made that metal tab was springy and intended to take up the end float on the helical shaft. Over time the metal gets less springy and even if you bend it back to "preload" it it will eventually lose tension. Your fix is probably the best under the circumstances, at least you can adjust it if necessary should it loosen.

[@VintageTechRepairs]

Fantastic Fix. I'll have to remember that one

[@ford1546]

Some cheap power supplies I have purchased from eBay do not have a noise filter on the input and output

[@Novabug]

The monitor would supply the 12v to the disk, but I assume you already know this Chris. Nice to see another cpc back on action, or will be.

[@GadgetUK164]

Thanks Chris =D Hope you are having a good Christmas =D

[@skonkfactory]

The index hole is for the sector 0; the CPC drives don't support changing the speed (the 12v motor is just connected to a transistor driven from the /MOTOR pin on the CPC). Without that sensor, everything works except formatting, which will fail.

[@GadgetUK164]

Very interesting! I would have never expected that! But thinking about it, for formatting it makes sense, if it has no way of monitoring rotation speed, regardless of where it starts writting on the first track, the 2nd track becomes a problem hitting sector 0, and every track thereafter. It has me wondering how sector 0 is found on other drives now lol!

[@skonkfactory]

@@GadgetUK164 It doesn't actually matter if they all line up. Once the disk is formatted, each sector starts with a unique number anyway, so that's how you find sector zero on each track. The index hole (and its sensor) is only used while formatting. I discovered this the hard way, making a cable to hook up an HxC floppy emulator to an Amstrad 6128 Plus- Amstrad used a 26-pin header rather than the standard 34-pin Shugart job and I didn't have the INDEX line hooked up in the right place. Everything worked for reading or writing, but I couldn't format anything; the FDC would take the format track command and then just hang, spinning the disc, waiting for an index pulse that never came. 5.25" floppies also have an index hole. 3.5" discs generate the index pulse from the position of the spindle motor since their hub is asymmetrical and the disc is always gripped in the same orientation.

[@denniskubik7360]

The Sensor is for detecting the Beginning of the Disc (Sector0).

[@GadgetUK164]

Thanks =D

[@AdamSommer70]

Great video, thanks for posting!

[@Kerveros1904]

14:35 you managed to deBUG the machine...a bug is leaving the area feeling defeated.

[@GadgetUK164]

LOL!!!! 🤣

[@HeyBirt]

The spring takes up the end float of the armature. Some motors will have a wavy washer inside to do the same thing. As you said the armature being allowed to be pushed back further affects alignment. Are the holes on the back of the motor threaded? That might be a way to attach a bracket to push in on it though I think your shim will work forever and is super simple.

[@GadgetUK164]

I am pretty sure the 2 screws that hold the motor on could be removed, cap fitted over the back of the motor, and the screws put back in to hold it on. That said, the alignment would then need correcting =/

[@HeyBirt]

@@GadgetUK164 It looks like there are holes in the back of the motor itself. If those were threaded there would be no need to alter the alignment. Of course, it could just slip over the back of the motor and be fixed in place with a grub screw or two that press on the side of the motor body. I still like your shim the best :)

[@GadgetUK164]

@@HeyBirt I will check that!! See if they are threaded!

[@isorokueightbit1974]

Use ferrites for cables to the psu output line, maybe 2-3 cm after not more, to reduce noise. This Y splitter of 5v make your tv in some cases a big disk drive led when loading. Give 5v from other 5v psu direct to RGB cable .

[@GadgetUK164]

Thanks, I will try that!!! I still have the PSU I added connectors on sat here!

[@isorokueightbit1974]

@@GadgetUK164 Inform about the result.

[@CooChewGames]

Noel's Retro Lab recently did a video for 2 player joysticks on the Amstrad machines :-)

[@GadgetUK164]

Yes, well worth checking out - he has other cool CPC videos on his channel too!!!

[@TheSeanBean]

Interesting, a Meanwell PSU gave my CD32 video interference. On my 6128's I ditched the floppys and am using Goteks. They fit nice with Gotek case cutting. Then you can ditch 12V and fit a push button in the space, this is wired to test points on the expansion connector to give 'push reset' instead of power on/off. I think your CRTC is a good one (Type 1). BBC Micro CRTC's are compatible. One of my 6128s had a type 2 which is not the best for demos, so that was removed and a socket added.

[@GadgetUK164]

Yes, done exactly that in part 2 =D

[@neilobusk]

just bought a 6128... site unseen...... hoping and praying you can help me out..... really lol loading tapes on a 464 sometimes gives black screen .. no idea why power reset is the only fix... N x

[@ford1546]

if power supply has a lot of noise then you can try a coil in series on 5v and a capacitor in parallel. tray small values and large worthy capacitor

[@GadgetUK164]

Thanks, I will give that a go! I have tried before to remove the damn switch mode noise without fail, but I didnt have any beefy coils.

[@ford1546]

@@GadgetUK164 Inside a switch mode power supply you will find coil and capacitors as noise filter. Coil must be ferrite core and it does not have many rounds of copper wire. Used oscilloscope if you have when making noise filter. Easier to see if it works. Power supply must have a load equal to that Amstrad gives you. sometimes you have to use NanoFarad in parallel or mf. value. EEVBlog Remove Power Supply Ripple. m.kzbin.info/www/bejne/raDTnnivj7Chj9E (You can also try this) images-na.ssl-images-amazon.com/images/I/419kD7aNxRL._AC_SY1000_.jpg

[@4034miguel]

Impressive work of patience and knowledge. How I would like to have one of those, but I would never be able to repair or solve issues if something happens to it. Could that drive be replaced by a 3.5 floppy drive?

[@GadgetUK164]

Thanks! I believe you can change the drive to 3.5" on this and the Spectrum +3.

[@bluefalcon7782]

Yes. But: - You have to swap some lines in flat data cable - You have to swap two wires in 5V connector - Standard 3.5" drive never fits the space for 3" drive

[@RetroMarkyRM]

excellent. must admit i've never owned an amstrad (except a PCW which I added a gotek to). might have to pick one up some day :)

[@Nevarden]

anyone know an issue where the space bar is not working and some of the keys is choosing the wrong options on the screen?

[@tooheystechgaming1977]

Cheers i have a +3 drive which im trying to get working...subbed

[@GadgetUK164]

Thanks for the sub!

[@philiphandforth4390]

You should try out symbOS for the cpc, it's a Windows type multitasking OS that's built around z80 CPUs. It's really quite clever and I'm after a msx or cpc to give it a go.

[@Xalior]

Yeah, the second side was blank on a lot of 3" software. Speccy, and Amstrad. -Dx

[@GadgetUK164]

Thanks =D

[@MrAlan1828]

I tore apart my 6128 to clean and do a external floppy mod, now after 5 years I can't find the case, floppy and keyboard. just have the mainboard intact, what project can I do with it now? I do have a CPC464+ laying around

[@GadgetUK164]

=/ Not sure really, other than keep / sell for spares? 464+ is nice!!!

[@laikesagores3258]

Unbelievable, there is Life out there or may be a trip to the Past!!!

[@Starchface]

That dreadful tab. It seems to be intended to take up slack in the mechanism. Predictably, it would weaken over time and produce this result. Apparently this was a cheapened design, and earlier ones had a proper coil spring inside the motor. Decent keyboard, internal drive with external drive port, many display colours, 128K RAM. A very nice machine. Too bad we never had Amstrad over here.

[@PJBonoVox]

Yeah, it's such a lazy design.

[@stephenwhite506]

Repairing and upgrading a cricket bat. ;-)

[@GadgetUK164]

LOL!

[@TrollingAround]

I thought the hole was for detecting sector zero, and the speed was fixed.

[@GadgetUK164]

No, the hole remains always in the same place in relation to the sensor and the head position - it's for RPM! The RPM is controlled via feedback from that sensor probably!

[@TrollingAround]

@@GadgetUK164 - en.wikipedia.org/wiki/Floppy_disk#Finding_sectors

[@GadgetUK164]

@@TrollingAround Very interesting! I am surprised by that!!! =O

[@cossasomi]

If the floppy is the only thing that uses 12V, couldn't you fit a DC-DC step up module and then run the whole computer off a known good (as in with a clean enough output) 5V PSU? Even if those converters are somewhat noisy, if 12V are for the motor only I guess it shouldn't care too much about the quality of the power it's getting.

[@GadgetUK164]

Yes, you could do that! One issue that can arise when using a DC-DC is switching noise. A few people have tried that on a Commodore 64 for example and it results in noise on the SID. But it may work OK here. The technique seems to work OK on Spectrums for example. The 12v is redudant in the next part as you will see! The PSU I've already serviced in a previous video and I added over voltage protection too.

[@skonkfactory]

@@GadgetUK164 That's because the Spectrum's already noisy as all heck anyway- that little homebrewed switcher they have to generate -5 and -12 volt rails is *filthy*, you'd never be able to get away with that these days.

[@cocoe68]

Hi, very nice video. I have a dude about disk belts, anyone knows where to find replacment belts for floppy drive? Any home made replacement? Cocoe68

[@GadgetUK164]

You need to measure the thickness of the belt, its diameter (approx - a little smaller will fit and work generally). Best place to find them tends to be eBay. Search on the diameter and you might find something suitable.

[@danielson9579]

Ive never seen a cpc128k game 🤔

[@stephenvalente3296]

I had a load of them when originally released. Unfortunately my parents threw out all of them, mostly disk versions that cost about £15 each back in the late-80’s! My release time 6128 suffered a dead monitor about 3 years in, which unfortunately I was unaware of the ability to buy the MP2 add on at the time, which would have saved it for years to come! Have another one now, but need time to try it out properly.