DD1 repair

[LambdaMikel]

Currently trying to revive a junkyard DD1 in terrible condition.
Replaced the belt with a what I though might be a good enough fit from this assortment of belts:


https://www.amazon.com/gp/product/B01HZD5JL4/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

This almost works, but I am still getting disk missing and read errors. I am wondering if this can be also caused by belts which are slightly too tight?

Another thing I am noticing is that the chip / controller on the disk drive PCB (the SMD chip facing downwards) is getting very hot. Is that normal? I guess I can compare with my working drive, but wanted to check if somebody can answer these question before I am opening it.

The drive has no pins, it's all LEDs.

I never had to adjust the potentiometer (drive speed?) before. Will this cause disk missing if the RPMs are off?

The thing is it can list a CAT, and I can load the BAS loader of fruity frank, but it fails loading the BIN then
(either with disk missing or read failure)

[gerald]

If the cat and loading the bas file is fine, I would more suspect an issue on the head stepper motor and head assembly.
It may just need a bit lubrification or worst, the motor itself (http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/the-end-of-the-eme-150a/)

[LambdaMikel]

If the cat and loading the bas file is fine, I would more suspect an issue on the head stepper motor and head assembly.
It may just need a bit lubrification or worst, the motor itself (http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/the-end-of-the-eme-150a/)

Thanks. I'll check if the felt pad is giving enough pressure and use some WD 40.
How about the temperature of the SMD chip? Do you know?

[simondo]

Unfortunately there are some quite complex alignment checks required needing an oscilloscope and a CF2 test disk. DDI-1 service manual details these checks.
Disc drive rpm can be checked using 'RPM' utility and motor adjusted fairly easily to obtain correct rpm depending on model of motor.

[Audronic]

@LambdaMikel

One of these helps, takes 2 Minutes to make.
the Piece of wood also has nails for the Tape belts on the other face

105 mm between pins for the Floppy drive
120 mm Between the pins for the Tape drive
53 mm  Between the pins for the Tape Counter.

Ray

[LambdaMikel]

Thanks guys, it suddenlty started working nicelty. Not quite sure sure what caused the problem, but I made 2 mistakes in the re-assembly:- one PCB screw was in the wrong hole- the black grounding cable was not attached to the motor, but floating freely. Maybe that touched some contacts on the bottom side of the PCB?
- then, some WD 40 and lots of canned compressed air ("xduster") to blow out some more junk- also, I had forgotten that my DDI-1 controller was jumpered to be in "CPC-powered mode". I put a switch in the DDI-1 now that allows me to switch betweeen CPC- and DD1-powered controlller....

The last point is paticularily funny. If you jumper the DDI-1 to use "CPC power", you can actually power the whole CPC over the DD1, even if the main switch on the CPC is off. Not sure that's healty though (the power then comes from the DD1 PSU, goes through the ribbon cable to power the controller, and then over the expansion port GND / 5V into the CPC)
Anyhow, all working now, thanks.

And the belts from Amazon above actually work fine... just in case somebody is tired of buying replacement belts for 5 $ per piece 

[LambdaMikel]

@LambdaMikel

105 mm between pins for the Floppy drive

Right, the assortment above contains about 15 to 20 of these I would say.
Maybe I'll make another attempt at getting rich, going to sell them for 5 Pounds or so (per piece of course) on Ebay  Just kidding...