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ADAM Maintenance #03

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As everyone knows or is learning after they take the plunge and pick-up an ADAM Computer, the hardest to find and most expensive item to add to your system is the Coleco made 5 1/4" 160K SSDD Floppy Disk Drive. More importantly is the fact that there are usually no guarantees that the drive will be in good operating condition even if the seller states so... you basically have to take an expensive leap of faith. I've taken this leap twice so far and have been, both times with two drives included with each purchase, lucky with 3 of the 4 drives... two of which are going nowhere (unless an SD Drive becomes a reality), one has found a new home and the final drive took me quite a bit of head scratching to finally figure out what was actually malfunctioning and a little help from an old friend, Terry of eColeco, to finally refresh my memory on what to try to fix the drive. I have included Terry's invaluable information, my original email to him as well as a couple pics for everyone's reference in case they experience a similar problem. BTW, the adjustment worked and the drive is working like a champ once again... and may soon have a new home if continued tested over the next week goes well.


My email:




I picked up a system with a 5 1/4" Disk Drive recently and after a couple weeks of light use the drive experienced a slow death that started with ever increasing access times and finally to the state now that it will very rarely bring up a directory in SmartWRITER and never load a boot-able disk. I opening up the drive and cleaned everything thoroughly, checked the few socketed chips, other connections, used a disk cleaner, etc. to no avail.


I was wondering if you still offer service/repair work on them and from what I have described, if it could just be an alignment issue or if it is something more serious and unrepairable. BTW, no disks came with the unit as I recall having a disk formatted by the drive in question helped with the re-alignment of the head.




Terry's response:




No, I don’t service the disk drives anymore because I have next to nothing in parts for them. Your drive sounds like a part is changing value due to age/fault that is causing the disk read problem. It could be in the read circuit or even in the power supply circuit causing the voltage to slowly change as you have used it over the weeks and the part in question is changing value. Trying to realign it with the variable capacitor might work, but since a part has changed value it might only be a temporary fix before it is out of alignment again if the defective part keeps changing. These are the type problems that drive a tech crazy sometimes since it is not a complete failure. I used to swap in a good mechanical drive to see which part of the drive had the problem. I never worked on the mechanics, just replaced a bad one with a good one.


You can try the alignment yourself by making small changes to the variable capacitor while trying to boot a good disk or read a directory. I used Disk Manager (included with each drive sold) since it was pretty picky about the alignment being correct before it would boot. The white variable capacitor with a small flat blade screw slot is located on the left side of the bottom board about midway back on the edge behind the on/off switch (as I recall). It is about the only variable capacitor. Remember where it is currently positioned and don’t turn it either direction more than one eighth of a turn to see if reading improves.


Hope that helps.




For everyone's information, the disk drives were developed by MPI Technologies and internally you have the drive mechanics (like what you would see installed in a PC 5 1/4" drive bay) and underneath the mechanics is the disk drive controller board that is populated with numerous chips that are soldered directly onto the controller board with the exception of one that is socketed... the BIOS chip. At this time, there is probably only one person that MIGHT have some spare parts available and that would be Bob S. (AA handle is Adamcon).


Here are the pics of an opened drive:



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Reviving this as I now have 3 160K drives all with the same symptoms. Used to work fine, then only worked when they had a chance to warm up for a while, now wont read/write.

All the other functions are normal, i.e. power on they spin, power up the ADAM and they stop spinning, put in a disk and pull reset, they spin again and lites go on, I mean I have owned them forever and know what to expect when doing different things.

If when turned off I move the disk head and power up again it re-homes itself.

None of the caps appear leaking or bulging. The drives have been babied so theres no dust, dirt, crap, corrosion.

I tried the variable resistor thing, didnt want to be too aggressive with that, made the recommended 1/8th turns to the left and right, maybe turned it a total of 3/8ths rotation each way. Nothing.

Its not like it continually tries to read and re-read the disk, it doesnt seem to try to read it at all.


Edited by coleconut

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I would continue to turn the Variable Resistor in small 1/8th increments clockwise with a Disk Manager disk in the drive and trying to load. IIRC, I ended up turning the adjustment screw on the one discussed above almost a full revolution in the clockwise position. If that doesn't work, then you have nothing else to lose but to continue adjusting the screw in these small increments going clockwise and if needed start adjusting in a counter-clockwise direction until you get back to the "original" screw setting. Then continue in this counter-clockwise direction all the while with the system trying to load Disk Manager.


If this doesn't work, then you have yourself a bad firmware chip or possibly some electrical damage to the controller board. I seem to recall this being an issue with defective drives, but not being the hardware guru that I should be from all my years of using the ADAM, anything else I can offer up would just be guesswork.

Edited by NIAD

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I'll try that thankyou. What I was doing was testing the drive, then powering down and turning the resistor a bit, then rebooting, then repeat. Didn occur to me to try it on the fly as you suggest.

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