[Coladam] MI Disk Drives

Geoff Oltmans oltmansg at bellsouth.net
Tue Jul 5 05:39:13 CEST 2011

You are partly correct about the Coleco drive. The biggest problem with the Coleco drives are the weak power supply. The solid state voltage regulators get really hot due to the load put on them, don't have adequate heat sinks, and in ideal circumstances they will do the job with adequate input filtering of ripple current. As such, the condition of the electrolytic capacitors is pretty crucial, and I'd bet that most drives out there have capacitors that are worn out. That said, I've yet to replace them in either of the two drives I currently have. :) A more reliable fix would probably be to bypass the internal power supply and instead use a PC power supply to the drive. They are certainly cheap enough these days. 

I'd like to take another crack at the drive if you're willing to give it up for a little while. I've learned a few things in the interim and have a few more tools at my disposal than I did the first time I looked at it.

Speaking of hardware... what sorts of hardware is everyone bringing to the 'con? I haven't seen a lot of exotic ADAM gear since I've been around. The most exotic was a TI Image Maker that I managed to get from someone on a TI board ages ago that I adapted to work with the ADAM (since they intended to market it toward the ADAM as well), but apart from the Coleco drives, MI IDE and MIB3 controllers and memory expanders, those are about the extent of my experience with third-party hardware. 

On Jul 4, 2011, at 4:06 PM, Frances and/or Richard Clee wrote:

> Jim - my guess is that you are misinterpreting things. As a dealer I 
> only got one drive from Mark that was DOA; that is how I ended up with 
> the "spare" board. (The backstory is long and complex). But the three 
> that I bought for myself (2 x 320k, later 1 x 720) are still up and 
> running. So is an Adam drive, provenance forgotten, converted to a 720k.
> I also have a couple of original Adam drives that work.
> It was my experience that only the toughest Adam diehards would pay the 
> price of an MI drive, which for the originals if I recall correctly was 
> about $300 back when that was serious money. (The original Adam disc 
> sold for $400 here -  think I still have a box with that price sticker 
> on it).
> By contrast I have generally been unwilling to sell Coleco drives 
> because they are so failure-prone. I'm told that the villain is the hot 
> spot - rectifier? - on the controller board, which simply fries all the 
> components around it. First the drive won't write, then it won't read, 
> then it won't even recognize there's a disc in place. It seems that the 
> culprit is pretty well certainly the board but even if the drive 
> mechanism is salvageable, it only responds to its own controller so is 
> pretty useless otherwise. Anyway I do not want to sell anything unless I 
> am pretty certain that it is working and will continue to work, and 
> given the prices Coleco drives bring I could not do so in good conscience.
> So my guess is the MI drives will only be pried from cold dead hands, 
> and the Coleco drives are dead and dying, which explains the market. But 
> I could be wrong - it's been known to happen.
> And Geoff, yes, I think the board alluded to above may be one I sent to 
> you for examination - so do you want to see it again?
> - rich c.
> On 7/4/2011 11:49 AM, Jim Notini wrote:
>> Yes, this is a presumption on my part just from everything I have seen and
>> heard over the last 2 years since being actively back in the scene after
>> over 10 years of just following things from the sidelines. I have heard from
>> a limited number of people that their M.I. drives have stopped working
>> properly (Rich C., Luc M. and some others) as well as a number of the
>> original Hard Drives designs that were made by M.I. that have become
>> inoperable. Is the rate of failure any more or less than is/has been
>> experienced in the PC World? Maybe not, but the end result is a lot more
>> devasting to the owner when you are talking about a retro system and a
>> repair or replacement option is usually not available.
>> As far as still working M.I. drives, until you let me know that your's are
>> still working, I have only heard that Bob S.'s large collection of M.I.
>> drives (Floppy and Hard) are still in working order and I hope there are a
>> lot more out there that may eventually surface.
>> Yeah, buying a Coleco drive, be it a Data or Disk Drive, on eBay or
>> CraigList is really a crap-shoot. I have been extremely lucky with the 5
>> Disk Drives that I have picked up by different means, and only one has had
>> an issue... an easily fixed alignment issue. The Data Drives have been a
>> mixed bag, but out of the 12 or so I have acquired, only 3 were completely
>> shoot and those were all the early revisions of the drive. The latest JVC
>> revision drives have all worked extremely well.
>> Another oddity is the total lack of converted Disks Drives (320K, 360K and
>> 720K). There were 100's and 100's of Coleco 5 1/4" 160K drives converted
>> back in the day by OBS, E&T, ADAM's House, ADAMLink, etc. and I haven't seen
>> one of these show-up anywhere... although there are a lot of people here on
>> the List here that still have their's.
>> As a whole, probably not the best "case study" ever done, but with such
>> limited numbers to draw from....
>> ----- Original Message -----
>> From: "David"<yyzonian at hotmail.com>
>> To:<coladam at adamcon.org>
>> Sent: Monday, July 04, 2011 10:02 AM
>> Subject: [Coladam] MI Disk Drives
>>> This is the first comment like this that I have heard. I own several of
>>> the MI disk drives and they seem fairly robust and have not had an issue
>>> with any of them. Is this a presumption or have you heard specific
>>> feedback about them being unreliable?
>>> I could also say that a lot of the original Coleco drives that do wind up
>>> on Ebay are not really tested working so that doesnt seem to stop too many
>>> people from selling them anyway.  And I bought at least 2 off Ebay that
>>> were not fully functional.
>>> But you are right, I watch for them too and cant recall ever seeing one on
>>> Ebay. I should put one up on Ebay and test the waters...
>>>> Date: Sun, 3 Jul 2011 22:37:48 -0500
>>>> From: "Jim Notini"<jnoti2 at comcast.net>
>>>> Subject: Re: [Coladam] disk drives
>>>> To: "Frances and/or Richard Clee"<cleechez at tamcotec.com>,
>>>> <coladam at adamcon.org>
>>>> Message-ID:<F55B537F5B9240E9BFA5C8579DDCB476 at HomePC>
>>>> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>>>> reply-type=original
>>>> Seems like the large majority of Mark's/Micro Innovations drives didn't
>>>> have
>>>> a very long lifespan unfortunately... probably why I haven't seen a
>>>> single
>>>> one go up on an eBay auction since I've been following things. It's
>>>> either
>>>> that or the simple fact that those ADAMites who were still around and
>>>> bought
>>>> these drives from Mark are the true hardcore fans and will probably never
>>>> sell their drive.
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