Duodisk Repair Help

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Joined: Jan 28 2016
Posts: 4

Well, I've been working on restoring an Apple IIe that landed in my lap with multiple problems, as one might expect.

What's been done:

1. Repaired garbled screen

2. Fixed indefinitely repeating key issue (any key typed would repeat forever).

3. Replaced multiple bad RAM chips on motherboard and memory expansion card.

4. Repaired a couple of damaged traces.

The DuoDisk has me stumped and I could use some help.

Symptom = No Power on DuoDisk

Repair hisotry:

Drive one worked when I first got the system but now it doesn't (drive two never worked).

~ I opened the DuoDisk and swapped the power for the LED from drive one to drive two & drive two LED lit up.

~ I swapped the 4 pin connectors labled (6252) to see if it made any change to disk two and honestly it's been a month and I can't remember what effect it had.

~ Now the DuoDisk has no indication of power when the system is turned on.

~ All the chips on the DuoDisk are in sockets and I've a chip tester (All chips tested good but 3 were of a type my chip tester can test and those 3 were replaced with new).

The DuoDisk is connected via a Superserial card and a 13 pin cable (Apple # 590-0037-B.

Any thoughts would be welcome.

Thanks

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Joined: May 27 2013
Posts: 792
Re: Duodisk Repair Help

Simon Bar Sinister wrote:

The DuoDisk is connected via a Superserial card and a 13 pin cable (Apple # 590-0037-B. ...Any thoughts would be welcome.

Thought #1: The DuoDisk drive is not supposed to be connected to the motherboard with a Super Serial Card. The DuoDisk drive is supposed to be connected to the motherboard with a 5.25" disk controller card (although other controller cards can be used).

Thought #2: The Apple part number you gave, "590-0037-B" after searching on Google, is a serial printer cable.

Thought #3: The correct part number for a Duodisk cable is 590-0114.

Thought #4: With all of these mistakes, I suggest you get another motherboard and get the right cable and controller card and a known good diskette and remove your modifications and see if your Duodisk drive works by then.

Thought #5: Uhhhh So many problems, I don't know what to tell you anymore.

speedyG's picture
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Joined: Nov 16 2011
Posts: 2377
Re: Duodisk Repair Help

Beyond the listing insanitor made.... at the moment no further guesses...

this is an excellent example what happens by the method:
"try and error"......
use the wrong cable and kill the super serial card.....
continue trying and kill the mainboard or the duodisk....

first research, then reading, then acting....
that order saves a lot of money - a lot of trouble - a lot of time......

at least a hint for the correct cable:
http://www.appleii-box.de/H084_7_AppleIIDiskService7.htm

next hint:
you will need the DiskII card with the DB19 Plug at the output....:
http://static.classiccomputershop.eu/Files/5/17000/17331/ProductPhotos/MaxContent/80579377.jpg
or:
http://q7.neurotica.com/Oldtech/Apple/DiskController-1L.jpg
or:
http://www.lloyde.com/wp-content/uploads/2012/08/5S5P2236-e1345728621977.png

next hint:
at the top right corner the inputbox "search" is used to search former postings for
keywords used in former threads and postings....

welcome to the board

sincerely
speedyG

__________________

In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....

Joined: Jan 28 2016
Posts: 4
Re: Duodisk Repair Help

Honestly while I appreciate both replies I could do without the condescension. I'm a manufacturing engineer not an electrical one and I'm learning electronics the autodidact way (fixing old tech is a fun learning tool).

Should I have read more before hooking the printer cable up to the serial card ( yes ) but, it's not like IIe parts are impossible to come by and I expect to make mistakes along the way.

I hope we can move forward from a position of mutual respect. Smile

So I suspected the 13 pin printer cable after the fact having read the DuoDisk required a 19 pin configuration & I thought that another card may also be required.

I had only done one a quick search though, so thanks for verification on both points. I'll build a 19 pin cable (thanks for posting the pin out) and see what damage was done to the Super Serial card. For completeness and possible future help to another, I'll post back with my results when I have them.

Thanks again for sharing your knowledge,

Simon Bar Sinister

Joined: Jan 28 2016
Posts: 4
Re: Duodisk Repair Help

Alright, that was quicker than expected. Per your advice Insanitor I connected the DuoDisk to another IIe ( I happened to have another enhanced version IIe on the shelf ) and the correct cable was in a box. I think it's the correct cable anyway. The cable part number is 590-0114.

I get the same behavior on both computers (two different control cards and two different motherboards). The DuoDisk now has power indicated on disk one at power up but the disk just spins indefinitely with Apple IIe displayed on the monitor. If I hit control & reset the disk stops spinning and I get the command prompt on both systems.

Also, I believe the disk to be good as I loaded and ran a program from it prior to the drive failure.

How would you proceed from this point?

Thanks

speedyG's picture
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Joined: Nov 16 2011
Posts: 2377
Re: Duodisk Repair Help

Hello Simon Bar Sinister,
the reply was not a offense .... just a statement on different aspect of the path
attempting a repair task....so this was not hitting mutual respect.... i try to
stay along the path of respect to all members...

if someone is aware of the risks of the "try and error" method and is willing
to accept additional cost and time but then instead profit from learning by doing
it´s O.K. ...... but we have rather often seen people here running along that path -
not realy willing to pay that extra on time and expenses and being frustrated by the
results of such kind of attempt.... so it was just mentioning a general warning....

besides the page with the cable pinout, i also made pages on service of diskdrives at:
http://www.appleii-box.de/H084_1_AppleIIDiskService1.htm

Up till now i have not made pages related to the Duodisk unit specificaly....
this thread reminds me that it would be worth spending a weekend making pictures and then
writing 1 or 2 extra pages related to the Duodisk itself and treating specially the differences
to the disks explained up till yet in that page.... ( and 6 "followup pages" ) and i put that on may tasklist
to add such pages within next 2 or 3 months....

But up to the moment that pages at least explain quite a lot of basics that you will recognize
again while viewing the internals of the Duodisk. The analog board has quite large similarity
and the mechanics are a kind of "mixup" between the previous DiskII and the later internal
Disk of the IIc. So reading that pages might be of quite usable information - also related to
the service and adjustments.... the only big difference are the additional wires to adress a
a single drive apart from the other one and few electronics to handle that decision...

wish you good luck and advances in the task

sincerely speedyG

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In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....

Offline
Joined: May 27 2013
Posts: 792
Re: Duodisk Repair Help

Simon Bar Sinister wrote:

Honestly while I appreciate both replies I could do without the condescension.

Sorry if I sounded anything other than good on my part. That was not my intention at all. Your problems are too numerous for me to deal with since I do not have enough knowledge about testing circuits and such and what sort of damage occurs from doing what you did.

What I do is the process of elimination where I get known good parts to find out what is wrong that way.

Simon Bar Sinister wrote:

Alright, that was quicker than expected. Per your advice Insanitor I connected the DuoDisk to another IIe ( I happened to have another enhanced version IIe on the shelf ) and the correct cable was in a box. I think it's the correct cable anyway. The cable part number is 590-0114.

I get the same behavior on both computers (two different control cards and two different motherboards). The DuoDisk now has power indicated on disk one at power up but the disk just spins indefinitely with Apple IIe displayed on the monitor. If I hit control & reset the disk stops spinning and I get the command prompt on both systems.

Also, I believe the disk to be good as I loaded and ran a program from it prior to the drive failure.

How would you proceed from this point?

Your symptoms do sound like you either have a bad disk or one with the boot sectors erased. The simplest thing I would do in your place is clean the heads on the DuoDisk drives. Also, check to see if the piece of fabric that goes on top of the head is present and not loose as this causes bad disks galore.

Joined: Jan 28 2016
Posts: 4
Re: Duodisk Repair Help

I'm glad to know the interpretation of the original post was my mistake ( one of the pitfalls of written correspondence ).

Speedy I missed the Disk II link in the last post somehow. Thank you very much for pointing it out, I'll give it a through reading.

Insanitor, I'll check your suggestions as well, thanks.

Again, I'll post back with my findings and I appreciate all the assistance.