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Myarc cards for sale/repair tips

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always bothered me that this wasn't well labeled as to where the hell pin1 is..  I assume its on the bottom based on this photo.. since I just moved (and again neglected to take pictures before unplugging) just confirming that..and where pin1 on the index cable is

 

Greg

I think you're right Greg, I'll check one of the cards for you to be sure. I remember using a black Sharpie to color the pin 1 from connector to connector, particularly on those 20-pin cables.  Pretty sure pin 1 is on the 'bottom' for all connectors. Does the HFDC manual point this out anywhere?:  I don't recall.

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My HFDC manual states the lower end of each connector is pin 1, when the card is upright in the PEB. 

If you look at the photo, there is a number two showing. It generally follows on these devices that the connector on the other side corresponds to connector 1.

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My HFDC manual states the lower end of each connector is pin 1, when the card is upright in the PEB. 

Thanks!

Sent from my LM-G820 using Tapatalk

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If you look at the photo, there is a number two showing. It generally follows on these devices that the connector on the other side corresponds to connector 1.

excellent point!  Now I really want to go look at a few cards to see  if they all have that '2' and if there is a '1' on the other side of any of them. :)

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I

 

excellent point!  Now I really want to go look at a few cards to see  if they all have that '2' and if there is a '1' on the other side of any of them. :)

'll look at my two tonight, and I do remember that on a recent HFDC repair that, that HFDC, had this 2 on it.

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All of the HFDCs that I have (3) have the 2 on them. They were bought at different times too, so multiple lots of the circuit cards had them.

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I took pictures of two cards.  On the older revision card the '2' and '34' numbers are partially cut off.  This isn't consistent among the older cards I have on the bench.  It appears the final run (lighter green card, #41) cut off less of the edges on either side of the connector. The lighter green card style was problematic in that many of the boards had one or more shorted traces.  In many cases the mask was missing in spots on the adjacent traces. Spent many an hour staring at boards BITD, looking for shorts... 

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I

 

'll look at my two tonight, and I do remember that on a recent HFDC repair that, that HFDC, had this 2 on it.

Mine look like the one with the 2 cut in half, like Insane One's lower picture.

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Spent some time today troubleshooting the last HFDC on my bench. 

 

The card had been jumpered for use with a PC power supply and at some point was placed in a standard PEB.  I've been chipping away at the problems over time and was left with an issue in the floppy drive circuitry. Since the hard and floppy ports share many of the same logic chips  I was able to "rule out" some things.

 

Today I picked up the card and ohmed out the floppy circuit.  Then it dawned on me: what about the 8Mhz crystal attached to the floppy disk separator (9216B) chip.  So I unsoldered a crystal from my own HFDC and soldered it into the problem HFDC.  The floppy disk cataloged on the first try. 

 

Before today, I don't think I've ever had to replace any crystal on an HFDC card.  Yet another 'first'  ;)

 

Now I just need to track down a possible intermittent connection which I hope can be cured by replacing a few of the single-wipe sockets.  Will be nice to get this card back to its owner.

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Spent some more time working with the HFDC in the previous post. Everything works as expected with one exception:  it will not format a hard drive.  The card will format, read, and write floppy disks.  The card will also read and write hard disks.  When I encountered this problem in the past, the read/write transceivers caused the problem.  I've replaced those chips and the circuitry all the way back to the 9234/9226 chips with no luck.  Unfortunately, there is no error condition and the card/formatter never 'return'.  The first cylinder is trashed in the process.  

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I may as well mention that I will be posting a few HFDCs for sale soon.  Just been bogged down by work and other things lately.

 

Taking a break from repairing the card from Hades.  Available:

 

1. Myarc HFDC with 32K update, 9216B update (high density capable on Geneve), capacitors refreshed, tested with both hard drive and floppy, with TI and Geneve.  Edge connector has been keyed.  No case, so you'll have to procure/make one.  Do not use a TI metal/composite clamshell unless it is modified!  I may have one 20-pin cable but no 34 pin cables.  Should work with DREM mfm emulator. $285.

2. Myarc 80-track floppy controller. $225.00.

3. Myarc RS232 card, black shell, $30.00

4. MiniMem cartridge with the Compute! game programming book.  $10.00

 

Same expectations apply as in first sale post regarding contacting me, shipping, customs, etc.  Busy week so I may only be able to respond to PMs  during the evening hours, local time.

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