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aftyde

Horizon HRD RAMDISK debugging / repair

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Hi All,

 

Looking for help - bought a HRD off eBay. It only reports 182K, gets errors on the memtest, however it loads the DSR OK and seems to function as it should. (have not tested for corrupt files) In any event - I suspect some of the jumper wiring might have come off over the years and need some assistance.

 

Anyone have a build manual?

Anyone have this card???

 

http://www.tyde.net/2.jpg

 

If you have it - can you look at the expansion jack pad and tell me if yours looks like mine???

 

http://www.tyde.net/1.jpg

 

In general, it's a clean looking card that appears to have suffered no electrical (visible) or physical damage. I'd love to put it back into service (I run a pretty big 35 year old database on my TI99).

 

Is there anyone out there with the skills and time to take a shot at fixing it? (it's beyond my skills to do a component level debug - though I could probably fix anything if I knew what to do).

 

Any assist would be very much appreciated...

 

Cheers, Arthur...

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looks ok to me. there is only 23 8K ram chips so you should not get more then 182k as the first 2k is used up by DSR.

 

What type of errors is it reporting?

 

Could be one of jumper wires is touching another one, and make sure all the piggyback memory chips the pins are nice and tight, it is reporting all the memory correctly, so if you getting errors, it could be one of piggyback pins either address or data is not perfect.

 

There should be chart someplace online that shows depending on error in memtest what stack of piggyback chips to look at.

Edited by Gary from OPA

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Nice clear pics! I don't own one myself. That said, one of my main troubleshooting tips is to have a close inspection for poor solder joints or other simple things. I spotted a few dicey-looking joints. The two legs of the IC near top left look soldered on while it was socketed. My own experience is you can melt the plastic of the socket and it can contaminate a terminal or prevent contact. That needs looking at and maybe checking with a meter from the board to those two pins for continuity.

 

Towards the bottom left, one or two of those have solder, but might be cold-soldered. The ones with arrows look messy and lumpy. A quick touch with a clean-tipped hot soldering iron with a bit of fresh solder on it might get those looking better.

 

Seems odd only one switch on the DIP-switch is on, but I don't know the "norm" for the amount of memory installed. Some HRDs were fairly small in size. It might be fully populated with chips, but they might be small capacity. I didn't look them up in a datasheet to see. NOTE: OPA beat me to this one! Might be it's just fine.

 

Finally, the regulator with the heat sink at bottom right seems to have the center terminal just resting on top of the board. That pin is also electrically the same as its metal mounting tab, so perhaps it gets connected via that. Good to verify it.

 

With this many potential things spotted from the top, I'd really look at the bottom of the board to make sure there are no solder bridges between conductors or more cold joints.

 

Hope this helps a little!

-Ed

 

post-38786-0-98522000-1397272889_thumb.jpg

Edited by Ed in SoDak

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Dip switchs are right, only one should be on.

 

Also a picture of BACK of the board might help.

 

Being one of first batch of Horizon's built the 00 series, means after the board was soldered, all the excess pins on the back were clipped off, which make it neater looking, but also over time makes it more likely to have cold or broken solder joints, so best to quickly go over all the joints on the back to fresh them up, the Horizons were hand soldered not wave soldered, so after so many decades of aging best to tight up the joints on back also.

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Hi Gary, Ed,

 

Really appreciate all the feedback - and I'll check the solder joints per suggestions. I have posted a pic of the back of the card.

 

http://www.tyde.net/3.jpg

 

I have also heard that some errors are caused by batteries. I have a very small Ni-MH 3.6V battery on it. I just picked up a proper 3.6V Nicad pack (which is a bit larger) and when it's fully charged will connect that and re-run the tests.

 

Cheers, Arthur...

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Hi All,

 

Looking for help - bought a HRD off eBay. It only reports 182K, gets errors on the memtest, however it loads the DSR OK and seems to function as it should. (have not tested for corrupt files) In any event - I suspect some of the jumper wiring might have come off over the years and need some assistance.

 

Anyone have a build manual?

Anyone have this card???

 

http://www.tyde.net/2.jpg

 

If you have it - can you look at the expansion jack pad and tell me if yours looks like mine???

 

http://www.tyde.net/1.jpg

 

In general, it's a clean looking card that appears to have suffered no electrical (visible) or physical damage. I'd love to put it back into service (I run a pretty big 35 year old database on my TI99).

 

Is there anyone out there with the skills and time to take a shot at fixing it? (it's beyond my skills to do a component level debug - though I could probably fix anything if I knew what to do).

 

Any assist would be very much appreciated...

 

Cheers, Arthur...

 

 

Hello Arthur.

 

If config is reporting 182 K then it is correct as far as RAM count goes and by default means that the 154 and the wires are most likely OK as config is seeing them..

 

How does MEMTEST act ? does it show the same errors each time you run it (Bad address/data line somewhere) or do the results change from time to time (bad socket connections ?)

 

What happens when you run MEMTEST twice in succession ? Does the second run through pass ?

 

small HRDs are fairly easy to repair and I'd be willing to do it for the cost of the new sockets/components and shipping. Amounts to about 35.00 usd + shipping for new double wipe sockets,VR & needed components. Or I'd be happy to walk you through it.

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Hi Everyone,

 

Replaced the battery (all the AA holders had aged into uselessness) with a new 3 cell 3.6 V 800ma NiCD pack for a cordless phone. I had read somewhere that a solid set of batteries made a difference. I also went and re-soldered all the joints pointed out by Ed and some others that just looked suspect. Also re-seated all the chips and inspected for bad soldering on the stacked chips.

 

I fire it up and it reports

 

total memory 186K

ramdisk 184K.

 

I can fill it full of files and all the "check disk" (non destructive) tests pass.

 

On MEMTEST, option D "24 Chips to Test on 18 test numbers" tests the first 180K and that seems to pass OK.

The U11 test also passes...

There were other programs that do memory tests on the disk I was able to find - and many of them fail. However, it seems like MEMTEST is the right one and the tests pass.

 

So - unless corrupted files start showing up I'll assume it's OK. I copied TI-Base over to it and it runs almost as fast as in an emulator - usually it loads slowly but now it's lightening fast! (which makes me want a bigger memory card)

 

Very much appreciate the advice and such - and if anyone runs across a manual or something I'd love to have a PDF. I got the card on eBay with no idea how to load it, use it, test it - and no idea what to expect in terms of memory.

 

Cheers, Arthur...

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I've always wondered how big a RAM disk or paged memory for a TI could be. 1 meg, 2meg, 5, meg 10 meg or more? With memory being so cheap these days, not to mention small, I have to wonder. I can only imagine the Doom like games that could be written, a TI Web browsers capabilities, among other things. Too many possibilities for me to imagine.

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Keep in mind that there are different kinds of memory. The memory modules that we can buy for little money is all DRAM, that is, they need a memory controller. This leads to a more complicated design than just soldering some SRAMs on the buses.

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I'll take your word for it, as I'm totally ignorant in these hardware design matters. Admittedly, I dunno about reality in this situation, but I just figured if a guy could make a complicated device like the Nano-PEB for a unit cost under $100.00, it should not be anymore complicated to make a single RAM disk. But then, I've been wrong before! ;)

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I have the same card, the information you have provided suggests strongly that there is nothing wrong with it.

BTW it can be modified with 2- 256k srams which would be equal to adding another layer of chips it will add around 250 sectors.

 

One common issue with these was when you press down on IC's that are piggy backed into the sockets to re-seat them, sometimes you can break the connection on pins between chips.

 

The chips circled are the additions

 

.

 

BTW the dip sw sets the CRU address, only one should be on.

 

Your card is also missing the upgrade that makes it invisible to the system. (note: switch on the upper right.

 

Pm me if you want more info

post-38705-0-17625300-1397620788_thumb.jpg

Edited by sjt

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