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InsaneMultitasker

Myarc cards for sale/repair tips

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17 minutes ago, Hans23 said:

It connects pin 5 of U17 to pin 12 of U9, so apparently the mod corrects an incorrect connection between the two?

I believe the wire is part of the modification to enable the HFDC to support hard drives with more than 8 heads.  This is not a common modification, and it disables the write precomp so drives requiring it may not function properly.  However, the HFDC should still work.

 

When you power on the system, does the HFDC LED flash?  If the CRU is at >1000, the floppy drives will respond as DSK5-8.  What error message do you receive when you attempt to access a floppy?  a hard drive?

 

If you use a MiniMemory cartridge to enable the ROM, and view memory address >4000, what do you see?

 

 

 

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49 minutes ago, Hans23 said:

here's photos of its front and back:

 

20210227_191322.thumb.jpg.d3091f714bf39c5a08bc2e661f6a8633.jpg

A few more observations (maybe @Schmitzi posted pictures some time ago as these seem familiar?)

 

1. U29 and U39 (LS31 and LS32) are stock chips and very susceptible to failure including failure to read/write or intermittent read errors.  They may not be the cause of the current problem, however,they should be replaced as part of the repair/update work if at all possible.

2. The machine screw sockets are not standard, original parts; this card was repaired or updated, as further evidenced by the regulators, heat sinks, and hard drive head modification.

3. Verify that the transistor next to the EPROM is not shorted -- it looks as if the leads are touching and that the transistor was pushed against the board. 

4. Check the regulator resistance between  (1) output and ground  (2) input and ground and (3) input and output.  Confirm that there are no shorts. 

5. Suggest wrapping some electricians tape around this area to protect the traces when you insert the card into the Peripheral Expansion Box.

image.png.c73b311232b6cf385381c02d67c0228f.png

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4 minutes ago, InsaneMultitasker said:

A few more observations (maybe @Schmitzi posted pictures some time ago as these seem familiar?)

 

1. U29 and U39 (LS31 and LS32) are stock chips and very susceptible to failure including failure to read/write or intermittent read errors.  They may not be the cause of the current problem, however,they should be replaced as part of the repair/update work if at all possible.

2. The machine screw sockets are not standard, original parts; this card was repaired or updated, as further evidenced by the regulators, heat sinks, and hard drive head modification.

3. Verify that the transistor next to the EPROM is not shorted -- it looks as if the leads are touching and that the transistor was pushed against the board. 

4. Check the regulator resistance between  (1) output and ground  (2) input and ground and (3) input and output.  Confirm that there are no shorts. 

5. Suggest wrapping some electricians tape around this area to protect the traces when you insert the card into the Peripheral Expansion Box.

image.png.c73b311232b6cf385381c02d67c0228f.png

And Maybe on the PEB metal framing too, shoot can't protect that enough lol..I see this and I shiver...

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34 minutes ago, InsaneMultitasker said:

I believe the wire is part of the modification to enable the HFDC to support hard drives with more than 8 heads.  This is not a common modification, and it disables the write precomp so drives requiring it may not function properly.  However, the HFDC should still work.

 

When you power on the system, does the HFDC LED flash?  If the CRU is at >1000, the floppy drives will respond as DSK5-8.  What error message do you receive when you attempt to access a floppy?  a hard drive?

 

If you use a MiniMemory cartridge to enable the ROM, and view memory address >4000, what do you see?

 

 

 

 

Yes, I posted some pics some weeks ago maybe.

 

Uuuuhrgg DSK5 ? I never tried DSK5, never read about this. In the manual there is DSK1. mentioned only...

Maybe this is the "problem" ? :) (Edit: But I tried with other jumper/adresses too)

(I also had problems to differ between the connectors J1 and J2, as there is no picture in the manual and no imprint on my controller)

 

Yes, the light goes on, and DU2K reports the DSRs like DSK1.

 

 

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4 minutes ago, Schmitzi said:

Uuuuhrgg DSK5 ? I never tried DSK5, never heard about this. In the manual there is DSK1. mentioned only...

Maybe this is the "problem"

The manual does not make it very clear about the floppy setup.  Someone typeset the manual ( @mizapf ? ) from the 4th edition. Is the editable document available?  It would be valuable to create a revision 5 with some of the recent information, add a few pictures to indicate the proper cable connections, and remove old information that no longer applies. 

http://ftp.whtech.com/datasheets and manuals/Hardware/Myarc/MYARC HFDC Manual 4th edition.pdf

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4 minutes ago, InsaneMultitasker said:

The manual does not make it very clear about the floppy setup.  Someone typeset the manual ( @mizapf ? ) from the 4th edition. Is the editable document available?  It would be valuable to create a revision 5 with some of the recent information, add a few pictures to indicate the proper cable connections, and remove old information that no longer applies. 

http://ftp.whtech.com/datasheets and manuals/Hardware/Myarc/MYARC HFDC Manual 4th edition.pdf

 

Yes, and please let´s change the description section for the jumpers, or add a second section.

For me, this was mission impossible to learn, very confusing this (2,4,6,8) (1,3,5,7) and how it is shown there.

I had to look 10, 20, 30 times for each setting to get sure what is meant.... really.

I think this is because the 2/4/6/8 - 1/3/5/7 order goes against all my brains logic... something like this :)

A small picture also could solve this immediately

 

 

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If someone intends to edit the file, please use LibreOffice and do not import the file in MS Word. The 99% compatibility leaves a 1% that sometimes spoils the layout beyond repair. I may also do a review of the resulting file if desired.

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On 2/13/2021 at 6:39 PM, InsaneMultitasker said:

Not without reversing some changes and jumpers.  Pop out that 384K chip and inspect the socket.  Is it a single-wipe?  Corroded or worn out wipes?  I'd suggest the same for the PFM (eprom) socket but check out the memory socket first, since PFM is gonna be a best to dismantle. 

 

I'm not in a position to do repairs right now but I would entertain taking a look at it later this year. It would be easy for me to swap both sets of chips with known working ones.   There is also some hardware-related work under way that might make updating the pfm and memory (with single layer 512k) viable.   We can continue to chip away in the meantime as long as you are willing and able.

Well I have seen data on the flash eeprom chips, whether it is corrupted or not is another question. I have pulled the three stack of sram chips apart and tested individual chips, on my Minipro, and they seem fine. One seemed dodgy, but holding it down while testing worked and it tested well. The next step is too replace both sockets (one is already removed) and replaced with tooled sockets, then reinstall the chips and wires, replace the resistor and see what happens. I am considering the 512K upgrade, instead of the 384k stack.

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9 hours ago, mizapf said:

Here it is (LibreOffice writer format).

MYARC HFDC Manual 4th edition.odt 95.25 kB · 7 downloads

I was able to load the file in LibreOffice without issue.  I jotted down some enhancements bullet points on my laptop and will post them here later.  DREM, some common updates, etc. all seem like good fodder for an update.

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11 hours ago, InsaneMultitasker said:

5. Suggest wrapping some electricians tape around this area to protect the traces when you insert the card into the Peripheral Expansion Box.

The board apparently works just fine, at least for the FD controller part - One just needs to talk to it the right way :)  I've put on some isolation to prevent PEB casing shorts.  I also socketed U29 and U39 to make further repairs easier, but as I don't have these in stock, I'm leaving the original parts in.


Thanks for your input!
Hans

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29 minutes ago, Hans23 said:

The board apparently works just fine, at least for the FD controller part - One just needs to talk to it the right way :)  I've put on some isolation to prevent PEB casing shorts.  I also socketed U29 and U39 to make further repairs easier, but as I don't have these in stock, I'm leaving the original parts in.


Thanks for your input!
Hans

That is good news.  :)  

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So this are great news, thanks :thumbsup: :thumbsup: :thumbsup:

Means the baby did not listen to me because I did not know its name (DSK5.) 😄 But if it works now, it works :lust:

 

If @InsaneMultitasker has the intention now to make the changes to the HFDC-manual, I think this is the best way.

Another question next to the DSK5-info is, do you also plan about a picture and some better text for the jumpers, or should I make a drawing or something like this ? And, does there exist a given "template/schematic pic",  to mark and address the jumpers and the connectors J1, J2, ... maybe ?

 

@mizapf : So I will wait with any changes what I was talking about, OK ? I can add more later, if needed at all then

 

Does is make sense just to add the information about the "Big harddisk Mod", as an addendum maybe ?

What would Elvis say ? It´s now or never ♪♫ :)

And the info that Tony gave to Ken in a shoort notice, about the "switchable harddisk drive search bypass" ?

Would be cool to have it all inside the manual. If you want me to to something, just let me know

 

thanks

ACK ACK ACK :)

 

 

 

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9 minutes ago, Schmitzi said:

as the intention now to make the changes to the HFDC-manual, I think this is the best way

My focus is on the Geneve OS release.  :)    But I will share my ideas for others that can or want to contribute now.

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20 minutes ago, InsaneMultitasker said:

My focus is on the Geneve OS release.  :)    But I will share my ideas for others that can or want to contribute now.

 

ah yes, so I can collect this for the HFDC manual and make some completely formatted change requests, if nobody else chimes in...

:thumbsup:

 

 

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On 2/26/2021 at 11:18 PM, wolhess said:

I‘m using an OSSC too for my EVPC2/V9938 TI-99/4a system. At the beginning I had the same issue (somtimes a black screen for a second or two). 
 

Then I played with the configuration of the OSSC with success and since about three months I never had a black screen. It is completely stable.


 

That sounds promising! I have had no time yet to deep dive into it. Just replaced the 12V regulator and 5V regulator for the HRD3000 to see if those give the issues, but will try OSSC tuning. 

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Tim,

 Looking at your boot screen, you and RickyD have the exact same symptoms - One or more Character(s) corrupted identically.

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As it seems to me, it suffices if the space character is redefined with pixels at its right edge.

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57 minutes ago, dhe said:

Tim,

 Looking at your boot screen, you and RickyD have the exact same symptoms - One or more Character(s) corrupted identically.

Sometimes when I load GPL, the title screen starts to "shimmer" with character patterns wildly change, then the displayed characters move around randomly and new, random characters are introduced.  Yet if I watch long long enough, the gyrations stop and many of the characters on screen (and some patterns) return to their original state. I would think that once the VRAM memory was corrupted that the definitions and locations would not return to normal.  

 

30 minutes ago, mizapf said:

As it seems to me, it suffices if the space character is redefined with pixels at its right edge.

Special release Geneve OS 7.0mz  ?   ;)   

 

Could two VRAM chips be enabled and competing on the data bus at the same time, possibly during the hardware vram refresh cycle?  I cannot think of any other way for some of the original patterns and characters to "fix" themselves once corrupted.  (At the GPL screen I reference above, there is nothing being written to or read from VDP while the corruption happens. )

 

I should also mention that I have reseated the chips, placed the Geneve in my extender cards, and "tapped" on the vram/wires with no ill effects. So for the moment, it doesn't appear to be caused by a loose connection.

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1 hour ago, InsaneMultitasker said:

Sometimes when I load GPL, the title screen starts to "shimmer" with character patterns wildly change, then the displayed characters move around randomly and new, random characters are introduced.  Yet if I watch long long enough, the gyrations stop and many of the characters on screen (and some patterns) return to their original state.

This is seriously spooky. Already talked with Mr. Shyamalan about a script? ;-)

 

What I meant was that the effect from the screenshot is only caused by a redefinition of the space character; no other characters are affected. I don't know, of course, how this could have happened.

 

Edit: Right now, I'm watching "It" (2017) on TV.

Edited by mizapf

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On 2/26/2021 at 12:30 AM, InsaneMultitasker said:

Mmmmm, did you unsolder the two chips?  

Okay, I am readying myself to start putting the flash eeproms back in. There was the initial socket soldered to the board, I presume you replaced when adding the eeproms 20 + years ago, then there was another socket glued to the bottom one that had some pins bent, not to touch the corresponding pin on the socket underneath. The one I am asking about is the pin with the white wire shown in the 1st photo. The pin was bent close to the body and wasn't touching the bottom socket, I suppose by design. I replaced the bottoms socket with a tooled sipp, and I am going to use a tooled socket for the upper socket replacement. So to prevent touching, I should be able to remove the pin from the sipp below that pin without adverse issues, right. Otherwise it will be hard to bend the tooled pin and solder the white wire back and still prevent touching the lower sipp pin. I am supposing this would not work right if it does touch. Am I correct?

20210225_221839edited.jpg

20210302_160817.jpg

20210302_160935.jpg

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1 hour ago, RickyDean said:

Okay, I am readying myself to start putting the flash eeproms back in. There was the initial socket soldered to the board, I presume you replaced when adding the eeproms 20 + years ago, then there was another socket glued to the bottom one that had some pins bent, not to touch the corresponding pin on the socket underneath. The one I am asking about is the pin with the white wire shown in the 1st photo. The pin was bent close to the body and wasn't touching the bottom socket, I suppose by design. I replaced the bottoms socket with a tooled sipp, and I am going to use a tooled socket for the upper socket replacement. So to prevent touching, I should be able to remove the pin from the sipp below that pin without adverse issues, right. Otherwise it will be hard to bend the tooled pin and solder the white wire back and still prevent touching the lower sipp pin. I am supposing this would not work right if it does touch. Am I correct?

20210225_221839edited.jpg

20210302_160817.jpg

20210302_160935.jpg

Interesting, I never used glue to secure the sockets. Thin tie-wraps were the practice by the time I started to install the modification.

 

In many installations, the socket pin is bent to 90 degrees and a wire is soldered to it, then connected elsewhere on the board.  So yes, if you remove the SIP from the bottom socket, that should be fine.  You do NOT want the "bent" pins to touch the socket below. 

 

At times the wire was wrapped around the socket lead then bent >95 degrees, melted slightly into the socket housing, to stop the lead from being straightened.  Removing the wipe was not an option as that would not allow reverting to standard 28-pin SRAM at a future date.

 

 

 

 

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This evening my Geneve glitched again so I put the card into the PEB extender. I couldn't make the ram fail again with any tap-tests, however, my infrared temp gun registered 182F (83C) on the lowest stack of VRAM

 

It looks like the ambient temperature max is 70C but I can't seem to find the reference to max operating temp.   

 

Anyone know of a good source to buy (or have some to sell) good, working video memory chips ?

 

If I feel up to it, I will replace the sockets and replace the power regulators with dc-to-dc converters to match Heatwave's configuration.  I've resisted modifying my workhouse Geneve but it might be time to put it on the bench.

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