ThinkPad 770z - HDD Connector and Caddy

[KLIPPER_777]

I am in the midst of restoring a 770z and I am wondering what the best solution is for fitting the HDD into the machine without the factory connector cable or caddy?

These parts are non-existent from the searching I've done. Is it possible to build one's own cable and possibly 3D-print a caddy?

I came across this supplier and thought it must be possible to fab a cable... The HDD is an IDE connector I believe; however, I don't know what the actual socket the cable connects to is called??

https://www.mouser.com/new/molex/molex- ... -solution/



Any advice you can offer would be great!


Thanks

[Lomax]

How frustrating not to have the caddy! This caddy was a strange design decision, and AFAIK only 760/770 series Thinkpads used such a solution. I suspect at least part of the reason was a desire to mount the HDD at a right angle to the motherboard, to reduce the width of the internals. The cable inside the caddy is made from flat-flex and turns 90 degrees. I imagine it would be quite difficult to make a replacement cable - but making a PCB seems reasonable, with the caveat that you won't have room to fit a conventional drive. If you can get hold of the right connector (right angled) I would suggest designing a PCB that joins the connector to a Compact Flash socket, which should fit comfortably. Far easier than soldering 44 wires to two connectors which weren't designed to accept cables - one of which is extremely fine pitch.

[Lomax]

On second thoughts, you could probably get away without the connector; if you make a double-sided 0.8-1.0mm thick PCB you can plug the board straight into the on-board connector, card-edge style. The connector has 2x30-pins with a 1mm pitch, and the layers are offset by 0.5mm. Someone needs to buzz out how these 60 pins are routed to the 44-pin IDE connector - the rest should be pretty straightforward.

[Lomax]

Function   Caddy      IDE     Caddy     Function
------------------------------------------------
 Slave       1   <   A   B  >   4        Slave
 Master      3   <   C   D  >   6        Master
                     -   -           
 Reset       5   <   1   2  >   8        GND
 DD7         7   <   3   4  >  10        DD8
 DD6        12   <   5   6  >  11        DD9
 DD5        13   <   7   8  >  14        DD10
 DD4        18   <   9  10  >  17        DD11
 DD3        19   <  11  12  >  22        DD12
 DD2        24   <  13  14  >  23        DD13
 DD1        25   <  15  16  >  28        DD14
 DD0        30   <  17  18  >  29        DD15
 GND        32   <  19   -              
 DMARQ      34   <  21  22  >  33        GND
 DIOW       36   <  23  24  >  35        GND
 DIOR       38   <  25  26  >  37        GND
 IORDY      40   <  27  28  >  39        CSEL
 DMACK      42   <  29  30  >  41        GND
 INTRQ      44   <  31  32  >  43        IOCS16
 DA1        46   <  33  34  >  45        PDIAG
 DA0        47   <  35  36  >  50        DA2
 CS0        49   <  37  38  >  52        CS1
 DASP       51   <  39  40  >  54        GND
 +5V        53   <  41  42  >  56        +5V
 GND        59   <  43  44  >  57        TYPE

Notes

• Caddy pin #1 is top left when facing connector on caddy, pin #60 bottom right
• Caddy pins 9, 15, 20, 21, 26, 27, 31, 48, 55 and 58 are connected to GND
• Caddy pins 2, 16 and 60 appear to be n/c
• IDE pin “A” is top right when facing connector on drive, pin #44 bottom left
• IDE pins “E”, “F” and #20 are blanked

[Lomax]

Further to this, I have added pin translations for a CompactFlash socket:

CF  Function  Caddy   IDE  Caddy  Function  CF
----------------------------------------------
     Slave      1     A  B     4   Slave 
     Master     3     C  D     6   Master  
                      -  -     
41   Reset      5     1  2     8   GND 
 6   DD7        7     3  4    10   DD8      47
 5   DD6       12     5  6    11   DD9      48
 4   DD5       13     7  8    14   DD10     49
 3   DD4       18     9 10    17   DD11     27
 2   DD3       19    11 12    22   DD12     28
23   DD2       24    13 14    23   DD13     29
22   DD1       25    15 16    28   DD14     30
21   DD0       30    17 18    29   DD15     31
     GND       32    19 -          n/c 
43   DMARQ     34    21 22    33   GND 
35   DIOW      36    23 24    35   GND 
34   DIOR      38    25 26    37   GND 
42   IORDY     40    27 28    39   CSEL      
44   DMACK     42    29 30    41   GND 
37   INTRQ     44    31 32    43   IOCS16   24
19   DA1       46    33 34    45   PDIAG    46
20   DA0       47    35 36    50   DA2      18
 7   CS0       49    37 38    52   CS1      32
45   DASP      51    39 40    54   GND 
     +5V       53    41 42    56   +5V    
     GND       59    43 44    57   TYPE       

Notes:

• This includes DMARQ & DMACK, which are required for DMA operation.
• CF socket pins #13, #36 and #38 should be connected to +5V.
• CF socket pins #1, #8-12, #14-17, #25, #26 and #50 should be connected to GND.

[Lomax]

I whipped up a quick board layout for this adapter:



This should allow you to plug a CompactFlash card straight into the on-board HDD connector on the 770 series ThinkPads.

[KLIPPER_777]

Wow, so much helpful feedback! Thank you @Lomax

I never thought of using a PCB, but that would surely simplify things rather than trying to replicate the proprietary male connector. I've contacted a PCB vendor in the hopes they can help me fab this board. I will keep you posted

Btw, what program did you use to design the board?

The other task is to now design and fabricate the caddy to allow the board to align with the female connector. Would you be able to measure the outside dimensions of your caddy and also locate the connector position on the rear @Lomax?

Thanks!

[Lomax]

The board was made with Kicad, a free and open source circuit design and PCB layout suite. I will tidy up the project and publish it on my Github - you can grab a copy from there and upload it to a PCB manufacturer to have the board made (e.g. PCBWay in China, ~$25 for five pieces). But it would be good if someone could double check the connections first - it's possible I've made some mistake or omission; it's a fairly complex board...




The PCB should sit ~7mm off the bottom surface of the bay. I would use a piece of soft foam to support it.

[Lomax]

The big challenge is going to be soldering the CF socket; this has 50 pins with a 0.635mm pitch. I would use a professional service for this.

[Lomax]

You can grab the Kicad project files from my Github:

https://github.com/clickworkorange/tp770cf

Pull requests welcome!

[Lomax]

The big challenge is going to be soldering the CF socket; this has 50 pins with a 0.635mm pitch. I would use a professional service for this.

Saying that, this guy makes it look very easy!

https://www.youtube.com/watch?v=bqBJUXM2CtE

[KLIPPER_777]

Thank you for all the help!

I've heard of PCBway, I will most likely reach out to them to manufacture the board. This seems like a decent CF connector to match it with: https://www.mouser.com/ProductDetail/3M ... e8XZooA%3D

I reached out to a local firm in Seattle WA to see if they can solder/assemble the PCB and the CF socket.


I will let you know how it goes!

[Edward Mendelson]

Just curious (partly because I still have a 770z) - how did this go?

[KLIPPER_777]

Still working on it, other projects are taking priority at the moment.

[kfzhu1229]

Well such kind of caddies were actually rather common back then. I've run into Toshiba Tecra 8000 with the same kind of caddy design as well. I believe they were like so so that IBM can sell you a hard drive with the caddy already included and make it look like it's a totally different hard drive compared to a standard 2.5" IDE drive and discourage you to replace it with one of your own drives... Note the caddy also says the capacity of the original hard drive and also puts big warning signs to not disassemble it.
Unfortunately I sold my only spare 770 caddy to Edward Mendelson... so can't help in this aspect...

[solidpro]

I'm pretty good at soldering and I'm willing to give it a go, if anyone has had some boards made and has some spare CF connectors to post to me with it?

[Voodle]

For anyone looking for one of these, I spotted an original one on ebay UK: https://www.ebay.com/itm/314103939352

[zephryn]

I ended up inadvertently stumbling across one of these strange caddies from a parts 770x that was listed as having no hard drive(!) very recently for a 770z project, but considering that I'm more or less aiming to replace the aged hard drive with a CF card anyways I'm still really interested in the PCB design here. I got to the point of making a very crude BOM and CPL for JLCPCB assembly- the only CF connector they seemed to have on-hand (part number C444350 on their site) seemed to be quite a bit different in design though, and I have no idea how that'd affect assembly even if the surface-mount pin pitches seem to match up.

[Lomax]

I'm happy to hear that there's some interest in the PCB I designed! If you can give me the MPN of the CF connector you want to use I can help redesigning the board so that it fits - I expect it's mainly the mounting holes that differ, though some CF connectors are reversed, which may be a bit much to deal with. Also, it would be best if someone could help with double-checking the wiring before ordering any boards; it's entirely possible that I've made some error that could damage your 770Z and/or the CF card! I have triple checked it myself, but a different pair of eyes might spot something I don't see...

[Lomax]

You also need to determine the correct thickness of the PCB, so that it makes good contact in the slot. Try with a few different thicknesses of plastic card and once you've found something that fits well measure it with a pair of calipers.

[solidpro]

I've got two 770s on the shelf I'm in the middle of restoring. Both do actually have their hard drives but I am interested in this little project. If anyone is prepared to share the raw files to use with PCBWAY, please let me know and I'll order one to test?

Thanks!

[Lomax]

I've got two 770s on the shelf I'm in the middle of restoring. Both do actually have their hard drives but I am interested in this little project. If anyone is prepared to share the raw files to use with PCBWAY, please let me know and I'll order one to test?

Thanks!

I'm sorry, only just saw your reply. I made the project files available:

You can grab the Kicad project files from my Github:

https://github.com/clickworkorange/tp770cf

Pull requests welcome!

To send this to PCBWay you'll need to generate the Gerber files, which is not as complicated as it might seem at first glance. I'll see if I can get these done and added to the Github repo.

[Edward Mendelson]

I've been experimenting with my 770Z (with the HDD caddy supplied, as described above, by an extremely helpful member of this forum), and would be very interested in having one of those boards when and if they become available. I don't want to waste anyone's time by asking when this might happen, but I'm sure I won't be alone in wanting to buy one.

[Lomax]

Sorry for the delay - I have now added Gerber and drill files in https://github.com/clickworkorange/tp77 ... ort/gbr002 You can preview these in KiCAD's Gerber Viewer. To the best of my knowledge these files should be compatible with the usual online PCB manufacturers, though I cannot accept responsibility for any errors or omissions. One critical step remains though, which is to determine the correct thickness of the PCB substrate, to ensure good contact in the mating connector. I don't have access to my 770 at the moment so cannot help with this, but it should be easy enough to do with a selection of card stock and a pair of calipers...

[solidpro]

I've got 4 x 770s on the shelves (which coincecentally all have their HDDs and caddies!) but if I can find the right tool I can probably measure either the caddy or the connector on the machine.

I've only made a few PCBS using PCBway but they all came out well. It was completely someone else's design though so I'm totally clueless. I tried opening any of those files in the Gerber viewer and they didn't show anything or froze the program...?

I am happy to order a few and see if they fit and/or continuity test....

[Lomax]

Just tested them myself in KiCAD's Gerber Viewer 6.0.11 - I went to "Open Gerber Plot File(s)" and selected all the files, and was presented with a preview of the board with all the different layers. The holes were not there though and had to be loaded separately with the "Open Excellon Drill File(s)" option, after which the holes showed up as well. It all looked ok to me, but I'm not very experienced!

[Lomax]

To measure the required thickness of the PCB I would just try different bits of card in the on-board connector until I find the thickest combination that fits well, and measure that with a pair of calipers. Then choose the nearest PCB thickness at or below this. Should be alright as long as it fits and makes good contact.

If you have access to a scope you could look at the signals on some of the pins on the CF connector once you have a completed adapter (with the adapter plugged in, of course). That could be a good sanity check before trying with an actual CF card installed. I'm pretty sure there are no shorts in the layout; I've checked it myself quite a few times, and the Design Rule Checker doesn't pick anything up, which it should do if there were any such problems. The only thing I had to tell the DRC to ignore is the proximity of the card edge connectors to the card edge(!). Apparently there's a bug affecting pads that have been designated as "Edge Connector" in KiCAD, causing them to erroneously throw a board edge clearance violation.

The only potential for problems is if I've made the wrong connections, but again I'm pretty sure they are correct. You can verify this by checking the schematic, which the DRC agrees the PCB layout matches (it won't let you get away with simple mistakes like forgetting a connection, or making the wrong connection, or creating a short). If you agree with the schematic (ideally you'd compare it to one of your original adapters) you can buzz out the connections once you have a finished board - if they match then you can feel pretty safe plugging it in.

[Lomax]

Updated 3D renders showing the current version of the board, front & back:

https://i.imgur.com/T4NMI8H.png

https://i.imgur.com/Z4VXTpk.png

FORUM warning:
picture(s) WAY too big, tags removed. Please read the Forum Rules, especially Section 5: viewtopic.php?f=16&t=14339

[Lomax]

FORUM warning:
picture(s) WAY too big, tags removed. Please read the Forum Rules, especially Section 5: viewtopic.php?f=16&t=14339

Ok, cropped to 800x600, hopefully acceptable.

[solidpro]

Hi

Ok thanks, I will stick a bit of card in and see what it measures out at. You may be a beginner but I have no idea what that makes me. How did you learn how to create these boards in KiCad?

Am I right in thinking the only part missing then would be the CF card attachment? I would be capable of soldering this on myself but what part did you base your design on (got a link)?

One last thing, I notice you have a 770X in your signature and you're in the UK. I'm currently trying to revive 2 x 770X machines which are SVP locked. If you ever consider selling your 770X can you let me know? I need a 'clean' one which I can read the ATMEL chips from to replace the chips on mine. The 770X seems to hit an 'unbootable' bug once the CMOS battery drains dead and if you don't know the SVP.

Thanks