Vintage HP 4145A Semiconductor Analyzer- should I?

[HarryDoPECC]

Advice from those who know the 4145A please.

I may have opportunity to pick one of these up, main cost would be time and effort.  It's said to power up OK without errors but there are no disks and no test fixture.

My use case is partly for testing in vintage calculator and comp restoration, and partly to play with.  My electronics is mostly self-taught so I would not mind to play around with curve tracing and so on.  Also kinda like the HP gear of that era.

So:
- does it NEED the  disk software?  I have put floppy emulators on my 16500C and some other gear, I'm comfortable with disk emulation (but there do not seem to be images for the 4145A disks, and the format seems to be ...odd)
- is the test fixture necessary, I am happy to hack my own.
- any comments about longevity, ease of repair, unobtanium parts (I see that there are ROM images and the HP gear of that era still had pretty good service manuals)
- any other comments about using it nowadays

Thanks in advance!

[LazyJack]

It is definitely a fun instrument to play with, but I don't think it is particularly useful for vintage calculator repair.
Also, when thinking about building your text fixture, consider the eye watering price of the triax connectors and cables that are required.

[Berni]

I have a working HP 4145B

It is a pretty nice piece of kit since its basicaly a 4 channel SMU that goes up to +/- 100V or +/- 100mA and can measure currents down into picoamps and having nice graphing capability to it. It can be useful for testing or matching transistors and such, or can be used as a regular SMU to provide power or measure small currents.

Repairing it is not that hard and it does share some boards with other semiconductor analyzers. Mine arrived with garbled text on the screen and that was traced down to a dead character ROM chip. With the help of this very forum i found the dump of it and had some guy from canada (He specializes in retro arcade game repair) burn me a new ROM chip. Worked flawlessly afterwards.

You don't need a test fixture for it but you will need 4 triax cables to connect to the back of it (Because of picoamp currents it needs guard shielding of the entire cable), these cables can be pretty expensive, but at least it uses the more common 3 lug triax BNC connector. The disk is also mandatory to make it run because the machine just has the boot loader built in, the actual firmware is loaded from floppy on every boot. Unfortunately the floppy controller is not compatible with normal PC floppy drives, so its not easy to just simply image the drive in a PC. My 4145B is capable of creating new copies of the system boot disk by inserting a blank disk and telling it to copy from the menus. Not sure if 4145A also has this feature.

EDIT: And by the way the 4145B uses the newer 3.5 inch floppies so a system disk made on mine won't fit into the 5 1/4 inch floppy drive on yours.

[Monolith]

i got a 4145 B version with no boot floppy. So i replaced the floppy drive with a HxC floppy drive emulator to boot from USB sticks. I believe it's possible for the 4145A too. For the start here is a link for some small instructions and a linkt to the boot image file. https://torlus.com/floppy/forum/viewtopic.php?t=1595

 For the floppy emulator hardware i bought from ebay the GOTEK Floppy emulator for Amiga 500 etc with the 3 digit LED display on the front for about 45$. For the floppy emulator you will need to buy a license to activate the GOTEK firmware. http://hxc2001.free.fr/floppy_drive_emulator/index.html#Download_HxCFirmwareForGotek

The most tricky part is the cabling from the 4145a to the GOTEK floppy emulator. It's similar to the 4145B solution where you can google more infos about the cable pin modification. Be sure to provide the correct supply voltages and control/data lines to the correct pins. The best approach is to compare the floppy interface pinout from 4145B an A version. Service manuals for 4145A and 4145B should be available on the web.

You have to do a lot of info research in the web to get the puzzle together but it's worth the result. Only buy the 4145A if you really want to accept the challange :-)