HP 4145B Semiconductor Analyzer: Repair with photos (dead ROM) [FIXED]

[Berni]

Ah good point. I did see some simple footprint adapters that let you plug a normal EPROM into the socket of a ROM so that's probably the better way of going about it if i needed one programed in the future.

[JFJ]

... I did see some simple footprint adapters that let you plug a normal EPROM into the socket of a ROM...

Beware that bipolar PROMs (like the N82S147N) were often deployed because their maximum access time was, typically, an order of magnitude faster than that of the EPROMs of the day. So, to replace your ROM, you would need an EPROM (or EEPROM) with a maximum access time of 60ns.

[Berni]

So i got the new ROM chip. Hauled the heavy botacnhor out again, taken it apart and stuck it in...and... Winner winner chicken diner! It works perfectly and passes self tests!

The front panel cleaned up very nicely with some PCB cleaner (IPA+Ethanol) and just look at how nice it looks now. There are still some scuff marks around the front frame but that would need to be touched up with paint.

Thanks for the help guys!






Because the system disk floppy is very important (Contains the firmware that gets loaded in on boot) i made a copy of the original one and stuck it inside the unit for safe keeping, the space at the top of the CRT module is perfectly sized to hold two floppies. Unforcenetly i could not figure out how to read these floppies in a PC because they use a weird format. The way i got these copies is that the HP4145B has a option in the menu that lets you duplicate the system disk by inserting a blank disk.






Now that it works its time to try it out. Luckily i have my triax cable set that was made DIY for a HP 4141B.






Here it is all plugged in. Look at all that triax goodness. One triax is left unconnected because this unit does not have a actively driven ground output.






And here is the money shot. Set it up on the bipolar transistor preset, hooked it up to the first 3 SMU channels and it spits this out at the push of a button.
Mmmm... graphs. Also notice how the display gets brighter close to the graph zero point, the lines are individually vector drawn so the overlapping lines add up and become birther. Those vector fonts also look so lovely clean.

[Berni]

Also i have gotten myself a GQ4x4 USB universal programmer and used it to read out the other ROM. Hopefully i did it correctly. I also wanted to dump the main CPU ROM, but that thing is soldered down and getting that thing out of the multilayer PCB is going to be a nightmare as i don't have a desoldering iron, so i decided not to.

This is for the 8x2K ROM marked U12 on the A2 board.

[james_s]

Nicely done!

[Berni]

Also i found a quicker fix for the switches:




What i simply do is hold the switch down so that the spring bows out and then use a flathead screwdriver to push the bowing bulge in the spring towards the end so that it bends it even more and if you are violent enough keeps enough of the bend to make the button actuate nice and smoothly again.

[texaspyro]

I'd keep a couple more backup floppy sets outside of the machine.  No telling what heat, etc will do to the ones stored in the machine.   Also things like deflection coils and degaussing circuitry if the machine uses those.

[Berni]

Not to worry that part doesn't get all that hot and its a electrostatic deflection CRT so there are no electromagnets at all in it.

I would want to make a real digital copy of it, but i think i would need to buy one of these to do it: https://www.kryoflux.com/?page=home

[james_s]

There are no deflection coils or degaussing on an electrostatic CRT. Still not a bad idea to keep some disks elsewhere though. Floppy disks were never known to be super reliable and pretty much any you find are likely to be 20+ years old now.

edit:
Perhaps you could find someone who has one of those things and send them a copy of your disk to try reading?

[texaspyro]

The disk format may be HP's "LIF" format.  It is basically MSDOS with adjacent bytes swapped.  There are utilities that can copy / create LIF disks on a PC.  Google:  HP LIF format

[JohnPi]

I have an HP 4156A 'Precision Semiconductor Parameter Analyser' which works OK, but a) the CRT is dim, and b) its internal battery (?) doesn't seem to work, so all settings have to be entered (e.g. date, CRT brightness settings etc.) when it boots.

I am interested in replacing the CRT with an LCD, but I can't figure how to take the thing apart -- do you have any more photos or description of how you got yours open ? Perhaps my 4156A is similar in construction to the 4145B ?

[james_s]

Assuming it uses a electrostatic CRT with vector deflection like the 4145, replacing it with an LCD would require considerable engineering effort.

[Berni]

I did take a look around for LIF and yes HP did make a PC utility for copying these disks. Only problem is that it runs on Win 3.1 to Win 98. I'm not a retro computer enthusiast so i don't have one around. I do probably still have enough old PC parts to build one tho.

That HP 4156A is a nice bit of kit. From the looks of it the CRT in there is the same as my Agilent 89410A Vector Signal Analyzer. These are not vector displays anymore. Its just a classical raster scan color CRT like you would see in a TV. Im pretty sure my 89410A has a VGA port on the back and some other similar gear has RGB video on BNCs. That would hint to me that the CRT in there is actually a VGA computer monitor. I don't know the details about the CRT since the only thing that was wrong with mine was a dead RAM backup battery and that was easily sorted by undoing a few screws on the back, pulling the whole CPU board out as a single card, sticking a new battery in and slotting it back in.

The CRT you can maybe buy a broken donor unit to rip the CRT out since many of HPs gear share this CRT or you can probably use this LCD retrofit kit to replace it: http://www.simmconnlabs.com/1401/2543.html
Its not all that cheap tho. The NewScope-5 model can replace the CRT module that i had to repair in my unit but its quite expensive so it was more of a plan B for me if i was not able to fix my original CRT. No need for that plan anymore

As far as disassembly goes i would take a guess they reused the same giant SMU cards that they use in most of these semiconductor analyzers and that would mean similar internal construction. If it is the same then all you have to do is take off any corner feet on the back and undo a single screw in the middle of the top panel to get it to lift right off. Same for getting the bottom panel off. This design is pretty common on old HP gear and i really like it (Very quick and easy to get the lid off and on).

[james_s]

You could use Virtualbox to set up an old Win9x install which you can then boot on a modern PC host. I think you can install Win3.1 under DosBOX too, it's another virtual PC type thing aimed at retro gaming but it works to run other software too. I use it to run the antiquated software for the PC control adapter in my (radio) scanner.

[texaspyro]

I think I saw some LIF utils for Linux on that Google search...

[Berni]

I could give virtualization a try but the modern PCs around the house also don't have floppy disk controllers on the motherboard. So that means i have to use a USB floppy drive. This does mean i can use USB passtrough to connect it to the virtual machine, but it also means that i will need win 98 drivers for a USB chipset likely made in the era of NT. And if i do get the drivers working its still highly unlikely that it will actually work because USB storage tends to work more highlevel using sectors rather that direct register access (Since USB is not memory mapped like Firewire or PCIe). Seeing the strict requirement of the LIF tools to run on non NT systems likely comes from doing that direct register access (This broke soooo many win98 drivers from working on newer systems).

So i do still need a PC with an actual floppy disk port on it so that the LIF tool can talk directly to a floppy controller. VM hardware passtrough of non USB stuff gets a bit problematic under windows, so the host PC would likely have to be running Linux and use KVM to run the win 98 virtual machine so that i can get real passtrough to the floppy controller. Then again configuring all this could be a headache so might as well just install win 98 directly on that machine.(Or get one of those Linux LIF tools working, and im not much of a linux geek so my chances of getting that working might not be very high)

I have already tried various forms of low level sector by sector access to the USB floppy drive but i could never get a single byte out of it. And this is what a VM running on a windows NT system would have to also do. Even things like a LPT port is very difficult to emulate under a VM in this way. Floppy drives are also problematic due to how low level they are. A floppy drive is actually so dumb that it doesn't even understand the concept of a bit or a byte. They just spin the disk while spitting out the amplified and square waved signal from the read head, its the job of the floppy controller to turn the modulated signal into actual bits and bytes and hence why oddball floppy formats are such a pain.

[suhaimi861009]

Hi Berni. Can you share the data inside the floppy disc? I think my one corrupted.

[Berni]

Hi Berni. Can you share the data inside the floppy disc? I think my one corrupted.

So far i have no way of reading the system floppy disk in a PC. I need a old PC with a floppy controller or perhaps the cryoflux USB adapter that supports these weird floppy formats.

The only way i was able to make a backup copy for myself is using the actual HP 4145B to write one for me trough the "Make system disk" option in the menu.

[picburner]

If in the future someone needed the 4145B U6 eprom, I just posted it on the KO4BB website.
http://www.ko4bb.com/manuals/93.35.167.81/HP_4145B_Semiconductor_Parameter_Analyzer_EPROM-04145-85203.zip

[vival-ga]

Hi Berni

     old thread, sorry about that. BTW nice job you have done on the cable set and restoration of the unit.

     I just got one 4145B without cables and fixture, may I kindly ask you advice regarding the proper setup..i.e. triax connectors PL75-47 fits this job? or maybe better PL75-29?

Thanks
KR,VB

[Berni]

Thanks

You do need the 3 nub triax connectors ( PL75-29 ) for this one.

I do also have a 2 nub triax (Same shell as a regular BNC) and they do not fit. This is how i discovered about this problem. I do have a old Keithley electrometer that instead needs the 2 nub one.