A broken Apple TechStep

[Ferrix97]

(not sure if this the right place to post this, technically it's a conquest + repair)

Sometimes I go on eBay and search for "Crazy expensive Hard to find Items", such as the Apple TechStep.

As always, there were just a few units on sale, but one of them caught my eye: It was listed at 99$ AS-IS without bag or manuals, but with two ROM packs.

...and 130€ later, it was mine!

Yesterday it finally arrived (after paying the postman 11€ for customs and import fees) and of course it was dead.

After a couple of quick measurements I found out why: The DC power jack is center negative (and somebody used a regular center positive power brick to test it).

I hate center negative jacks! I killed (and later fixed) a Sinclair ZX Spectrum for the same reason!

Inside I found a blown tantalum cap and a broken MC34063 regulator, after replacing the regulator it came back to life!





Here's a picture of the main logic board:



And what's inside a ROM pack:



Technically you could burn new ROMs and swap them using a single ROM pack. A friend of mine has a TechStep with a few more ROM packs (2 and 4 if I remember correctly), I could try and make a clone of them and swapping them with on my Voume 1 pack.

 

[Carboy7]

Isn't the TechStep an ultra-rare prototype?

I'll google it.

 

[Ferrix97]

It's a device given to technicians to troubleshoot broken macs, similar to ASD on the todays macs.

Before it, they had the AppleCAT (where CAT stands for Computer Aided Testing), they used a working mac to test the broken one.

 

[jsarchibald]

Gotta love a TechStep!  Mine has 4 ROM packs, and I've just passed on my other one to another forum member who has been on the hunt for a very long time.

 

[olePigeon]

Wow, what a steal.  $99. :O

I'd love to get a TechStep, too.  I just recently settled for a Snooper card, but a TechStep would be a lot more useful.

 

[Unknown_K]

How do they connect to the computer?

 

[Ferrix97]

For connecting to the UUT (unit under test) there are all the necessary ports (two serials, two ADBs, SCSI and sound) on a removable module (port pack), not all ports are needed to run a specific test.

There is also another serial port on the side of the unit that is used to download test logs on a mac for printing (very similar to the logs on ASD).

Using the TechStep test software you can also connect the TechStep to a good working Mac and use the Mac to test the TechStep!

if you are interested, I have a digital copy of the manuals and the disks that came with it.

Right now the manuals are just raw jpeg scans, I still need to crop and OCR them, to make a nice PDF. If somebody wants to that, I'll upload somewhere the scans.

Here's a part of the manual that talks about the removable port pack, they only made one model



And here's the first page of the TechStep diagnostic

 

[olePigeon]

What's the newest computer ROMs available for the TechStep?

 

[Ferrix97]

I think they only made four of them (plus the SCSI hd test) and it goes up to the performa 520 or so, I don't think there are 68040 or PPC machines compatible with it.

 

[jsarchibald]

I remember reading somewhere that there were 6 packs, but this might include a couple of revisions.

One of mine is a v1.1, and then I have a newer version of the same pack but v1.1.1.

 

[Ferrix97]

Well, the case itself has only room for two packs, right? plus another two inside the unit. (I don't have the case)

 

[jsarchibald]

I think it's only got the two packs in the side, the carry case has a spot for an additional two packs.

 

[olePigeon]

Oh, OK.  According to my Snooper Card manual, it works on everything up to a Quadra 950.  So this would be a great complement to a TechStep.  Only machines left out would be the Color Classic & LC 4xx, I think.

 

[BadGoldEagle]

I have Acrobat Pro, so if you want I can create that PDF. (Add the scans on dropbox/mega and PM me the link). Maybe I could add this to the Mac Garden afterwards...?

But I think it would be great if someone dumped the ROMs, just so they never disappear... These things are getting rarer and rarer!

 

[Ferrix97]

Great!, thanks. I'll soon send you a PM with a google drive link.

As for the ROMs, I don't think I have a reader compatibile with them (not without an adapter for sure), but online I found another website that should have them: (scroll to the bottom)

https://mac68k.info/wiki/display/mac68k/Diagnostic+Mode

They also talk about how the diagnostic works and the commands sent

 

[bibilit]

Nice, i will like to have one of those.

Have you been able to use it for a repair already ?

 

[Ferrix97]

Actually yes, I was able to fix a RAM issue on my SE/30, it didn't like mismatched pairs.

It also fails serial handshake on the same machine, probably another broken trace (the board is not in great shape)

 

[Bunsen]

If those ROMs are a standard, obtainable part, it should be possible to make up a single ROM with switchable ROMs in it.  It's a semi-common trick with older systems that use a ROM - find a larger, pin-compatible replacement, and switch the most significant address lines.

 

[Ferrix97]

Yes, the ROMs are standard (but each pack has a different size).
The board itself just contains the two memory chips (one ROM for the tests, one EEPROM for the logs), a resistor and the connector for interfacing to the TechStep, so it should be possibile to recreate said board to house a modern, bigger memory and the necessary switches.

I don't have the knowledge to design a new board, but i can make a pinout of the interface connector and create a 3D model of the existing case

In the Volume 1 and SCSI HD Test, the ROM is a AM27C512-155JC in a PLCC package and the EEPROM is a X25C02P. 

In the Volume 2 and 4,  the ROM is a Macronix 27C1000QC-12 in a PLCC package and the EEPROM is a X25C02P. (The board looks a little different, probably just the silkscreen and the resistor placement)