Harris Lanier C-1200 - ca. 1985 Z80 System

[theletter0xff]

I acquired this system because of its looks. It was listed as a 286 and untested. I dont have any software, the keyboard, nor have I been able to power it on. I havent found sales info about this thing. I've never had or used a z80. Some adjacent research -- 086 systems -- suggests this may have been a dedicated word processor.
There it is in all its late early 80's industrial design goodness; its one of the auction photos I didnt take any of it staged.

It arrived safely, and I opened it up looking for nasty RIFAs, before powering it on.
On the rear, there is a DB15 connector to the monitor that carries power and I believe the keyboard in addition to video.

Inside is a Seagate ST-225, Mitsubishi floppy drive model M4853, a heavily built power supply, and a few PCBs.
The ST225 is date stamped 1987, its possible it was replaced since the rest of the system has date codes from 83 to 84.
The MFM controller connects to both the drive and system board via ribbon cables. The first of many bodge wires are visible in the photos.


The ribbon cables snake their way over to a board filled with LS logic, the IO headers, and a pair of headers that go to the processor board and bodge wires.



The Z80 board has two fixed ribbon cables connecting it to the IO/Power PCB, and still more bodge wires.




The front panel board has indicator lights and a reset switch, also connected to the IO board via ribbon cable.





There was a blown component on the video input board inside the monitor. I cant identify what it was; my guess from the bit of blue casing left, a Y1 capacitor. I cant power it up until its fixed or I figure out the pinout to connect a generic monochrome monitor.




This is what I know about the system, and the max number of photos I can attach. Next steps include testing the PSU under a dummy load, fixing the video board, dumping the ROM(s), and figuring out a keyboard. I'd like to make a raw image the drive during its first power on test, though I dont have the hardware necessary.
Suggestions for next steps, more info about the system, etc? all is welcome.

 

[theletter0xff]

The ROM is an AM2732B, with a date on the sticker of 84. Attached is the binary.

I believe I dumped it correctly, but since its the very first time trying such a thing, I am not sure. Saved as both a binary and hex, both are in the archive.
Double checking my math, the system has 256kB of RAM; four banks of 9x 64kbx1 (parity)

 

[alan6502]

Hi, I have a niche interest in Z80 or at least non 8088/IBM compatible computers with hard drive interfaces, non PC PCs I guess. You at least have me as an audience so far - thanks for posting

 

[Chuck(G)]

The blown cap appears to be a tantalum device that has gone to capacitor heaven.

 

[theletter0xff]

The blown cap appears to be a tantalum device that has gone to capacitor heaven.

Not sure how to determine an appropriate replacement, what values would work. Its across the DC input from the computer. Not sure if is it acting as a bleed to discharge the CRT or something else. Nothing left but a little blue stub.

 

[theletter0xff]

Perhaps including images of the PCB may help someone with more experience guess at the missing part. I havent completely toned this out, the ribbon goes to the CRT driver board, the wires go to a DB15 connector. Power is provided through the same cable as video.

 

[theletter0xff]

I cleaned up the case, the manufacturing is spectacular. Very over built, perhaps it was for a government contract. The bottom, top cover, and front plate are a very heavy plastic with a mat black coating inside, two-tone mat beige, with a blue racing stripe outside. Under the top cover is some aluminum RF shielding. Brass threaded inserts are molded into a surprising number of stand offs for attaching the sub-chassis . The face plate has molded openings for floppy disk drive and its unusual mechanism, three rectangular indicator LEDs sit flush and are almost friction fit, and reset switch. It's mounted to the bottom case with three screws. There was no optimization of design as one sees in high volume production. I was not able to locate a mold mark for production date/plastic type.




The interior chassis is made up of three separate passivated steel plates stamped, punched, bent, and screwed. I was annoyed by the sharp edges left from the stamping, so I deburred them, I've sliced my fingers one too many times on old equipment. They support the, what I assume to be nylon, slides where the PCBs mount; there are slots for two large boards, and four "half-width" boards. The floppy drive slides into place and is held forward by an adjustable metal bracket secured with one screw. The MFM hard drive is securely mounted with two very different brackets, notice the one on the right is chamfered and the left is oval to allow for a few mils of freedom. This assembly is then secured to the chassis with two pair of screws -- two round head, two flat. There are about ten different screws, all with different pitch, length, and head shape. At least they are all either JIS PH1 or 2.




Most interesting is the rear IO panel, the bottom corner has a square notch, that steel was welded after stamping and folding. I imagine quite a bit of manual processing would be required for that. The lower three ports are sized for DB25 connectors, the upper three are two round and one oval. The two round ports are about the size of a DIN connector, not sure about the small oval. The nylon stand-offs press against the edge of the boards when installed, preventing them from sliding backwards. The power supply sled also has a matching welded notch. It's a nice detail, since it continues the shape of the front and sides, though corner finishing details are unlikely to ever be seen when deployed.
The PSU sled has beveled through holes for the PSU, houses the fan, a combination IEC power socket line filter, grounding stud, and a fuse holder. The fan, Sprite model SU2J9, is powered whenever the computer is on. Manufactured in USA by HankCo Roton rated for 115V consuming 0.06A during operation; its diecast metal housing contains a very easy spinning bearing and fan. Bolted to the sled, the fan is held by four #6-32 1" philips round head screws and 11/32" captive lock nuts. It hasnt been load tested, but expectations are loud. The line filter and IEC 60320 C14 power jack are a single sealed unit rated for for both 115/220vac 2/3A in the range of 0-40 C, also held in place with the same size #6 screws. The grounding stud is crimped to the seld and flush with the painted surface. The M4-0.7 stud is located with a helpful green label, inexplicabliy using 9/32" nuts. I will provide no further detail about the fuse.

 

[Chuck(G)]

The cap in question appears to be connected between two (thick traces) power supply rails. It's likely a decoupling cap; I'd go with 470 µF at 35 volts just to be safe. Do observe polarity, if the original component labeling isn't visible. I suspect that the - capacitor terminal connects to the trace that also connects to the black wire. Looking at the photos, the thing may not have been a tantalum, but an aluminum electrolytic. Hard to say from the wreckage. In any case, I doubt that the actual type (tant or aluminum) matters in this application.

 

[theletter0xff]

And we're back.

Behold, the open frame power supply!



Checked for dead shorts to ground, found none. Tested the power supply with a load crudely cobbled from CD-ROM and a fan. The 120VAC fan is fantastically quiet. I let the power supply run for a few minutes, and checked the voltages. Reasonably close for a modern PSU, fantastical for a 40 year old PSU that's been disused on a shelf somewhere for the last 20+ years. The power supply gets some beauty shots, it would not surprise me if it could handle double the rated amps with active cooling. The aluminum plate is cleverly used as a base and heat sink.
On my tester, the DC voltages were : 4.95, 12.06, -12.06

I tried to slide the power assembly back in with the drive plate installed, unfortunately the power switch would not clear the bracket. I had to remove the drive plate, which is held in with eight (8) screws. The face plate must come off, it laps over the bracket. The reset switch bracket straddles the drive bracket and the card cage, so that also needed to be removed. Eleven screws in total.
Five round head 5mm in two different lengths, two flat head 2mm, one flat head 5mm, and! two 4mm round head.
Then the sled went in, doubling the system weight. The power switch went into the case with a reassuring and solid click of the plastic retainers. Also note the 16A 250V switch from Arrow, now offered by Eaton, it's a 2600 11E with legend 734, described as "Switch Rocker ON None OFF DPST Quick Connect/Solder Lug Rocker 22A 250VAC 14VDC 745.7VA 50000Cycles Medical". A splash guard is available, now that's a quality switch. Datasheet attached.



Three screws hold the back of the PSU to the main chassis. Only one can be used at the moment, the other two also secure the drive cage cover.
With one screw in the back, the whole computer can be flipped on its side, granting access to four counter sunk screw holes. Screw in the four (4) M3-0.5 screws that hold the bottom of the PSU sled to the plastic case.



I had discovered during disassembly, two of these four screws were rusted out.
I was able to remove three of the screws with little difficulty and some penetrating oil. The last screw refused to move. So insistent in its desire to remain immobile, the drive recess failed; more drastic measures were clearly necessary.
After using a large drill bit to create a paste of iron oxide and oil from the screw head, I was able to remove the PSU from the sub-chassis. Carefully setting the PSU to the side, I was then free to apply any degree of force in my relentless pursuit of removing the remaining screw core, threads and all.
I had a wee stub of screw, just shy of 2mm, peeking above the threaded insert, and a shallow bowl of screw shaft below. It refused to move in either direction; the vise-grips deformed the remaining material, so it was back to the drill press.

I clamped the PSU sled, and carefully drilled out the M3 screw. I did not have a 2.50mm drill bit, so I was reduced to using a 29/32" bit. This left more of the screw threads than I would like, and it made re-tapping slightly more troublesome. An excuse excellent opportunity to acquire a serviceable set of miniature metric taps, finally able to cut threads from M2 to M20 should a fastening emergency arise in the future. I took a moment to use a wire wheel to remove the corrosion and messily covered the bare metal with black paint. Some corrosion remains, including a bit that is visible after final assembly on the rear near the power rating sticker. Some patina is called for. This is the only existent action shot of repairing the sled, all other photos are unreal making attaching them impossible.




I refrained from purchasing two replacement M3-0.5 4MM Philips flat head screws -- even though the case has countersinks cast into it -- because the round head hex drive screws at hand did not sit proud of the case nor pose a treacherous scratching hazard to my work bench. Well, I tried to acquire them, but my local hardware store did not have screws that small in any grade or material.




The power supply is secured, and the computer anxiously awaits its next bits.

 

[theletter0xff]

Anyone have an MFM emulator? I would like to image the hard drive, I have not applied power to the drive yet...

 

[theletter0xff]

"Good news, everyone. We've got a very special delivery today."

I was able to get the matching keyboard from the vendor!
It is in dire need of refurbishment.


The lower case is the same heavy stamped steel as the computer, it is unfortunately missing one foot -- the bracket was snapped off. The foot is rather large and cast in some type plastic. The upper case is the same heavy plastic and finish as the computer. The matching Harris badge is slightly tarnished.




Foiled again!

The keyboard was made by Cherry model 026-1009 revision C. Acting as the brains of the operation is a Toshiba TMP8048P, interesting choice given Harris makes keyboard controllers, perhaps the OEM already had an existing design and just adapted it. With an internal power regulator and beeper, the keyboard connects to the monitor through a 6P6C RJ12 style jack. The key caps are a mix of double shot and and single shot, some with likely dye sub labeling on the user facing side.
The key switches are capacitive foil on foam.
The foam is now a slightly tacky green-grey dust.
Sadly, they are not common round pads, but have notches to allow for the slider.



After cleaning it, I'll see if my local tool and die shop can machine a cutting die to make new pads. My CAD skills are limited and my G code is non-existent. For testing, I'll most likely use self-adhesive foam with some mylar as a facing, then just stick them to the switch body.