PDA

View Full Version : Zenith eaZy PC, not-so-easy repair



vwestlife
February 20th, 2016, 09:41 AM
I have a soft spot for vintage all-in-one computers -- as evidenced by the Tandy Model 4D, IBM PS/1 Model 2121, and iMac G3 in my collection. I had wanted a Zenith eaZy PC for quite a while, so when one came up on eBay, complete in original box, I knew I had to have it. The seller had it listed at an outrageously high price, but I was able to negotiate a price that was still high but was at least in the "I would hate myself more for missing out on it than for paying this much for it" range.

When it arrived via FedEx Ground, I was happy to see that the seller had double-boxed it. Unfortunately despite a copious amount of foam packing peanuts (the newer Cheetos-style kind) inside both boxes, due to the lack of any solid foam or thick bubble-wrap wedged between the CRT and the CPU base, combined with the brittleness of 27-year-old plastic shipped in the winter cold, caused the weight of the monitor to crack the plastic shell it was resting on into many pieces:

http://i66.tinypic.com/dfukaq.jpg (http://www.amstereo.org/images/eazypc/broken1.jpg)

http://i68.tinypic.com/o6frxv.jpg (http://www.amstereo.org/images/eazypc/broken2.jpg)

Thankfully the CRT itself and the electronics appear to be undamaged.

http://i63.tinypic.com/17eptx.jpg (http://www.amstereo.org/images/eazypc/overview.jpg)

The heart of the beast: a NEC V40 CPU running at 7.16 MHz:

http://i68.tinypic.com/ighwyf.jpg (http://www.amstereo.org/images/eazypc/motherboard.jpg)

Other oddities: the "mouse" port (an RS-232 serial port missing some pins) and the ISA bus pin header used for the external RAM box, expanding it from 512K to 640K.

http://i67.tinypic.com/2re01zb.jpg (http://www.amstereo.org/images/eazypc/ports.jpg)

http://i66.tinypic.com/v5vln6.jpg (http://www.amstereo.org/images/eazypc/rambox.jpg)

A 3.5" 720K floppy drive an a notoriously unreliable Western Digital 20 MB IDE-XT hard drive. The hard drive has a fan blowing on it, but there is no intake grille for the fan, so it just circulates air inside the case.

http://i65.tinypic.com/33ygj60.jpg (http://www.amstereo.org/images/eazypc/drives.jpg)

The best part of the whole computer: the solid-as-a-tank keyboard with a metal backplate, delightful linear mechanical key switches, and an internal keyclick beeper.

http://i68.tinypic.com/o09y5t.jpg (http://www.amstereo.org/images/eazypc/keyboard.jpg)

http://i64.tinypic.com/8wgsjr.jpg (http://www.amstereo.org/images/eazypc/eazylogo.jpg)

Any tips on how to repair the broken plastic would be greatly appreciated. I could super-glue it all back together, but since it has to support the weight of the CRT, I fear that wouldn't be strong enough. I need to find some way to brace the cracks from inside the case, perhaps with extra strips of plastic glued into place. Would something like JB Weld be suitable for doing that?

Chuck(G)
February 20th, 2016, 09:49 AM
You don't want "glue" for this stuff, you want "solvent cement".

Try some methyl ethyl ketone (MEK) from your local hardware or paint store. Use a Q-tip or toothpick to apply it sparingly to both parts to be joined. You'll note that the MEK dissolves the plastic a bit, which is why you don't want to go overboard. Clamp or otherwise secure the broken parts together until the solvent has evaporated (usually just an hour or so, depending on the size of the join). After you've got a section done, let it cure overnight and the join will slowly gain strength. The repaired item will be nearly as strong as the original--and if the break is clean, the join will be almost undetectable.

One advantage is that you can stick very small (i.e. about the size of a grain of ground pepper) bits together if you're careful.

http://www.hollistons.com/images/products/07948.jpg

Osgeld
February 20th, 2016, 11:40 AM
I have a tab broken off my old pizzabox mac so I took it as an opportunity to try different methods of reattachment, especially on a part meant to flex a little to unlock the case (aka stress)

Superglue - worthless, snapped right off as soon as slight force was applied
Model Cement - almost all this stuff is designed for polystyrene, all it did was stink up the place and easily peeled off with my fingernail
Plastic welding epoxies - I have had good luck in the past when the break was all jaggie (more like a tear than a snap), but the break on my mac was smooth and clean, didnt last very long
Chemical Solvant welding - I have used MEK in the past but all I had on hand was acetone, which takes longer but does the same job, and this is the best way to do most household plastics, but it wont work on all plastics, like polypropylene,polyethylene, Acetal Resin aka derlin, and other high tension surface plastics

DDS
February 20th, 2016, 11:55 AM
Damn!

And here I thought my H27 doors looked bad.

Anyway. After you: a) glue the shards back into some semblance of their original shape, or b) weld them with MEK or another suitable solvent I'd also lay down a layer of fiberglass mat on the inside after saturating the mat with a resin that's compatible with the plastic of the case after roughing up the inside surface a bit with an abrasive. Be advised that some resins will happily dissolve some plastics so you would be advised to do a bit of testing beforehand. The resin might also not stick well to what appears to be a layer of grey paint on the inside of the shell so you may also have to remove that.

Some 70's - 80's American cars had plastic parts that have also become brittle with age. I have had some success in using the suggested technique to repair them. Note that this seems to be a function of the type of plastic used. DEC and IBM used plastics for structural parts that have held up well for 30+ years. Too bad you can't say the same for some vintage GM products.

Almost forgot....

The plastic of the shell probably had residual stresses left over from when it was injection molded. So some of the fragments might have a subtly different shape now that they've been allowed to release those stresses. As a result you might find that the pieces of this jigsaw puzzle don't quite fit together. So you may have to join the pieces in a particular order to get them to fit back together well. Small model builder's C-clamps (or clothes pins) are your friend!

Hopefully you're giving some thought on how you're going to refinish the case after you've done all that work to put it back together.

Good Luck!

vwestlife
February 20th, 2016, 05:14 PM
I picked up some MEK and will give it a try as soon as I can devise a suitable way to clamp the pieces together.

In the meantime I made a makeshift stand for the CRT, plugged in the wires, and powered it on. At first it gave a hard drive controller error and it froze at that point. I discovered that by pressing Ctrl-Break I could get it to try to boot from a floppy. The floppy drive (an Epson SMD-400) would seek but would not spin. After some "percussive maintance" I got it to spin and boot DOS, but it sounded very rough, and eventually it stopped spinning and I couldn't get it going again. I don't know if the floppy drive uses a belt? I'll have to open it up and see. I tried a standard 1.44 MB floppy drive but the Zenith didn't recognize it. I can try borrowing one of the 720K drives from my Zenith Supersport laptop and see if that works.

On the good side, while I was fussing around with the floppy drive, amazingly the hard drive started working. It has lots of seek errors but at least I can get it to boot up. It has an eaZy PC-specific copy of Zenith MS-DOS 3.20 which I'd really like to save if I can get it to read the files successfully. The only other thing on it is a copy of WordPerfect 5.1.

Chuck(G)
February 20th, 2016, 05:18 PM
You don't even need to clamp things with MEK. Just coat both pieces along the edge of the break (using a Q-tip that's been wetted with MEK) thoroughly--you'll be able to tell when the plastic is just getting sticky--and press them together carefully using your hands; hold for about 3 minutes in position or until stable. Use some masking/painters tape for a bit more stability after you've released the result. It'll stay a bit flexible for a few minutes, so you can correct registration errors.

I recently reassembled a floppy drive faceplate that had been smashed into about 50 pieces. No clamps, just patience and tape. Aside from a few bits that had been lost during shipping, the faceplate works fine. I'll fill in the missing gaps later with some Bondo and then paint the whole thing.

Osgeld
February 20th, 2016, 05:47 PM
also rubber bands make awesome clamps in situations like this

but when melting plastics together either chemically or with heat too much pressure can cause gaps, I would just use tape to hold stuff in place

vwestlife
February 20th, 2016, 09:13 PM
Success! It's not pretty -- up close you can definitely see the cracks and the missing part of the edge that I couldn't find -- but at least it's in one piece again.

http://i68.tinypic.com/2w5v9lj.jpg (http://www.amstereo.org/images/eazypc/repair1.jpg)

http://i63.tinypic.com/nvqqkg.jpg (http://www.amstereo.org/images/eazypc/repair2.jpg)

http://i65.tinypic.com/np03k4.jpg (http://www.amstereo.org/images/eazypc/repair3.jpg)

Osgeld
February 20th, 2016, 09:42 PM
looks good from here

cough spakle and plastic paint lol

DDS
February 21st, 2016, 06:36 AM
Close enough = good enough.

;-)

vwestlife
February 23rd, 2016, 05:06 AM
This is the first machine I've come across in which the CuteMouse (CTMOUSE) driver doesn't work, while the Microsoft and Logitech DOS mouse drivers work fine. CuteMouse recognizes the mouse at the correct I/O address and IRQ settings but the cursor doesn't move; it just stays stuck in the upper left corner of the screen. I tried the 1.9, 1.9.1, and 2.1 versions and they all have this problem. I guess it doesn't like the NEC V40's not-quite-fully-IBM-PC-compatible integrated serial and parallel ports? I don't think serial mice make use of the extra data lines that the eaZy PC's "mouse" port is missing, so that shouldn't be the problem.

Chuck(G)
February 23rd, 2016, 07:58 AM
I don't know what the chip complement is on the EZPC, but I do know that the integrated serial capability on the V40 is pretty much a clone of the Intel 8251, not the NSC 8250, which is used on most PCs (I have seen one or two using the 8274). That's probably at the root of your problem.

vwestlife
February 26th, 2016, 05:17 PM
As I can tell by the original shipping label on its box, my eaZy PC was originally purchased from the Damark discount catalog company, and thanks to the September 1990 Damark catalog (http://www.vintagevolts.com/damark-the-great-deal-catalog/) which someone very helpfully scanned in and posted online, here is the original ad for it:

http://www.amstereo.org/images/eazypc/eazydamark.png

I feel sorry for anyone who thought they were getting a great deal on it, as by late 1990, 386s running Windows 3.0 were already becoming mainstream, and a 7.16 MHz XT with a monochrome CGA monitor and no expansion slots was badly obsolete right out of the box. It would've been OK for DOS word processing, especially with its nice hi-res 640x400 text mode and solid-feeling keyboard, but not much else. The newest files I could find on the original hard drive were from 1993.

The ad does say 512K RAM, but as part of their last-ditch effort to help get these turkeys out the door, Zenith did include the RAM expansion pack as standard.

rankin
September 18th, 2018, 06:44 PM
I have one of these machines but one of the FDD only version. Iím in need of the boot disk. Does anyone by chance have a copy of the Zenith DOS for this thing? Would be greatly appreciated.

vwestlife
September 23rd, 2018, 06:55 PM
I have one of these machines but one of the FDD only version. I’m in need of the boot disk. Does anyone by chance have a copy of the Zenith DOS for this thing? Would be greatly appreciated.

Here is Zenith MS-DOS 3.3 Plus:

https://vetusware.com/download/Zenith%20MS-DOS%203.3%20-%203.5%20Disks%20Zenith%203.3%20Plus/?id=8634