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Nice 5155

jafir

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Looks nice and complete. I wonder what that little dongle hanging off the card goes to.

Perhaps something happened to the internal monitor connection, or that's not an IBM CGA card, so they needed to get the monitor input?
 

ibmapc

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Something's not right with that thing.
  1. The monitor should be amber.
  2. There is a hole in the back where expansion slots 6, 7, 8 should be.
  3. Why is it booting to basic? Either the A drive doesn't work or the seller doesn't know to put a boot disk in it.



I would not by one that has been modified like that!
 

jafir

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Interesting. That could explain that cable plugged into the RCA jack.
 

Agent Orange

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Something's not right with that thing.
  1. The monitor should be amber.
  2. There is a hole in the back where expansion slots 6, 7, 8 should be.
  3. Why is it booting to basic? Either the A drive doesn't work or the seller doesn't know to put a boot disk in it.



I would not by one that has been modified like that!

I'm not at all familiar with the 5155. Is it not possible that the amber CRT was simply replaced somewhere down the line? My eyes are not what they used to be, but I'm having a problem locating that 'hole'. Also, rather than dinging the seller's 5155 and treating it as a pariah, why not contact him for an explanation. Maybe it's not for the 'purist', but I'm thinking that there are plenty of IBM people out that would like to have that unit. It appears to be all in one piece and working. Not taking side - just an observation,
 

ibmapc

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...Is it not possible that the amber CRT was simply replaced somewhere down the line?
yup. If it's not original, it's not "complete". I also don't like seeing them with the floppy drives switched out(Not the case here. Just sayin').
My eyes are not what they used to be, but I'm having a problem locating that 'hole'...,
00C0C_2RwwWhvd2Fy_0CI0lM_1200x900_LI (5).jpg
Looks like they made a storage compartment.
 
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Eudimorphodon

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[*]Why is it booting to basic? Either the A drive doesn't work or the seller doesn't know to put a boot disk in it.

It's on BASIC in one of the pictures, but in another it's at the MS-DOS prompt.

I don't want to be the guy that pulls the usually-false-alarm "RARE PROTOTYPE!" lever, but what the heck is with that hole on the back? If it's a homemade modification they went to great lengths to do it, because it's clearly not a crude modification of the "original" 8-slot backplane, it's a completely new piece with only five slots in it, and it otherwise looks professionally fabricated. Also notice that there's no IBM manufacturing sticker under the power switch/jack, nor that bar code sticker with the serial number.

It also seems to be missing the IBM nameplate under the handle. Compare:

00h0h_4rfkLhhwfm5_0CI0lM_1200x900.jpg

With:

ibm5155-case.jpg


ibm-5155-portable-xt-8088-personal-computer-as-is-2.39__88644.1490085279.jpg

Shouldn't there be an IBM badge in the upper right-hand corner?

There's something special about that unit, and I don't think it's because someone hacked it after the fact.
 

Eudimorphodon

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The 5155's internal monitor is composite video, plus not that difficult to swap the CRT with one from/for an Apple IIc.

But why would you? And that doesn’t explain the case anomalies. That missing badge in particular looks like it fits into a square indentation that isn’t in the plastic on this case. And, again, no manufacturer sticker on the back.
 

VERAULT

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Crap, how did I miss that?!? Yes, it's an aftermarket screen which explains the different card and cable. So that's worth no more than $200 in today's market. Whoops.

If that... I bought one back in.. I dunno 2016 or 2017. The psu was shot and I tried like mad to fix it. I just swapped the guts with a 5160 PSU and ran a 12V line to the monitor (even had the correct fitting for the power cable so it looks correct) But yeah, green crt, no internal pSU... Who knows what else. Id say $130 max
 

Eudimorphodon

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I'm still curious about the explanation for how the guy that "swapped the monitor" also fabricated what looks like a factory-alternative back panel with that storage compartment in it and de-badged the case so thoroughly.

(More to the point about that back panel: I don't have a 5155 myself, but in the pictures I can find it looks to me like the slot area of the 5155 is formed by a 90 degree bend of the same sheet of steel as the bottom of the case where the motherboard is mounted. *If* that is correct I am mystified how someone replaced that piece with the modified one with the hole in it because, again, look at it and it's clear it's *not* just hacked out from where the slots are in the factory models, it's "virgin" metal under that hole.)

EDIT: Photo that support my "back panel is part of the same piece of metal as the motherboard tray" guess?

IMG_0892.jpg


If that is correct that's a *big, complicated piece* of metal you have to change out to make that storage compartment unless they did something incredibly clever to splice in their new slot area.
 
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Hugo Holden

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I have never seen a 5155 with a green CRT. The monitor in the 5155 was made by Zenith for IBM I think and had a unique Amber CRT with a very specific part number. Though there would probably be a range of substitute CRT's that would work with the Zenith electronics.

The original Zenith monitor was very well designed. It produced an excellent sharp focus image with a very fine spot resolution and the raster had good rectangular geometry due to the multiple correction magnets arranged around the yoke. The video output stage is good to 8MHz, so it is a pretty hard monitor to beat for performance I think. In fact the resolution was so good that when you feed it with the composite color signal from the CGA card the chroma carrier causes unwanted patterning effects, so its best to disconnect the resistor that mixes in the chroma to the video output transistor on the CGA card, that is if you do not plan to use the color composite signal for an external composite monitor.
 

SomeGuy

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That compartment looks like a place to store a power cord. Never used a 5155 before, they don't normally have any kind of cord storage compartment like the Compaq Portable? With the power supply on the other side, I'd guess there would be room there using a 5-slot 5150 motherboard but not an 8-slot 5160 board.
 

Eudimorphodon

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That compartment looks like a place to store a power cord. Never used a 5155 before, they don't normally have any kind of cord storage compartment like the Compaq Portable? With the power supply on the other side, I'd guess there would be room there using a 5-slot 5150 motherboard but not an 8-slot 5160 board.

A normal 5155 has a 5160 XT motherboard in it and a different backplane that has slots where that storage compartment is. And, like I said, that compartment is clearly not just amateurly carved into a stock 5155's backplane, that's a different piece of sheet steel, and unless I'm misinterpreting the pictures I've seen of how a 5155 is put together that same sheet of steel is a major structural element of the chassis, not a part that comes off separately.

I really think this machine might be either a prototype, or it's some sort of professional custom job. A prototype would better explain the green screen phosphor, because the decision to go with amber could have been made at any point in the product development cycle. I also am still wondering about the missing IBM badge; again, I don't have one here sitting here to check, but in the pictures I've seen it *looks* like that badge on the top of the case near the handle is recessed into a square indentation in the plastic like the one on the front of the 5150/5160 are, not just glued to the surface. That case has no indentation there. And, also, again, there's no IBM stickers on the back, neither the model identification sticker that should be under the power plugs nor does it look like it has a serial number sticker. It's been a long time since I handled one of those machines, but I'm pretty sure those stickers don't come off easily and it doesn't look like there's any residue there.
 

Agent Orange

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I made an attempt to contact the seller in order to either clear up or add to the mystery.
 

Hugo Holden

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A while back I did a project using IBM5155 VDU's:


http://worldphaco.com/uploads/THE_AMBER_COMPUTER_VDU_PROJECT.pdf

By far and away the most challenging aspect of the project was to create a 3D mask which would interface with the original amber monitor CRT faceplate, have a look on page 4 of that article.

IBM got it just right with the molding on their 5155 computer, so that the rounded corners of the CRT were just masked off, to give a "modern" rectangular look. Also, the amber CRT has "mounting ears" on an encircling faceplate band, to correctly center it behind the mask on the mounts there.

If you look at the posted photo with the green CRT you will see it is not centered correctly on the mask. Which means its mountings must be non standard.

Many small CRT's might or might not have the mounting bands depending on the types. Unlike large CRT's these are not really implosion protection bands, you can cut them off if you want, but if a CRT is supplied without one and the original mounting calls for one, like in the 5155, it can be "awkward".
 

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