• Please review our updated Terms and Rules here

IBM 5150 monochrome monitor video problem

Joined
Sep 25, 2014
Messages
15
Location
USA
Hi,

I bought an IBM 5150 yesterday with an old monochrome monitor (It's not an IBM monitor by the way). The problem is, this monitor has no power switch! Do you guys no if this monitor just activates with a video signal or what? I've tried it a couple times with no success. With the power cord plugged in, it doesn't make any noise but it does feel a little warm on the vent after a while. I (carefully) opened the case and everything looks decent with no blown fuses. I also checked the video cable for shorts and tried the brightness controls and such.

The IBM 5150 passes the self test (just by listening to it and seeing that the floppy drive gets activity after a short while) so I assume it's working okay. (I believe it has a EGA card installed) I tried the monitor on another vintage PC as well with no changes.

Any ideas would be great,
Thanks!
 
In the case of monochrome monitors, the usual practice was to connect the monitor to the female IEC power connector on the back of the 5150. The monitor even had a power cord so configured.

There's absolutely no reason that your current monitor can't be (or shouldn't be) so configured.

Adapters, if your monitor power cable isn't removable, are available.
 
The IBM 5150 passes the self test (just by listening to it and seeing that the floppy drive gets activity after a short while) so I assume it's working okay. (I believe it has a EGA card installed) I tried the monitor on another vintage PC as well with no changes.
FWIW, I don't believe you can test that mono monitor with an EGA video card.
 
Great! I'll probably buy one of those adapters and hopefully the monitor will work! In the mean time though, I noticed that my video card has some headers on the top that say RCA near them. Can it be configured for composite video so I can use my old B/W CRT TV as a monitor? I know this was an option when it came out but my IBM doesn't have the original composite out shown in the user manual.

Here's some pics:

DSC_0549.jpg

DSC_0551.jpg

I tried to look the manual for this video card but couldn't find it.

Thanks
 
Thanks for the replies!

I'm wondering if this monitor is dead because usually you can turn the brightness up and see that it's working, but this one does absolutely nothing. That other old PC that I have has a setting for monochrome and even the proper power plug for this particular monitor. But like I said, that one didn't do anything ether.

While I figure out what's going on with the monitor, I'm wondering if I could use a composite out signal so I can use my old B/W TV with the IBM. I know this was an option when the 5150 came out, but mine doesn't have the card shown in the user manual that accomplished that. But I noticed on my video card that it has a header with six pins on the top that says RCA near it. I wounder if that's for composite out? I can't find the manual for my card though. It's a Video7 card that looks pretty much like this
 
The monitor is on as soon as power is applied (so don't leave it plugged in unnecessarily).
But you won't see anything at all until it receives a video signal.

It also takes a few seconds to warm up and if it's fairly clean you should see a slight glow from the back of the tube.

NB: as mentioned, you will need an MDA/MGA input - check what card you have.
 
Last edited:
Okay, I fired up the computer with the cover off the monitor and saw a light on the back of the tube but within a seconds it went away. Is this a sign of some bad circuitry or bad power supply in the monitor?
 
I bought an IBM 5150 yesterday with an old monochrome monitor (It's not an IBM monitor by the way).
How confident are you that the monitor is monochrome (MDA)? Is there a marking of some sort?

Here's some pics
The video card has a BIOS expansion ROM it. That puts two requirements on the 5150 motherboard, both of which must be met:
1. That the motherboard's BIOS ROM be the third (dated 10/27/82) revision. See [here].
2. Switches 5 and 6 on switch block SW1 be set to on. See [here].

Re point 2. That is the case even if a card (one with a BIOS expansion ROM) is configured to produce CGA or MDA signals.
 
I'm wondering if this monitor is dead because usually you can turn the brightness up and see that it's working, but this one does absolutely nothing.
Per what SpidersWeb wrote, if it is a monochrome monitor, and it has been designed to behave just like the IBM 5151, then you will not see anything on the screen until an MDA signal is received.

That other old PC that I have has a setting for monochrome and even the proper power plug for this particular monitor. But like I said, that one didn't do anything ether.
Not a good sign.

It's a Video7 card that looks pretty much like this
That is my card that you 'pointed to'. It is a VGA card that also does EGA/CGA/MDA, controlled by the card's switches.

Your card appears to be a cut-down version. VGA connector absent, a chip absent, and a different BIOS expansion ROM. Perhaps yours does EGA/CGA/MDA, or perhaps CGA/MDA, or perhaps MDA only.

You could try the switch settings [here] for my card. In case you are unaware, 'open' on a switch means off. Note that some vintage monitors can be damaged if an incorrect video signal is applied for too long.
 
Thanks for the replies again!

On SW1, I made sure that switch 5 and 6 are set (it wouldn't pass the self test with those off). I have also tried the switches on video card for different video settings. That's rather disappointing that my card is stripped of the VGA stuff. It's only two components though. I haven't looked to see if that missing IC chip is rare but if I find one of those, a suitable VGA jack, and burn the proper bios in the eprom, do you guys think it would work?

Also, I've been looking for my monitor online and finally found someone that has one. It's a Sperry branded monitor and this guy says that his is CGA. Ours both look identical but mine says Monochrome on the back! Another interesting thing about the monitor, I found that the bottom of the circuit board in the sector where the flyback is located looks a little burned. The solder joints and surrounding board have a slight rust color to them. But the components look good and they're no leaking caps.

I do have a couple 16-bit ISA VGA cards but I'm sure those won't work since the 5150 uses 8-bit cards.
 
Last edited:
... And although 'monochrome' usually refers to TTL MDA/MGA monitors, there were CGA-compatible monitors that were only one colour (usually green or amber)...
 
As well as VGA-compatible monochrome monitors.
They were actually quite common since spreadsheets, word processing etc. generally didn't need colour (and the extra cost) but benefitted from the higher resolution. They were also usually 'real' gray scale, i.e. white or paper-white.
 
I used a couple of the Tatung 14" mono VGA displays. They were okay for a time, but then rapidly became useless as color became predominant in VGA program displays.

Cheap they were, however.
 
These two VGA cards look most promising. Especially the bigger orange colored one. The others are from around 1992 and up. The bigger one says PVGA PLUS-16 but I can't find a brand name.

DSC_0554.jpg

DSC_0555.jpg
 
... And although 'monochrome' usually refers to TTL MDA/MGA monitors, there were CGA-compatible monitors that were only one colour (usually green or amber)...

The Princeton Graphics MAX-12 was a fine example of a TTL mono monitor that was CGA compatible; it was dual-mode so it worked with either CGA in 16 greys (ambers?) or MDA. (I remember this one well because the first PC clone the family ever owned was one of those carbon-copy 5160s with a CGA card and a MAX-12. ) These dual-mode TTLs were certainly less common than plain MDA monitors but I know the MAX-12 wasn't unique.

(Undoubtedly it was probably more common for a monochrome monitor+CGA combo to use composite instead.)

Edit: Google Books hit on an ad for the MAX-12 mentioning its dual mode capabilities.
 
Back
Top