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IBM 5154 Troubleshooting

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dongfeng

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Having recently got hold of a couple of Paradise EGA cards, I thought I'd try and hook up the IBM 5154 EGA monitor to my 6MHz 5170.

The previous owner dismantled the machine 10-15 years ago, and I rebuilt it from a box of parts 6 months ago. The original IBM EGA card had died, so I've been using it with VGA.

Both of the 'new' Paradise EGA cards seem to work - I've tested them with a 5151 and 5153 with no problems.

When I originally hooked up the 5154 6 months ago, it started smoking so I had assumed it to be dead.

With the arrival of the new cards I did a little experimenting before Christmas. With the EGA card switches set to 'high' EGA resolution, it worked! Picture seemed good, but with a slight flickering to the left hand edge of the screen which made the first letter on each line unreadable. Adjustment with the controls on the back and inside the monitor didn't make any difference. Monitor then started smoking from around the power cord area, so immediately switched it off.

The next day I powered it up, and it was working again. So I set the card switches to EGA 'low' resolution (it appears to be the same resolution as CGA, but with the EGA colour palette) and that was working great. In fact, the computer was on for several hours like that.

On returning from my holiday a week later, I booted up the AT (with EGA still at low-res) and everything is good. A couple of hours of constant running I shut down the machine and set it back to 'high' resolution. This time the screen is a blur (looks like V-Sync is out as the text is racing along) and I could smell something wasn't good inside it and would probably smoke again. I powered off, but then re-set to 'low' EGA resolution and it has been fine ever since.

Any ideas what is wrong? I thought it could be something in the power supply unit of the monitor as that is where it was smoking from, but if so I assume that would also effect the low-resolution? How come high-res smokes but low-res does not?

I'd like to repair it if possible (or safe), but if not I am more than happy with low-res EGA!
 
I've had wavy edges (and sometimes text "twinkling") from excessive ripple in the power supply. Smoking from the psu area would also suggest bad capacitors.
 
I have a 5154 monitor which smoked about ten minutes after I plugged it in.
Lots of smoke.....
It worked great for those first ten minutes though :)

After opening the monitor I found that there was a capacitor in the power
supply which had overheated, burst open and was leaking oil which was causing the smoke.
Its a unique capacitor, rectangular shaped, which I think actually contains two capacitors internally
and is oil filled. It says "0.1 uf X 2" on the top.

I haven't found a replacement capacitor for this yet, but I was able to
get the monitor working again using a power supply from another 5154
I have. I've worked on several 5154's , and they ALL had one or more
bad electrolytic capacitors in the power supply. If you're serious about
fixing the monitor....For a few dollars its a good investment to just replace
all the electrolytic capacitors in the power supply. However ,you can probably
ignore those two large (220 mf) capacitors as they cost about 4 bucks apiece.
Unless of course they are obviously leaking.
 
X2 isn't "times 2" it means that the capacitor is suitable for going directly across a mains input. it's a filter capacitor, and can be removed for testing purposes, and eventually replaced (when you get fed up of not being able to receive anything on AM radio) with another 0.1uF X2 capacitor.
 
Thanks for the info. Looking at the schematic I see that there
are two of these X2 caps and they are both across the AC input.

nige the hippy said:
X2 isn't "times 2" it means that the capacitor is suitable for going directly across a mains input. it's a filter capacitor, and can be removed for testing purposes, and eventually replaced (when you get fed up of not being able to receive anything on AM radio) with another 0.1uF X2 capacitor.
Click to expand...
 
If you need a replacement, search using 'mains suppression capacitor'.
You'll see that there are different classes of mains suppression capacitor: X1, X2, Y1, ...

Mains suppression capacitors seem to be a high failure item in certain pieces of old equipment, just ask owners of the Osborne 1.

But it sounds to me like 'hi-res EGA' could be using higher sync frequencies that 'normal' EGA (V=60Hz, H=15.7/21.8Khz) and as a result that your 5154 is being run beyond what it was designed for. Does your documentation indicate the frequencies used?
 
Thanks for the replies!

modem7 said:
But it sounds to me like 'hi-res EGA' could be using higher sync frequencies that 'normal' EGA (V=60Hz, H=15.7/21.8Khz) and as a result that your 5154 is being run beyond what it was designed for. Does your documentation indicate the frequencies used?
Click to expand...

The "low-res" I get with the 5154 exactly the same output on screen when I run my 5153 through the EGA card on AutoSync. CGA resolution, but with the EGA colour palette. The "high-res" is I assume the standard resolution expected with an IBM 5154, but causes the left edge of the screen to flicker and the PSU to smoke.

mikey99 said:
After opening the monitor I found that there was a capacitor in the power
supply which had overheated, burst open and was leaking oil which was causing the smoke.
Its a unique capacitor, rectangular shaped, which I think actually contains two capacitors internally
and is oil filled. It says "0.1 uf X 2" on the top.

I haven't found a replacement capacitor for this yet, but I was able to
get the monitor working again using a power supply from another 5154
I have. I've worked on several 5154's , and they ALL had one or more
bad electrolytic capacitors in the power supply. If you're serious about
fixing the monitor....For a few dollars its a good investment to just replace
all the electrolytic capacitors in the power supply. However ,you can probably
ignore those two large (220 mf) capacitors as they cost about 4 bucks apiece.
Unless of course they are obviously leaking.
Click to expand...

Thanks, very useful info! I'll dismantle the PSU and replace any suspect caps. I guess if the oil-filled caps are gone I am out of luck though :(
 
nige the hippy said:
X2 isn't "times 2" it means that the capacitor is suitable for going directly across a mains input. it's a filter capacitor, and can be removed for testing purposes, and eventually replaced (when you get fed up of not being able to receive anything on AM radio) with another 0.1uF X2 capacitor.
Click to expand...

Oh, so I guess they can be replaced then? I'd better start scouring the Maplin catalogue :)

Does anyone have a schematic they could copy for me?
 
I found this on Google Groups:

IBM 5154 AND 5175 MONITORS
--------------------------

EGA (5154) and PGA (5175) monitors are nearly identical except for the
video electronics contained in a metal box on the left side (when
facing the screen). Schematics ARE available from IBM, in _Technical
Reference, Options and Adapters, Volume 3_ of the "Personal Computer
Hardware Reference Library." Introduced in the mid 1980's, many 5154
and 5175 monitors are nearing the end of their service lifetimes,
i.e., tubes have dim picture and poor focus, and numerous capacitors'
values have decreased. In severe cases, we advise users to scrap the
monitors and convert to VGA.

The most common failure is in the power supply: Symptoms include
chirping noise, repetitive startup/shutdown (blinking LED pilot lamp)
or jagged edges on left and right of picture.

Replace three small electrolytic capacitors in the power supply:
C11 (47uF 40v), C13 (10uF 35v) and C14 (1uF 35v). These capacitors
fail from heat after long service.

The power-supply unit is removable. You must drill-out three pop-
rivets to open the metal box; replace them with sheet-metal screws.

Symptom: Vertical foldover in EGA mode, or incorrect vertical
centering.

Replace C311 (100 uf 40v) near vertical amplifier (IC300).
 
Thanks, very useful info! I'll dismantle the PSU and replace any suspect caps. I guess if the oil-filled caps are gone I am out of luck though
Click to expand...

You can always get replacement caps. As I said in another posting, they're usually a little smaller than the originals. Vintage TV & wireless buffs often remove the guts of the originals & put the new component inside the old case, you've really got to avoid handling the "oil" though it's a poly-chlorinated-biphenol, it's got a long name and it's nasty!

If you need help with getting the correct components, email me a list & I can help to give you part numbers & suppliers.
 
Don't get too hung up on the filter capacitors. Beyond popping the fuse, they won't have much effect on the functionality of the monitor.
The ones that cause other problems are the big electrolytics, which tend to reduce in value & leak, both electrically & physically. There's usually a small electrolytic on the primary side too, which is part of the power supply for the chopping circuit. it's initially fed with current through a big resistor to the HT rail, then when the supply is running, it gets fed from a diode connected to an auxilliary winding on the chopper transformer. when that gets leaky, the resistor can't supply enough current to initially charge it, and the power supply (sometimes) won't start, that also manifests itself in burning the big resistor.

Rules are - replace anything bulgy and/or brown!
 
I have now removed and opened up the PSU, and suprise suprise - two broken caps! I am pretty sure these are the two that Mikey99 was referring to.
What exactly do I need to replace them with?

5154psu_01.JPG


5154psu_02.JPG


5154psu_03.JPG


5154psu_04.JPG


I think I'll replace these, along with the other few detailed in my previous post that are common failing components.

The big brown 'monolith' you can see also has a bit of green fluff on the legs. Replace that too? I don't even know what it is!

Is there anything else I should replace while the PSU is open?
 
The capacitors can almost certainly be replaced with maplin part number N69CN, or possibly SC93B (you may or may not have to do some leg-bending)

Don't bother replacing the big brown monolith, green fluff or otherwise unless it is faulty. It's only a 4.7ohm high power resistor, probably there to reduce switch-on power drain Check with a meter.

The other component I've known to stop monitors switching on is the little black plastic cuboid with "C02200" written on the top. They're usually a 3 terminal thermistor device designed to provide automatic degauss and switch on power surge reduction in one. there should be a replacement part around, but will have to do some googling to be certain.

REMEMBER TO ALLOW TIME FOR CAPACITORS TO DISCHARGE, THEN CHECK WITH A LONG HANDLED SCREWDRIVER!
 
The strangest thing just happened. I took the monitor EGA control box (I assume) out to check inside that (which was fine) and then re-assembled the PSU. The monitor now works in proper 640x350 EGA resolution!!! Absolutely perfect picture quality with no bending over of the first letter or shakiness of the text that was there before. I've been using it for an hour now with no signs of smoking.

Maybe since the monitor smoked twice, that was each of the caps going at different times?

I will replace those two capacitors anyway. Thanks for the part numbers Nige :)
 
Hi folks!

I've had the very same problems as dongfeng described. When I was trying to reactivate my old 5154 lots of smoke came out. A look at the PSU revealed that both 0.1u capacitors were broken. I replaced them (about 50 cents each), and now power supply is working again :))

My problem is that the display doesn't show the image correctly. It looks extremely condensed at the vertical axis and it fills only the upper 25% of the screen. Adjusting V-Size and V-Size2 at the rear side of the monitor doesn't change this effect. Also turning the knob on the unit labeled "25.000 V" doesn't help. Is there any other potentiometer inside of the monitor which I might have manipulated by mistake that can cause this effect? Or does this mean that the cathode ray tube is broken?

I'm looking forward to your comments (and sorry for the baaaad English)
Best regards
postnukem
 
1) DON'T turn the knob marked 25.000V unless you know what it's for! :eek:
2) I suspect that the shrinky vertical is down to other bad capacitors, it could be the supply voltage to the vertical amplifier being too low, or it could be a fault in the vertical amp itself. If you have schematics, a TV repair engineer could possibly help on this one. It's almost certainly not the tube.
3) when you do take it to the TV engineer (together with a pc for driving it) get him to re-adjust the 25KV EHT back to what it should be, it will save you getting X-rayed while you compute!

(And yes Dongfeng, I will get them in the post today, (plus a little something else;-) been a bit busy again!)
 
Thanks

Thanks

nige the hippy said:
1) DON'T turn the knob marked 25.000V unless you know what it's for! :eek:
Click to expand...
Alright - got it ;) I was extremely careful in testing this knob (25 kV doesn't sound fun to me) and I marked the original position before getting hands on it.

I guess I will replace the other capacitors in the PSU and see if this solves the problem. Think I can't afford a TV engineer...

Anyways, thank you for your comments Nige!
 
Some info on the 5154 that you may be helpful.

EGA runs at one of two vertical sync frequencies, 15.7 kHz or 21.8 kHz, which one depending on the current video mode.
And that is why on the 5154 you'll see a lot of adjustments in pairs, such as VSIZE1/VSIZE2 at the rear, and paired adjustments within the monitor.

In the 5154 schematic I had long ago, the '1' and '2' are referred to as 'mode 1' and 'mode2'. Mode 1 is operation at 15.7 kHz, mode 2 operation is at 21.8 kHz.

In the EGA video standard, the polarity of the vertical sync pulses is different between 15.7 kHz and 21.8 kHz. The 5154 selects mode1/mode2 operation based on the polarity of those sync pulses.

The video mode used at the DOS prompt is one that results in mode 2 operation. If you want to test/align mode 1 operation, run the video tests in CHECKIT 2.1 (http://members.dodo.com.au/~slappanel555/software.htm). Of the video tests, the text ones are mode 2, and most the graphics ones are mode 1. Certainly the first graphic one, video mode 04h, results in mode 1 operation.

The heart of the "vertical amplifier" that Nige referred to is the TDA2653 vertical deflection IC. According to my notes of the 80's, the TDA2653 was a common failure item in our 5154s, causing full or partial vertical collapse. But in a monitor of the age that your 5154 is, I agree with Nige - suspect the electrolytic capacitors first.
 
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