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IBM 5154 Troubleshooting

Hi! I'm so glad to be able to connect with you people!

@VintageVic I did see that thread and I will go over it again. The experiences others have had with real 5154's is invaluable for pointers to causes of symptoms.

@modem7 I have experience with high voltage in broadcast transmitters and other CRT based units. I understand that parts of the circuit boards also have voltages in excess of 100V. Thanks!

I do have good metering and oscilloscopes. I have just ordered an ESR70 capacitor checker from Digikey. I have good soldering stuff and have replaced the usual .1uF AC Line capacitors in 3 units.

I just got one of those XTIDE boards but need to learn how to use it...

I have the rest of the power supply module capacitors ordered. I do have soft copy of the SAMS Photofact but I need to print and patch it together. And I need to study the schematics! I need to dig my old IBM Manuals out of the barn. I THINK the options/adapters manual does not have the actual 5154 schematic, but maybe has the PGA display?

The 3 5154's have these symptoms as of now:

(1) Worked for an hour and then Smoked The Usual Smoke. Replaced the two .1's and the two large 220uF/250V capacitors. Working well now for >40 hours and many restarts. Running on IBM CGA in a 5160 XT. (I need to find an EGA card to test the other scan frequency. ) I must have one Somewhere :)

(2) Quickly Smoked. Replaced the two .1's and the two large 220uF/250V capacitors. Works now but has horizontal character wiggles that change over time/warmup and not so noticeable after 1/2 hour warmup. [Suggestions?]

(3) Preemptively replaced the two .1's and the two large 220uF/250V capacitors. Dead: power on LED does not come up. Pretty sure the power supply is seated well and all connectors in place. {Where To Start?]

I am trying to get at least 3 complete XT's with two floppy disks and EGA displays working. I'd like to sell two of them to be able to support some other projects.

I have done some work on the original Tandon full height diskette drives, especially methods of cleaning the heads with 99% Isopropyl and clean room paper. But that should be in another thread. What do you think is the best place to discuss that?

The XT's have an interesting history in which they have been taken totally apart down to the system board on the table with the power supply and speaker (Dah Dit-Dit) and then the display and disk cards plugged in to show how it works with those parts, and then reassembled into the case. By middle and high school kids as part of a program that IBM supported me in called "Computer Demolition". I wrote all that up and it was used many many times by me and other IBM volunteers from about 1990..1995. As XTs came out of use at IBM Vermont, I had volunteers remove or wipe the hard drives. Many were donated to schools; some became Computer Demolition candidates with no hard drive. After I 'retired' in 1995 some volunteers kept Demolition running for a few years. In 1995..2000+ my wife Mary Alice Osborne and I did the Demolition for several classes and she did a detailed project with 3rd grade kids about How Computers Work in which they studied and drew diagrams of all the parts.

So these XTs and EGAs have been hibernating in my unheated barn in Vermont for over 20 years. I am trying to wake them up in the world of highly integrated computers with multi-Ghz processors.

Thanks for connecting and I hope to be able to get more of these 'historic' parts working!

Regards, Terry King
...In The Woods In Vermont
The one who dies with the most Parts LOSES! WHAT DO YOU NEED??
 
>(3) Preemptively replaced the two .1's and the two large 220uF/250V capacitors. Dead: power on LED does not come up. Pretty sure the power supply is seated well and all connectors
>in place. {Where To Start?]

I had the same issue at first, no power, no green power on LED. In my case it was:

> Bad 12V regulator at psu (IC2, 7812CT)
> Symptoms: 12V leg of regulator showed 0 V. No 12V, no 5V, no green power on LED, no raster, screen remains black.

5V is derived from the 12V rail if I remember correctly. I would start by checking that you have the 12V available.
If not, that 12V regulator is at least one suspect. If you have 12V, go further at the schematics where the +5V should be
available and go on checking from there.
 
Thanks! Vic... Glad you wake up earlier than me...

I will dig in again later today... I'm feeling better about my chances.

OTHER: Someone somewhere referenced powering the power supply module on while removed from the rest of the display. Anyone have pointers on that?? I MaybeCould rig some load resistors... Hmmm...
 
I might go to sleep soon, it's around 8pm here in Finland ;). Done my dayjob for the tuesday.

Yes, I troubleshooted the psu while it was plugged out from the rest of the display. Of course
if you want to power it on while out of the display, you have to at least connect it to the power switch.
I believe it was the two cables on the left, yellow and black that are attached to the psu.

Obviously, like Modem7 pointed out about the hazards, you have to be really careful not to give yourself
a good (=bad) shock. Especially mind that lethal 25-30 kV and find a safe way of discharging it before you tinker
with the thing.

My psu is 230VAC unit, so it must have some difference from 110VAC unit. I remember that the 12V regulator
was located on the psu, but I think the +5V was not derived on the psu pcb, but the main pcb instead. That
had me confused for a while. But the schematics will help to see what is going on and where.
 

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Hi, I have the "5154001" which is 120VAC nominal.

I am less worried about the 30KV than the 380V Pulses in the power supply board. "One Hand In The Pocket" to quote my Dad, Fred King, who was Chief Engineer of WELI in New Haven, Connecticut for 40 years or so. Occasionally some adjustment on a broadcast transmitter needed to be made inside, with the interlocked doors open. Dad had that rigged with a key switch that disabled the door interlocks and turned on bright red lights in each cabinet.

I'm studying the power supply module schematic. You can see it here: http://internationalschoolphotos.com/IBM-5154001-EGA-Display-Schematics-Info-1/index.html
 
TerryKing said:
I just got one of those XTIDE boards but need to learn how to use it...
Click to expand...
The information at [here] may assist the learning.

VintageVic said:
Especially mind that lethal 25-30 kV and find a safe way of discharging it before you tinker with the thing.
Click to expand...
Only required in certain circumstances. Hugo Holden has a good write-up in post #8 at [here].
 
TerryKing said:
(2) Quickly Smoked. Replaced the two .1's and the two large 220uF/250V capacitors. Works now but has horizontal character wiggles that change over time/warmup and not so noticeable after 1/2 hour warmup. [Suggestions?]
Click to expand...
Just in case relevant later, can you tell if it is a horizontal collapse, or a horizontal shift?
Do you have any freeze spray?
Does tapping the side of the monitor provoke the symptom?

I once had small horizontal instability in my 5154, and the cause was a dirty pot. I cannot remember if temperature played a part.
 
TerryKing said:
(3) Preemptively replaced the two .1's and the two large 220uF/250V capacitors. Dead: power on LED does not come up. Pretty sure the power supply is seated well and all connectors in place. {Where To Start?]
Click to expand...
See 'Failure of small-value electrolytic capacitors in the power supply' at [here].
I remember it being very common.
 
@modem7, THANKS for the pointers....
------
"Just in case relevant later, can you tell if it is a horizontal collapse, or a horizontal shift? "No, it's a small deflection wiggle, worst at power on. There's a video here:
http://internationalschoolphotos.com/IBM-5154001-EGA-Display-Schematics-Info/#img=5154-3-HorizontalWiggle.mp4
(Sorry, my phone was in vertical mode... But..)

"Do you have any freeze spray?" No but some spray "Air" could work....

"Does tapping the side of the monitor provoke the symptom?" No effect.
---------
"See 'Failure of small-value electrolytic capacitors in the power supply' at [here]." I found C11, C13, C14 on the schematic. I have them coming from Digikey. AND a cap tester.

OTHER: What about testing the power supply module while removed from the main system?? Ideally I'd like to present some appropriate load on the outputs. The schematic shows outputs for:

11.9V coming from the 7812 regulator
5.0V coming from the 7805 regulator (Both of those would function without load.)
7.4V
56.7V
21.2V
21.0V
154V
-6.3V (The CRT Heater) probably not correct without load

I haven't analyzed the other outputs to think about what they would do with no load..

Anyone have ideas on this? I don't want to CAUSE smoke :)

******************************************************

UPDATE: WOW.. Now I'm REALLY confused about that schematic... I assumed that everything on there was IN the power supply module. But I THINK I'm wrong.
That whole rightmost section of the schematic with the M1 M3 etc etc connections. Anyone have this figured out???
OK, I'm trying to figure it out....
 
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>UPDATE: WOW.. Now I'm REALLY confused about that schematic... I assumed that everything on there was IN the power supply module. But I THINK I'm wrong.
>That whole rightmost section of the schematic with the M1 M3 etc etc connections. Anyone have this figured out???

Yes, this is what I was trying to point out earlier - it had me confused for some time also.
Like I said, the +5V is derived from the 12V rail and this happens NOT in the psu, but in the main board. So you've got it right.

The M1 connector is just the one which connects the psu to the main board. I drew voltages that I measured over the picture of psu pcb back
side. You can see from that where you should find each of the desired voltage. You will get approximately the voltages even without load (at least in this 230V unit),
even when the psu is disconnected from the main board.
 

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Hi Vic, THANKS and I am digging into this today.

Question: What jumpers did you need to power up the module separate from system? The schematic shows the main power switch is remote and there are 4 connections to it. Looks like 2 jumpers could route power from the power cord to it. Or 120V (in my case) could go directly to 2 connections. This diagram shows some of that - (Anyone know WHERE that graphic is from?? I Got It On The Internet. Would be nice to see the whole thing!

5154schem01.jpg

I am going to try to draw a line through the schematic showing what is on the module and what is on the main board etc...
 
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TerryKing said:
(2) Quickly Smoked. Replaced the two .1's and the two large 220uF/250V capacitors. Works now but has horizontal character wiggles that change over time/warmup and not so noticeable after 1/2 hour warmup. [Suggestions?]
Click to expand...
modem7 said:
Just in case relevant later, can you tell if it is a horizontal collapse, or a horizontal shift?
Do you have any freeze spray?
Does tapping the side of the monitor provoke the symptom?
Click to expand...
TerryKing said:
No, it's a small deflection wiggle, worst at power on. There's a video here: .....
Click to expand...
Considering your known-good video/sync source, I think I would describe that symptom as 'horizontal jitter in the raster'. It's a line-by-line shift (shift, rather than partial collapse).

Temperature sensitive, and cannot be mechanically induced.

Yes, If I saw that, for efficiency, I would first be targeting the horizontal circuitry with freeze spray.
If unsuccessful, in with a CRO.
 
@modem7 , Quote "I think I would describe that symptom as 'horizontal jitter in the raster'.
Click to expand...
Yes that's a good description. I'll study the schematic some more. I do have a CRO (7854 Tek) but I have a handy small LCDO ;) At one point today after 5 Hr poweron it really smoothed out. Makes me suspect an electrolytic that reforms a little.

Thanks for help thinking this through.

OH! Hey, just noticed I'm now UNmoderated! Think I'll go grab a beer...
 
>Question: What jumpers did you need to power up the module separate from system? The schematic shows the main power switch is remote
>and there are 4 connections to it.

I did not jumper it, actually I just plugged in the two cables from the monitor coming to the psu.
You can do this too, and just power it on using the original power on switch at the monitor.

Then, you will also see that the power switch is working as it should. If you get any voltages, the power sw should be ok.
 
VintageVic said:
I did not jumper it, actually I just plugged in the two cables from the monitor coming to the psu.
You can do this too, and just power it on using the original power on switch at the monitor.

Then, you will also see that the power switch is working as it should. If you get any voltages, the power sw should be ok
Click to expand...
GOOD Point! M3 is the cable from the on-off switch. And M1 and M2 which would send all voltages to the main board are disconnected and can be test points.

Thanks!
 
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