IBM 5153 Help

[lyonadmiral]

My IBM 5153 (Personal Computer Color Display) finally arrived in pretty good shape. Only issue I can find with it is that the image is shifted somewhat to the right of the screen, it is not centered like it should be. On the bavk of the screen there are two knobs that deal with rolling sync and what not but nothing that deals with orientation on the screen. Anyway I can adjust the position of the image to be more correct?

 

[Chuck(G)]

Try adjusting R413 (H PHASE).

There's also a (H CENTER) L401 slug-adjusted coil, but I'd leave that as a last resort after I checked the output of the power supply. Unless tinkered with by the previous owner, it shouldn't normally require adjustment.

 

[lyonadmiral]

Nothing....

Nothing....

Hi Chuck

So there's nothing I can do without dismantling the case? I guess you can say I have an aversion for this type of stuff. I prefer not to work inside the case, due to a very bad previous experience. So unless we end up starting some kind of mailin CRT service... I guess I'll just have to put up with it.

Thanks,
Dan

 

[Chuck(G)]

So there's nothing I can do without dismantling the case? I guess you can say I have an aversion for this type of stuff. I prefer not to work inside the case, due to a very bad previous experience. So unless we end up starting some kind of mailin CRT service... I guess I'll just have to put up with it.

You can temporarily shift the display slightly to the left or right.

MODE 80,R

will shift the display to the right and

MODE 80,L

will shift the display to the left. (You can use this with
any display MODE setting).

Of course, if the program you're running does its own CRT controller manipulation, the change specified in the MODE command won't have any effect on the program.

But it might be a stopgap for you.

 

[Fallo]

You can temporarily shift the display slightly to the left or right.

Even better, type MODE CO80,R,T. The T parameter displays a test pattern on the screen to help you align the picture, and it also loads a TSR that intercepts INT 10h calls and centers the screen every time you change video modes. This is the first thing I do whenever I boot my 5150, since the TV I'm using with it causes the picture to be pushed off to the left.

The off-centered picture is a problem with some TVs, but I didn't imagine it could happen on a RGB monitor. I'm not exactly sure why it happens, either.

Of course, if the program you're running does its own CRT controller manipulation, the change specified in the MODE command won't have any effect on the program.

That's pretty rare though, and would only affect programs that set the video mode directly (some games such as Digger do this). It is a problem on booter games, because there's no TSR loaded to center the screen. A few games (some of the Atarisoft ones for example) have an option to adjust the picture, but most don't.

 

[Chuck(G)]

Even better, type MODE CO80,R,T. The T parameter displays a test pattern on the screen to help you align the picture, and it also loads a TSR that intercepts INT 10h calls and centers the screen every time you change video modes. This is the first thing I do whenever I boot my 5150, since the TV I'm using with it causes the picture to be pushed off to the left.

I don't see the rationale behind the test pattern, as the amount of shift isn't variable ("right" or "left", with no degree). Either the display looks right or it doesn't--you can't fine-tune it.

Since the MODE function clearly manipulates the "HSYNC position" register (index 2 in the 6845 CRTC), it could have been made more flexible. It would not surprise me if there's not a program in the Simtel library that gives exactly that capability. The way the MODE function operates is that you get a shift of one 40-character position or two 80 character positions one direction or the other. That's it, period. ISTR that the horizontal retrace interval on the CGA is something like 15-17 characters in 80 character mode, so there's a lot to play with there.

Amazingly, the functionality is still there in DOS 7.1 MODE.

 

[Fallo]

ISTR that the horizontal retrace interval on the CGA is something like 15-17 characters in 80 character mode, so there's a lot to play with there.

I don't think it's that many. I've found that you can only shift it by a few characters before the picture loses sync. I was going to mention the HSYNC register in my previous post, but I forgot. The default values are 45 in 40-column text and graphics mode, and 90 in 80-column text mode. Setting it to 44 and 88 centers the screen on the TV I'm using.

Amazingly, the functionality is still there in DOS 7.1 MODE.

That would be the DOS in Windows 98, if I'm correct? You can still format 160k floppies there, so why not?

 

[Chuck(G)]

That would be the DOS in Windows 98, if I'm correct? You can still format 160k floppies there, so why not?

Thankfully, I think it's easier to leave things in than take them out of old code!

 

[lyonadmiral]

If anyone has the technical workups of the monitor; i.e. the service guide, I do have a slew of service repairmen who can work on it. Thanks!

 

[Chuck(G)]

No maintenance manual, but the schematic is in the 5150 Tech Ref (as well as in the O&A):

http://www.retroarchive.org/dos/docs/ibm_techref_v202_3.pdf

 

[NotLiable]

See other thread for useful information

See other thread for useful information

You fellows can take a look at the IBM Model 5153 CGA monitor repair thread I started a month or so ago for relevant information:

http://www.vintage-computer.com/vcforum/showthread.php?t=16035

There were postings pointing to useful CGA documents. I downloaded the Sam's Repair Guide, which includes schematics, board layouts, test procedures, etc.

Art

 

[Lorne]

If anyone has the technical workups of the monitor; i.e. the service guide, I do have a slew of service repairmen who can work on it. Thanks!

The Sam's computer facts for the 5153 mentions adjustments for "horizontal & vertical centering". If you don't have a copy, PM me with your email address, and I'll send you an email with it as an attachment.

I've taken a couple of 5151's apart in the last two months, and they're a breeze (and I'm no service tech!). You've got a few screws to remove to get the cover off to get at those adjustments, but that's about it. it should be real easy.

 

[Fallo]

I've taken a couple of 5151's apart in the last two months, and they're a breeze (and I'm no service tech!). You've got a few screws to remove to get the cover off to get at those adjustments, but that's about it. it should be real easy.

I wish I could fix the off-centered picture on the TV I'm using with my 5150, but you'd have to go into the service menu to do that, and if you mess anything up there, your TV will die a horrible death. I really would rather not risk that happening. Anyway, it's only a problem when running some booter games, as you have no MODE command to keep the picture centered.

 

[modem7]

I've taken a couple of 5151's apart in the last two months, and they're a breeze (and I'm no service tech!).

For anyone thinking of removing the cover from their 5151, note the "Do not remove the other 2 [screws] or the mains transformer will fall onto the CRT. Seriously!" that appears at http://www.classiccmp.org/pipermail/cctech/2006-April/058611.html
Whilst the heading is "5154", the 5151 is discussed in the latter part, and that's where the "Do not remove the ..." sentence appears. It may not be applicable to all 5151s because there may have been variations of the 5151 (I've never needed to dismantle 5151s and so I don't know).