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per
April 3rd, 2010, 06:37 AM
I decided to split up the other thread I had because it contains quite a lot of unrelevant information in terms of what I'm asking about here.

I tried the new 5151 monitor today, First at 120v, then at 220v.

At 120v, I did in fact get a picture, but the entire picture was stretched and compressed horizontally in a waving pattern (slowly, not fast). The amplitude of this wave was at some points as much as 3cm! In less than 1 minute after starting, I turned it off.

Then I decided to go for 220v. This time I got a much more stable picture, but it still got the waves. However, the amplitude was now reduced to about 3mm. In addition to the slow waves, the entire picture also seems to sligthly shake vertically after having the monitor on for some time.

I guess the powersupply may have something to do with it, but I'm a little unsure. That's why I'm asking you if you have any idea what the actual cause may be and how to fix it?

Chuck(G)
April 3rd, 2010, 08:27 AM
The obvious test would be to power the monitor up and put a scope on the power supply output and look for ripple. Absent a scope, the easiest solution would be to replace all of the large electrolytic filter capacitors in the power supply. The 5151 isn't rocket science--it's a very simple piece of equipment with a linear power supply.

cosam
April 3rd, 2010, 08:33 AM
This sounds a lot like the symptoms I've seen caused by a faulty voltage regulator in the power supply. Mine also got progressively worse the longer the machine was on (and the warmer that poor regulator got). A scope on the power rails would be a good start. An even better start would be determining if this is a 110-120V or 220-240V monitor before plugging it in again ;-)

per
April 3rd, 2010, 08:43 AM
The obvious test would be to power the monitor up and put a scope on the power supply output and look for ripple. Absent a scope, the easiest solution would be to replace all of the large electrolytic filter capacitors in the power supply. The 5151 isn't rocket science--it's a very simple piece of equipment with a linear power supply.

Well, I do got a scope, but not right here and now. In addition, I don't know 100% which of the wires are what, and I don't have those special thick rubber-gloves electricians usually uses :shocking: .


This sounds a lot like the symptoms I've seen caused by a faulty voltage regulator in the power supply. Mine also got progressively worse the longer the machine was on (and the warmer that poor regulator got). A scope on the power rails would be a good start. An even better start would be determining if this is a 110-120V or 220-240V monitor before plugging it in again ;-)

I think I have concluded that it is 220v. At 120v, it had severial sympthoms of faulty power.

Chuck(G)
April 3rd, 2010, 09:13 AM
Well, I do got a scope, but not right here and now. In addition, I don't know 100% which of the wires are what, and I don't have those special thick rubber-gloves electricians usually uses :shocking: .

There's a nice schematic of the 5151 in the IBM Techref. Parts are well-labeled within the monitor and there are very few places inside where you can receive a serious electrical shock, even if you tried. When in doubt, put one hand in a rear pants pcket and don't work bare-footed.

per
April 3rd, 2010, 10:22 AM
There's a nice schematic of the 5151 in the IBM Techref. Parts are well-labeled within the monitor and there are very few places inside where you can receive a serious electrical shock, even if you tried. When in doubt, put one hand in a rear pants pcket and don't work bare-footed.

Ok, but first I have to transport my scope to where I keep the monitor, and I won't be able to do that before next weekend.

I do got a scan of the techref, but it's not a good scan. However, I do got a scan of Sam's computerfacts on the IBM 5151 of signifficantly more bits per inch.

billdeg
April 3rd, 2010, 12:55 PM
this may have been mentioned already, but did you try another controller?

per
April 3rd, 2010, 01:11 PM
this may have been mentioned already, but did you try another controller?

I have not tried another card, but I've tried another monitor with the same card. By using my regular 5151, its all right; no signs of any kind of stretching or compressing at all there. Therefore, it must be the new monitor.