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ldkraemer
April 16th, 2014, 02:12 PM
My Kaypro II had a Horizontal Line across the Display after my recent move. I thought it could be a
bad Capacitor, so I removed the Toshiba Video Board, and dug out my Electronic Design Specialist
CapAnalyzer 88A. (Nice piece of Incircuit Test equipment.)

After checking every Electrolitic Capacitor twice, there weren't any that had a questionalble ESR. None
had buldges, showing signs of leaking, or were partially raised off the circuit board.

I did notice that the Pins on the Toshiba Video Board that connect the cable to the CRT Neck, had a blueish
tint on them. I located my crocus cloth, and easily removed the blueish coating on those five pins.
All the Solder joints looked fine, so I re-inserted the Video Board in the Kaypro II.

On Power up, I had the standard PRO8 MONITOR ROM Message displayed on the Screen.

Now, I just have to dig through the multitude of boxes, looking for my Kaypro II Floppy's.

Maybe, this information will help some other Kaypro II user with a similar Horizontal Line.

Larry

MikeS
April 16th, 2014, 02:29 PM
What's the bottom line? Something was wrong with the video board and replacing it fixed the problem?

Stone
April 16th, 2014, 02:32 PM
If it's a single horizontal line across the middle of the screen it's not Kaypro related, or computer related ... it's the same problem that can affect all CRTs. The vertical deflection circuit has failed.

ldkraemer
April 17th, 2014, 12:22 AM
MikeS:
BOTTOM LINE:
I did notice that the Pins on the Toshiba Video Board had a blueish tint on them.
I removed the blueish coating on those five pins. Nothing was replaced.

Stone,
That was my Diagnosis too! The vertical deflection circuit had failed, or a bad Capacitor.

It turned out to be the same symptom, but not exactly the typical cause of a Horizontal Line Centered on the Screen.

Larry

KC9UDX
April 17th, 2014, 06:45 AM
I would be concerned about the bluish tint. That's usually a sign of significant heat. But if not heat, then something chemical maybe? Either way it's not normal.

ldkraemer
April 17th, 2014, 07:24 AM
KC9UDX,
Yes, I agree it's not normal. But, I've got a 2003 Silverado with Daytime Running Lamps (DRL's) that also had
a bluish tint on the DRL Bulb wires, and I had intermittent problems with those too. I ended up taking my pocket
knife and easily scratching the bluish tint off the used, and NEW bulbs and they have worked since.
So, New DRL Bulbs from O'Reily Auto parts with a blusih tint on the wires isn't normal either, but you get it
in the package for $8.xx+. That's what led me to clean the Video connector pins.

Larry

MikeS
April 17th, 2014, 07:44 AM
MikeS:
BOTTOM LINE:
I did notice that the Pins on the Toshiba Video Board had a blueish tint on them.
I removed the blueish coating on those five pins. Nothing was replaced.
...I located my crocus cloth, and easily removed the blueish coating on those five pins.
All the Solder joints looked fine, so I replaced the Video Board in the Kaypro II.The way I read that is that neither cleaning the pins nor checking for bad solder joints fixed the problem so you ended up replacing the video board.

I take it that you meant that cleaning the pins did fix the problem (not surprising) and that you then put everything back together (also not surprising).

Dwight Elvey
April 17th, 2014, 08:19 PM
No signal to the vertical deflection coil.
( Horizontal line ).
Dwight

gimgim
May 26th, 2014, 09:57 AM
The heat-caused bluish coating should behave like a diode.
A blued Gillette razor blade is typically used in foxhole radios:
http://tymkrs.tumblr.com/post/5734376441/foxhole-radio-questions-ii-bluing-steel