HP 8399-xxx B/W monitor repair

• 1. About the Author
• 2. Disclaimer
• 3. Handy-dandy guide for repairing mono monitor problems
• 4. Monochrome display cable pin outs

1. About the Author

The black and white displays were built by PHILIPS in Canada. The plant there has been shut down, when I last enquired with Philips re: purchasing spare parts, I was informed that they did not want to support anymore new customers for this product line. Philips makes the new HP b/w monitors too, but it looks as if everything is manufactured in Taiwan.

You can also get a list of technical info for the color and monochrome monitors, part of the Sync-On-Green (33KB) FAQ.

2. Disclaimer

You may get if you don't read these Notes on Safety V1.00 (7KB)

3. Handy-dandy guide for repairing mono monitor problems

• Screen wrap problem or the horizontal width has grown too large and the screen appears to be wrapping back around on itself. Replace C205 and C206 on deflection board, 10 ufd/50V, electrolytic caps. (Actually only one of these is causing the problem, but I'm too lazy--change both) Cost: $0.12 per cap.

• Screen is shrinking from both sides. Change C161, 100 ufd/63V, electrolytic cap near bottom right of deflection board. Cost: $1.00.

• Characters seem to be wiggling or vibrating. Change C101, 10 ufd/50V, electrolytic cap, upper left quarter of deflection board. Cost: $0.12.

• On all white displays or on white backgrounds there appear bright horizontal streaks. Replaced C315, 100 ufd/25V, electrolytic cap, just below C101. Cost: $0.75.

• Top of display appears to losing a few lines of text sort of gradually getting darker on top few lines. Replace C318, 4.7 ufd/100V, electrolytic cap located left center on deflection board. Cost: $1.00.

• Display is too large vertically and cannot adjust in. Replace C310, 0.01 ufd/63V, P.S. cap, aluminum colored just above IC301.

• If the display is too dim and after adjusting brightness it is out-of-focus, you can try the focus adjustment, but if that doesn't really work well enough you will need to replace the CRT. This is not that difficult, takes about 45 minutes, costs: $125.00. I use the on-line diagnostic "/systest/grtest" to perform focus adjustments. Just enter ad (adjustments) at the grtest prompt and select test 13. Save all of the magnets from any scrapped monitor yokes, you'll need them to adjust display geometry with the new CRT's.

• Also save your old flyback transformers on any scrapped displays, flybacks cause several different problems: Squeals no picture and a 'jittery' display are both flyback problems. The key to flyback jitter is when the display shrinks or jerks both top, bottom and both sides simutaneously. Another flyback problem is a slow expansion and contraction of the display, some of my customers tell me that it's 'breathing'.

• As far as adjusting focus goes, the pot labeled 'DYN FOC HOR' adjusts the focus on the far right and left side of the screen. It also balances the focus between these sides, so be sure to check both left and right sides when adjusting this pot. The pot labeled 'DYN FOC VERT' just adjusts the focus for the top and bottom of the display. I usually can't get perfect focus on the very top of the display, especially at this site where the brightness has to be turned up especially high. If no matter what you do with the focus pots does not work, you might try playing with the 'focus phase' adj. Focus phase is controlled by the coil with the adjustable core in the center of the board. The way I play with it is to turn the main focus pot, R431, to midrange and do the same for the two dynamic focus pots. I then adjust focus phase for good focus in the center of the display, then go through the normal focus adjustments, i.e. turn R431 for best focus overall then adjust dynamic for sides and top and bottom.

4. Monochrome display cable pin outs

Pin 1 - ECL Video
Pin 2 - No connection
Pin 3 - Horizontal sync
Pin 4 - Vertical sync
Pin 5 - No connection
Pin 6 - ECL Video
Pin 7 - Video Shield
Pin 8 - Horizontal Sync Return
Pin 9 - Outer Shield Chassis