PhilipA
Experienced Member
All,
With my Portable getting some good use, it's coming to the point where the screen drive board is beginning to act up. The image wavers around on the screen, most noticeably in 320x200 graphics mode. I've read elsewhere from the vintage TV guys that this is particularly common to bad power smoothing capacitors, of which there are several on the board.
20130826_211821 by renault9gta, on Flickr
The innards of the VDU show an interesting thing. Running diagonally across the yoke in that image is a second high voltage wire, with a tubular section under heat-shrink rubber.
The HT wiring is connected from the flyback, to the anode, then out through that wire to the chassis ground.
Is that a HT bleeder resistor? I don't want to start poking around in there without first making sure everything's discharged- but that should discharge the tube overnight if it's still in working order?
--Phil
With my Portable getting some good use, it's coming to the point where the screen drive board is beginning to act up. The image wavers around on the screen, most noticeably in 320x200 graphics mode. I've read elsewhere from the vintage TV guys that this is particularly common to bad power smoothing capacitors, of which there are several on the board.
20130826_211821 by renault9gta, on Flickr
The innards of the VDU show an interesting thing. Running diagonally across the yoke in that image is a second high voltage wire, with a tubular section under heat-shrink rubber.
The HT wiring is connected from the flyback, to the anode, then out through that wire to the chassis ground.
Is that a HT bleeder resistor? I don't want to start poking around in there without first making sure everything's discharged- but that should discharge the tube overnight if it's still in working order?
--Phil