Newsgroups: rec.games.video.arcade.collecting Subject: TECH:CINEMATRONICS - Repair of V'beams w/dead Hi-V P.S. (long) Date: 18 Sep 1995 13:32:29 -0600 Organization: University of Denver, Dept. of Math & Comp. Sci. Lines: 85 Message-ID: <43khgd$9ed@nyx10.cs.du.edu> NNTP-Posting-Host: nyx10.cs.du.edu Hi Folks, This should be of interest to anyone who has a Cinematronics B/W X-Y monitor (Vectorbeam) that has either died or is dying due to it's Hi-Voltage supply. The supply MUST be the 'off-board' type such as the Keltron HP160124A, this can't be done (at least not easily) with the Hi-V supply that is part of the big monitor pc board. I've also seen another supply used that does not look like the Keltron, but it's hook-ups were the same, so all this applies to it also. The supply has three outputs: 16kV, 400VDC (FOCUS) and 90VDC (CATHODE). On several supplies that I have the 90V output will fail and drop down to about 45V. If all the normal intensity lines on your screen dissappear leaving only the high intensity lines, there's a good chance your 90V output is dying. The 90V is used in the brightness circuit which drives the Pix tube's cathode, controlling the amount of beam current, hence, picture intensity. The failure, at least in my supplies, is due to a component within the voltage quadrupler circuit; the potted and plastic encased section of the Keltron. I haven't tried to repair one yet, it may not be possible. For now, assume it's not. The manufacturer of these supplies, Keltron Corp. of Waltham MA, wants nothing to do with them anymore, can't blame them. The only option is to replace it. That is, if you can find one. Another option is to replace it with a similar power supply. Not that many to choose from. What I've found is that the Electrohome G05's Hi-Voltage supply can be used as a replacement. This MUST be the older version Assy #02-160007-01 with the PC Assy #02-160008-01 Issue 5. The newer version, Assy #05-160006-01, with the PC Assy #02-160016-01 (02-160027-01 ?) will not work. The former is rated for up to 16KV where the latter is rated for 12kV (different design). The Wells-Gardner version of this supply [38A5583-000 using PCB300] is rated for 14.5KV. I've got one ready to go but I haven't tried it yet. Connecting the Electrohome supply to the Vectorbeam it trivial. The drawback is that new mounting holes will need to be drilled in the monitor's metal side panel. The new cable needed is simple enough to show below. The only caution here is that the wire for the 400V connection MUST have an insulation rated for 600 Volts or greater. Cinematronics Electrohome deflection bd Power Supply PCB connector Connector P900 +90V 1 <-------------------------<5 2 > +400V 3 >-------------------------<1 +25V 4 >-------------------------<8 GND 5 >-------------------------<7 6 > Chassis --------------------