Troubleshooting guide

Cinematronics Vector Monitor Repair Guide v.1.0
Page 20 of 53
HV Replacement
By David Fish
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 the failure of its Hi-Voltage supply. The supply MUST be the 'off-
board' type such as the Keltron HP160124A. This cannot 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 disappear leaving only the high intensity lines, there's a good chance your 90V
output is dying. The 90V is used in the brightness circuit that drives the picture 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, so it may not be
possible. For now, assume it's not.
The ‘goo’ inside the discrete HV is an electrically isolating potting compound. It’s injected in at
vacuum so as to eliminate any voids (air bubbles) which could cause an electrical breakdown if it
was run without the potting but I’d guess that there’d be some corona in there. As I remember it
was pretty tight as far as component spacing.
The manufacturer of these supplies, Keltron Corp. of Waltham MA, wants nothing to do with them
anymore, and I cannot blame them. The only option you have is to replace it. That is, if you can
find one.
Another option is to replace the Keltron unit 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 from the G05-801 (Assy #02-160007-01 with the PC
Assy #02-160008-01 Issue 5). The newer version of the G05 HV, 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 V2000 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.