Does anybody have schematic of PSU/CRT section of Main Board. I downloaded full service manual from BAMA site only to find this schematic missing. Should be labelled No 9. I have problem with scope recently purchased, low psu voltages resulting in short horizontal trace.
This is often a sign the filter caps are going bad. If there are four chapstick-sized silver upright electrolytics near the inside corner of the PS, they're probably the culprits.
Thanks but have replaced these capacitors and PSU voltages still low out of spec. Checked current limit resistor on pre-reg board and find current is at limit value (>1A) suggests one of the supplies is loading psu but cannot find which one
raymon schrieb:
The power supply of the 2213/2215 is a combination odf teh prereg , follwed by a swithcmode. The switchmode part runs from 42 VDC -- so you can check the switchmode by external powering it from a Dc supply (I recommend a lob type, 0-50V, 0-3A, CV/CC mode adjustable for repair).
If the switchmode works well with the lab supply, go for the prereg: the flywheel diode, a fas 400V/1A type near the prereg inductor caused me a lot of headaches while looking for a fault similar to the one you describe.
hth, Andreas
"Andreas Tekman" wrote in news: snipped-for-privacy@e3g2000cwe.googlegroups.com:
I've been trading some email with him on this,and it appears his HV multiplier may be the problem. Hopefully,not the CRT itself.
-- Jim Yanik jyanik at kua.net
H ijim,
I had this once in a 2215, a dead HV multiplier. The smps part tried to start up, but due to overloead it ended in continous "tweeeeeeet" sound. E.g. swichting frequency turned too low, ended in audible range.
Desoldering the multiplier and everything worked well (except HV, of course). The multiplier I later rebuild by discrete , 5 HV-diodes and 5
3.3 nf /3kv caps were handy, so this works well for years. It a x4 multiplier, and one (5th diode/cap) for the -2kV.The original, molded HV-multiplier might be hard to get. So, the above DIY solution is may be helpful.
hth, andreas
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