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.

raymon wrote:
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.

Ancient_Hacker wrote:
raymon wrote:
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:

Ancient_Hacker wrote:
raymon wrote:
...

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

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
ps.com:


raymon schrieb:

Ancient_Hacker wrote:
raymon wrote:
..

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

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



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

Jim Yanik wrote:
"Andreas Tekman" wrote in
ps.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.

--

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