DIYbanter - View Single Post - Tektronix 2236 , Won't power up , makes sounds .

Jim Yanik

" wrote in news:f57df5eb-4033-
:

Hey all ,
Well the power supply schema is similar to 2215, pretty much any
22XX .

except for 2205,2210.

when i turn on the scope it makes high pitches noise in a rate of
about one sec , tsk.....tsk.....tsk....

the line filter is ok , diode bridge is good .

what could be the problem ? something shorts the PS .

The PS is a switcher,and will go into "burst" mode(current limit) if
overloaded.

it could be a shorted rectifier diode,or some bad electrolytic caps;their
ESR goes too high.
Caps and diodes are the most common PS problems.

A bad HV multiplier could also be the problem.

The PS first rectifies mains voltage to DC(127-350VDC),then PWMchops it and
charges a cap to ~43v DC,uses that to run an inverter oscillator that
generates the secondary supplies.
the pre-reg current limits at around 650ma in the 2215,in the 2236 it may
be 1A,don't know for certain.
the 2230/2232 digital scopes limit at ~1.3A.

--
Jim Yanik
jyanik
at
kua.net