HP 214B - SERVICE BLOCK 2 HIGH VOLTAGE SUPPLY A4

Model 214B Service
SERVICE BLOCK 2
HIGH VOLTAGE SUPPLY A4
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THEORY OF OPE RATI ON
General
Th e 2148 high volta rle supply co mp rises a r eg ulated - 155 V supply, which ;;, tU iIl is used as re fel'ence pot ent
i
,)
fo r a +22 volt su pply. A functiona l diagram of these two supplies is given in Figure 8 - 2-- 1.
,..------_ . _--- _. _._- -- - --
T601
r -- -
L
-lSSV (-260V)
- 66V(1 06V)'
- ---- -- - - 133V (- llay)
I +
n y
, -
~
.- ,
-- . • t _. ,t- ov
G NO -=;"'nH NEG OUT PUT PU LSE
lSSY flOA T ING WITH r cs OUTP UT Pul Sf
L- _________ ..... ,_ - ___ -1.~ '5';', :- 76C V!
--- _ ._ . _-- -_ .. -_ .. - -- -_ ._-- .. - .- ._ -- ---- -- -- _ ._. __ .. .. _ ---- -_. _- --
Figure 8- - 2-1. Functioll ill diagram of high voltage supply.
In Figu
re 8-2-1, the voltages indicated in brackets, i.e. - 260 V, - 238 V are gener ateclwhen 30 V - 100 V
ampl
itude is selected. When negative output pu Ise is se le ctee!, the - 155 V (- - 260 V) ilnd - 133 V (- 238 V)
are refel'enced to chassis ground. With positive output se l ec ted, this ground becomes floa t ing.
22 V Supply
Th e +22 V supply is referenced to the -- 155 V (-260 V) s upply , and is the po we r soul'C e on the outp ut ampli fier board
for
the input Schm i tt trigger, overload detec tion circuit , amplitude vernier and the FET dri ve circuits. Thi s supply
must be adjusted to 22 volt , although the absolute value of the I-e fe rence potential (-155 V (- 260 V), may liary sl ight Iy.
Adjustment is achieved via the adjustable voltage divider R604, R6 05 and R60 G, which sets th e reference voltdge fo r the
3-terminal pos
itive voltage regulator U606.
Two ot her points for mention in the +22 V regulator circuit al ': CC 52 7 usee! to bypass th e input, alld C628 wh ich imp roves
transient response.
8
-- 9
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Scans by ArtekMedia => 2009