ZX Ferrum #03 27 февраля 2005

Железо

Iron - Repair monitor color images, "Electronics 32 WTC 202.

 Repair monitor color images, "Electronics 32 WTC 202"

                                                 Terentyev D.



  This article was not to be in this room, but still fresh
vpechatleniya need to write everything down, maybe samomu 
useful. Case all that long ago (see "From the Editor") y menya 
slomalsya monitor. Week I was sitting at a black-and-white 
television set, waiting for the ordered detaley. And as the 
"Electronics 32 WTC 202" is very popular among spektrumistov, 
then repair experience will be helpful to many. All links will 
be placed on the concept of a monitor, if someone this scheme 
will not be upset not worth it, because I will figure the 
location of cards and motherboards by themselves are symbols of 
each element (a pleasant legacy of Soviet times). 



  Now, first things first:

1. The first problem which attracted my attention on my monitor 
(and every day it attracted more and more), it periodically to 
the unauthorized trip, after the cotton on the lid is switched 
on. This fact suggests that the reason mechanical, especially 
since after the building was demolished, worked fine. This 
whole mess with the assembly, disassembly Monitor lasted quite 
a long time until it was catch the "spark" a fault in 
disassembled form. 

  The first suspicion fell on "fee filter feeding, but then
found (with volmetrom in your hands) that the power of "fee
Filter goes into "power supply", there is lost.

  With careful examination board "power supply" (and not with 
the first times) revealed that in one location path from the 
output # 1 transformer TW1 (he's single, visible at once) to

collector of transistor VT4 (KT838A) is broken (if the "cow
tongue lapped up, "ie, the metal simply dissipates and does not 
burn). At this point, the track width was 0.8-0.6 mm instead of 
3-4 mm. The cause of burnout (or evaporation?) Was the 
high-voltage tension.


  Eliminated propaykoy the path a piece of copper wire. 
Soldering should be very careful not zalipov ("snot"), the tin 
should not be extend beyond the track, do not use soldering 
acid. When not subject to these measures, risking to see 
beautiful fireworks (I 've seen! Flew three transistors and a 
thyristor, respectively, VT1, VT2-KT209I, VT4-KT838A, 
VS1-KU112A). 

  And the last point on this issue. On the derivation of # 2 
size sockets XS1 measure the voltage, which should be 99-101 
volts, if it does not fall within this range, it must be 
adjusted variable resistor R2 (between transvormatorom and 
radiator transistor VT4).



                          WARNING!

  Before working with the power supply to discharge the 
capacitors C16 and C19 (the biggest on the board), or may cause 
electric shock 300 volts. 


2. Along with repairing the power supply it was decided to 
return the monitor, old paint (over time the color became 
faint, especially red). Through trial and error, as well as 
analysis of the scheme (the old overwritten and a copy of, some 
things are no longer visible, and some were not visible) was 
found: 

   -Brightness can be set up resistor R25 on the board "unit 
developments." Must configure on a white background that there 
were no drawdowns colors. Then adjust the focus resistor R21 
(to the most a clear image).


   -Sharpness and saturation of individual colors set up a 
variable resistor on the board "video channel module" R28, R29, 
R30, respectively green, blue and red, when bred to a maximum 
of resistors adjust the color on the back of the monitor. 

   In the absence of the desired result can also try
shorted resistors R58, R59, R60, respectively, green, blue
and red.

   And the final touch on the same board resistor R17 adjusts
contrast.


                          WARNING!

  Settings under two should produce a well-lit
room (that would be a sunny day you could make out the image) 
and handles all external image control (brightness, contrast, 
color settings on the rear panel) derived the maximum. 


3. Skeletal wiring diagram of the monitor (a rear view that has 
been deployed). 



           block block

        video channel scans



                                                May 6


           1

                               3


                                              7



              2 4 8 9



                  > <



  Notation on the chart:

  1 - video channel module;

  2 - motherboard filter feeding;

  3 - Board of kinescope;

  4 - power supply unit;

  5 - voltage multiplier;

  6 - FA;

  7 - processing module;

  8 - generator module line scan;

  9 - Vertical generator module.