CTC175L chassis. Unit acts dead. Unit has standby voltages. But has continous
activity on the data and clock lines of the EPROM U3102(5 & 6) Tech
wants to use the Chipper Checker to try to reload the initial software
from the vendor.
||Instructed the tech
to use the Chipper Checker and verified the software is upgraded with the
latest software that wil support the CTC175 chassis. This would be Chipper
Check II at least version 1.0. Tech will need to Resolder the tuner grounds,
and initialize the EPROM using the 8 pin clothes pin clip adapter that
I made for the Chipper Checker interface box. This proceedure corrected
the fault. Fixed unit without using any parts.
||F27252FE1 CTC177 chassis
with broken F-59 connector on rear of chassis for tuner. Needs to replace
connector part number
||Part number 215543
||25GT520 CTC177 Buzz in audio for channel
7 only. Does not show up in mono or SAP mode. Only Stereo. Symptom also
shows up with a MTS stereoonly. A VCR is connected to the Aux inputs of
television. The VCR is a stereo type but not MTS stereo only HIFI.
||Based on the fact the symptom is only
noticeable channel 7 stereo on the TV and VCR It puts the problem within
the CAT , mainly the channel 7 L-R signal. Problem was in CATV system.
||CTC177 Unit will blank on and off, After
resoldering the tuner section the set no longer turn on.
||Asked tech to check the data at pins
5 and 6 of the EPROM. It is very possible That in the process of resoldering
the tuner, a solder splash could have contacted the data or clock line
and prevent the unit from turning on. Tech did find a solder splash on
the Data line touching next to the newly soldered shield.
||G27303 CTC177AM Collector
of Horizontal out measure shorted to ground.
||After Removing all
active components in the Horizontal output circuit the short was still
present. Had tech float pins 1,2,& 3 on primary of the transfomer and
measure from these pins to cold ground. Tech found that the resistance
to ground from these pins top the secondary of the transformer was less
the an ohm. Tech needs flyback. T4401
||CTC177. Unit shuts off as soon as the
TV is turned on with the front panel controls or with the remote.
||Putting the unit on a variac it would
not stay running if line voltage was lowered to 90 volts. In fact when
voltage was dropped to below 90 volts the TV blows the line fuse. Replaced
the regulator (U4101) fixed trouble.
||G27343BK . Unit has a bright screen with
||I had tech check the cathode of the CRT
and relay the voltage. It was only 100 volts. This is too low. It should
have a dynamic range from dark to bright screen 190=black to 150=bright.
This voltage is measured at the collector of each video drivers on the
CRT socket. Unit had defective C4703 47 mfd @ 250 vdc.
||G27302 CTC177 Unit has no stand by power
||I had tech check for raw B+ at U4101(7)
which was 166 vdc. But the soft start input U4101(4) was almost 25 volts.
This pin is typically not this high. No excessive loads on secondary of
power supply. Unit has defective U4101.
||F27253. Unit does not receive any reception.
All snow on all VHF channels. UHF works fine
||Band 1 covers channels 2 through 17(CATV),
band 2 covers 18 through 50(CATV) , and band 3 covers 51 through 125(CATV)
or 14 through 69 (UHF). Further checking of Quad op amp U7501(7, 8,&14),
while in band 3 the voltage would rise when the next higher channel is
selected. However in band 1 and 2 (2 ~ 13) the voltage was always 33 vdc
no matter what channel was selected. All other band switching was occurring
normally. This indicated the local oscillator (VHF) for band 1 and 2 is
not running. It is recommended to replace the U7301 the UHF/VHF mixer oscillator.U7301