[TechAssist] Re: ITT 3426 TV fault - brightness and colour
- From: "Damon" <DAMON101@xxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Thu, 29 Nov 2001 19:55:21 -0500
First, check your cathode voltages, they are about 120 to 170 volts with
signal, if lower or near 0 volts, your 200 volt supply for the cathodes
could be missing, it normally comes from the IHVT, so check the diodes and
resistors coming off the secondary of the IHVT. I doubt that one of the crt
output transistors could be shorted, as that would cause a single color to
dominate. You have excessive white, which means the 200v is missing, or one
of your cathodes is shorted to the heater--verified by reading the 200v 1st,
then disconnecting the crt from the socket and measuring 200v again--if the
200v comes back with crt disconnected and disappears when reconnected and
crt warmed up and failing.....well now it's time to isolate the heater from
ground.
Another possibility is the screen voltage may be exceeding normal voltage
from an open on the ground side of the screen control, if your screen reads
over 500v then it's time to take a look at that circuit.
Damon Brunger
damon101@xxxxxxxxxxxxxx
Telrad Electronic Services
Ft Wayne, IN 46815
----- Original Message -----
From: "babalino" <babalino@xxxxxxxxxxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, November 29, 2001 11:50 AM
Subject: [TechAssist] ITT 3426 TV fault - brightness and colour
>
> Hello, I have an ITT 3426 Chassis 110 and the problem is that there is no
> blue and also that there is flyback (white) lines that I cannot get rid
> of.(even reducing screen does not help)
> It is almost as if the beam sensing is not working as it is on full
> brightness.
> I do not have a schematic but would love any advice here.
> I have tried the hue control, checked amps on CRT board. Looked at IC
> colour decoder (this would not cause brightness like this?)
> Possibly 2 problems - need components to check as I have had a good look
> around the crt board.
> Thanks again
>
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