Philips Magnavox TR2502 Chassis 25B800 tuner issue

[Lee]

I replaced a burned up D409 and vertical IC, got it to stay on and
picture is back fine now (menu works fine, picture is perfect).
However, nothing seems to be coming out of the tuner, or at least the
RF input section. I see the channel on the screen, but it finds no
channels. No snow, no noise, nothing. Any thoughts? Thx!

 

[Jerry G.]

Did you check the voltages at the tuner module to see if there is anything
supplying it? This includes checking if the AGC bias to the tuner is also
correct.

Did you check that in the TV mode, that the source switching circuits are
infact working correctly to pass the video signal from the decoding (output
of the IF detection) through its proper path?

If the above complies, then check to see if the IF module is getting the
proper supply. If so, then you will have to feed a known signal in to the
tuner section, and use a scope to see if there is any output from the tuner.
Then follow through the IF stages. Following the schematic, and careful
evaluation of the bias voltages, and signal paths would be the key to
finding the fault. There is no simple answer for this, unless it is just a
missing DC voltage supply to the IF or tuner sections.

--

Jerry G.
==========================


I replaced a burned up D409 and vertical IC, got it to stay on and
picture is back fine now (menu works fine, picture is perfect).
However, nothing seems to be coming out of the tuner, or at least the
RF input section. I see the channel on the screen, but it finds no
channels. No snow, no noise, nothing. Any thoughts? Thx!