Montgomery Ward (Sylvania chassis, OEM NAP) Tuner Trouble

[liammc00]

First off I'm pretty ignorant when comes tuners especially the ones in TVs as I have not had to mess with them much. The last thing I need to fix is tuner on this set. Please look at videos provided in link. Video 1 is what happened when I first got the set. Since than I have repaired a bunch of cold solder joints and capacitors that had gone bad. Yes I did open the tuner it's self and there was one bad capacitor and made sure not to touch any of the coils. On video 2 which is test after service(sorry in advance for poor camera work). If anyone has any ideas wear I should I be looking at IF on main board or is it problem in the tuner module itself. I will continue to look around and with Sam's im going to check the voltage on the pins on IC601.

https://drive.google.com/drive/folde...cv5ecr0ODXEvBy (also a copy of service manual and chassis is 26C616)

https://archive.org/details/36112731...93729186_n.jpg

[old_tv_nut]

If you're getting snow like that, it seems the tuner and IF amplifier are working.
Guesses: May be a problem with AGC or sync (which could be on the same module as the IF), or a connection between modules, or a ground connection.

[liammc00]

Originally Posted by old_tv_nut

If you're getting snow like that, it seems the tuner and IF amplifier are working.
Guesses: May be a problem with AGC or sync (which could be on the same module as the IF), or a connection between modules, or a ground connection.

IC601(NTE1413) in the IC functions in the Sam's it says that IC601 does these things sync demod, IF amplifier, AGC DET/Noise INV, White Spot Inverter, video preamp, AFT sync demod, and REF amplifier. I did test the voltage on the pins that the Sam's (2660 folder 2) in troubleshooting the IF/AGC with a signal attached from a VCR out putting a blue screen as my signal. I did mark the adjustment pot for the RF AGC and no matter were I moved it. The results were barley noticeable after that I put the pot back at the factory spot.

Results:
Pin 3 .7v the Sam's says .6 volts
Pin 4 11v the Sam's says 4.7volts ( 4.5 -11volts ) RF AGC range
Pin 14 12v the Sam's says 7volts ( 6.7- 11volts ) IF AGC range
Some other pins were reading not what the schematics said they should.
I will go and check the connection between the modules. Also I will check the grounds as this TV has had bunch of cold solder joints I had to fix.

[old_tv_nut]

Pins 4 and 14 are far out of spec. Have you checked all the power supply voltages?

[liammc00]

Originally Posted by old_tv_nut

Pins 4 and 14 are far out of spec. Have you checked all the power supply voltages?

On the schmatics pin 4( 4.5 -11volts ) RF AGC range and
Pin 14 ( 6.7- 11volts ) IF AGC range. So it is in range and its like it's trying to drive the gain as hard as it can like a weak signal.