Modify an old VCR TV modulator to channel 5

[sunchasers]

I have a 2 year old ILO TV from Walmart that's a piece of junk. The motherboard failed and will accept only channel 2 input (no replacement parts available). I'm pretty good with a soldering iron, but weak on electronic knowledge. How difficult is it to modify a VCR to output on channel 2, instead of 3 or 4?

[wa2ise]

Originally Posted by sunchasers

I'm pretty good with a soldering iron, but weak on electronic knowledge. How difficult is it to modify a VCR to output on channel 2, instead of 3 or 4?

You'd be looking inside the VCR tuner/modulator module for something that looks like the below 4 legged creature. Many just have 4 pins without skipping a position. Usually! you want to identify the ground pin (usually 2nd from one end) and once you remove this thing from the board, install the new 2 lead crystal so one lead is on one side of the old ground pin, and the other lead the hole on the other side of the ground. If I call the ground pin 2, that means I want the crystal to connect to pins 1 and 3. Once that's done, then you may need to change the channel 3 or 4 switch position. Use a 18.432MHz crystal, which should put you on channel 2.

Some newer VCRs used a common crystal for the tuner and the modulator, those can be identified by the presense of only one crystal (usually 4MHz) and no 4 legged creature. Unfortunately, you'd be SOL if that's what you find.

[sunchasers]

The VCR tuner didn't have individual SAW resonators for channel 3 and 4. I did see an RF modulator on eBay that I can modify, but I can't find a four-pin 55.25 MHz resonator to substitute for the channel 3&4.

[wa2ise]

Originally Posted by sunchasers

The VCR tuner didn't have individual SAW resonators for channel 3 and 4. I did see an RF modulator on eBay that I can modify, but I can't find a four-pin 55.25 MHz resonator to substitute for the channel 3&4.

Use a 18.432MHz 2 legged crystal. It will operate on its 3rd harmonic, approx 55.25MHz. Of course you need to figure out which of the 4 connections to connect the 2 wire crystal to. Usually, these SAW resonators have a ground lead connecting to its case. Usually tne 2nd lead from one end. Connect the crystal to holes 1 and 3 after removing the resonator.

[Old1625]

You are pretty darned clever! And a dang sight more motivated than I am at this point to engage in such stuff. Good on ya!