Adding Composite Input (Capacitor Question)

[ARC Tech-109]

Friday the 5th and the tuner is once again alive with a new RF amp and osc/mixer. My theory is they were somehow damaged internally when the IF connector brushed against the 120VAC terminal of the fuse holder and the replacement confirms this. Everything is now on the mark up to the video amp and now I have to sort out the chroma problems.

To back up some 40 years the set took on some lightning damage when a tree was hit and this killed both the phase detect and killer diodes, I replaced them with modern silicon small signal diodes but it was never quite the same and this was the real reason the set was replaced with a Zenith S-III and I ended up with the albatross in my bedroom. Now I want to get the set running like it used to and this has been quite the uphill battle. I found a set of what I thought were good NOS 1N270's and 1N34A's but they're all leaky passing tens of mv in reverse with no two quite the same. Plan for the time being is to "soft wire" in a 6JU8 and see how that goes, not the most elegant but they worked before in this service.

I will post my findings here so as it's been said in the past, Stay Tuned.

[kf4rca]

Try 1N914 or 1N4148 diodes. They're good to about 100 MHz. and are cheap. Radio Shack used to sell them for $1.99 for a hundred diodes.