Quote:
Originally Posted by Jon A.
Yeah, those SG613s are easier to get than a high-value, fully-insulated focus control or a spare sync separator for my Sylvania Superset. I've been looking for the latter since shortly after I got the set well over a year ago.
So the Sonys got singled out along the way, kind of like the Pintos and Bobcats did for catching fire when rear-ended when many other cars of the era could go up just as easily. Still, I don't like that the CRTs go bad easily, don't rejuvenate well and can't be subbed with another brand. I have a Sony parts set with a CRT whose code starts with 520; not a common size.
So lots of problems with Zenith huh? I'm not really surprised. Mine was troublesome the whole time I was using it, and apparently the horizontal picture shift is common and can't be corrected. My Electrohome console produces a nicer picture, has a far nicer cabinet (a far cry from the Zenith's crap plastic, I'd rather particle board) and hasn't given me a lick of trouble since I fixed the cold joint on the left horizontal blue control and set it up.
I though bringing up a SS set on a variac was a no-no.
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As to the focus control most were 10-20 Meg in value. We used a Zenith control in most sets - 63-6444. It allowed for modest adjustment and easier replacement. As to the sync separator, do you have a WTB ad in the VK classifieds? Is it a chip or transistor? Sync Separator is pretty generic..
520 jugs re 20" tubes - some 19V tubes are actully 20". KV20SXX sets used them - most had the bar tuning on them - we saw a few - most were simple fixes.
As to variacing a SS set, you bring the AC up to 90V with the Variac, and most sets will come on at this voltage - albeit with reduced sweep. With the lower B+, shutdown circuits aren't tripping yet, so you can see if the set will operate once the shutdown problem(s) are fixed. Standard procedure with Transistor output sets. Shutdown problems could be regulator feedback loops, HV too high, HOT collector current too high (most used a 1 ohm resistor to measure - it gives 1:1 V:A ratio), as well as other shutdown problems such as no horiz drive, no CRT screen voltage (shutdown to prevent arcing), high B+ and other B+ issues (Hitachis shutdown if there is too much ripple in the B+).
If the set runs at 90V, we'd clip a 100W bulb in series with the B+ at the HOT - this solved the problem of blowing the HOT if you had a bad safety cap, poor Horizontal drive/wrong waveform, a short in one of the scan derived supplies (secondary of the flyback), a short in the flyback (it'd get warm quickly, but not eat the HOT - see Sylvania "white flyback" issues...).
There's a good monograph from NAP on power supplies - I have part II, the switching supplies section. There was also a 19 minute video that accompanied the monograph for training - I used to have it too. I got it from ISCET - apparently NAP had them left over from service seminars, and gave them to ISCET, who gave them to us members. It's a great information source, and the linear monograph shows how to do the variac thing for most sets.
Zenith TVs were problematic because they were sold in volumes here by two home centers and dealers, not to mention the Navy Exchange. All the barracks were full of them. My brother once bought 5 pallets of System 3 sets at a DRMO auction and restored half of them, and Dad got the rest for parts...Being in a Navy town, we saw it all, although I've never seen either a Coronado or Electrohome set....but everything else. like ELKO sets from Europe, all-in-one boomboxes from Sharp and Wards, and even a older mirror lid set from the 40s. Dad used to get Motorola VT-71's and restore them and sell them, and he even brought several Predictas back to life. NAP, believe it or not, had replacement parts for Predictas up until 1990 or so. We got replacement multi-section caps for Predictas from NAP - it was a modern replacement that upped the value on two sections of the cap...Mallory had dropped their replacement by then.