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Originally Posted by zenith2134
These were an extremely common set around here. The 17" did indeed have an absolutely blinding picture with sharp focus that rivals anything. However, the 19" was the more common model, and they started showing up dead on the curbs well before the DTV switchover. Instead of just jockeying-in Mexico rebuilt boards, I often kept these running by changing out the main filter, sparkgaps if applicable, plenty of soldering around the 181 and 186 edge connectors' and flybacks when you could still dig through your junkpile for a free one that matched.
The thin film flat resistor assembly on the crt neckboard always needed attention or you would have a solid runner with the intermittent bright red screen with retrace (or green...) mimicking a shorted tube.
I have at least 5 or six of this cabinet style in my climate controlled garage. Have around 25 sets on breakers which I fire up once or twice a year to keep the caps alive somewhat.
It's funny, the GE 17" AB/AC also had the nicest picture of their series' screen size. I reckon that this size was a sweetspot in terms of inline crt deflection angle and EHT regulation.
The series that succeeded these, with the 9-470, was not a favorite. It had Hitachi IC color demodulation which was rock solid, but the writing was on the wall for Zenith by the late eighties.
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I don't remember the module numbers, but there was a 19" chassis that was made after the 9-181/9-186 sets had their run. This one had a main board on the bottom, a stand-up HV board on the right, and a stand-up regulator board on the left. After this chassis, came the 9-470 sets (I think those were made from roughly '86-'92). The chassis seemed to be OK and they had a good picture, as long as the jug was good, but not as good of a picture as the older ones. I've seen a good many weak jugs in those, and jugs that would go blurry on a bright scene (turning down the picture and/or G2 control would sometimes help that condition). The newest 470 set that I've had was a hospital set from the early '90s, and it had a weak tube. Cosmetically, it looked just like the older hospital sets from the early '80s that used the 9-160 module. I also had a late '80s "custom series" 19" set with rotary tuning and a 470 module. That one also had a weak jug.
I don't think I've ever changed a flyback on a 9-186 board, but I've changed several on the 9-160 module (they would usually arc and burn up stuff). I don't think the flyback was available as a stand-alone replacement part (Zenith wanted you to change the module) and I always managed to rob one from a junk set.
I also remember what I called the "cube" 13" and 19" Zenith sets from the late '80s-early '90s. I don't remember the module number, but those always had bad caps in the vertical circuit and dried out caps in the power supply that would fry the STR53041 switching regulator. With a strong tube, those had a nice picture.
I think the best System 3 chassis was the first one with the 9-153 horizontal sweep/HV module and I don't recall running into a bad flyback on one of those, but those didn't get all of the operating voltages for the set from the flyback and that likely put less stress on the flyback.