RCA 170PO63 Portable (KCS126 chassis)

[RetroHacker]

I was given this black and white portable by someone that had heard I liked old TVs, and was about to throw it away. It's in so-so condition, a ding in the upper corner, and missing a knob (and are these even all the right knobs?), but not too terrible. Seems to be a fairly high quality set when new, a power transformer design as opposed to the cheaper series string models.

This was given to me as non-working, but, it's over 50 years old, I wouldn't expect it to work. Initial inspection shows that the internals are fairly intact, but quickly located a major red flag. The flyback insulation appears to have some small cracks in it, and evidence of dripping wax. The high voltage rectifier tube is also up to air - no doubt the whole thing ran really, really hot. The 17DKP4 CRT is a little weak - just to the bottom edge of the "Good" on the tester, but I've seen worse produce a usable picture. Might just need to cook a little longer, it showed as almost dead for the first minute, but after running for a bit, started to wake up.

I haven't done anything with it yet, I'd like to fix it, but that flyback is a big question for me. I've seen flybacks in similar condition function, but it bothers me that it got hot enough to crack the 1X2B.

Now, I do have a Heathkit IT-5235 yoke/flyback tester that I picked up at a hamfest recently, but I honestly don't know how to use it. I found the schematic easily online, but not the user's manual. I also don't yet have the schematic for the TV.

-Ian

[Phil Nelson]

Coincidence -- Last week I saw one exactly like that in a building full of mostly-radio stuff belonging to a long-time collector. The red color really caught my eye, but I'm trying to avoid hoarder's syndrome, so it stayed there.

Phil Nelson

[Electronic M]

Cause and effect could be the opposite of what you think. The 1X2 may have cracked and leaked from a manufacturing defect (I've seen it before in a variety of tubes), and the owners may have let it run a few minutes that way (stressing the fly) to catch the last few minutes of the new episode of Gilligan's Island in sound only....

I would not sweat the fly if if ohms out correctly. If it is not open it is probably fine since if it were shorted it would probably look like it had been on fire.

[Eric H]

That flyback actually looks great for a set from this era, many of them had a black coating that fell off in chunks (Predictas).

I have one of these sets and it's a terrific performer, very well built as you noted.

The knobs look like a mixture, some correct, some not, but the good thing is there are plenty of others that will fit and look good also, I used some from a later 60's color set.

The 1X2 may have gotten gassy, when that happens they glow purple and start getting really hot.

[Radiotronman]

I have a portable set with handles on the side instead of on top. I think these were called "sportables" by RCA. They're excellent performers and made very well. Those are the correct knobs on your set. You can see mine below.

[El Predicta]

That's an excellent set. I have 3 of them, red, brown, and black. Also, spare parts if you need anything. I rented the brown one to the movie makers of PARKLAND.

[RetroHacker]

Did a little more poking around, and have a little more confidence that the fly might be OK, I checked a couple windings and it's not open. CRT is a toss up, it's pretty weak, even after allowing it to cook for a while, but I haven't tried rejuvinating it yet - I'll see what kind of picture I can get out of it before I resort to that. I know I have spare rectifier tubes, just need to find which box I put them in...

Anyone have the schematics for this?

-Ian

[old_coot88]

I'll bet on the fly being good. A little drippage doesn't generally mean anything unless it's accompanied by a distinct scorched smell (from the old servicing adage "the nose knows")

[dieseljeep]

Originally Posted by RetroHacker

Did a little more poking around, and have a little more confidence that the fly might be OK, I checked a couple windings and it's not open. CRT is a toss up, it's pretty weak, even after allowing it to cook for a while, but I haven't tried rejuvinating it yet - I'll see what kind of picture I can get out of it before I resort to that. I know I have spare rectifier tubes, just need to find which box I put them in...

Anyone have the schematics for this?

-Ian

I never worry, when I see a cracked tube, I just try another one.
The CRT might come back. It was probably dormant for 40 years.
I like that chassis a little better, as it uses a 5U4 instead of a voltage doubler, like the next years models. I always admired the horizontal hold control design. One of the early multi-turn types.
The set you have, has the metal back. The next years models had a back that was made of some funky, crumbly plastic that didn't stand the test of time.

[DavGoodlin]

Originally Posted by RetroHacker

Now, I do have a Heathkit IT-5235 yoke/flyback tester that I picked up at a hamfest recently, but I honestly don't know how to use it. I found the schematic easily online, but not the user's manual. I also don't yet have the schematic for the TV.

-Ian

I built a IT-5235 in late '79. I found it more useful for taking accurate High Voltage measurements with the probe accessory.
It did rat out a few bad flybacks, mostly red-plating 6JE6 tubes in RCA color sets with proper grid drive (Go Figure) which I confirmed with replacements.
It has a ring generator with settings A-F and you try each to get the meter to reach the green zone. Connect hor output cap to one lead and hv rect cap to the other lead.

[rca2000]

I would NOT turn down that set either...as you noted it has a nicely designed cold chassis...and is well built.

Your fly is likely ok...nearly ALL of them drip some wax--and/or have cracks in the "tire" by now..and still work fine.

[Eric H]

I'd bet a Donut that set would work, or at least show something on screen with a new 1X2.

Mine worked as found and it was a lot more abused.

[RetroHacker]

Well, Eric, you owe me a donut. Or, perhaps, maybe a donut hole... I went over the set, and didn't see any other major faults, so I went ahead and plugged in another 1X2 and fired it up. Tubes all light up, and I soon get a roaring noise from the speaker that's odd - not your usual 60 cycle bad filter cap hum - this is more like motor boat sort of noise - and it's affected by the vertical hold control. Turning that changes the pitch of the noise (makes the boat go faster or slower...). The noise is unaffected by the volume control, but if I turn up the volume, I can hear normal static in the background of the overpowering motor boat noise.

The horizontal oscillator appears to be running, I can hear the horizontal, and the horizontal hold control changes the pitch of the squeal. Brightness and contrast controls at maximum, I can't get any light on the screen. I *thought* I saw a single flash, but I was not able to reproduce it. Even shutting down the set doesn't produce the usual flash on the tube. I don't believe I'm getting high voltage, I can't feel it on the screen (although there is that plastic cover over the CRT), and after the set it shut down, there isn't even the slightest zap when discharging the CRT. I didn't hear any high voltage crackle either. I'll have to dig out my HV probe and actually measure it, but, I'm pretty sure there isn't anything there.

But, it's kinda almost working. It wants to go. It's going to need, at very least, some new electrolytics, as I'm fairly sure that's the cause of my motor boat noise. Need to find the schematics too. It's in Sams 457-1. I checked with a local source here, and he doesn't have that folder.

-Ian

[Eric H]

I may have the Sams, it won't be scanned if I do but I can do that easily enough.