Toshiba "Family Vision" 10PK Japanese 10" portable restoration

[cj_reha]

I think I have a problem, folks...I can't stop buying adorable little tube-type Japanese TVs!



Seriously though, I've been looking for one of these metal-cabinet 10" Toshibas for a handful of years now, but for one reason or another kept missing out until now. There are a handful of different models I've seen (10PG, 10PK, etc.), some with "Family Vision" branding, some plain, and a whole slew of cabinet colors, but they all seem to use a very similar - if not identical - chassis. My service data book only has a schematic for a 10PG, but so far it's matched this set in most circuits I've studied. So let's dig in!



This particular example is complete, but grimy as hell, and clearly has a billion hours on it. The horizontal output tube, although an original Toshiba part, has almost no getter left!



Perhaps unsurprisingly, the 250CB4 CRT tested pretty poorly at first. It came back into the green after a restore cycle on my Sencore CR70, but I don't really put a lot of faith in rejuvenation as a concept...we'll have to resurrect the set and watch it for a while to see if that lasts. Maybe it'll produce a good picture, who knows?



This is a series-string set with a solid state B+ rectifier. Before powering it up, I wanted to get the chassis out of the cabinet to reform the electrolytics. This set uses quite a few in the power supply - a 200uF cap in the doubler, and four (!) 100uF caps in the pi filter for the +220/210V supplies. I've had pretty good luck with 1960s Japanese can electrolytics, and it's easy to reform them in this particular power supply configuration, so I always try to save them if I can. But before I was able to do that, a mystery polystyrene capacitor fell out of the case into my hand while taking it apart



After about an hour of looking, I determined it to be C179 - a small 100pF cap on the plate supply to the 6BN8 sound detector/preamp. Phew! Easy enough to replace; I found a 500V silver mica in the stash that will work fine. I hope this is the only part gone AWOL



The mechanical engineering of the set is excellent. All connections to the CRT have removable plugs, so it is very easily removed without bothering the yoke, a requirement on a lot of contemporary American sets. There is a B+ interlock on the yoke socket, but that's easily bypassed for reforming purposes.

[cj_reha]

On a whim, before starting the reforming process, I decided to check the four (!) fuses on the back panel. I almost immediately ran into some confusion. According to the schematic, there should be a 3A fuse for the AC line, and a 350mA fuse for the horizontal output circuit. The tube diagram in the back of the set specs, from top to bottom, a set of 3A, 2A, and 350mA fuses. A bit confusing, but it might simply be one of the production changes between the 10PG model in the schematic and my model 10PK. But where the heck does this fourth fuse come into play



And to add insult to injury, it looks like at some point someone changed out the 350mA horizontal fuse with a 2 AMP replacement, which was ALSO BLOWN! Baaaaad omen! But without much else to go on, I found a more appropriately-specced fuse and continued with reforming the electrolytics. The flyback can't be bad if I don't think about that possibility



With a 15W lightbulb in series, it took approximately 25 minutes to reach the correct B+ voltage at the 210V test point. One of the two multi-section electrolytics in the pi filter got slightly warm, but cooled off after a while. It definitely would have been a problem if I simply applied full power. I decided to be a little ballsy and reinstall the CRT to see if it would produce high voltage:



A very good baseline! The tuner/IF frontend does not appear to be alive yet, as there's no static, but both deflection stages working is fantastic. I'm not sure what was up with the massively oversized horizontal fuse being blown, since it seems to be working fine now...I'm just not gonna think about it. I think many of the problems with the picture will be solved by changing out dozens of paper capacitors. I'll be spending tomorrow doing that and will report back as things develop

[jhalphen]

Hi to all,
Hi cj_reha,

interesting and well documented (many photos) restoration story,
Thank You !

i understand the attraction to small Japanese TVs,
Will follow progress with interest.

In the same small size form factor, RCA made a 8" all-tube B&W TV circa 1956; seen it or have one ?

Here is one restored by Phil Nelson :
https://antiqueradio.org/rca16.htm

Best Regards
jhalphen
Paris/France

[cj_reha]

Originally Posted by jhalphen

Hi to all,
In the same small size form factor, RCA made a 8" all-tube B&W TV circa 1956; seen it or have one ?

Here is one restored by Phil Nelson :
https://antiqueradio.org/rca16.htm

Best Regards
jhalphen
Paris/France

Hi Jerome! Yes, I have seen them but not found one yet! I'd really love an example of the Emerson 1232, another set Phil restored and documented.

[cj_reha]

I made some fairly decent progress today! I focused most of my time on cleaning up and rebuilding the vertical and horizontal sync/deflection circuits. First item on the list was cleaning the high voltage cage, especially around the rectifier tube. I was a little irritated by the design of the removable portions of the shielding; the top section, where the flyback mounts, can only be removed if you unmount the yoke socket and undo some of the harness looming. I ended up leaving it in place and using Q-tips to get the worst of the grime out. The 1X2 HV rectifier appears to be original. I noticed the vertical output tube and one or two of the IF tubes have been changed, so I have to say I'm impressed it's still on its original set of horizontal sweep tubes



Most of the deflection circuitry is on the PCBs, but a non-insignificant portion of the horizontal section is hand-wired underneath. It looked deceivingly simple at first....





....but there are actually SEVEN capacitors down here that need to be changed! Technically eight to start with, but two of the paper capacitors near the horizontal width coil are in parallel (a .02 and .05uF) - easily replaced with a modern .068. I was initially expecting to have this portion of the chassis done in an hour, but kept finding more paper caps the more I dug Mercifully, the resistors test great so far. They're all within 20%, but many even measure 10% or better. Perfectly acceptable for a tube set, and I would rather keep as much of this onion un-peeled as possible!



I managed to get most of the deflection PCB recapped as well. With one exception - there's a 0.025uF 1.5kV paper cap on the vertical output tube plate, I don't have any of those. I experimented with using a few 0.01/0.015uF caps in parallel, mounting one on the underside of the PCB, but nothing came out to my satisfaction. Mostly, the top-side capacitor rested too close to the tube for comfort. I don't want them to get baked and potentially damaged over time. I've got some 2kV axial films on order and hope they arrive later this week so I can wrap this part of the set up for good. In the meantime I'll try to get a little more of the grime out...this thing is FILTHY!

The 9-5 coal mine beckons me to return, so things will slow down over the week, but I hope to have the rest of the paper capacitors replaced by next weekend so I can begin testing and potentially diagnose more problems.

On an unrelated, brief note, I found the first actual difference between the schematic for the 10PG and my 10PK. The 10PG uses a 4R-HH2 for the tuner RF amp; my 10PK uses a 3D-HH13 subminiature there. I have to admit I've never seen a subminiature of this type before, it's kinda cool! I just hope it's good as I have no way to test it...

[Electronic M]

Originally Posted by cj_reha

Hi Jerome! Yes, I have seen them but not found one yet! I'd really love an example of the Emerson 1232, another set Phil restored and documented.

I've got and recapped one of those RCAs... They are tiny! Basically occupy the same space as a stack of 8" x11" copy paper. The chassis is like a multi-layer sandwich and somehow they got a power transformer in there.

I've also got 3 of those Emersons Red, dark green, and blue. They weren't hard to fix. They crapped out several hours in to havingthe cases back on and I need to revisit them eventually.

That Japanese set is cute. The oddball Miniature reminds me of an overgrown newvistor.

[old_coot88]

Har. Great minds think alike. My first thought lookin at that goofy tube was "how nuvistorish".

[cj_reha]

I finally finished changing the paper caps last night. Boy, what an effort! Lots and lots of parts crammed in areas with very little access.





Even though I'd like to keep the big electrolytics original to the set, I elected to restuff the main doubler cap, as I noticed its safety vent had failed. Easy enough to do, and arguably the most important capacitor in the entire set, so it's worth the effort!



The chassis isn't perfect, but it's at least a lot cleaner than it used to be. I pulled and tested all of the tubes - my emissions-only tester isn't great, but can at least weed out duds and tubes with leakage. Fortunately, all of these test well enough I think they'll work as-is.



So, the question: does it work?







It's not perfect, but I didn't screw anything up!

There are a handful of problems I want to fix before I will consider the set good enough to button up and use. Although the video bandwidth seems quite good, its RF sensitivity is quite weak - I can only get a snow-free picture with the local-distant switch set to distant, and with my Sencore VA62's RF output cranked up all the way. The tuner and IF tubes are original, and tested "okay" on my tube tester, but I'll try swapping them out to see if sensitivity improves at all. Also, the sound IF is misaligned - best picture does not produce the best sound, and vice versa. I was really hoping to avoid touching the alignment on this set lacking official instructions, but I am hoping with the schematic and instructions describing similar American B&W sets I can bring it in without getting too in the weeds. Also, although the vertical linearity is fairly good, the control needs to be set to one extreme. I found a handful of drifted carbon resistors in the audio output circuit (30-50%+ out), so I will need to check around in the deflection circuits next. However, the fact it is making a reasonable picture as-is is quite encouraging. I can't wait to watch old movies of the Tokyo Olympics on this thing

Hopefully more soon...

[6GH8cowboy]

Always been curious to me that so many foreign sets like this Japanese one here, have English is the printed labeling on parts.

[Kevin Kuehn]

Originally Posted by 6GH8cowboy

Always been curious to me that so many foreign sets like this Japanese one here, have English is the printed labeling on parts.

Why, weren't they aimed for our American market? I would of thought so. I've really enjoyed this restoration with it's very nice pictures.

[TV-collector]

Originally Posted by 6GH8cowboy

Always been curious to me that so many foreign sets like this Japanese one here, have English is the printed labeling on parts.

Hi folks!
I asked the same question to a japanese friend, just because japanese sets for the japanese market do the same!
In the front or back, most is written in english, before and after the war!

There are no radios with japanese writing on the scale!

My friend told me, that it was a kind of "chic", when written in english!
Only complicated discriptions for using controls are in japanese, when written inside a lid (vintage TV sets of the 50s).

Regards,
TV-collector

[cj_reha]

Originally Posted by Kevin Kuehn

Why, weren't they aimed for our American market? I would of thought so. I've really enjoyed this restoration with it's very nice pictures.

Thank you Kevin! I fully intend to circle back around to this set to finish it up and get it back together, just sidelined by some more pressing projects I need finished for our vintage computer club's festival next month. I wanna see it work right!