Suitcase TV Fun

[jr_tech]

Today, I decided to take a shot at repairing/restoring a couple of suitcase style electrostatic sets that have sat in a dark corner of my display room for at least 20 years. They seem to be virtually identical, but likely will offer up a few surprises.

The first is a Sentinal 400-TV, which I slowly powered up on a variac... all tubes including the CRT seem to have heater glow... no smoke, slight hum and volume control scratch, but no HV or sound. It is only drawing about 95 watts, so perhaps one supply is down. The base cap is stuck on the CRT, so I am proceeding slowly and carefully and have not removed either chassis.



The second is an Airline, which is in somewhat better condition (no chassis rust) but has an unfortunate hole drilled above the tuner knob, (perhaps for fine tuning) and no light from the tuner tubes, but otherwise behaves the same as the Sentinal (no HV, no sound, no smoke, about 95 watts draw).



Looking forward to some good fun in the days (weeks, months?) ahead.

jr

[decojoe67]

Two of the best playing '40's 7 inchers ever made. They don't take up much space either. They look like nice examples. With a little ingenuity you might be able to repair the hole in the Airline front plate. Good luck!

[timmy]

Power supply caps and the hv caps probably, just the usual. Hope the 7jp4s are good then it's all worth it.

[compucat]

I always liked the wood cabinet version. I think it was a Silvertone brand but the same set as these.

[decojoe67]

Originally Posted by compucat

I always liked the wood cabinet version. I think it was a Silvertone brand but the same set as these.

That was actually a Sentinel model. It's a fairly scarce one.

[Electronic M]

Originally Posted by decojoe67

That was actually a Sentinel model. It's a fairly scarce one.

I've got one. I need to finish the repairs on it for it's owner....I may offer to buy it off of them once the resto is done.

[jr_tech]

At first glance, both appeared to be relatively untouched. I really see no signs of repair on the Sentinal chassis.



The Airline chassis has had the two electrolytic caps behind the terminal strip replaced with a two section cap.



However, its IF stages have also been modified to allow the use of 6CB6s rather than 6AG5s, perhaps for higher gain. There is a tag taped inside the set for a service company in Corvallis Oregon, which was a fringe reception area for Portland and Eugene stations. Hope it was aligned after the mods....

jr

[dieseljeep]

Originally Posted by compucat

I always liked the wood cabinet version. I think it was a Silvertone brand but the same set as these.

The Silvertone set was made by Tele-Tone. Totally different!
The Sentinel was a lot better design!

[jr_tech]

Interesting... Anybody here know how many manufacturers made these vertical format suitcase sets?

A little progress... it was fairly obvious looking at the schematic that the lack of vertical deflection and inability to focus the Sentinal set could be related to an open HV divider chain. I almost jumped out of bed and went back out to the shop last night when I figured that out, but waited until this morning to find and replace a couple of 4.7 meg resisiors in the HV chain. Set now makes somewhat of a picture, and will get a full re-cap this weekend. I always prefer to start with a semi-working set, so I can judge progress, and catch errors that I might make.



jr

[decojoe67]

Originally Posted by dieseljeep

The Silvertone set was made by Tele-Tone. Totally different!
The Sentinel was a lot better design!

Silvertone, Tele-Tone, and Firestone all were the same basic sets, although no wooden tabletop versions. I have the Tele-Tone version and it isn't nearly as good a set as the Sentinel/Airline models. There's also the unique Raytheon-Belmont 7" suitcase sets, but I've actually never seen one restored and working. They had a strange tuner design.

[jr_tech]

Finished up re-cap job on the Sentinal sweep/display chassis, including selenium rectifier replacment. Chassis looks "wide open" but there are some caps that are difficult to get to, horiz oscillator is crammed against the chassis edge, under a wiring bundle and terminal strip.



Now I have a fairly decent, fairly stable pix, with a little bit of horizontal "jitter", HV is now about 4.5 kV, which seems a bit low, but I really don't know what is correct for this set...anybody know what it should be?



Ordered a NOS 6Y6 for the HV oscillator, and am going through about 50 6SN7s to find the best for the set. Will scope out waveforms to attempt to locate the cause of the jitter tomorrow. Perhaps I should re-cap the Airline sweep/display chassis next, to compare behavior/waveforms.

jr

[old_tv_nut]

Nice!

[Sandy G]

I gotta quit coming here-Always thought the 7" Suitcase style sets were kinda crude, junky, & beneath consideration. Now, I think I wants me one- Better make that "Gots to HAVE Me One"...

[Titan1a]

Very good!

[ZackN920]

Cool sets! I know I want one. Also doesn't look-too complicated. I thought that the chassis's would be a jumbled up mess in these suitcases!

Keep up with the good work, its obviously payin' off!