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Old 07-16-2017, 05:39 PM
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Suitcase TV Fun

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
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Old 07-16-2017, 08:25 PM
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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!
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Old 07-17-2017, 06:19 AM
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Power supply caps and the hv caps probably, just the usual. Hope the 7jp4s are good then it's all worth it.
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Old 07-17-2017, 08:12 PM
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I always liked the wood cabinet version. I think it was a Silvertone brand but the same set as these.
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Old 07-18-2017, 08:40 AM
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Quote:
Originally Posted by compucat View Post
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.
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Old 07-18-2017, 09:09 AM
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Quote:
Originally Posted by decojoe67 View Post
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.
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Old 07-18-2017, 02:13 PM
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Initial examination rf/if/audio chassis

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
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Old Yesterday, 02:16 PM
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Initial examination sweep/display chassis

Not so original here... both have had a bit of repair work. Here is the Airline:





And the Sentinal:



Looks like some good fun ahead sorting out the repairs and modifications made on these sets.

jr
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Old Yesterday, 11:14 PM
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The cat is alive, Erwin!

Bypassed the voltage doubler input caps to get some B+ and checked out both sweep chassis. Both jugs seem to make light, and both sweeps appear to be running on the Airline sweep chassis, while only the horizontal sweep is running on the Sentinal.

Airline:



Sentinal:



All voltages are low, HV on either set is in the 2.5 to 2.8 KV range. Some audio was heard from the Sentinal rf/if/audio chassis.

Both sets show promise.

jr
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