17" Motorola B&W from '55 (not a good day)

[radiotvnut]

A friend spotted this TV at an estate sale for $75. Of course, it didn't sell on the first day and my friend ended up getting it the next day for $55 ($5 would have been too much). I foolishly agreed to take it, since I don't find many (no, make that zero) '50's tablemodel B&W's in my area.

Cosmetically, I think it will clean up OK. So, I made testing the CRT the first thing on my list. The CRT in the set is a Dumont replacement and it tested dead as a doornail. So, I did what I've done many times before and attempted to cook it at 8V. After about two minutes, just as the emission was starting to hit the upper end of the "bad" scale - POOF! The filament blew open. So, unless I can find a cheap good 17HP4, this set is dumpster material and I might as well have flushed $55 down the toilet.

Now, I'm going to have to have a long, stern talk with my friend and tell him not to pay over $5 or $10 for these old sets, unless I'm in a position to check the CRT before purchase.

Needless to say, I'm not in a very good mood right now.

[Electronic M]

I've heard some claim that if you put a pulse of HV across the fill pins and possibly give the neck a tap that you can sometimes re-weld an open filament....At this point I see nothing to loose trying.

[radiotvnut]

I attempted discharging a HV electrolytic capacitor across the open filament. First, I tried a 22uf charged up the 300V. With this capacitor, I could get a flash by tapping on the neck; but, it didn't hold. I moved up to a 68uf and got a bigger flash. It held until I applied 6.3 volts and it then popped like a flashbulb and that was it. So, unless I can find a 17HP4, this set will be parted out.

[Username1]

That's a funny story..... Sorry....

I have seen over the years that some picture tube filaments running at their correct
voltage look really dim, and others look scary bright.... I have always wondered
what if anything is "up with that...?" but in each case the tube works just fine....

So you can see the spot that gives the arc or you just see a flash....?

I think since the thing burnt out from over voltage, plus its years of use, that it's
got a missing piece of wire, and it may be hard to get it to weld....

I think your right..... you need a new tube....

I like the look of that tv.... hope you get to fix it....

.

[radiotvnut]

I was first going to check this tube with my Sencore CR70; but, it decided to misbehave. So, I pulled out the old beat up B&K 465 beast and I made sure that it was putting out the correct filament voltage as per what it was registering on the meter of the tube tester. Before my filament blew, it looked unusually bright on 6.3 volts.

[zenith2134]

Sorry to hear about the blown filament.
I have a 465 Dynaquik tester, and it's a good basic tester, but I'm very hesitant to ever push that red button!!!! Brute force design

[Kevin Kuehn]

I know it's difficult, but I'd just hang onto the set for a while. I don't think that a good used 17HP4 will be that hard to come by, but you'll need to be patient. It may take a few years before one falls in your lap. Then again you might get lucky and find one next week.

[dieseljeep]

Originally Posted by radiotvnut

I was first going to check this tube with my Sencore CR70; but, it decided to misbehave. So, I pulled out the old beat up B&K 465 beast and I made sure that it was putting out the correct filament voltage as per what it was registering on the meter of the tube tester. Before my filament blew, it looked unusually bright on 6.3 volts.

The heater was already damaged when you got the set. It evidently failed and re-welded itself. Also too heavy tapping on the neck, in a rejuvenation attempt.
Check with ETF. They might have one, as I got lucky and bought a high-quality rebuilt 23EGP22A. Those are more rare than a 17H.
You can also use a 17BP4, but you have to fit a magnetic focus unit.
I see it has yoke plastic rot.

[StellarTV]

Ah yes, a Moto with the infamous 'sex' logo on the front.

Good looking set, even by today's standards. Love those metal cabinets. It should clean up very nice!

[kramden66]

whats the difference in the 17hp4 and 17bp4 ? hp doesn't use a focus coil ?
i have a westinghouse with a 17" unsure the number , i know its good , might use a focus coil

[dieseljeep]

Originally Posted by kramden66

whats the difference in the 17hp4 and 17bp4 ? hp doesn't use a focus coil ?
i have a westinghouse with a 17" unsure the number , i know its good , might use a focus coil

If the Westinghouse uses a focus coil or magnetic focus unit, it's probably a 17BP4. If it doesn't, it could be a 17HP4. Westinghouse also used a 17YP4, which uses a different face curvature.

[jr_tech]

Originally Posted by kramden66

whats the difference in the 17hp4 and 17bp4 ? hp doesn't use a focus coil ?

Correct ! The 17HP4 is shown in my old GE tube manual as Low Voltage Electrostatic focus... does not use a focus coil (or focus magnet assembly).

jr

[Electronic M]

If you were local I'd offer you a spare 17" CRT I have, and the magnetic focus unit for it.

[Boobtubeman]

Looks like the horizontal output tube is kaput as well..

SR

[dieseljeep]

Originally Posted by Boobtubeman

Looks like the horizontal output tube is kaput as well..

SR

I forgot to mention that in my entry. I hated those smaller BQ6 type tubes and never used them. The tubes I would use were the GE or CBS 25BQ6GA/25CU6 and the 6,12 and 17 volt versions. The price was the same and less prone to failure.