Hi,

I am looking for a 17HP4 (or direct substitution 17RP4, 17HP4A, 17HP4B) for my Firestone 13-G-54. It's in beautiful mint condition, due to the fact the filament was burnt out on the CRT (looking at the repair ticket) and the customer probably left it garaged for 60 years. I can get a 17KP4 for 100 plus shipping, but being as this is my first TV project, piece of mind of not getting stuck on why it won't work would help.

If you know anything about these CRTs, I included the schematic I got from SAMS.

If the 17KP4 or 17BWP4 will work just as well let me know, I included the datasheets and the 17KP4 looks promising as grid 4 (pin 6) isn't on the schematic) except I heard that the Electrostatic Focus on the 17KP4 is automatic (there is an internal resistor between the cathode and Grid 6). Although I've fixed many radios, this is my first TV project and I'd like the piece-of-mind of not having to modify a circuit I'm trying to troubleshoot.

PM or Email me if you know where to find a 17HP4. Thanks a bunch!

-Rob

17KP4 should be ok as a replacement for 17HP4. Don't try to use 17BWP4 as this one is 110 degree deflection and shorter than 17HP4, 70 degree deflection.

Cool, thanks a lot. I was concerned as the "Crossover Guide" I had from 1959 says I can use a 17KP4, but that it is "Automatic Focus", where the schematic shows a focus circuit and pot tied into the HV and horizontal.

If anyone has time, 422.pdf is the factory schematic for my TV let me know if there's anything I need to be concerned about putting the KP4 in.

I have another question - if you get a chance take a look at the schematic (422.pdf), my set has notices for upcoming "Color TV" from 1960 (just like when we switched to digital) still on there, and that it needs some Firestone model 122 adapter. I thought NTSC was backwards-compatible, and the B&W set simply ignored the color burst after the falling edge (sync).

Do I need to find this "Firestone 122" color adapter? I mean, they obviously didn't mean to make the set color as 17HP4 isn't a color CRT.

Thanks,
-Rob

Rob
May have been like a radio from the 1930's set up to receive TV.

Color TV takes a lot more than was available in this set. Would be nice to see what the 122 adapter did? There were experiments with color wheels.

You're right. It's interesting as there's a notice from 1960, just like in early 2000s about TV having to be compatible with digital, that Firestone would make an adapter model 122 that would make the set compatible with color. I can't find any info on the 122, so I imagine it was never actually manufactured.

http://www.earlytelevision.org/cbs_color_converter.html

The output to the 122 is B+, Video, Sync, and looks like from the horizontal sweep and focus, which would make sense. One thing weird on my set, is it says B+ is 450V, but straight off the transformer / rectifier I show 380V. I could have gotten a weak tube possibly, not sure

DLP TVs of the early 2000s actually use this technology inside. I hear of problems of "grinding sounds" on Sharp DLP TVs, and then the picture would go out

its common for the solder joints in the crt pins to open up.
much more common than a open heater.
you may be able to save the tube if this is the case.
suck out the solder and try to get fresh solder and flux down the pins.

How can I take the socket off without damaging the tube? I don't want this thing to implode / blow up in my face

Found the original repair ticket from when it broke, said "Customer complains that picture started to draw in and finally went out. Declined repairs due to the fact that the CRT was almost completely dead, and might need other things. Customer declined repair due to th.e age of the set" 7/5/62 (only 2 years old, I'm going to repair it 57 years later).

Anyway, do you think this indicates an open heater or heater circuit like you say (solder joints)? I show an open circuit, but if it STARTED to draw in, you might be right as an over-voltage would make the picture sharper at first.

What do you think?

Here are a couple of pictures of my TV. Firestone, I know they make tires... but not TVs. So you think I can pull that cap off the back, heat the pins up and re-flow the solder?

kc8adu, sorry I meant "how do I take the plug off the tube itself", didn't want to sound like an idiot "how do I take the CRT cap off.

I have to heat all 12 pins up at once? Or can I just solder individual pins?

have you ever fired up the set?
i am in the service industry and take other shop and customer diagnosis with a grain of salt.
best would be to test with a crt tester.
you can resolder the pins one at a time without removing the base.
if it is actually open.

Removing the base of the CRT is not a trivial task. You run the risk of snapping off one of the connection wires at the glass, in which case you've got a fish bowl. I'd first try just reheating the pins, but better if you have a solder sucker and can try and extract all the solder from one pin at a time so as not to overheat the ancient base, then some new flux and solder. Since your filament is reading open, start with those two pins. That might be all you need to do.

You run little risk of snapping off the neck seal unless you get WAY too aggressive with the socket. Best not to try and remove it regardless. If you do get to the point where you have tried everything else and want to remove the socket, you may be able to loosen it up by some gentle, and I do mean GENTLE .. rotating a degree or two back and forth with a pair of pliers, then heating each pin in sequence and working it off while gently pulling on it at the heated pin. This will take a lot of time, since any too aggressive twisting or tugging may easily snap off one of the wires, then you're done.

Wear heavy clothes and eye protection just in case.

The guy at the place I bought it fired it up once. He told me that the rectifier tube (a 5U4GB at the time) made a loud BOOM!.

Got it home, looked at the 5U4GB. Part of the plate was exploded so I ordered a new one

I pulled the tube, and fired it up to check the filaments - it literally started on fire underneath the tuner. I immediately put it out with CO2, and pulled the chassis. All that were burnt up was a low-value resistor and a few capacitors-to-ground. It was close to the vertical transformer - but I tested it and did not lose it. Looks like the shop tried to take a cap out of circuit to test it, and didn't solder it back down. It shorted a joint-to-joint, probably shorting B+

I pulled the power transformer, and ordered a 5U4G online (used, the original "coke-bottle" style. I get, with the new 5U4G on the socket transformer, (if you look at the schematic there are 4 secondaries) 5VAC (to 5U4G heater), 380VDC B+, 6.3VAC, and 6.3VAC. This tells me that the transformer is good, but B+ is 380VDC and in the schematic it shows 450VDC. Did some math (380 * 1.41) since I have a "True RMS" meter, and it came out to 500 something. This doesn't make sense, so I asked SAMS to make sure the right schematic.

Bad rectifier (5U4G) tube I ordered? Why 380V instead of 450 in the schematic (for B+) straight off the transformer? Maybe no boost (flyback) since it was not in circuit? Transformer certainly isn't dead, but I hope this thing is still worth fixing

Did you replace electrolytic filter and other capacitors? Shorted capacitors can cause rectifiers to blow or worse, the power transformer. Capacitors become leaky even without use.

I haven't replaced anything yet except the 5U4G tube, just looking for parts and testing capacitors, resistors etc. That might be why I only have 380V, I'm not hooked up to any capacitors. Just the tube. If the power transformer was blown out, I'd have an open winding not -70V right?

When a power transformer blows you will see smoke and smell the burning. Best to at least replace electrolytic filter caps before applying power.

Next on the list, just trying to find a 17HP4 as I saw one for sale 3 years ago.. and knew it would take me quite a while to find one (unless he's right and it is a solder joint).

That's why I removed the damn thing, as I wanted to make sure it wasn't bad before buying a CRT (I saw one for 250, but geez... I'm not bill gates here especially if I'm gonna find a CRT).

Right now it isn't hooked to anything. The caps are 450V - looks like power transformer is OK, but any reason straight off the rectifier tube I'd see 380 instead of 450? I hope the dude didn't short a winding, only reason I could think why it could be blown. My hypothesis is that it's not hooked up to anything

Oh, right after the transformer I see a cap to replace in parallel, then "L13" in series. L13 must be a choke but could also boost it up to 450. I haven't hooked the power transformer back up yet, think I should "ring test" that secondary or I should be OK? Doesn't get hot. 380 instead of 450 was my only concern. Anyone worked on sets like this? Do you usually see high 300s or mid 400s for B+?

Probably just jumping the gun... just don't want to start a "money pit' here

I'm going to try re-soldering the tube. If that doesn't work and no one can think of a problem with the 17KP4 replacement, I'll order it. Will be cool to have this old beast running again, have to watch all the Twilight Zone on it when I'm done

Only concern I had was the focus circuit - it doesn't look like "Grid 4" pin is even wired (although there's wires on the socket), but the internal K-to-G4 resistor on the KP4 was the only thing I was concerned about. There are focus adjustments on my set, and the KP4 sheet is dated 1953, whereas the HP4 1957 (which makes me think it's an improvement).

A bit late to the party here, but I don't see anything on that schematic that specifies what your B+ should be, just that the filter cap is rated for 450V, and if that's the case your B+ had better be below 450V. 380 probably sounds OK with no load.