Prototype set is here

[miniman82]

My brother Tim stopped by on Saturday, and I gave him the paper copy schematics. Being that there are folks on here who have an interest in viewing what we have written down to date, I asked if he could 'computerize' everything we have so I can upload it. A number of people I emailed the paper scans to made comments to the effect that it's just too hard to interpret, and I have to agree. For example, just the IF section takes up close to 3 sheets of regular printer paper.

As soon as he has everything in order, I will post the result here. We are hoping to have it done by the coming weekend.

[ChrisW6ATV]

It is nice to hear of your progress with the documenting of your color prototype TV chassis. I look forward to learning more.

[TVtommy]

ditto!!!!!

[Sandy G]

Ditto, me, too, even if I don't understand a lot of the "Tech" stuff...I sorta get the general "Gist" of it-I think, anyway, but that's about it...

[miniman82]

Might have a potenial power supply, it's from an old organ. Thanks to Bob G for the parts. Top transformer is the B+ stuff, bottom is filament only. Should have enough power to do the job, I think.

[leadlike]

Yeah, building a power supply like that will really show you how much power those filaments need. I think I had to use a 15A filament transformer to run my GE 802's power supply, where the filaments consumed something like 12A. What's the filament draw on your set going to be?

[miniman82]

Originally Posted by leadlike

What's the filament draw on your set going to be?

No idea, but this filament PTX came from an organ which always have a bazillion 12AU7's in them. I don't think it will be a problem as far as that goes, I just hope I can come up with all the B+ supplies it's gonna need. I think right now I'm looking at a 250-ish rail, 380-ish rail, some yet unknown B- supply (maybe around ~100), and possibly a small positive bias supply. Interestingly, one of the filament windings on the B+ PTX is 6.6v center tapped... I guess I could always run 5U4's at a volt more than normal, but perhaps 3DG4's would be more appropriate? Then again, it's entirely possible that the voltages will get a little lower once the thing is loaded down really good.

[earlyfilm]

Originally Posted by miniman82

Interestingly, one of the filament windings on the B+ PTX is 6.6v center tapped... I guess I could always run 5U4's at a volt more than normal, but perhaps 3DG4's would be more appropriate?.

Since the early vacuum tube TV days, the ubiquitous 5U4 has gone from the lowest-priced commonly-replaced bottle to being quite dear today. I'd say running those babies at 6.3 volts could get expensive in a hurry. I wonder if they make 1.3 volt 3 amp pilot lights?

On a twin-tube "B" supply, if one tube opens a filament, the other tube promptly melts before the user notices and can shut the system off. On 5U4's this problem seemed to be worse with the fat G's and first generation GT's than with the GB's

If the filaments were wired in series, this would protect the second tube.

Are the tubes in the picture from the organ? If not, any idea what tubes the organ used?

[Kevin Kuehn]

Originally Posted by miniman82

Might have a potenial power supply, it's from an old organ. Thanks to Bob G for the parts. Top transformer is the B+ stuff, bottom is filament only. Should have enough power to do the job, I think.

So, I guess what we've got here, is an organ donor?

Sorry... late night humor

[dieseljeep]

Originally Posted by Kevin Kuehn

So, I guess what we've got here, is an organ donor?

Sorry... late night humor

Nick! I was looking at the schematic for the first Westinghouse. It shows two B+ supplies, using three 5U4's. Two of The 5U4's are connected in parallel and supply the 280 volt source. The remaining one supplies the 390 volt source. The original transformer had a tapped HV secondary plus two five volt rectifier windings. I would also go with a different power supply chassis, like from a Magnavox radio.

[miniman82]

No, only an isolation transformer off the heater string that supplies all the other tubes.

[DrRick]

Please let me know what else you may need for the power supply. If I have anything you need, it's yours for the shipping cost.
I have, literally, a ton of PS iron, etc..

Rick

[miniman82]

OK, thanks for the offer! Right now I have the chassis Bob gave me, with a pair of tranformers that look like they are up to the task, twin ST glass 5U4G rectifiers and enough stuffable caps to build something useful. If I need anything more, I'll keep you in mind.

[miniman82]

Update: I may have a line on a very nice cabinet for this chassis. It's a 9-T-79, which uses the 19" tube. It's got 4 doors, 2 for the screen and 2 for the speaker. Very classy. The seller says it's 24" deep, which should be more than enough to hold the entire color chassis without any of it sticking out. Only question is, will I be able to make a nice bezel to adapt this cab to the smaller 16" pix tube mask?

[zenithfan1]

I've already got an idea on how to make a mask for it, we could whip one out in less than a day. ( If nothing goes wrong :3 )