1950s or '60s vintage Zenith TVs, Need some info

[vortalexfan]

Originally Posted by jr_tech

“ Your 6AQ5 is a 450ma tube, so you're really pushing that one as well. “

For grins, I connected a 6AQ5 to a constant current power supply set to 600ma and measured the voltage drop across the heater. The heater voltage stabilized at about 10.5 volts! This is indeed really pushing it for a 6.3 volt tube... I suggest that proper 5AQ5 be ordered as well.

jr

OK well I also noticed that the previous owner of this TV had installed a 6BU8 in place of a 3BU8 tube in the TV I'm guessing that should also be replaced with the proper tube as well?

[old_coot88]

Originally Posted by vortalexfan

OK well I also noticed that the previous owner of this TV had installed a 6BU8 in place of a 3BU8 tube in the TV I'm guessing that should also be replaced with the proper tube as well?

First, you might want to see if someone's put a shunt resistor across the 3BU8 heater (pins 4 and 5). It'd be a low value resistor, something like 20 ohms. Without the shunt for protection, seems like the 6BU8 would be lighting up like that 6CB6 did.

[vortalexfan]

Originally Posted by old_coot88

First, you might want to see if someone's put a shunt resistor across the 3BU8 heater (pins 4 and 5). It'd be a low value resistor, something like 20 ohms. Without the shunt for protection, seems like the 6BU8 would be lighting up like that 6CB6 did.

It was a 3BU8 after all, the way the dirt and grime buildup was on the tube it made the 3 look like a 6.

[vortalexfan]

OK, so the tube in the TV that I thought was a 6BU8 was actually a 3BU8 tube it was a GE branded replacement tube dated 39th Week of 1963, there was a bunch of dirt buildup on the tube designation number and the way GE does their tube numers in a "stencil" font the dirt buildup made the 3 look like a 6.

And then as far as the 5AQ5 goes, I took it and rechecked it in another tube checker I had laying around (a B & K DynaJet Model 666/606 Tube Tester) and the tube checked fine (no shorts in it anymore) so I wonder if I somehow blew off whatever was causing the short in the tube, I know that can happen sometimes.

So it looks like all I need is that 3CB6 tube and a 6CN7 tube which I don't happen to have in my stash anywhere, the 6CN7 tube in the TV which is an original Zenith badged GE tube dated the 20th Week of 1956 only had one section that tested good, the other 2 sections tested completely dead.

[Kevin Kuehn]

Originally Posted by vortalexfan

OK, so the tube in the TV that I thought was a 6BU8 was actually a 3BU8 tube it was a GE branded replacement tube dated 39th Week of 1963, there was a bunch of dirt buildup on the tube designation number and the way GE does their tube numers in a "stencil" font the dirt buildup made the 3 look like a 6.

And then as far as the 5AQ5 goes, I took it and rechecked it in another tube checker I had laying around (a B & K DynaJet Model 666/606 Tube Tester) and the tube checked fine (no shorts in it anymore) so I wonder if I somehow blew off whatever was causing the short in the tube, I know that can happen sometimes.

So it looks like all I need is that 3CB6 tube and a 6CN7 tube which I don't happen to have in my stash anywhere, the 6CN7 tube in the TV which is an original Zenith badged GE tube dated the 20th Week of 1956 only had one section that tested good, the other 2 sections tested completely dead.

Although I've never used them findatube.com is looking like a reasonable place for common TV tubes. 3CB6-$2.50, 6CN7-$3.00. And only a state away from you?

[vortalexfan]

Originally Posted by Kevin Kuehn

Although I've never used them findatube.com is looking like a reasonable place for common TV tubes. 3CB6-$2.50, 6CN7-$3.00. And only a state away from you?

OK, I'll give them a try.

So if the Horizontal AFC/Horizontal Phase Detector Tube is bad would that cause issues with the TV not receiving/dsiplaying signals from the tuner properly or would that be the Video IF tubes that would cause that?

[vortalexfan]

OK so I sent Bob over at Find A Tube a message with the tubes I'm looking for and hopefully I'll hear back from him on Monday or sometime after that (since its Christmas this weekend.)

[vortalexfan]

He actually got back to me right away. It would only be $6 to ship to me he said.

[vortalexfan]

A little update:

Still waiting on the tubes that I ordered for my Zenith "Bugeye" TV that I had ordered around Christmas and were supposedly shipped the monday after Christmas, and here it is the middle of the first week of January and I still haven't gotten my tubes yet.