Restoration question from beginner

[jr_tech]

Perhaps the CRT is drawing excessive heater current due to poor vacuum...can you measure the current at 6.3 Volts to see if it is in spec (1.8 Amps).

jr

[Yamamaya42]

Originally Posted by jr_tech

Perhaps the CRT is drawing excessive heater current due to poor vacuum...can you measure the current at 6.3 Volts to see if it is in spec (1.8 Amps).

jr

It's been working fine since the summer of last year.
https://www.youtube.com/watch?v=7V3etX2NsS4&t=18s

Just a few minor things to work out.
Vertical blanking / retrace not fully working, minor video streakimg , a few more old caps need to be changed, but not gonna pull chassis just for that, will wait till I try to fix IF problems ( alignment )

[Electronic M]

Originally Posted by Yamamaya42

I have a bk precision 490b, but the damn thing lies to me...

It always worked fine with all sorts of mono tubes, and 25vxxx tubes and projector tubes, and so on.

But when I hooked up my 21fjp22 that had been it storage forever,, VERY LOW emissions, scared the hell out of me, I thought the tube went dud in storage, took me a while to spot what was going on...
heater V @ 4vac, barely, it could not put out enough power for the heaters in the CRT.
So, I got a 6v 3amp xfomer and it came right up into the "really good" range on all 3 guns...
But, WTF? not enough power to light up a roundie? come on BK...

I'm guessing the 490 has only a switch to set heater voltage.
Different CRTs have different heater current which load the filament transformer differently...my 466 has a continuous heater adjustment knob and you set it by reading the heater voltage on one of the scales of it's meter....a CRT can draw as much current as it wants and you will still be feeding it the right voltage even if you have to set the coarse heater adjustment switch to a higher a range... Some of the low current 6.3V monochrome portable CRTs barely need adjustment of the heater pot, but a power thirsty roundy will need it set fairly high.

[MIPS]

Being someone who jumped into a side-of-the-road-chassis with only the ability to test every other tube in the set and no previous tube set restorations, if you see a good filament and an indication high voltage is present I say go for it! As others have mentioned even older tubes that read weak usually still have useable life left in them without needing a rejuvinator.

[Yamamaya42]

Originally Posted by Electronic M

I'm guessing the 490 has only a switch to set heater voltage.
Different CRTs have different heater current which load the filament transformer differently...my 466 has a continuous heater adjustment knob and you set it by reading the heater voltage on one of the scales of it's meter....a CRT can draw as much current as it wants and you will still be feeding it the right voltage even if you have to set the coarse heater adjustment switch to a higher a range... Some of the low current 6.3V monochrome portable CRTs barely need adjustment of the heater pot, but a power thirsty roundy will need it set fairly high.

correct, it only has 2 heater settings

https://i.ytimg.com/vi/cidneB0ziYE/maxresdefault.jpg

found the perfect pic on the net!

[MadMan]

Shango - yes, he does get awfully preachy about it, but he has a valid point. He is being an actual repairman. That's what a proper repairman does, he diagnoses, pinpoints, and repairs only what is needed. The fact that he practices his proper repair strategies on tvs that've baked under the sun for decades is besides the point.

What most of the folks around here are doing are restorations, which is a completely different ball game.

[AlanInSitges]

I was just thinking about this the other day. In my Walter Mitty daydreams I think about making a video series showing young people how to troubleshoot and repair TVs, hifis, etc. so that these things don't all become cat beds once the current generation is no longer here.

But then...does repair really even exist anymore? I bit, I guess...but every one of these old sets that people are still pulling out of estate sales, basements, attics, garages, thrift stores and landfills don't need a repair. If the intent is to be able to watch it, you're going to go directly to a full restoration: anything less will eventually see it burn up or stop working again. I guess there are some newer, XL-100 generation and BPC sets that may benefit from repairs, but I wonder if in the future anyone is going to be interested in those pressboard consoles.

[Electronic M]

Originally Posted by AlanInSitges

I was just thinking about this the other day. In my Walter Mitty daydreams I think about making a video series showing young people how to troubleshoot and repair TVs, hifis, etc. so that these things don't all become cat beds once the current generation is no longer here.

But then...does repair really even exist anymore? I bit, I guess...but every one of these old sets that people are still pulling out of estate sales, basements, attics, garages, thrift stores and landfills don't need a repair. If the intent is to be able to watch it, you're going to go directly to a full restoration: anything less will eventually see it burn up or stop working again. I guess there are some newer, XL-100 generation and BPC sets that may benefit from repairs, but I wonder if in the future anyone is going to be interested in those pressboard consoles.

Asside from certain tanks like monochrome tube Zeniths from the late 50s on and portacolors every tube set that is used a lot (say over a hours a day) will need repairs every 6 months to 5 years even if it was restored prior to being made a regular watcher....tubes wear out, other parts occasionally let go, adjustments need touch up etc....to run these things you either have to know enough to do basic maintenance/troubleshooting or know a guy that can do it for you.

I'm in my late 20s so assuming I have a normal lifespan I should be actively keeping this hobby going another 40 years...there are some other younger hobbiests too. The repurposing trend will eventually fade.

[zeno]

I would be suspicious of the CRT. Going to a bright dot was often seen
even if the CRT is bad.
When you turn off the TV HV remains charged but there is no deflection
so any electrons being emitted by the still hot cathode. They all land on
the same spot & can fool you.
IMHO best to run the set for 1/2 hr then turn off all lights in the room.
If you see some raster but very dark odds are its the CRT.

Price is another factor. Others know better than me but being a combo
it probably aint worth much of anything......

SHANGO is what we call a "character" in N.H. He does do some amazing
things with mostly pure junk. He is worth watching, you can learn a lot
from his antics. Thing that drives me nuts is this cat can make a 4 course
meal out of a potato chip. BUT I still watch him

73 Zeno
LFOD !

[Tim Tress]

I am a recapper.... After working as a technician for 50+years, I know that most of the capacitors in a vintage TV, radio, or amplifier will be leaky. Once upon a time, when the stuff was relatively new, we only replaced defective components and tubes, as customers would not pay for a complete rebuild job. Today, the first color sets are 65 years old, and early B&W sets are even older.

[decojoe67]

In my experience owning likely 50 vintage TV's in all my years is that, overwhelming, the CRT's are decent. Many times very good. Once you find that the CRT is not completely dead, you have to try in with a restored chassis to really know what the story is.
The old "white dot" in the center of the CRT screen is not a bad situation, but it actually should not happen when all components are in spec. often CRT's that had many hours with it will have a light ion-burn in the center.

[Electronic M]

Originally Posted by decojoe67

In my experience owning likely 50 vintage TV's in all my years is that, overwhelming, the CRT's are decent. Many times very good. Once you find that the CRT is not completely dead, you have to try in with a restored chassis to really know what the story is.
The old "white dot" in the center of the CRT screen is not a bad situation, but it actually should not happen when all components are in spec. often CRT's that had many hours with it will have a light ion-burn in the center.

The dot on power off is normal for some models, there were even articles in 50s Electronic magazines on how to modify sets to suppress the dot.

[Tube TV]

For me the dot in the center would be a green light to move forward.
You know the CRT hasn't went to air, which is a huge bonus.
I didn't have a CRT tester till 2007 / 08 when a VK member gave me his old B&K.
Over all the sets I've worked on I haven't ran into many that had a bad CRT.
You could do the bare minimum, replace the electolytics in the power supply.
Replace wax/papers in the horizontal / hv circuit and get an idea even if the vertical isn't working and all you have is a flat line.
Myself, I would continue without hesitation.