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same CRT pin systems?

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berniedd

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I have come across a few instances where the only problem in 14-inch sets is a weak CRT. I have access to many 14-inch sets with defects in the main board. I would like to swap these weak CRTs with the good CRTs from the bad sets. The pin system in all these tubes look alike to me, even if the tube types and manufacturers are not the same. Are you guys aware of any pin system incompatibilities here? Otherwise, it seems a simple matter to transplant the tubes with yoke and correction magnets undisturbed, into the good sets with weak CRTs. I know that the swap may not be that feasible because of differences between yokes, horiz and vert voltages, etc but I'm willing to try my luck.
 
Many CRT's are simple direct replacements, it's easy to try it and see?.

In the past I've often done 'back to back' temporary connections between the CRT in one set, and the chassis in the other. Amazing what you can do with crocodile clip leads :D you need to be aware of what you're doing though!.
 
I found that the pinouts are normally standard in colour CRTs. Even the old tube power pentode audio output tubes were standard. Quad op-amps seem to be standard except once in a while you find an weird exception, like a LM339 quad comparator.

You might find that if the tubes do not have identical numbers, the focus voltage might be out of range and require adjustment.

Don't operate a CRT designed for 25KV 2nd anode voltage at 40KV. Higher voltage CRTs are designed with more lead in the glass for Xray protection.
 
haha, that's strange. i was opening up a crt monitor the other day to get the flyback transformer out, and on the pic tube there was a sticker saying, warning, device may emit x-rays:D :D :D :eek:
 
If look on the cone of the CRT there should be a label marked with the tube type.

If you can find the CRT type, search the web for the datasheet.
 
why do they put warning labels on the tube, but not on the outside where people can read them? do crt's actually emit x-rays???
 
things said:
why do they put warning labels on the tube, but not on the outside where people can read them?

Because the notice is for engineers, NOT users!.

do crt's actually emit x-rays???

Not if used within their design limits, and TV's normally have circuits that shut it down if those limits are approached.

But an over driven CRT produces xrays, and it's how they used to be produced (not actually with a CRT, but with something essentially similar, an electron gun device).
 
Oh, thanks for that:D :D :D meh, i use a laptop, so i guess theres no x-rays coming from that?:eek: :eek:
 
Bob Scott said:
Don't operate a CRT designed for 25KV 2nd anode voltage at 40KV. Higher voltage CRTs are designed with more lead in the glass for Xray protection.

Noted. I guess I won't have this problem if I substitute with the same size CRT since generally, the larger the tube the higher the voltage needs.
 
berniedd said:
Noted. I guess I won't have this problem if I substitute with the same size CRT since generally, the larger the tube the higher the voltage needs.

Caution! You can't judge the high voltage capability by the size of the tube. Colour 25 (26) inch tubes used to have physically identical dimensions.

B&W TVs used to use about 10KV. 1960s era Colour tubes used 25 KV. Then the manufacturers decided to increase the picture brightness. In order to do that they needed to increase the electron beam energy reaching the phosphors. Increasing the beam current would wear out (deplete) the CRT cathodes early, so instead they raised the beam energy by increasing the HV to 40KV. This increased the acceleration and speed of the beam electrons.

Xrays are produced anywhere electrons are subject to sudden change in velocity, like hitting the phosphors on the face of the CRT. More electron energy = more Xrays.

Bob
 
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