Slow G07 start up

[Mauzy]

Hey everybody.
I have a G07 that was bought in a junked cocktail table. The tube was backwards and all cables were cut. I reconnected everything, and saw some sparks. Crap. I bought a new set of chassis with a new cap kit preinstalled, and it works fine, but it takes about a minute to a minute and a half for the picture to come up on the tube. I don't know how long the tube sat without being used, but it had the heaviest Galaga burn I had ever seen.

Is it normal for it to take this long to come up?

[qrz]

a weak crt will take some time to display a pic.
 
a strong tube should have a pic within 10 - 15 seconds ...

sometimes a rejuve procedure may help for awhile .

phosphor burn can not be fixed short of replacing the crt 

qrz

[Mauzy]

The burn doesn't bother me when the game is on. A piece of smoked plexi fixed that.

How does one rejuvenate a tube?

Do you think this is a case of a tube not being used for so long that it has weakened, or just a case of a 24 year old monitor being a 24 year old monitor?

[qrz]

sencore made a couple of models that do a nice job . i think b&k may have had some as well.....
seen some sencore on ebay for far less than i pd new in '84     ( cr70 )

a weak tube can be compared to a mineral build up in plumbing. the more gunk in the pipe the lower the flow.
a weak crt has less available electrons in which to bombard the phosphor. the greater the kinetic energy of the electron impact, the brighter the emited light ( hence the high 2nd anode voltage )

what the rejuve procedure involves.. briefly increasing the filament temperature by applying a higher than normal
voltage . this will increase the volume of available electrons at the cathode  .
a momentary high positive voltage is applied to g1. the sudden presence of the voltage attracts the electron cloud from the more negative cathode . the sudden burst of current ( limited to 100-150 ma ) will burn off a layer of cathode "crud" thereby restoring normal beam current.  however.......,
cathode material has a finite life. eventually, the emitting material will be depleated . nothing further can be done short of replacing the gun assembly .  this is called a rebuilt tube .,or grade B crt

tubes generally will not degrade from disuse.

sorry u asked ?   

qrz

[Mauzy]

Hmm... sounds interesting.  Thanks for the great info.