My computer has a bad tube

  • Thread starter Dr.RogerSlapinski
  • Start date
D

Dr.RogerSlapinski

I have a older computer and all of a sudden it wont run. When I put
in my startup floppy nothing happens. The dial dont even light. I
called my grandfather because he used to fix washers dryers and
refrigerators before he retired. He asked me if its plugged in, I
said yes. Then he told me to plug a lamp into the outlet and see if it
lights up. It did. He said my computer probably needs a new tube and
told me to look for one that has the numbers 5U4 on it. He said that
is the bad tube. I cant find any tubes with that number. In fact I
cant find anything with that number. There is a thing that looks like
a spider and a couple metal boxes and on the bottom is this big brown
thing with all kinds of little funny looking things one it. Lots of
wires too. When I push the button on the back the wires move and that
wire that goes to my screen falls out if I pull the computer off the
desk. There's a round black thing in the box that looks like its been
turned or rolled over on the tiny gray round one next to it. Last
there is a ting with a smiley face on it stuck on the box. Maybe that
is what I need. But where is that tube? Please tell me. Grandpa
said I should take that tube to the drugstore and get it tested, but I
got to find it first. Need help.
I had to sneak on my parents computer bnefore they wakes up to ask
this. I Better go.
 
M

meow2222

I have a older computer and all of a sudden it wont run. When I put
in my startup floppy nothing happens. The dial dont even light. I
called my grandfather because he used to fix washers dryers and
refrigerators before he retired. He asked me if its plugged in, I
said yes. Then he told me to plug a lamp into the outlet and see if it
lights up. It did. He said my computer probably needs a new tube and
told me to look for one that has the numbers 5U4 on it. He said that
is the bad tube. I cant find any tubes with that number. In fact I
cant find anything with that number. There is a thing that looks like
a spider and a couple metal boxes and on the bottom is this big brown
thing with all kinds of little funny looking things one it. Lots of
wires too. When I push the button on the back the wires move and that
wire that goes to my screen falls out if I pull the computer off the
desk. There's a round black thing in the box that looks like its been
turned or rolled over on the tiny gray round one next to it. Last
there is a ting with a smiley face on it stuck on the box. Maybe that
is what I need. But where is that tube? Please tell me. Grandpa
said I should take that tube to the drugstore and get it tested, but I
got to find it first. Need help.
I had to sneak on my parents computer bnefore they wakes up to ask
this. I Better go.

Maybe these people could advise you:
http://www.ominous-valve.com/tour.html


NT
 
P

paulmd

I have a older computer and all of a sudden it wont run. When I put
in my startup floppy nothing happens. The dial dont even light. I
called my grandfather because he used to fix washers dryers and
refrigerators before he retired. He asked me if its plugged in, I
said yes. Then he told me to plug a lamp into the outlet and see if it
lights up. It did. He said my computer probably needs a new tube and
told me to look for one that has the numbers 5U4 on it. He said that
is the bad tube. I cant find any tubes with that number. In fact I
cant find anything with that number. There is a thing that looks like
a spider and a couple metal boxes and on the bottom is this big brown
thing with all kinds of little funny looking things one it. Lots of
wires too. When I push the button on the back the wires move and that
wire that goes to my screen falls out if I pull the computer off the
desk. There's a round black thing in the box that looks like its been
turned or rolled over on the tiny gray round one next to it. Last
there is a ting with a smiley face on it stuck on the box. Maybe that
is what I need. But where is that tube? Please tell me. Grandpa
said I should take that tube to the drugstore and get it tested, but I
got to find it first. Need help.
I had to sneak on my parents computer bnefore they wakes up to ask
this. I Better go.

No computer since the 1970s (or earlier) used tubes. Chances are its
not THAT old.

We need more information about the computer, what is the make and model?
 
R

Rod Speed

No computer since the 1970s (or earlier) used tubes. Chances are its
not THAT old.

We need more information about the computer, what is the make and
model?

Whoosh...clang....
 
P

philo

I have a older computer and all of a sudden it wont run. When I put
in my startup floppy nothing happens. The dial dont even light. I
called my grandfather because he used to fix washers dryers and
refrigerators before he retired. He asked me if its plugged in, I
said yes. Then he told me to plug a lamp into the outlet and see if it
lights up. It did. He said my computer probably needs a new tube and
told me to look for one that has the numbers 5U4 on it. He said that
is the bad tube. I cant find any tubes with that number. In fact I
cant find anything with that number. There is a thing that looks like
a spider

<snip>

the 5U4 is a full wave rectifier tube...
i may have a few spares left over from my ham radio transmitter.

the thing on the bottom that looks like a spider...
actually *is* a spider...
i probably have a few spares down in my basement!!!!
 
R

Rod Speed

heh. I did see some advertised that had a single valve on the mobo for a sound output.

Yeah, the most utterly bizarre offering I have seen in many many years.
 
C

CBFalconer

philo said:
<snip>

the 5U4 is a full wave rectifier tube...
i may have a few spares left over from my ham radio transmitter.

the thing on the bottom that looks like a spider...
actually *is* a spider...
i probably have a few spares down in my basement!!!!

Nice troll. However the OP can replace the 5U4 with a pair of 400
PIV silicon rectifier diodes. For a plug in replacement find a
burned out 5U4G and break off the glass, just saving the octal
base. Solder the diodes into the base. Just pick one of the
heater pins as the common point for the cathodes.
 
M

Michael C

CBFalconer said:
Nice troll. However the OP can replace the 5U4 with a pair of 400
PIV silicon rectifier diodes. For a plug in replacement find a
burned out 5U4G and break off the glass, just saving the octal
base. Solder the diodes into the base. Just pick one of the
heater pins as the common point for the cathodes.

It just won't have the warm valve sound any more though....

Michael
 
M

Michael C

CBFalconer said:
Nice troll.

BTW, a troll and a joke are 2 different things. I don't know why people here
take offense to posts like this. I have found alt.comp.hardware to be the
least humourous ground in existance.

Michael
 
M

meow2222

Nice troll. However the OP can replace the 5U4 with a pair of 400
PIV silicon rectifier diodes. For a plug in replacement find a
burned out 5U4G and break off the glass, just saving the octal
base. Solder the diodes into the base. Just pick one of the
heater pins as the common point for the cathodes.

You've got to watch the temperature issue though, silicon doesnt like
heat half as much as valves, so a good derating is called for.

With the kilowatts those valves put out, you'd probably need to derate
the computer user in summer time too. Its not like you can just open
the windows, as you'd get bugs.


NT
 
P

philo

You've got to watch the temperature issue though, silicon doesnt like
heat half as much as valves, so a good derating is called for.

With the kilowatts those valves put out, you'd probably need to derate
the computer user in summer time too. Its not like you can just open
the windows, as you'd get bugs.


Right.
I agree that humor and trolling are two separate things...

and the reference to 5U4 was quite funny I thought.

Anyway...the silicon rectifier is considerably more efficient than a vacuum
tube...
and if used will result in a higher plate voltage...which may not
necessarily be desirable...
so a dropping resistor may be in order!!!

Two's and three's instead of ones and zeros!!!!!! (BFG)
 
C

CBFalconer

Michael said:
BTW, a troll and a joke are 2 different things. I don't know why
people here take offense to posts like this. I have found
alt.comp.hardware to be the least humourous ground in existance.

I differentiate between a troll and a nice troll. The latter are
rare. If you had snipped in units of paragraphs it would be
obvious that I joined in and took no offense. I also didn't point
the the added ripple from the 5v heater winding in my substitute.
 
J

Jon Danniken

philo said:
Right.
I agree that humor and trolling are two separate things...

and the reference to 5U4 was quite funny I thought.

Anyway...the silicon rectifier is considerably more efficient than a vacuum
tube...
and if used will result in a higher plate voltage...which may not
necessarily be desirable...
so a dropping resistor may be in order!!!

Two's and three's instead of ones and zeros!!!!!! (BFG)

The other concern is that you won't have the "soft start" that you would get
from a valve recto. In such a case, it would be prudent to install a
standby switch to allow the other heaters in the computer to come up to
temperature before you switch in B+.

Jon
 
M

meow2222

Jon said:
"philo" wrote:

well, would enable it to compute bigger numbers :)
The other concern is that you won't have the "soft start" that you would get
from a valve recto. In such a case, it would be prudent to install a
standby switch to allow the other heaters in the computer to come up to
temperature before you switch in B+.

This could be quite a problem, as the machine may !BOOT with a 1 at
start of file instead of a 0. Who knows what it would then do.

At least you could memtest it to check. Though admittedly the odds of a
valve computer being memtest86 compatible are maybe less than ideal. I
mean who needs memtest for travelling wave memory. Unless theres a bug
in one of the RAM tanks. Maybe try Memtest56 or earlier.


NT
 
C

CBFalconer

Jon said:
The other concern is that you won't have the "soft start" that you would get
from a valve recto. In such a case, it would be prudent to install a
standby switch to allow the other heaters in the computer to come up to
temperature before you switch in B+.

5U4s have filaments, so heat up much more rapidly than the heavy
cathodes heated by a heater. So that is probably not a major
concern.
 
M

meow2222

CBFalconer said:
Jon Danniken wrote:
5U4s have filaments, so heat up much more rapidly than the heavy
cathodes heated by a heater. So that is probably not a major
concern.

usually part of the function of the rect valve is to keep B+ off until
the other valves were up to emission, to avoid capacitors being exposed
to well above running voltages, and maximise the life of the other
valves. So I dont think an old 5U4 would be the best choice, as its
quick warmup could end up with a large amount of caps failing during
warm up. RCs are used to drop a lot of voltage in valve kit - but only
do so once the valves are emitting.


NT
 

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