Wanna smash a CRT? Let Australia Post do it.

[Bob Parker]

Location ?

Southern Sydney

 

[Bob Parker]

I guess he didn't want them to become more of a target ?

I keep hearing rumours that Australia Post staff have a lot of fun
with packages marked "Fragile". That's what I was referring to.

I've done a web page complete with all relevant communications
between Aust Post, the Ombudsperson and me. If you liked Sir Humphry's
beaurocratic red tape in "Yes Minister", you might find it
interesting...

http://members.ozemail.com.au/~bobpar/Q1803/austpost.htm


Bob

 

[atec 77]

I keep hearing rumours that Australia Post staff have a lot of fun
with packages marked "Fragile". That's what I was referring to.

I've done a web page complete with all relevant communications
between Aust Post, the Ombudsperson and me. If you liked Sir Humphry's
beaurocratic red tape in "Yes Minister", you might find it
interesting...

http://members.ozemail.com.au/~bobpar/Q1803/austpost.htm


Bob

I sent an artical today marked FRAGILE in huge letters with this way up
do not throw etc , and a logger.. will be interesting to see what happens .
Qld to Vic

 

[Bob Parker]

I sent an artical today marked FRAGILE in huge letters with this way up
do not throw etc , and a logger.. will be interesting to see what happens .
Qld to Vic

I reckon the mail handlers will have some fun with that! Please
tell us what the logger recorded.

 

[Richard Freeman]

**Mea culpa. I was thinking BWD 521.


**The 521 had no internal cratcule, but was, of course, a PDA tube.


**The 521 is a 30MHz device.

I have a 50Mhz module for mine.

**I stopped using my BWD when I bought my first Tektronix. The BWD was
nice, because it can be serviced economically.

If you are offering the 521 Parts and Tube I will not turn them down .....
;-)

Regards
Richard Freeman

 

[Bob Parker]

** Very hard to believe that is the result of a fall impact with zero damage
to the packaging or scope.

The electron gun has SFA mass and is supported and centred by internal
metal springs.

After I removed the external rubber sleeve, some of the aquadagged
glass fell into the tube and now I can see that at least one of the
gun support "rails" was snapped by the shock. The deflection plates
are rattling around, shorting to each other and possibly the aquadag,
and it's lucky it didn't take out some of the circuitry when I powered
it up.
I've added a close-up photo to
http://members.ozemail.com.au/~bobpar/Q1803/austpost.htm

** A new scope may well be cheaper.

DSE actually sold me a replacement at a very reasonable price. The
first bit of good news in all of this.

The only problem with the new tube is that the intensity pot needs
to be about 90% of full clockwise before I see the trace and it's not
real bright at full clockwise. Is your Q1803 like that? I got the
schematics for it, and there's no sub-intensity trimpot, only a
trimpot for setting the G2 voltage which I presume's the astig
adjustment?


Cheers
Bob

 

[Phil Allison]

"Bob Parker"

After I removed the external rubber sleeve, some of the aquadagged
glass fell into the tube and now I can see that at least one of the
gun support "rails" was snapped by the shock. The deflection plates
are rattling around, shorting to each other and possibly the aquadag,
and it's lucky it didn't take out some of the circuitry when I powered
it up.
I've added a close-up photo to
http://members.ozemail.com.au/~bobpar/Q1803/austpost.htm


** Remember - once the glass fractures, there is 7 kg of force per
square inch ( due to atmospheric pressure ) behind the chunks that implode.
Do a bit of damage, they would.

DSE actually sold me a replacement at a very reasonable price. The
first bit of good news in all of this.

** Would they sell me a spare for the same ??

Looks like those tubes are tad fragile ;-)

The only problem with the new tube is that the intensity pot needs
to be about 90% of full clockwise before I see the trace and it's not
real bright at full clockwise. Is your Q1803 like that?

** No - the trace is visible from the 8 o'clock setting onwards.

About 1 or 2 o'clock is my normal setting in subdued room light = about
50 to 10 lux incident on the screen.

I got the schematics for it, and there's no sub-intensity trimpot, only a
trimpot for setting the G2 voltage which I presume's the astig
adjustment?

** Yep.




........ Phil

 

[Bob Parker]

** Remember - once the glass fractures, there is 7 kg of force per
square inch ( due to atmospheric pressure ) behind the chunks that implode.
Do a bit of damage, they would.

You're not wrong. Whatever happened, the forward part of the gun
assembly's a real mess now.

** Would they sell me a spare for the same ??

I don't see why not. By 'very reasonable' I mean a bit over $50.
Cheaper than a new CRO, anyway.

Looks like those tubes are tad fragile ;-)

The glass is fairly thin, except on the flat face of course.

The only problem with the new tube is that the intensity pot needs


** No - the trace is visible from the 8 o'clock setting onwards.

That's what I'd expect. Looks like I might need to adjust the value
of the intensity limiting resistor in series with the intensity
pot/rheostat. Unless this little incident's damaged something else...

About 1 or 2 o'clock is my normal setting in subdued room light = about
50 to 10 lux incident on the screen.

Thanks for the info. It always helps to compare a repaired one
against one which has been OK from the start.


Bob

 

[Bob Parker]

** No - the trace is visible from the 8 o'clock setting onwards.

About 1 or 2 o'clock is my normal setting in subdued room light = about
50 to 10 lux incident on the screen.

I've just torn the CRO apart and checked everything related to the
G1 voltage adjustment.
My schematic shows R115 as 33K but the actual resistor's 75K. Seems
likely that they select them on test.
Now if only my component collection was still here, not where I'm
working...

Bob

 

[Phil Allison]

"Bob Parker"

I've just torn the CRO apart and checked everything related to the
G1 voltage adjustment.

My schematic shows R115 as 33K but the actual resistor's 75K. Seems
likely that they select them on test.

** You bet.

Dem tubes are exactly as " dim as they sim " .....





........ Phil