A big "Thank You" to Jim Popwell for helping this person get his 465B
running... AND for the excellent tip about using an NPN transistor's EB
junction as a zener!
The first 2N2222 transistor I tried had a starting zener point of 7.4
volts and a very square knee on a curve tracer.
Many zeners do not have a trace that nice!
tom jobe...
On 12/5/2014 8:27 PM, Jim Popwell jpopwell@... [TekScopes] wrote:
do you have any 6.2v zener diodes¡.or any spare npn 2n2222
2²Ô3904¡.³Ù°ù²¹²Ô²õ¾±²õ³Ù´Ç°ù²õ¡..
you can make a zener out of a spare NPN transistor emitter to base
junction¡..the base should be connected to the cathode point and the
emitter connected where the anode is of the original zener¡. this will
give a ¡°zener of about 6 to 7v to see if it affects the amps gain¡..
jim
On Dec 5, 2014, at 8:19 PM, Kevin Crossett kcrossett@...
[TekScopes] <TekScopes@...> wrote:
Oh. Thanks for the education...
On R4344
54.85 vdc
108.5vdc
On Fri, Dec 5, 2014 at 8:14 PM, Jim Popwell jpopwell@...
<mailto:jpopwell@...> [TekScopes] <
TekScopes@... <mailto:TekScopes@...>> wrote:
there should be 6.2v difference across VR4341¡. measure both sides of
R4344¡. on side should be 55v the other 103.8.
the blackish coating on the leads is silver oxide, not burned
stuff¡. a
lot of zeners from these years have it¡. usually diodes from
Motorola and
¹ó²¹¾±°ù³¦³ó¾±±ô»å¡..
jim
On Dec 5, 2014, at 8:09 PM, Kevin Crossett kcrossett@...
<mailto:kcrossett@...>
[TekScopes] <TekScopes@...
<mailto:TekScopes@...>> wrote:
Interesting VR4341 has some blackened materials on each of the
leads. Not
sure if that is normal, but to the untrained eye, it looks like
it might
have been toasted.
VR 4341 measurements
Cathode 110.6
Anode 108.6
On Fri, Dec 5, 2014 at 8:01 PM, Jim Popwell jpopwell@...
<mailto:jpopwell@...> <mailto:
jpopwell@... <mailto:jpopwell@...>> [TekScopes] <
TekScopes@... <mailto:TekScopes@...>
<mailto:TekScopes@... <mailto:TekScopes@...>>>
wrote:
find vr4341, a zener diode. measure both sides of it please
On Dec 5, 2014, at 7:58 PM, Kevin Crossett
kcrossett@... <mailto:kcrossett@...>
<mailto:kcrossett@... <mailto:kcrossett@...>>
[TekScopes] <TekScopes@...
<mailto:TekScopes@...> <mailto:
TekScopes@... <mailto:TekScopes@...>>> wrote:
Hi Jim. The symptoms do still exist when I press the 10x mag
button.
On Fri, Dec 5, 2014 at 7:56 PM, Jim Popwell
jpopwell@... <mailto:jpopwell@...>
<mailto:jpopwell@... <mailto:jpopwell@...>> <mailto:
jpopwell@... <mailto:jpopwell@...>
<mailto:jpopwell@... <mailto:jpopwell@...>>> [TekScopes] <
TekScopes@... <mailto:TekScopes@...>
<mailto:TekScopes@... <mailto:TekScopes@...>>
<mailto:TekScopes@...
<mailto:TekScopes@...> <mailto:TekScopes@...
<mailto:TekScopes@...>>>>
wrote:
one other thought¡. push in the X10 mag button and see if your
original
symptoms still exist¡..
jim
On Dec 5, 2014, at 6:46 PM, Kevin Crossett
kcrossett@... <mailto:kcrossett@...>
<mailto:kcrossett@... <mailto:kcrossett@...>>
[TekScopes] <TekScopes@...
<mailto:TekScopes@...> <mailto:
TekScopes@... <mailto:TekScopes@...>>> wrote:
OK. So I made the measurements on the test points as
directed by
Albert.
I
have not checked the transistors because I'm still not
sure the
best
way
to
do so. I also checked the wires to the deflector plates,
and they
seem to
be secure.
Here are the measurements based on the following
criteria. Scope
in
XY
and
both channels set to GND. Defocused the beam and
manipulated the
horz
control while reading voltages on the test points as
identified
in
the
manual figure 9-7.
TP VDC
85 1.42 to 3.90
86 2.35 to 4.90
87 -1.46 to -4.19
88 -2.10 to -3.34
89 36.25 to 36.80
90 35.60 to 37.07
These seem a little wonky to me, especially test points
86, 89
and
90.
Any thoughts?
On Fri, Dec 5, 2014 at 1:11 PM, aodiversen@...
<mailto:aodiversen@...> <mailto:
aodiversen@... <mailto:aodiversen@...>> <mailto:
aodiversen@... <mailto:aodiversen@...>
<mailto:aodiversen@... <mailto:aodiversen@...>>>
[TekScopes] <
TekScopes@...
<mailto:TekScopes@...> <mailto:TekScopes@...
<mailto:TekScopes@...>>
<mailto:TekScopes@...
<mailto:TekScopes@...> <mailto:TekScopes@...
<mailto:TekScopes@...>>>>
wrote:
Yes simply set both channels to GND and defocus the
spot. That
way
you
won't burn-in the screen.
Albert
---In TekScopes@...
<mailto:TekScopes@...> <mailto:
TekScopes@... <mailto:TekScopes@...>>,
<kcrossett@...> wrote :
Ah. I think I understand. Do I need to inject a
signal, say
from a
small
signal generator that outputs a dirty square wave, or
can I do
it
simply
by
turning on the scope, defocusing the spot and
manipulating the
horz
control
while measuring the voltage on the two test points?
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