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I have a fluke 3330b , have no output . I am not sure where to post for a fluke but i figured someone could point me in the correct direction for a group that can help me , or if someone here knows anything about going about fixing this voltage standard .

Hi Keith,

Obviously my suggestions are too cryptically for you. I hesitate to
continue since in my opinion you should understand the purpose of test
measurements, to learn something and also to protect the equipment and
yourself from damage. But let me try to clarify my previous suggestions.
Q1418 is the heart of the oscillator. Oscillation occurs because of the
feedback from collector to base provided by the windings 6-7 and 8-9 of
the transformer. The voltage and current amplitude in these windings is
determined by average base current which has to come from the regulator
circuit, Q1416 emitter. The oscillator produces an up-transformed
alternating voltage in the HV winding between pins 23 and 5 which is
half-wave rectified by CR1421 to give a negative HV at C1421 to C1424 and
CRT cathode.
A fault could be that one of these HV caps (or even C1488) starts to leak
at say 70 V. That would put extra load on the oscillator in its start-up
phase and and prevent the amplitude to rise further.
Another fault could be that CR1421 starts to leak, with the same
consequence.
Both these fault would show up of you externally feed TP1423 with a high
enough negative voltage (scope disconnected from the power inlet of
course). I simply use my 576? curve tracer for this purpose but you have
to improvise something. A DC supply, preferably variable, would be needed,
with + to scope ground and – to TP via a DMM. The DMM at say 200 V DC
range. The DMM is 10 M (usually), the load on TP is about 30 M. So the DMM
reading should be about 25% of the supply voltage and maintain that
percentage when the supply voltage is increased. When the percentage
starts to increase it indicates leakage somewhere, and you can also try to
estimate how heavy that leakage is.
Of course this would eliminate only a leakage fault in the branch from
CR1421.
A fault in the branche from pin 3 is not very likely, it’s low voltage.
That leaves a fault in the transformer itself (any winding could be
involved) or in the HV multiplier.

Suppose you disconnect P1400. Then you can supply an AC voltage across the
collector winding between pin 1 of P1400 socket and the fuse holder
terminal. I use a sine wave function generator for this. The generator
output is w.r.t. generator ground, so I connect that side to the fuse and
the live side to mentioned pin 1. (Additionally the fuse side can be
shorted to scope ground to prevent any floating voltage levels inside the
scope.) Some people use an audio amplifier.
This way I can control the input frequency an voltage amplitude. I also
monitor the generator output current and the TP voltage. With all this
information I can check that the resonance frequency is about what it
should be (maybe 50 kHz for a 465? I didn’t look it up) and also see if
stange things happen if I increase the amplitude.

L1419 and C1418/C1419 mainly serve to prevent oscillator signals to enter
15 V elsewhere. I think that even without these C’s the oscillator should
still work.

Albert

On Fri, Jun 15, 2018 at 05:50 pm, Keith Ostertag wrote:

Thanks for your continued help Albert. I _might_ be able to cobble

together a

power supply in excess of 100V... but I am not understanding what that

will

tell me, possibly because I am unsure of your use for the term leakage

in this

context. Since TP1486 is in the secondary side of T1420 (correct?) how

can

anything I do with it eliminate T1420 as a fault? For instance if

T1420's

primary (inline with Q1418) is shorted or partially shorted? At least

that 's

the question that comes to my mind, since I don't understand the

circuit. What

if L1419 is shorted or partially shorted? And how does that eliminate

(or

indicate) the HV multiplier as the fault?

Let's see... you are suggesting that I might "drive the collector

winding from

an external source" by adding a negative voltage to TP1486 (which is

connected

to the T1420's secondary), is that correct? So if I had a +200VDC power

supply

I would connect the +200V positive terminal to ground and the negative
terminal to TP1486?

In the case I could obtain an power supply, where exactly would I

measure the

leakage current and what level would be the pass/fail amount? I assume

you

mean replace the fuse F1419 with an ammeter as I did before in order to
measure Q1418's collector current?

My only guess is... by adding voltage to the secondary, a working

primary must

likewise increase, thus increasing the collector current. So... if it

does not

increase Q1418's collector current then that suggests a problem with

L1419 or

T1420 (or C1419)?

And if that is close to being correct as a strategy, then wouldn't

slightly

increasing the positive voltage at the fuse test it similarly? I say

that

assuming T1420's secondary is unlikely to have been damaged by anything

I

might have shorted in front of it...

Oops... rereading your message I see:"Then you could see at which

frequency it

resonates and how it responds to increasing primary amplitude.", which I

somehow missed in the above...

Let me start over... Q1418's circuit drives the signal taken from Q1416
through T1420, multiplying it by whatever the turns ratio of T1420 is.

You are

suggesting I unplug Q1418 and replace it with a short? Then read the

current

through F1419? Not sure how we are to read a resonate frequency when we

are

not applying a sweep... Sorry, as you can see this is a bit over my

head...

Thanks for your continued help Albert. I _might_ be able to cobble together a
power supply in excess of 100V... but I am not understanding what that will
tell me, possibly because I am unsure of your use for the term leakage in this
context. Since TP1486 is in the secondary side of T1420 (correct?) how can
anything I do with it eliminate T1420 as a fault? For instance if T1420's
primary (inline with Q1418) is shorted or partially shorted? At least that 's
the question that comes to my mind, since I don't understand the circuit. What
if L1419 is shorted or partially shorted? And how does that eliminate (or
indicate) the HV multiplier as the fault?

Let's see... you are suggesting that I might "drive the collector winding from
an external source" by adding a negative voltage to TP1486 (which is connected
to the T1420's secondary), is that correct? So if I had a +200VDC power supply
I would connect the +200V positive terminal to ground and the negative
terminal to TP1486?

In the case I could obtain an power supply, where exactly would I measure the
leakage current and what level would be the pass/fail amount? I assume you
mean replace the fuse F1419 with an ammeter as I did before in order to
measure Q1418's collector current?

My only guess is... by adding voltage to the secondary, a working primary must
likewise increase, thus increasing the collector current. So... if it does not
increase Q1418's collector current then that suggests a problem with L1419 or
T1420 (or C1419)?

And if that is close to being correct as a strategy, then wouldn't slightly
increasing the positive voltage at the fuse test it similarly? I say that
assuming T1420's secondary is unlikely to have been damaged by anything I
might have shorted in front of it...

Oops... rereading your message I see:"Then you could see at which frequency it
resonates and how it responds to increasing primary amplitude.", which I
somehow missed in the above...

Let me start over... Q1418's circuit drives the signal taken from Q1416
through T1420, multiplying it by whatever the turns ratio of T1420 is. You are
suggesting I unplug Q1418 and replace it with a short? Then read the current
through F1419? Not sure how we are to read a resonate frequency when we are
not applying a sweep... Sorry, as you can see this is a bit over my head...

I would like to affordably put together the things needed to repair plated
through holes. Anyone have any thoughts? I'm asking because I dont want to
buy this more than once. My pocket has not much room for mistakes right now
and i seem to do a lot better asking here before buying. Thanks guys

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Craig Sawyers
Sent: Friday, June 15, 2018 10:12 PM
To: [email protected]
Subject: Re: [TekScopes] S6 Sampling Head Bridge Cavity Question

I see now that I have been stuck in an endless spiral of screw-ups

of

my own making. Fixing them has certainly kept me busy most of my

life.

But every once in a while I surprise myself by doing something

really

astounding (at least to me) and I think all this stuff I learned had

a purpose.

Dennis Tillman W7PF

Hey - don't beat yourself up Dennis. The head might not be bust, there
might still just be a duff connection.

You didn't do something really stupid, like me when I plugged a
harmonica connector one pin out on the power supply of my 577 curve
tracer (unplugged originally to find a dead tant). Blew up most of the
silicon in the thing.

I've now got it pretty much sorted, other than one remaining problem
with either the step generator or amplifier. Real nightmare to sort
out. Rather fortunately every piece of silicon was easily available,
and socketted - even the dual FETs, which are still made.

Craig

You could likely make one. You'd need something for an anvil, could
easily be made from a 4mm or so rod, put a handle on it. The "hammer"
part could be made from an automatic center punch with a different
punch part. They're made to be removed. You'd want a design that
curled the end of the rivet over.

Note that eyelets work best if they are either solid copper, or tinned
copper. I'm not sure that any other variety would even accept solder.
Also, you may have to drill out the hole a bit if you are trying to
get the same inside diameter. A third (and slightly fatal) problem is
that I can't see any way to make this work on multi-layer boards.
Double sided is the most. It could hold down lifting foil on a single
sided board, also.

A little lathe work (if you have one) and it might just come together.

Harvey

Hi Bruce,
I think what you really are asking is what I ask every time I am going down to Beaverton: "why can't the Country Store be open when it is convenient for me because I happen to be in the area."

I think the answer is obvious. The store loses money. Being open twice per month is all they need to satisfy their regular customers (Ex-Tek employees) and just about everybody else.

Tek isn't interested in dealing with walk-in traffic for lots of reasons:
1) There is no reason to be open more often. If you are there on one of those days you would see there is only a very small group of people waiting to go in and they are mostly Ex-Tek people. So there is no reason to add more hours.
2) It is expensive to be open. You need someone (two people actually) to keep an eye out for people stuffing their pockets with small parts that have significant value.
3) Walk-in customers are a pain in the ass. I know because I am one. I will automatically ask them to lower the price enough on something I want so I can buy it.
4) Online sales via Ebay or whatever else they use are more cost effective because they can list big ticket items there.

Dennis Tillman W7PF
"Quando Omni Flunkus Terra Retreatum"

-----Original Message-----
From: Bruce Lane Sent: Friday, June 15, 2018 8:26 AM

Fellow Tekkies,

I've gotten curious about the rhyme or reason to the RAMS store's
limited public hours (two Thursdays a month, less than half a day).

Thoughts on this?

Thanks much.

--
---
Bruce Lane, ARS KC7GR

kyrrin (at) bluefeathertech dot com
"Quando Omni Flunkus Moritati" (Red Green)