Date   

Re: Adventure in tracing down jitter

richg_1998@...
 

Hi Windsor
Your Email address no longer works. I hope you have sent the tek 475
fan. Let me know.

Richard




--- In TekScopes@y..., mongteen@e... wrote:
Hello,

I have a RM31a that has a 54x CRT that works reasonably well.
Thanks
Dean :) There is a slight horz. jitter about 2mm worth. So I check
the left deflection pin and see that there was no jitter. I check
the
right deflection pin and see jitter. So I go about measuring and
changing tubes associated with the right deflection pin. Then I
sleep on it for a while. It occured to me to check for jitter at
very
low sweep speeds. I connect my 7704a to the right deflection pin
set
the coupling to AC and volia I found that the jitter is 120 Hertz.
So
I measured the 500 V supply and found ripple of about 1 volt PP. So
I
added a small cap to help filter out the ripple and the jitter is
gone!

The moral of the story is that alway check the PS first! I fell in
to
the trap of seeing that everything else worked OK and assumed the PS
was OK.


Windsor


Re: Adventure in tracing down jitter

 

--- In TekScopes@y..., Don Black <jeans@n...> wrote:

If it's got selenium rectifiers they may be getting weak, not
supplying
enough voltage or the regulators to work. Replace them with silicon
diodes
with added series resistors to compensate for the higher efficiency
of the
silicon diodes.
Even the Selenium Rectifiers aro OK (at this time), REPLACE them!
Often they fail suddenly with a short and not in any case the fuse(s)
blown fast enough to prevent damage to the transformerwinding(s)!!!

Seen those often enough... (not only in Scopes)

Jorgen
dj0ud


Re: Adventure in tracing down jitter

Stan or Patricia Griffiths <w7ni@...>
 

If you have identified the bad filter cap, I probably have a good salvaged
replacement that you can have for a few bucks. Let me know.

Stan
w7ni@easystreet.com

mongteen@excite.ca wrote:

Hello,

I have a RM31a that has a 54x CRT that works reasonably well. Thanks
Dean :) There is a slight horz. jitter about 2mm worth. So I check
the left deflection pin and see that there was no jitter. I check the
right deflection pin and see jitter. So I go about measuring and
changing tubes associated with the right deflection pin. Then I
sleep on it for a while. It occured to me to check for jitter at very
low sweep speeds. I connect my 7704a to the right deflection pin set
the coupling to AC and volia I found that the jitter is 120 Hertz. So
I measured the 500 V supply and found ripple of about 1 volt PP. So I
added a small cap to help filter out the ripple and the jitter is
gone!

The moral of the story is that alway check the PS first! I fell in to
the trap of seeing that everything else worked OK and assumed the PS
was OK.

Windsor

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Re: 21A and 22A for 555

Stan or Patricia Griffiths <w7ni@...>
 

Mixing 21,22,21A, 22A. Let me say I don't know of any reason why you
couldn't do it but I have never tried it . . .

I will keep my eyes open for some plugins for you. I just enlarged my
collection by an addtional 350 instruments (to a total of about 1100) so I
might just have some by the time I get all that stuff transported to my shop
. . .

Stan
w7ni@easystreet.com

morriso2002@yahoo.com.au wrote:

--- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:
morriso2002@y... wrote:
There was an extensive modification to the 21A and 22A tunnel diode
triggers

<snip>

I would stay away from
those
unless they have had Mod Kit 040-0417-00 installed.
Hi Stan,

Thanks for the advice. The only 21A/22A I have ever seen, which
belongs to a friend, has the later version triggers. These timebase
plugins are not easy to find and I suspect "beggars will have to be
choosers" if a pair ever turns up. Mind you, the 21/22 works very
nicely indeed.

Incidentally do you know if it is possible to mix a 21 and 22A or 21A
and 22 in the one mainframe?

Morris

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Re: 21A and 22A for 555

morriso2002@...
 

--- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:
morriso2002@y... wrote:
There was an extensive modification to the 21A and 22A tunnel diode
triggers

<snip>

I would stay away from
those
unless they have had Mod Kit 040-0417-00 installed.
Hi Stan,

Thanks for the advice. The only 21A/22A I have ever seen, which
belongs to a friend, has the later version triggers. These timebase
plugins are not easy to find and I suspect "beggars will have to be
choosers" if a pair ever turns up. Mind you, the 21/22 works very
nicely indeed.

Incidentally do you know if it is possible to mix a 21 and 22A or 21A
and 22 in the one mainframe?

Morris


Re: 21A and 22A for 555

Stan or Patricia Griffiths <w7ni@...>
 

morriso2002@yahoo.com.au wrote:

Timebase plugins however are not so easy to find - in fact if anyone
has a spare 21A/22A combo for disposal I would be happy to give them a
good home here in Melbourne Australia :-)

Morris
Hi Morris,

There was an extensive modification to the 21A and 22A tunnel diode triggers
at SN 11000. 21A and 22A timebases have the older tunnel diode trigger
circuitry in them from SN 7000 to SN 10999. I would stay away from those
unless they have had Mod Kit 040-0417-00 installed. The kit is very complex
and includes a double sided circuit board and lots of hard to find parts so
it would be almost impossible to try to put this kit together from scratch.
The early TD triggers were very unstable and I can remember being very
frustrated trying to get them adjusted so they would continue to operate
reliably.

They way to tell if the mod has been installed or not is too look in the
timebase in question on the top of the chassis and just behind the front
panel about an inch to see of the etched circuit board is installed there.
The early 21A and 22A timebases had a couple of short rows of the small notch
ceramic strips installed there with the early TD trigger circuits installed
on them.

Stan
w7ni@easystreet.com


Re: Adventure in tracing down jitter

Don Black <jeans@...>
 

Hi Windsor,
You seem to have found the source of the jitter however I
think you're working around the fundamental problem with your small bypass
capacitor.
Check the regulated power supply, perhaps the main filter capacitors are
weak, allowing too much ripple before the regulator or the regulator tubes
could be weak and saturating, passing the ripple.
If it's got selenium rectifiers they may be getting weak, not supplying
enough voltage or the regulators to work. Replace them with silicon diodes
with added series resistors to compensate for the higher efficiency of the
silicon diodes.
Your bypass capacitors might be a cheap way of working around the problem but
be prepared for it to get worse and you'll have to look further.
Don
Black.
PS check the mains voltage settings match the local supply, if it's set for a
higher voltage than your local supply so the set's not getting enough supply
voltage that could cause it to drop out of regulation.

mongteen@excite.ca wrote:

Hello,

I have a RM31a that has a 54x CRT that works reasonably well. Thanks
Dean :) There is a slight horz. jitter about 2mm worth. So I check
the left deflection pin and see that there was no jitter. I check the
right deflection pin and see jitter. So I go about measuring and
changing tubes associated with the right deflection pin. Then I
sleep on it for a while. It occured to me to check for jitter at very
low sweep speeds. I connect my 7704a to the right deflection pin set
the coupling to AC and volia I found that the jitter is 120 Hertz. So
I measured the 500 V supply and found ripple of about 1 volt PP. So I
added a small cap to help filter out the ripple and the jitter is
gone!

The moral of the story is that alway check the PS first! I fell in to
the trap of seeing that everything else worked OK and assumed the PS
was OK.

Windsor

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Adventure in tracing down jitter

mongteen@...
 

Hello,

I have a RM31a that has a 54x CRT that works reasonably well. Thanks
Dean :) There is a slight horz. jitter about 2mm worth. So I check
the left deflection pin and see that there was no jitter. I check the
right deflection pin and see jitter. So I go about measuring and
changing tubes associated with the right deflection pin. Then I
sleep on it for a while. It occured to me to check for jitter at very
low sweep speeds. I connect my 7704a to the right deflection pin set
the coupling to AC and volia I found that the jitter is 120 Hertz. So
I measured the 500 V supply and found ripple of about 1 volt PP. So I
added a small cap to help filter out the ripple and the jitter is
gone!

The moral of the story is that alway check the PS first! I fell in to
the trap of seeing that everything else worked OK and assumed the PS
was OK.


Windsor


8233/E55L

Steve B.
 

Greetings;

I am trying to understand the failure mode of one of these in a 3A6.
Both cathode tabs are melted and the 47^ screen resistor is smoked.
With great trepidation, I replaced the defective tube after checking
the asssociated 6DJ8s, xistors, and diodes. The replacement held and
the screen resistor stayed cool. However, there is a DC imbalance on
both traces that the controls won't comp. I suspected possible
filament-cathode leakage in the otherwise fresh looking dead tube. No
way to check for that now. I definitely don't want to risk a
presently good 8233/E55L. Any ideas on the probable failure mode?
Thanx in advance; Steve

P.S., Hi Stan, nice to find you again. Great Resource!


Re: Tektronix 500 Series Scope Plug-In

Phil (VA3UX) <phil@...>
 

At 01:11 AM 5/31/2001 +0000, morriso2002@yahoo.com.au wrote:
--- In TekScopes@y..., "Phil (VA3UX)" <phil@v...> wrote:

Finding a non-blank plug-in for a 555 is tough enough,
The 555 will take quite a wide range of vertical plugins including the
53/54 series, the letter series and the 1- series. With some of them
(such as the 1A4) you have to be careful that the timebase plugins
have been appropriately modified to remove DC bias from one of the
pins which could otherwise damage the plugin (I have details if anyone
needs them).

Sorry Morris. It was the 21A/22A timebase plug-ins I was referring to in my comment, rather than the vertical plug-ins.

Timebase plugins however are not so easy to find - in fact if anyone
has a spare 21A/22A combo for disposal I would be happy to give them a
good home here in Melbourne Australia :-)
I *might* be coming into some of these shortly. If I do I'll let you know.

Phil

Morris



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Re: Tektronix 500 Series Scope Plug-In

morriso2002@...
 

--- In TekScopes@y..., "Phil (VA3UX)" <phil@v...> wrote:

Finding a non-blank plug-in for a 555 is tough enough,
The 555 will take quite a wide range of vertical plugins including the
53/54 series, the letter series and the 1- series. With some of them
(such as the 1A4) you have to be careful that the timebase plugins
have been appropriately modified to remove DC bias from one of the
pins which could otherwise damage the plugin (I have details if anyone
needs them).

Timebase plugins however are not so easy to find - in fact if anyone
has a spare 21A/22A combo for disposal I would be happy to give them a
good home here in Melbourne Australia :-)

Morris


Re: Tektronix 500 Series Scope Plug-In

Phil (VA3UX) <phil@...>
 

At 11:12 AM 5/30/2001 +1000, Andrew Campbell wrote:
Hi All,

Could anyone tell me where I could find a "blank" vertical plug-in module
for a Tek 555 series scope?

Apparently there was a kit available at one time.
Finding a non-blank plug-in for a 555 is tough enough, let alone a blank one. I've never seen one Andrew but I'll keep my eyes open during flea market hunts. Stan G. and Deane Kidd are the only other potential sources I can think of at the moment.

Phil

Regards,

Andrew





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Support for Tektronix TDS Oscilloscopes

Andrew Campbell <service@...>
 

Hi All,

Does anyone know of a company or business that may be able to supply boards
for the Tektronix TDS model oscilloscope. They could be boards that have
been pulled from non-repairable instruments.

Tektronix has recently removed from their "Long Term Support Program" a
variety of early model TDS oscilloscopes.

In particular I am interested in obtaining TDS540 Acquisition Boards and
TDS540 Processor Boards. I have recently tried Verizon (GTE) and they won't
part with boards, they want me to send in the instrument for them to survey.

Not a good option from Sydney, Australia.

Best Regards,

Andrew


Re: Tektronix 500 Series Scope Plug-In

morriso2002@...
 

--- In TekScopes@y..., "Andrew Campbell" <service@c...> wrote:

Could anyone tell me where I could find a "blank" vertical plug-in
module
for a Tek 555 series scope?

Apparently there was a kit available at one time.
I would be surprised if a kit is still around. When I wanted to build
a custom plugin I butchered an old type 80. The dimensions are the
same and the plug just has to be reversed. I'm sure there are plenty
of junker plugins around at hamfests etc.

morris


Tektronix 500 Series Scope Plug-In

Andrew Campbell <service@...>
 

Hi All,

Could anyone tell me where I could find a "blank" vertical plug-in module
for a Tek 555 series scope?

Apparently there was a kit available at one time.

Regards,

Andrew


tek 321a-broken time sweep

sidkeo@...
 

need help on repairing the time sweep for tek 321a-everything else
works.

thanks,
sid


tek 2221 service manual

sidkeo@...
 

does anyone know how i can get a hold a tek 2221 tek
service manual.

thanks,
sid


Re: 1L20 Spectrum Analyzer

dd@...
 

The 1L20 manual is available for rental from W.J. Ford:

http://www.falls.igs.net/~testequipment/manuals.html


Re: 1L20 Spectrum Analyzer

Stan or Patricia Griffiths <w7ni@...>
 

Hi Andrew,

You are right about the 1L20 being used in the 555. It can also be used in any
other 530/540/550 mainframe.

There are a lot of places to look for manuals if your request here does not
turn one up for you. You might try eBay. Another possibility is to take a
look at the list of manual suppliers on my web page at:

http://www.reprise.com/host/tektronix/resources/manual_sources.asp

Stan
w7ni@easystreet.com

Andrew Campbell wrote:

Hi,

I am looking for a manual for a Tektronix 1L20 Spectrum Analyzer plug-in. I
believe it is used with the 555 Scope?

Regards,

Andrew



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Re: 475 hor.jitter

Richard Gagnon <richg_1998@...>
 

Thank you Dean. As soon as my manual arrives I will
look into this. I thought the fan was maybe a 12vdc
fan.

Richg




--- dhuster@pb.k12.mo.us wrote:
Rich, the 465, 465B, 475, 475A, 464, 466 and 468 had
identical fan
modules. And by the way, this has nothing to do
with bearing noise,
but if you have a fan that has a dead spot and won't
always start up
and you don't know whether to blame the motor or the
driver chip,
just put the motor on the dead spot and then pull
the driver chip and
reinstall it "backwards". It has a symmetrical
pinout, and if one of
the transistors in the driver chip is bad, you'll
have moved it to a
different spot in the switching sequence, the motor
will no longer be
on a dead spot with the reversed chip and will
probably start up when
power is applied. If the dead spot is still in the
same place, then
you can blame the motor.

And Rich, the 475 has had several reliability mods
over it's life,
and if you have a lower serial number, it may need
some of them.
The -8v P/S should have a new rectifier that's much
larger than the
others (i.e., it's NOT a 152-0488-00) and will be
laying down rather
than standing up in order to clear the case.

There's also a bluish 1% resistor (with the scope
upside-down as you
look on the main board with the front panel facing
you, it's along
the left edge maybe 2 or 3 inches from the front)
that overheats,
turns brownish and changes value, goofing up the
timebases. If
there's a black resistor in that spot, the mod has
already been
made. Otherwise, it needs replaced with a
higher-power resistor.

And the one mod that may concern you most is down
near the hole where
the horizontal deflection plate leads go down to the
jug. An
unmodified scope has a silver-colored, axial-lead,
tantalum, 1000�F
capacitor just to the front of the hole. If it's
there, get rid of
it, for it's underrated in voltage and will cause a
jittering
problem. A modified scope usually has a
physically-larger, black
aluminum electrolytic with a higher voltage rating
installed in it's
place.

Dean



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