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Old 1st Sep 2012, 6:01 am   #161
6AL5W-Martin
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Default Re: Oscilloscope Collection / Junky

typically for the Tek 422 is a bad intensity pot...
Exactly this is the problem. All other works best.
Extra: this unit have a mesh in front of the screen.
The soft foam in the cover is to change for new,
The complete case likes to be painted,
The little solder roll in the cover is missing, I have to put a new.


422, Classic Tek, 15MHz, MIL quality, 1965



greetings
Martin
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Old 7th Oct 2012, 10:18 pm   #162
6AL5W-Martin
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Default Re: Oscilloscope Collection / Junky

hello friends,

our old subject is still actually ...

Today arrived:

a 100 MHz "Gould" Scope, cold and heavy. Problems: hv and may be more.

a poor 535A: missing parts, but I will restore him also.

a 502A: dirty, and very welcome in my warm Dual Beam collection.

greetings
Martin
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Old 11th Oct 2012, 9:45 pm   #163
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Default Re: Oscilloscope Collection / Junky

If I had another scope I could fault-find my Tek 422 which gave up the ghost a couple of days ago. It must be 40 years old or more but I have the manual and I'm going to resurrect it.
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Old 12th Oct 2012, 4:50 pm   #164
6AL5W-Martin
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Default Re: Oscilloscope Collection / Junky

hello Frank,

422 ist one of the best Scopes Tek made..
the most oftenly problem is a defect intensity pot.
I have 3 of them..

greetings
Martin
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Old 12th Oct 2012, 7:42 pm   #165
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Default Re: Oscilloscope Collection / Junky

Hello Martin,

Do you have 3 422 scopes or 3 intensity pots? Seriously, thanks for the comment, I will look at that pot. I took the covers off for the first time today and checking the power supply found about -550V on the HT test point (crt grid). I'm not in the workshop just now but I think the expected value is around -1350. I will get back onto it tomorrow.

Regards, Frank.
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Old 13th Oct 2012, 4:36 am   #166
6AL5W-Martin
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Default Re: Oscilloscope Collection / Junky

hello Frank,

I have 3 of that scopes.
All of them was with a problem at intensify pot...

If you need compare measurement in a running 422 I can do that for you.
There are both versions of 422: the "with nuvistors" and the "without".

greetings
Martin
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Old 14th Oct 2012, 6:23 pm   #167
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Default Re: Oscilloscope Collection / Junky

Martin,

I have taken some power supply measurements using my Fluke 8020A dvm. If you have a copy of the Tek 422 manual I am looking at page AC Power Supply. here +12V, -12V, +95V, +55V and -110V are all good. When I go to the HT test point on the crt base I find only -548V where there should be -1375V.
I went to the previous manual page CRT Circuit. Here the focus and intensity pots are good and the diodes etc on the multiply board are good. With the power back on I measured the output of transformer T801 into the multiplier board and see 200V ac. I think this should be 400V or more for the circuit to work correctly so back at the power supply I look at the collector voltage for Q675 and Q685. The dc conditions for the chopper are good but on these collectors only 6V ac. I think this is too low and maybe the 3.3nF capacitors may be leaky I have seen these yellow things give problems before. I will get some caps this week and let you know what happens. If you think of anything I may have missed please say.

Regards,
Frank.
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Old 17th Oct 2012, 11:57 am   #168
6AL5W-Martin
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Default Re: Oscilloscope Collection / Junky

hello Frank,

disconnect the transformer and look if the high voltage is up. If yes there is an overload, mostly by a bad Disc C.

greetings
Martin
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Old 17th Oct 2012, 11:16 pm   #169
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Default Re: Oscilloscope Collection / Junky

Oh have I got a big smile on my face.

I was at the Lothians club's annual surplus equipment sale and I picked up a Tektronix 2221 digital storage scope which does 60MHz bandwidth, readouts and measurements all in a portable case, and a spare Tek 465B in nice clean condition. Loads of brightness, but the focus pot is at one endstop, to act as spares for my 465B in the radio shack.

THere were several Gould scopes and one Panasonic. A good night for the scope collector!

David
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Old 22nd Oct 2012, 11:54 am   #170
6AL5W-Martin
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Default Re: Oscilloscope Collection / Junky

I am very happy,

have buyed a Tek 575
it`s the greatful curve tracer.
greetings
Martin
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Old 23rd Oct 2012, 1:27 pm   #171
G0HFCFrank
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Default Re: Oscilloscope Collection / Junky

Martin,

Many thanks for your help, the problem on my tek 422 was not one but two disc caps on the HV board.

thanks again,

Frank.
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Old 23rd Oct 2012, 4:39 pm   #172
6AL5W-Martin
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Default Re: Oscilloscope Collection / Junky

Fine that your 422 is wake up again

in the Tube Teks there is always bad Disc C in the HV area,
in 422 I have not seen that. But very possible...
In my workroom is a very large box of them, 10nF 3kV mostly, some 4kV. Food for 500 series scopes

like this : see picture.

greetings
Martin
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Old 26th Oct 2012, 7:13 pm   #173
G0HFCFrank
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Default Re: Oscilloscope Collection / Junky

You must have a very large workroom Martin, I used a 545 at work back in the 1960s then in 1972 when I went on the road as a service engineer I was given this 422 which stuck to me when I was upgraded 20 years later.

Regards, Frank.
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Old 27th Oct 2012, 4:49 am   #174
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Default Re: Oscilloscope Collection / Junky

hello Frank,

it was a small work room, now it`s a home of 30 old scopes with a little place to work between them... my hobby, to see on my home page.

greetings
Martin
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Old 28th Oct 2012, 7:36 am   #175
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Default Re: Oscilloscope Collection / Junky

502 A Restoration,


the glowing dual beam family of Tek,
555, 551, 565, 556, and now on the table, 502A

http://www.wellenkino.de/502A/001.jpg

http://www.wellenkino.de/502A/014.jpg

http://www.wellenkino.de/502A/018.jpg

http://www.wellenkino.de/502A/016.jpg

http://www.wellenkino.de/502A/021.jpg

greetings,
Martin
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Old 5th Nov 2012, 5:22 pm   #176
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this is my 535A No2,

a very muddy scope, and a very lot of domestic ...

greetings
Martin
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Old 26th Nov 2012, 10:46 pm   #177
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Default Re: Oscilloscope Collection / Junky

Yesterday I went to a local amateur radio rally. I was using the train so that should have prevented any oscilloscopes or other large equipment from joining me on the journey home. However I spotted this CT52 'miniature' oscilloscope, for sale at a modest price, which included the proper Plessey Mk4 connector on the mains lead. It was in clean condition and seemed to have been well cared for. It was stated to have a timebase fault which indeed was true. However this was an easy fault to find as the photos show. Apart from a couple of replacement electrolytics it seems to be original inside.

The CT52 dates back to the early 50s, my example being dated 1953. They were intended to be used by all three armed services and mine has an Air Ministry number on the chassis of the psu as well as the normal services label on the front panel. It also has a test label indicating that it was in civilian use until 2000 but there is no indication of the owner of what was by then was a very basic unit. Somehow I don't think it will replace my Teks but all the same it is a nice find.

Edward
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Old 9th Dec 2012, 10:34 am   #178
6AL5W-Martin
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Default Re: Oscilloscope Collection / Junky

hello Alan,

the old 535A is not finished, there was a lot of problems...

misssing or defect / removed parts:
the black plugs in the front ( I have useful spare, =repaired)
the 10 turn pot complete demolition ( I got a spare part, = repaired)
the reset switch ( I got a spare part, = repaired )
3 dead 6DJ8 ( changed by E88CC TFK, = repaired )

defect 12AL5 ( open, I have to buy a new )

no long time, then it will wake up.


coming soon: An old RM565 is on the way to it`s new home. Cute & heavy

greetings
Martin
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Old 9th Dec 2012, 12:30 pm   #179
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Default Re: Oscilloscope Collection / Junky

Here's my latest acquisition, a Wayne-Kerr RA200 audio response analyser. Picked it up last Sunday at RWB from a fellow forum member.
Also marketed under the Ferrograph name, both brands having the same parent company.
Date codes suggest this was manufactured late 1980.
Fairly straightforward fix, one of the -15 V supplies was missing, this was tracked down to a failed LM301A op-amp.
Borrowed a replacement from a line testing add on unit that came with it.
After leaving on soak for a couple of hours I tempted fate by refitting the covers.
Sure enough another fault appeared, now the other -15 V supply had disappeared.
It uses separate supplies for the output and input stages to prevent earth loops.
Luckily I had ordered two replacement 301's, so now back in full flight.
As per usual those god awful latching push button switches need a good dose of switch cleaner, as did the slide switches on the rear panel.
Well pleased with the unit, I've added some pics showing the response of a Gardners microphone matching transformer (excellent) and the response of an interstage driver transformer (not so good).
Thanks for looking,
Rob.
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Old 9th Dec 2012, 2:38 pm   #180
6AL5W-Martin
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Default Re: Oscilloscope Collection / Junky

hello Rob,

that is an amazing instrument.
Looks like a TV-CRT. Is that P7 Phosphor? (fast = light blue, slowly follower = yellow-green)

greetings
Martin
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