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 Post subject: Re: Tektronix 453 Restoration
PostPosted: Oct Fri 06, 2017 8:10 am 
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Location: germany
I think that is made like in the 556 unit, the 5642 is for the screen HV, and the VARO is for the neg. cathode HV
greetings
Martin


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 Post subject: Re: Tektronix 453 Restoration
PostPosted: Oct Fri 06, 2017 5:35 pm 
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Location: Hillsboro, Oregon
Yes, Martin, but there should be a second VARO for the grid supply. I think it should be on the bottom, out of sight in the OP's pictures, unless it is now the lonely DL800.

Since the CRT intensity depends on the difference between the grid and cathode, these two supplies need to match and track. Substituting a different type diode for one of them will change that one without changing the other, causing the intensity to change, maybe all the way to zero.


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 Post subject: Re: Tektronix 453 Restoration
PostPosted: Oct Fri 06, 2017 7:10 pm 
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Joined: Nov Wed 15, 2006 7:56 am
Posts: 1403
Location: germany
This Tek must be test with a hig Voltage Probe whats going on there.
I am missing facts :wink:

Dave have written the - Voltage is -1950V , this is to test.
If this is the Cathode, the negative supply must be around 100V more negative, means -2050V,
then the CRT want to work.

When the grid is enoug more negative then the cathode the beam will be darker (controlled by intensitiy. )
other ways to make off the beam can be:

the heating, filament is defect = new CRT required. Test by Ohms Meter at the CRT
the time base have a problem and you have "always dark", normally this is only giving dark when the beam goes back to the left start position. This needs repair
the positive high voltage for the screen is too low or not present.

I think when the - cathode HV is not present or the grid voltage, you will see anything, but no darkness.

So please checking:

Filament of CRT,
HV by HV Probe.
and the unregulated Voltage for feeding the HV oscillator, including the fuse what it have, there is one.

greetings
Martin


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 Post subject: Re: Tektronix 453 Restoration
PostPosted: Oct Fri 06, 2017 7:21 pm 
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Location: Columbus Ohio
Danke Martin
I'll look at those circuits.

best regards
Joe

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 Post subject: Re: Tektronix 453 Restoration
PostPosted: Oct Fri 06, 2017 7:36 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
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Location: Sunbury, Ohio 43074
what SERIAL NUMBER is your 453? Maybe it's close to mine and I can help you with photos of the insides and perhaps manual scans

barry

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 Post subject: Re: Tektronix 453 Restoration
PostPosted: Oct Fri 06, 2017 8:31 pm 
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it's a 453, mod163D, serial 041848

Joe

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 Post subject: Re: Tektronix 453 Restoration
PostPosted: Nov Sat 09, 2019 9:38 pm 
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Joined: Nov Sat 09, 2019 9:06 pm
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Hello,
I apreciate many great insights into the complexities of these old scopes here on this forum - very expertly advice.
I recently became the lucky owner of a Tektronix 454 in quite good condition. I’d like to do what I can to bring it back to very good/excellent condition. Some basic tests from the 454 manual have shown it works for the most part. All power supply voltages OK too.
A lot of switches and knobs are flakey, need to be wiggled to work properly, esp the slider switches.
So I want to get behind the front panel and carefully clean them up, preferably permanently. My questions are:

1. Is there or has there ever been a separate Service manual for the 454? I couldn't find any. I already have the original “Instruction manual, Type 454/R454 Oscilloscope”.
2. Has anybody ever removed the front panel? I looked at the manual closely, lots of disassembly instructions, but NONE for the front panel.
It seems it cannont be done without basically removing all the boards/components behind it first? Looks like the front panel control elements need to be left in place
and reached as good as I can.
3. What do you think of using this contact cleaner (in small amounts) on all sliding contacts: DEOXIT Gold G100L?
The description reads: “ improves conductivity and provides long-lasting protection on gold, base metals and other precious metal contacts and connections (gold, silver, rhodium, copper, bronze, nickel, etc.)”. Are the 454s slider contacts in that category? I Don't know what theyre made of.
I once was very skeptical of hugely expensive liquids like that. That is Until I tried special "F5 fader lube" on badly crackling/jittering
potentiometers, and it seemed to work miracles - the effect seems permanent too, so far 3+ years.

So in short I’m inclined to just treat all the front panel controls with Deoxit Gold G100L, at least whichever ones I can reach without too much disassembly. Any suggestions?


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 Post subject: Re: Tektronix 453 Restoration
PostPosted: Nov Sun 10, 2019 2:34 am 
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Location: Rochester NY USA
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 Post subject: Re: Tektronix 453 Restoration
PostPosted: Nov Sun 10, 2019 4:17 am 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 5375
Location: Sunbury, Ohio 43074
I would spray into those switches and controls ONLY AS A LAST RESORT, and expect to scrap the scope after that. I've brought many of this series back to life by just exercising the switches until my fingers got numb. Give that a try first, all of them. Pushbuttons, wafers, sliders, everything. One by one. Then do it again. And perhaps again.

I've never tried to remove a front panel... I'm not sure you could. But if you could, it would be one herculean project to say the least.

There is a service manual for the 454. I've got one. It's huge, just like the 453, and 465, and basically all of the Tektronix manuals.

Back to spraying ... if you do decide to take the route of last resort, I'd first try just plain isopropyl alcohol spray followed by air blast before powering it... but please try just exercising the switches first.......

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 Post subject: Re: Tektronix 453 Restoration
PostPosted: Nov Sat 16, 2019 3:18 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Beaver Falls, PA. USA
The 454 is a great scope; I have been using one on my bench for several years. The big problem with mine was a bad tunnel diode in the "A" time base circuit.

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 Post subject: Re: Tektronix 453 Restoration
PostPosted: Nov Sat 16, 2019 11:59 pm 
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Joined: Nov Sun 07, 2010 7:16 pm
Posts: 730
Location: Manchester, MI
IIRC, at least some of the panel switches in the 454 are open and I think a little judicial use of DeOxit would be useful. RestorJan did not say spraying and that should be avoided at all costs. For the most part, operating the switches a few hundred times would bring them back to life. I would be particularly careful around the attenuator switches, even with DeOxit Gold. There are good service manuals available free online and printed ones aren't very expensive (well worth it in my opinion), but taking the front panel off would be a significant task. You' d probably have to disassemble most of the scope; this was a discrete scope and the controls were wired in place. I would pass on that.

I restored a 454 a couple years ago and I was surprised at the availability of NOS parts. It's now one of my favorite scopes. I have a 454A in my queue which is similar in specs, but has a larger screen. I think that one is the best discrete portable analog scope ever made.


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