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Old 15th Nov 2021, 10:17 pm   #1
Chris55000
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Default Dumont Oscilloscope been under the sea!

Hi!

Can anybody give me some recommendations for renovating the metalwork on this DuMont 1602 Oscilloscope I've pulled the trigger on please?

(All that white verdigris everywhere suggests it's been under the sea, and not in a sub either!)

From what I understand, it was built as part of a U.S. Defence Contract and issued the type–designation AN/USM281E, but I can't find that exact manual, so I'll have to use the AN/USM281A one for the HP 180 series as a guide – the back is very similar to the one shown in manual AN/USM281A.

I'm happy to completely strip this metalwork out completely so it can be cleaned and renovated properly – I assume it's aluminium, but if not can anyone confirm what metal it will be please?

Has any other Member seen one of these in the past?

Chris Williams
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Old 16th Nov 2021, 12:45 am   #2
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Default Re: Dumont Oscilloscope been under the sea!

Seeing the state of the housing I'd be even more worried about what the inside looks like.
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Old 16th Nov 2021, 1:18 am   #3
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Default Re: Dumont Oscilloscope been under the sea!

Hi!

Since there are many similarities between the back view of this and the rear view diagrams shown in AN/USM281A I'm taking a gamble that I can use bits from the HP180 remains I have under the bed!

Since my initial query I found someone selling a paper copy of AN/USM–281D/E which I now have on order, so this if book turns out to be correct I can confidently proceed with stripping out what's necessary to dismantle and clean the internal metalwork!

The book has to come from the USA so I doubt I'll see it before Christmas!

It does puzzle me how these American oddments get over here in the first place – the HP 180 was a mainstream seller that thousands know about over here, but Dumont are as rare as hen's teeth, and modern solid–state Dumont even rarer – odd–ball American models like this over here are usually antediluvian old heavy valved beasts!

(I'm currently stripping down a Cossor CDU130 to document all the internals, but got stuck with a rusty knob grub–screw that won't come out, but that's another story!)
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Old 16th Nov 2021, 7:52 am   #4
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Default Re: Dumont Oscilloscope been under the sea!

The various cabinets HP used for their instruments in the sixties onwards were based on a number of castings. The castings and other cabinet parts were also sold to other companies, so there's a lot of gear out there that has that HP look.

PAECO Palo Alto Enngineering Co was set up as a subsidiary, manufacturing cabinet parts, transformers and a number of items with common useage.

Those look like 180 scope cabinet castings, but he scope is probably completely different.

The HP cabinets with the cast-in side handles were 'System I" the later cabinet stuff assembled from front and rear castings of various sizes with various length cast front-read struts was "System II" this could make an immense range of boxes. The front and rear castings were done in rack, half rack, third rack widths and a variety of heights, then there were the different struts to multiply the whole lot by several depths.

A true delight for any meccano enthusiast!

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Old 16th Nov 2021, 11:43 am   #5
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Default Re: Dumont Oscilloscope been under the sea!

Perhaps: Take the covers off and give it a cycle in the dishwasher.

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Old 16th Nov 2021, 5:10 pm   #6
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Default Re: Dumont Oscilloscope been under the sea!

Construction likely to be part aluminium part steel, and as it's probably been in a draughty outbuilding near the sea, the intersection between the steel and ally components could be the worse bits for crumbling- aluminium oxide is such a harsh abrasive that commercially it's glued to paper and sold as such- not good news for all the knobs and pots..!

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Old 16th Nov 2021, 6:22 pm   #7
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Default Re: Dumont Oscilloscope been under the sea!

It's good to see something different- I certainly wouldn't go as far as to say that HP180s were "mundane" or "common as muck" but it's interesting to see a 'scope from an outfit as hallowed in the CRT annals as DuMont. Presumably, the contract called for 'scopes of similar proportions, it certainly recalls the HP180 in that respect. I hope it hasn't actually been in the sea, just rather damp and neglectful storage- that looks like a water stain on the lower edge of the bezel, as if condensation has been dripping off it for some time. Fingers crossed that things like the mains and EHT transformers are still OK (I assume that an instrument of this grade would use the HF power oscillator technique for EHT generation) as well as the CRT.

With harder aluminium alloys, like extrusion alloy, I've found that the dark green plastic fibre pan scourers can clean speckly surface corrosion up quite well- with softer sheet alloys they can leave a cloudy, fine scratch finish. As always, gently does it to start with on an inconspicuous bit.

Good luck with it, it'll be interesting to see how it turns out,

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Old 16th Nov 2021, 10:24 pm   #8
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Default Re: Dumont Oscilloscope been under the sea!

Hi!

I haven't yet had notified of either of them (there was another identical model for sale as well, admittedly in the U.S.A., so I pulled the trigger on the second as well!), having started on their travels to me yet, all that appears wrong with the second cosmetically, apart from what appears to be a thick cocoon of dust, is the finishing disc from the centre of the red T.B. variable knob missing – but I'll post plenty of pics and circuit extracts, which will be in a new thread detailing the repair progress in the Vintage T & M Equipment Section!

Since it very much based on the '180 down to the panel layouts, control designations and lettering, it could even have the '180's panel circuit designs, re–labelled "DuMont" of course – I have bookwork on order for them!

Chris Williams
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Old 17th Nov 2021, 10:51 pm   #9
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Default Re: Dumont Oscilloscope been under the sea!

Hi Chris55000 don,t know if you have seen this , lot of info here may help.
https://www.antiqueradios.com/forums...hp?f=8&t=90779
can't wait to see the inside, good luck
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Old 18th Nov 2021, 10:09 am   #10
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Default Re: Dumont Oscilloscope been under the sea!

Hi!

Yes, I read that page, a bloke on there said he had the Dumont 1062 circuits but didn't offer to post them, one of my pet annoyances!

No internal views of any of the boards tho', but there will be from me – I'm expecting mine later today or tomorrow!

Chris Williams
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Old 18th Nov 2021, 11:03 am   #11
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Default Re: Dumont Oscilloscope been under the sea!

This is a bit peripheral, because I thought that Dumont was the instrument company that was the subject of a landmark case that Tektronix won.

It wasn't. Tektronix, in 1965, sued the United States. And won.

What happened was a decision not to buy large numbers of (expensive) oscilloscopes from Tektronix, but to buy them at a cheaper price from a subsidiary of Hickok called duMont.

Tek spotted a rat, and immediately put a hole in the rear panel of the 5xx series valved oscilloscope plugins that had absolutely no function. So when duMont plagiarized the design, they copied the useless hole.

Gotcha. Since the purchasing order specified a functional equivalent of the Tek scopes, Tek sued the United States.

Craig
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Old 18th Nov 2021, 12:47 pm   #12
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Default Re: Dumont Oscilloscope been under the sea!

NOT Dumont that was the plagiarizer! It was LaVoie who copied the Tek equipment.

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Old 27th Nov 2021, 12:11 pm   #13
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Default Re: Dumont Oscilloscope been under the sea!

Hi!

Not yet arrived yet so still nothing further to report yet I'm afraid, altho' I've been notified they're now in the UK!

Chris Williams
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Old 21st Dec 2021, 6:42 pm   #14
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Default Re: Dumont Oscilloscope been under the sea!

Hi!

DuMont 1062 just arrived the day before my sister and b.i.l. arrive to run me to theirs for the Christmas Holliers so I'll have to post my pics after the holiday period!

I got a book for it from the USA but apparently it's not the correct one for it, so I might have to do a load of scribbling to repair this one as well!

Chris Williams
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Old 21st Dec 2021, 8:31 pm   #15
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Default Re: Dumont Oscilloscope been under the sea!

Hi Chris,

If you do strip it to the metalwork, maybe try a hot dishwasher with double dose of detergent and long wash, followed by a hose wash.

May have remove one DW tray or spray to fit it in.

Good luck
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Old 21st Dec 2021, 9:30 pm   #16
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Default Re: Dumont Oscilloscope been under the sea!

Quote:
Originally Posted by Craig Sawyers View Post
NOT Dumont that was the plagiarizer! It was LaVoie who copied the Tek equipment.
And Hickok, and Jetronic, apparently https://w140.com/tekwiki/wiki/Hickok
That Dumont scope does look curious. I've never come across one before.

Chris
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Old 27th Feb 2022, 12:23 pm   #17
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Default Re: Dumont Oscilloscope been under the sea!

Hi!

Most of the DuMont Oscilloscopes that appear for sale are of the Fairchild valve variety with "valvephoolery" prices to match, but these are 60 MHz dual–channel fully solid–state units!

There's definitely a family resemblance between these and the H.P. 180 series Oscilloscopes tho!

First project on these is to document the differences between the manual I have (imported from the U.S. along with the oscilloscope) and the actual unit!

I expect to begin on them in the next two weeks, unfortunately our boiler has broken down so that's why my project work is on hold as it's simply far too chilly to sit in there for long – the cold makes my fingers painful!

Chris Williams
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Old 14th Mar 2022, 11:42 am   #18
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Default Re: Dumont Oscilloscope been under the sea!

Dumont 1062 mod 116.
Chris, I have the full manual for this version. I suspect the AN/USM 281E.
It appears that version USM281A is the HP180/1821/1821. USM281C is Tek 7403N/7A18/+TB.
And version E is this Dumont 1062. Uses the transistor array CA3046 in the Y Amp, several ua709 in the power supply and a Philips D14-162 tube. The TB delay 10 turn pot is oddly placed up beside the tube screen under the Horiz shift on the HP180.
This might help to identify if this is the version you want.
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Old 15th Mar 2022, 11:58 am   #19
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Default Re: Dumont Oscilloscope been under the sea!

Hi!

Ah, perfect !

PM sent to WME_Bill re 1062 Mod 116 Manual !

Chris Williams
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