HP 180A: chances of repair?

[factory]

There is a 182A in the offered section at the moment if your interested, the EHT is present but arcing over somewhere (stops when EHT connector is disconnected).
https://www.vintage-radio.net/forum/...d.php?t=169818

David

[turretslug]

Originally Posted by Radio Wrangler

The flood gun grat illuminator is gorgeous.

It sure is a thing to behold- I hope I'm not the only one who, on encountering one for the first time and unclipping the covers, thought "Where the heck are the bulbs and holders, and how did they get the illumination so even?" The answer being, of course, the tube is the "bulb".

Well worth seeing if you can get it going, something of an all-time classic IMHO (and apparently I'm in good company there). They are electronic pensioners now though, and there's always the chance of something terminal as mentioned by Skywave, so prepare for a possible letdown. At least there is plenty of good advice and knowledge from the likes of WME_bill and Radio Wrangler. Good luck with it, Colin.

[Radio Wrangler]

Sadly, I come across a number of tubes where the grat flood filament is open circuit.

The building where the CRTs and most of those scopes were made was flattened a long time ago then accountants ceremonially salted the ground and did a little accountancy dance on it for good measure.

David

[Craig Sawyers]

Originally Posted by David Simpson

I was sorry to read that Woodchips didn't like his dozen 180A's. To me, having initially worked on Hartley 13A's,

The 13A was my first 'scope aged 15. When you could by NOS ones that were released from the MOD. Had all the leads and cathode follower probe in the front cover.

A real hernia job, and useless performance. But it taught me about using a scope.

Sold it aged 17. Then got a Solartron CD1400 for nothing at university as department surplus on its way to the skip. That worked perfectly for 20-odd years until I got the Tektronix bug. And that way boys and girls lies collection madness.

Craig

[turretslug]

A 'scope company that makes its own tubes gets big respect from me, another trait now slipping into history. I'd heard that Tektronix started making their own tubes because they didn't want their cutting-edge electronics to be held back by the limitations of other makers' off-the-shelf tubes, even though it must have been a big investment. I recall that some of their tubes have a ceramic flare, rather than glass- was this for maintaining precision alignment of gun and screen or something?

If it wasn't for concern over phosphor and other internal coatings, a 'scope CRT would make for a striking carafe.... I did hang onto the gun assembly from a gassy AEG tube with its cobweb-fine PDA mesh.

[woodchips]

As I said, it is the plug ins that are awful.

Tek used the mainframe for the final X and Y amplifiers, HP put it all in the plug in with direct feed to the plates. Makes the plug ins rather packed and I found them to be impossible to service.

[Skywave]

Originally Posted by woodchips

Tek used the mainframe for the final X and Y amplifiers, HP put it all in the plug in with direct feed to the plates. Makes the plug ins rather packed and I found them to be impossible to service.

As we are all aware, electronic equipment - and indeed many products aimed at the 'domestic market' - are now designed to be frequently unrepairable, and where a repair might be achievable, it will nearly always prove to be an uneconomic prospect for its owner. I have long suspected that that result is driven by the need to simply increase sales of new - or replacement - items for the users. The easier an item is designed to be maintained and repaired, the longer the time period will be before a replacement item is then purchased. In essence, the manufacturers will then make less profit if their products are designed to be repairable over a substantial time period. At which point, it could simply be argued "O.K.: I'll now buy products from a different manufacturer". Unfortunately, that usually fails, since every manufacturer of a similar product to the one that has failed seem to adopt the same design philosophy.

Al.

[Bufo Bill]

Thanks for the help and advice guys. One of my favourite parts of life on this forum is that so many of you have stories to tell about this tech we all love.
Back to topic now, I calculate I have had this for three years now in the "to do" pile, will I need to use a variac or some such device to reform the caps? Should I risk switching on?
Cheers from Bill.

[David Simpson]

This thread of Bill's has highlighted a common problem related to the mass of now vintage(but were once SOTA) test equipment spread amongst the vintage radio fraternity. In an ideal world, all the design & service engineers who worked for AVO, Mullard, HP, Marconi, Tektronix, etc., back in the 50's,60's & 70's, would've joined this Forum &/or other forums that we all know, when they retired. Hence many of us wouldn't need to struggle to understand & repair our cherished bits of T/Eq.
Bill, by all means use a Variac. Always a good idea when powering-up dormant equipment anyway.

Regards, David

[WME_bill]

HP180 repair.
Sorry to hear that Woodchips has found the HP plug-in units awkward to repair.
I agree that access is difficult while they are plugged into the Main Frame. So take it out of the main frame.
I made up an extension lead about 2ft long with a 32way Amphenol plug and socket, which allows me to work on both the X and Y plug-ins out of the chassis. Yes, there is no connection to the CRT deflection plates, but that is no matter, as I am using a voltmeter or another oscilloscope anyway to fault find, and the adjustments for final setting up are all accessible when the units are plugged back into the main frame. The rack mounting main frame (HP180AR or 180D) is slightly easier to work on than the upright one, but the extension lead makes it very much easier.
I have made up a similar one for the Telequipment D63/75/83 series of scopes, with edge connectors and 0.15 veroboard plugs.

For perfectionists, HP did make a proper plug-in extension unit, which connects everything including the deflection plates. I have one, and never use it, as my extension leads is much easier. So if anyone would like it, then please send me a PM. But it is awkward to post, as it is almost 24" long.

Following CraigSawyer's coments, my first commercial scope was a Solartron CT484/CD1212 -very heavy. The trigger point was unstable (old age?) and I changed it for a Hartley 13A, which was slightly easier to lift onto the bench, and at that time, allowed me to do all I needed with radio repair.
The big joy was to get a Solartron CT436. Light, lovely to operate, reliable. I still have one and also it's 1970's Services replacement SE Labs CT570/SM111. These both seem reliable when all others fail. And that is the tale, as I seem to spend more time keeping the other scopes going than anything else.

Following Skywave's comments, once you get specialist integrated circuits which make it cheaper to manufacture initially, then the unit cannot be serviced, as the vital chip is no longer made. That is why I avoid anything with integrated circuits. Scopes up to 50-75Mhz use discrete components or the transistor arrays like CA3086, all general commodity style, and so are repairable.
My workshop scope is a HP1707B. All discrete, bandwidth an easy 75/80Mhz (overspecified?) and keeps working. Though I have a another one here now where the Tube had lost emission from old age and then the EHT transformer failed. Now that is terminal. But it is a source of spares. This model does not use tunnel diodes and triggers very well indeed. I prefer it to my Tek 453, and no fan noise.
wme_bill

[Techman]

I've got one of these scopes.

Seeing this thread reminded me that it was still on the floor in bits in the 'clutter' room. It's been in bits for a few years. I took it outside a couple of hours ago to blow the dust out of it yet again - actually it was quite clean, as I did the same thing to it last summer and then never got round to doing anything with it. I started a thread on it a few years ago, but seem to remember that there wasn't an awful lot of response to it at the time.

It was given to me by an electronically competent person who had tried to fix a triggering fault and had given up. He'd removed a couple of components that he had narrowed down the fault to and they were in a small bag with the instrument, luckily I haven't lost them. The components were a tunnel diode and a FET. A mate and I knocked up a little circuit to test the tunnel diode at the time and it performed as it should, also the FET conducted normally when gate voltage was applied. I never did any more to it, so it's probably now time to put it back together and see what happens. I suspect that there never was an actual fault and that it was just down to the perceived triggering issue that folk talk about with regards to these scopes.

With regards to the OPs scope, these scopes are complex beasts and I think that if there's much wrong with it, then he's going to struggle. This isn't remotely comparable with that Quad amp he worked on last and look how involved that got, but fingers crossed for him that he'll be successful in repairing this scope with help from members. It'll involve total commitment, with sleepless nights and not eating, and no time whatsoever for listening to any music on the Quad system - or perhaps he'll sort it easily and then he can tell me how to fix mine.

[Bufo Bill]

Techman, i have had a look inside and I see why you provide a note of well warranted caution, but all the best learning curves are steep ones; I have learned several new curse-words from the Quad II, and as long as I don't kill myself I will consider it a success, just because I will have learned something more.
Bill.

[Craig Sawyers]

Originally Posted by David Simpson

This thread of Bill's has highlighted a common problem related to the mass of now vintage(but were once SOTA) test equipment spread amongst the vintage radio fraternity. In an ideal world, all the design & service engineers who worked for AVO, Mullard, HP, Marconi, Tektronix, etc., back in the 50's,60's & 70's, would've joined this Forum &/or other forums that we all know, when they retired. Hence many of us wouldn't need to struggle to understand & repair our cherished bits of T/Eq.
Bill, by all means use a Variac. Always a good idea when powering-up dormant equipment anyway.

Regards, David

Alas the three main founts of Tektronix knowledge have gone to the big blue case in the sky.

First to go was Deane Kidd. He was not only the Quality rottweiler at Tek, in retirement he had a basement full to the gunnels with Tektronix spares. Anything you could possibly need was there for the asking, at almost free prices. On occasion he sent me stuff from his stash free, including the postage. He eventually went into a home, and died well in his 80's

Next was Stan Griffiths. He ran the repair facility and then a field sales office. He was exceptionally knowledgeable and wrote "Oscilloscopes - selecting and restoring a Classic". He sent me his personal copy, a gift to his father on Fathers Day in the early 90's. He recovered it when his dad died, and sent it to me. His wife Pat died suddenly, and Stan went downhill somewhat, suffered a stroke and died in his mid 80's.

Finally the last great link with the golden days, Barrie Gilbert, died earlier this year at 83. Along with the Gilbert Cell (also called the Trans-linear cell), he was also responsible for the on-screen readout of the 7000 series scopes. Apparently, the intention was to use the same readout as the 576 curve tracer using fibre optics and having a module next to the screen. Gilbert hated the idea, and constructed an electronic readout unit out of logic chips and analogue electronics. It won the day, and Tek committed to custom silicon.

Fortunately the torch is carried by https://vintagetek.org/ , a site well worth looking around. There are four company videos on there about CRT manufacture alone https://vintagetek.org/video-gallery/

Craig

PS there is an excellent YouTube video of Barrie in full flight explaining the Translinear principle https://www.youtube.com/watch?v=LQNJVtcFrCc

[Radio Wrangler]

Originally Posted by Craig Sawyers

PS there is an excellent YouTube video of Barrie in full flight explaining the Translinear principle https://www.youtube.com/watch?v=LQNJVtcFrCc

Highly recommended!

David

[factory]

Originally Posted by Radio Wrangler

The building where the CRTs and most of those scopes were made was flattened a long time ago then accountants ceremonially salted the ground and did a little accountancy dance on it for good measure.

David

A bit earlier than the 180 series, but I recently received an article on the 141A storage scope (reprinted by HP from a 1965 magazine), HP made some of parts for the CRT and Westinghouse completed the assembly.


If anyone is interested I'll search for the link to the whole magazine.

David

[Radio Wrangler]

The HP180 is a pretty typical discrete transistor scope. Overall, it looks complicated, but it is just a large number of simple circuits, flying in formation.

A bit of systems level work will get a fault down to a small area, and then fault finding is very straightforward. Most other scopes are pretty much the same. A few can be absolute swine but they are the exception and the 180 isn't one of them.

Access to some parts is fiddly. Not impossible, just fiddly and this is one of the better scopes. You can access a lot with the plug in in the scope and the mainframe covers off.

Take care over the voltages around the tube supplies, the mains inputs and around the X amplifier and you'll be safe.... be aware of the BeO insulators under the Y amp output transistors.

You need to understand differential amplifiers and diode beam switches, but they're not hard.

These are VERY fixable scopes and they reward you with good performance and silence!

David

[turretslug]

A bit tangential- wouldn't these 'scopes now fall foul of the "no live parts accessible without the use of a tool" business?- those cover clips are handy but a bit behind the times.

[Skywave]

Originally Posted by Radio Wrangler

These are VERY fixable scopes . . . .

Unless the HV transformer has failed, of course!

Al.

[high_vacuum_house]

Good afternoon,
You are right about the ceramic cones,

Tektronix did make some of their CRT cones from ceramic rather than glass. There is a film on YouTube which takes you through the manufacturing process.

Basically if you mould a glass cone you end up with ripples on the inner surface making the PDA electrode less consistent on a batch of the same tubes.

The idea behind the ceramic cone is that a solid polished stainless steel mandrel is used which forms the pattern of the inner surface of the cone. A loose rubber boot is fitted over the top of the mandrel and powdered ceramic material is forced in between them. The whole lot gets put into a very high pressure chamber which compacts the ceramic powder to a solid over the mandrel. Thus the inner surface of the cone is completely smooth and perfectly consistent from tube to tube. The solid cones then get baked to harden before the PDA coating and feed through wires are fitted. The remainder of the CRT assembly is using the same traditional methods.

Christopher Capener

[factory]

Originally Posted by turretslug

A bit tangential- wouldn't these 'scopes now fall foul of the "no live parts accessible without the use of a tool" business?- those cover clips are handy but a bit behind the times.

Did you mean live parts are accessible with the plug-ins removed, the covers on both of mine (cabinet model & rack model) are held on with screws.

David