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Old 18th May 2021, 10:16 am   #41
dave cox
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Default Re: HP 180A Oscilloscope.

Sorry Bill, your scope must be confined to the ground without the foam

Good new that another 'classic scope' is staying in service
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Old 18th May 2021, 11:18 am   #42
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Default Re: HP 180A Oscilloscope.

Dave, thanks for your help with this project.

Its a shame it must be grounded, it was going to go in the back of my Vulcan resto-mod in the summer.
Cheers from Bill
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Old 11th Jul 2021, 1:33 pm   #43
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Default Re: HP 180A Oscilloscope.

Well I've ended up rescuing another 180A, I always wanted to add the rack width version to my collection and found one recently in Germany, it's not in great condition but is quite an early one from the South Queensferry factory (U647-00149), the 1801A/1821A plug-ins are a little bit newer (must have got swapped at some point).
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Powering it up resulted in not much happening, the beam find button did produce a spot on the CRT, but initial testing was quickly interrupted by smoke emerging from the 1821A timebase section.

Yesterday I had some time to look at it, first thing as always was to check the power supply rails (I removed the plug-ins), all were OK apart from the -12.6V rail, which was over 20V.
After checking the voltages around some of the transistors it became apparent the amplifier transistor Q412 was faulty, it was not turning Q409 off. Q412 was completely open circuit, the manual gives part no. 1854-0071 and the part fitted was marked MPS3391, I replaced it with a 2N3704 (pinout is different to the old part) and the -12.6V was now working & could now be adjusted.
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The plastic cover for the fuses was missing, they helpfully left the screw in place though, I found a plastic draw divider that was good size to cover the fuses, it was drilled and fitted a couple of plastic spacers fitted to get the height correct.
Many of the missing screws from the frame & one of the PCB's have been replaced and I cut a piece of thin plastic sheet to replace the piece missing from the metal cover for the HV section.
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Old 11th Jul 2021, 2:04 pm   #44
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Default Re: HP 180A Oscilloscope.

Now to look at what caused the smoke release from the 1821A timebase, resistor R309 was found to be burnt, but not open circuit.
Checking for shorts found the axial tantalum capacitor C308 next to it was shorted. I replaced both the resistor & capacitor before testing the plug-ins.
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With the plug-ins refitted we now had a trace, well half a trace. None of the controls seemed to be able to get it to fill the screen.
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I decided to try a signal to see if the vertical plug-in was working first, in the time it took to retrieve an oscillator the trace had filled the screen. The problem turned out to be the beam finder switch having dirty contacts (a common problem with HP scopes).
Both inputs were working, but it would benefit from some switch cleaner too.
Everyone knows HP scopes do not trigger and this was no exception, I cheated and used the external trigger input for the picture below.
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It needs a couple more capacitors replacing in the 1821A before I think about further checking & probably adjustment to cure the trigger problem. These capacitors are C327/328 and are wet tantalum types, I will probably end up using a slightly higher value regular electrolytic to replace them due to cost.
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Old 16th Jul 2021, 8:46 pm   #45
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Default Re: HP 180A Oscilloscope.

Well things have gone backwards, last thing I did was clean the beam finder switch contacts on Sunday, I didn't have enough time to try it then.

Tried it tonight and I now have no trace at all, not even when the beam finder is pressed and the scale illumination has gone too.
Need to check I still have voltage going to the two CRT heaters tomorrow (fed from the mains transformer), but I'm worried the CRT is dead.

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Old 16th Jul 2021, 9:14 pm   #46
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Default Re: HP 180A Oscilloscope.

Hmm. I know I have a CRT, mag shield and the front metal casting, but I'm not sure about the plastic surround. I've only kept one lump of 180 display section because I know my 1740s use the same tube.

I'll look in the attic when I'm back home

That serial number puts it in the fists year sinve the opening of the South Queensferry plant.

Hugh Walker (famed for stereo mixer* in WW and the disagreement over noise in the letters page with JLH) has just written a history of the site along with photos, run down of products and a run down of local characters... 3 volumes! getting distributed around the end of the month.

*(Did I forget 'Sources of intermodulation distortion in diode ring mixers' in proc IRE?)

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Old 17th Jul 2021, 12:38 pm   #47
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Default Re: HP 180A Oscilloscope.

Good news, I've got it working again.

The flood gun filament pins are accessible through the gap in the side of the shield and visibly working, glows brighter than I expected too.
On to the main heater, I removed the back panel and took the connector off the CRT, filament on pins 1 & 14 was also intact.
On refitting the CRT connector I noticed things seemed a bit loose, the tube moved forwards very slightly too (the clamp is not tightened). Tested it again & I now have the spot back.

Hopefully it was just a bad connection and another part a previous owner loosened before giving up on this scope, I'm surprised it worked at all last week. Note all the missing screws I mentioned before.

The plastic bezel isn't urgently needed, hoping one will turn up eventually, the older round metal ones seem to turn up regularly.

Quote:
Originally Posted by Radio Wrangler View Post
That serial number puts it in the first year since the opening of the South Queensferry plant.

Hugh Walker (famed for stereo mixer* in WW and the disagreement over noise in the letters page with JLH) has just written a history of the site along with photos, run down of products and a run down of local characters... 3 volumes! getting distributed around the end of the month.

*(Did I forget 'Sources of intermodulation distortion in diode ring mixers' in proc IRE?)

David
I found Volume 1 of Hugh Walker's history of the HP UK operations a few weeks back, when searching for the second product that was designed in the UK (the 3734A counter at the Bedford site), it does mention the 180 series was one of the first batch of US products to be built at the South Queensferry site, as well as some quality issues with one they sent to Canada.
Didn't know about the other volumes, as google didn't link to this page, instead of only the pdf.
https://www.hpmemoryproject.org/time...ker_memoir.htm

Mine must date to sometime after the November 1966 design revision (647) and before the next one in February 1967 (709), the plug-ins have been swapped with later ones though, I think I have an older 1801A plug-in somewhere.
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I'm guessing Bill's 180A must also be one of the early ones built over here, with the original plug-ins too, all of which have the black stripe on the bottom of the front panels with the model details.
https://www.vintage-radio.net/forum/...0&postcount=67

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Old 17th Jul 2021, 2:00 pm   #48
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Default Re: HP 180A Oscilloscope.

One of the glass windows was etched. It was in building 1 (then called 'phase 1')on the north side looking out into the stair tower. It was the residue of the grand opening. I think the date was in summer 1966 and opened by Roger Bannister who at that time was a government minister.

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Old 18th Jul 2021, 3:32 pm   #49
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Default Re: HP 180A Oscilloscope.

Quote:
Originally Posted by factory View Post
Good news, I've got it working again.

I'm guessing Bill's 180A must also be one of the early ones built over here, with the original plug-ins too, all of which have the black stripe on the bottom of the front panels with the model details.
https://www.vintage-radio.net/forum/...0&postcount=67

David
Excellent news David.
If anyone is interested in monitoring my decline, since first getting my unit running I have obtained an HP8558B Spectrum Analyser double unit, an HP1820C and a HP1806A to go along with my HP 1801A/HP 1821A.
The disease has worsened to the point that I often feed a sine waveform into the units, just to watch and interact with them regularly.
I no longer wish for my affliction to be lifted. Its too late for me now.
Bill.
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Old 18th Jul 2021, 3:53 pm   #50
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Default Re: HP 180A Oscilloscope.

It's when you get as far as Lissajous figures running in the background that we start to worry about you building a lair and a positronic ray weapon.

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Old 18th Jul 2021, 4:22 pm   #51
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Default Re: HP 180A Oscilloscope.

I have been known to try and recreate Doctor Who "Ray gun" effects from the 1960's, so not far away!
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Old 18th Jul 2021, 6:40 pm   #52
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Default Re: HP 180A Oscilloscope.

Quote:
Originally Posted by Radio Wrangler View Post
One of the glass windows was etched. It was in building 1 (then called 'phase 1')on the north side looking out into the stair tower. It was the residue of the grand opening. I think the date was in summer 1966 and opened by Roger Bannister who at that time was a government minister.

David
I don't think Roger Bannister was Lord Hughes, but perhaps there was some last minute searching for a significant public figure and Roger's name was in the short list?

"There was a great gathering that day of VIPs, employees and people from South Queensferry
and neighbouring communities. Unfortunately, Willie Ross was unavailable for this special
event and his place was taken by Lord Hughes, Under-Secretary of State, so the glass panel
was always a bit of a misrepresentation!"

Peter
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Old 18th Jul 2021, 11:15 pm   #53
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Default Re: HP 180A Oscilloscope.

Aye, that's the glass.... now why have I got Roger Bannister in my head... Phase two? Phase three was Mr Tebbit and during the miner's strike at that, so there were all sorts of security concerns for that opening.

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Old 21st Jul 2021, 5:08 pm   #54
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Default Re: HP 180A Oscilloscope.

OK, been in the attic. I did find a plastic bezel for the 180 CRT. Hopefully the new ballcock side of the trip up there was also successful and the foghorn sound effect gone.

FOC if you want it

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Old 22nd Jul 2021, 5:08 pm   #55
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Default Re: HP 180A Oscilloscope.

Thank you for having a look and yes I still need the plastic bezel.

David
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Old 22nd Jul 2021, 5:50 pm   #56
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Default Re: HP 180A Oscilloscope.

Quote:
Originally Posted by Bufo Bill View Post
Quote:
Originally Posted by factory View Post
Good news, I've got it working again.

I'm guessing Bill's 180A must also be one of the early ones built over here, with the original plug-ins too, all of which have the black stripe on the bottom of the front panels with the model details.
https://www.vintage-radio.net/forum/...0&postcount=67

David
Excellent news David.
If anyone is interested in monitoring my decline, since first getting my unit running I have obtained an HP8558B Spectrum Analyser double unit, an HP1820C and a HP1806A to go along with my HP 1801A/HP 1821A.
The disease has worsened to the point that I often feed a sine waveform into the units, just to watch and interact with them regularly.
I no longer wish for my affliction to be lifted. Its too late for me now.
Bill.
I was going to reply sooner but my computer had a couple of malfunctions earlier in the week and refused to power-up, just my luck I guess.

Apart from the 1801A/1821A pair that came with both the HP 180A scopes (also have a another set too), I also have the 1815B TDR/sampler plug-in saved from Woodchips on here and the 1601A logic analyzer plug-in acquired last year from Germany, going to have to see what else appears on eBay.

Also have many older HP scopes including the bigger & heavier 140A/B & 175A series, plus the 150A & 130A which were the first scopes offered by HP in the late 1950's. https://www.hpmemoryproject.org/wa_p...ge_12.htm#anim

You only have a mild affliction at the moment, careful it doesn't get worse like mine.

Quote:
Originally Posted by Radio Wrangler View Post
Aye, that's the glass.... now why have I got Roger Bannister in my head... Phase two? Phase three was Mr Tebbit and during the miner's strike at that, so there were all sorts of security concerns for that opening.

David
Somehow that glass panel survived (in a cut down form) and got passed to the local museum, there is a picture in the full Volume 1 of the history, I guess the archive of product info didn't get saved though.

David

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Old 22nd Jul 2021, 7:04 pm   #57
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Default Re: HP 180A Oscilloscope.

Quote:
Originally Posted by factory View Post
Good news, I've got it working again.

The flood gun filament pins are accessible through the gap in the side of the shield and visibly working, glows brighter than I expected too.
On to the main heater, I removed the back panel and took the connector off the CRT, filament on pins 1 & 14 was also intact.
On refitting the CRT connector I noticed things seemed a bit loose, the tube moved forwards very slightly too (the clamp is not tightened). Tested it again & I now have the spot back.

Hopefully it was just a bad connection and another part a previous owner loosened before giving up on this scope, I'm surprised it worked at all last week. Note all the missing screws I mentioned before.

David
I was going to add these pictures taken at the weekend.

Some views through the CRT shield showing the flood gun filament (pretty hard to photo), glows more like a torch lamp when turned up. Oddly those connectors on the CRT pins are faston spade types.
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The loose jubilee clamp* and the CRT socket which doesn't seem to go on a far as normal, was loose & caused the CRT to appear dead last Friday.
*People that have only worked on Tek scopes often seem to ask why the heck a hose pipe clamp is used in HP scopes.
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Something else I haven't figured out yet, the holes for the mu-metal shield aren't in the right place to fit the screws, no idea if this was a production problem with the early run, or parts have been replaced at some point, it's not loose anyway.
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The beam finder switch that required cleaning to get the trace to fill the screen, instead of only half of it.
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Old 22nd Jul 2021, 8:16 pm   #58
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Default Re: HP 180A Oscilloscope.

Overall views of the rack width 180A.
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Just compared this with the regular cabinet model and noticed I need to label the fuse cover I made, to match the original below.
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Thought I would add some comparison pictures, as I read somewhere they quickly updated the rectifier board with some beefier T0-5 size package diodes. The later board is from the 1969 designed 180A.
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Old 22nd Jul 2021, 9:04 pm   #59
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Default Re: HP 180A Oscilloscope.

I replaced the two leaking/corroded 40uF 30V wet tantalum capacitors (Sprague 109D) C327 & C328 in the 1821A timebase on Sunday.
The best I could find in my stock were some Philips 030 aluminium electrolytics rated at 47uF at 40V, every tantalum I had was too big to fit in the available space. The Peak ESR was used to check them & they tested better than the original parts.
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Testing out after cleaning the beam finder switch, changing those wet tantalum capacitors and the loose CRT base problem from last Friday. Also a chance to try out the recently arrived HP 203A. Still need to track down the trigger problem, someone has done a lot of work of the 1821A timebase (many transistors & tunnel diodes show signs of rework), probably try the adjustment procedure first as it's been mentioned the tunnel diodes bias can drift for couple of reasons.
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Old 22nd Jul 2021, 10:17 pm   #60
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Default Re: HP 180A Oscilloscope.

David (Factory), thanks for posting these pictures, very nice to ogle someone else's collection!
Re the famous glass, a Chinese Takeaway here in Wolverhampton must have bought those plants displayed behind the panel, the resemblance is uncanny!
Here is a picture of my 1820c. The unit cost a third of the price of getting it shipped here, so very surprised that it works so reliably with just a dusting and some switch cleaner.
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