Textronix 453 oscilloscope

[Mike-repairman]

Found one of these at a table top sale in the village and offered £5 for it which was accepted. One never knows what amount of work will be needed and whether a unit made in the mid 1960s will be completely restorable.

However it had all it's probes with it, a new x100, a x10 and a x10/x1 switchable one; so if the scope itself turned out to be beyond repair at least the probes would have been a good buy.

Upon power up it appeared to actually work; with the exception of the channe1 position control which needed to be turned fully clockwise to get the trace on the screen. After puzzling over this, downloading the manual from BAMA and printing out the necessary pages of the circuit, I located the board in question. A tap on the chassis seemed to do something to the trace posirion so a loose connection somewhere seemed to be more likely than a faulty component.

Looking at the board closely it was discovered that all the transistors were plugged into transistor sockets for easy replacement; and would you believe it, that was all the problem turned out to be. Wriggling all the transistors slightly in their sockets restored correct working.

This may be handy to know for someone working on these scopes; well worth going over all the dozens of transistors on the board, wriggling them before starting to diagnose further. All working and up to spec now; a test with sig. gen indicates that it is good to at least 30MHz with just a 10% attenuation at that frequency.

http://i7.photobucket.com/albums/y29...n77/Scope1.jpg

http://i7.photobucket.com/albums/y29...n77/Scope2.jpg

http://i7.photobucket.com/albums/y29...n77/Scope3.jpg

[XTC]

A nice find and well done to sort it out. Nice photos too.

Since they were selling it at a jumble sale, if you hadn't offered a fiver, it might well not have been sold and taken back home, eventually ending up in the local dump.

So, the seller has a fiver they wouldn't have had, you've got a nice scope and the satisfaction of fixing it, and a tragedy has been avoided.

Pete.

[Mike-repairman]

I doubt many others in the village would have even known what it was; and as you say, if it had not have been sold it would doubtless ended up in a skip.

I hadn't seen one of these for ages, since I worked in surplus electronics 30 years ago; surprised it fired up straight away after probably 14 years. Last PAT label on it was June 1994!

Has pride of place in by workshop now and will come in handy.

Came from the same place as a 100W valve guitar amp I bought for £1 earlier this year; I was the only one that wanted it. Quite amazing as they can fetch up to £400 these days. Restored that to working order as well.

Mike.

[geofy]

They don't come much better than Textronix, a great find for a fiver, the gold plated tracks are worth more than that. Well done on getting it fully functional agian

Geof

[ALANS ANITAS]

Hi

I met my first Tektronix in 1959 (a 545) and fell in love with it. I purchased one in the '90s, but I'm still looking for some plugins mainly the differential amplifier, and the four input amplifier.

Regards

ALAN

[Brased]

Great purchase and well done for saving such a delightful instrument. The 453 is amongst my favourites. The controls feel more solid than the later Teks, more like the earlier valve scopes. The screen may be small but it produces a good bright sharp trace. Also the nominal 50MHz response does most jobs for me.

It may be easier to keep working than later models as it doesn't use any custom chips. If you do have any problems the guys on the Yahoo TekScopes group can often help.

Edward

[OErjan_S]

WOW!, one great find, those TEC scopes are solid winners in my book.
most of the TEC and HP equipment of that era was built like battleships and tend to be real workhorses.

[Mike-repairman]

Thanks chaps; I'm working through the user guide at the moment; there are quite a few refinements on this model than the general run of scopes.

How I wish modern equipment was so easy to repair; it only takes 30 seconds to remove the lids and 10 seconds to change a transistor (all plug in sockets).

Alan, I remember the larger 545s, we use to sell a lot of those reconditioned, where I worked, as well as the plug-ins. Some of those plug-ins were very rare in those days (30 years ago) so must be like hen's teeth now. A very versatile instrument.

Mike.

[Top Cap]

That''s a good find Mike, as I mentioned in another thread, it can be useful to have the ability to invert channel 2 (which this scope can) and be able to add the verticals. This is also selectable on this scope so you have the choice of a differential input using two probes. I note also the dual timebase - very nice.
Les

[Steve_P]

Nice scope there old boy. Well done! Very versatile scope and as you say, dead easy to fix.

Cheers,

Steve P.

[Brased]

Large numbers were bought by IBM for their field staff (identified as MOD210H and labelled on the front panel). They needed to be tough and reliable to survive many years of being carted around no doubt suffering various knocks along the way and still working reliably and within calibration. The front cover, which you presumably don't have, was metal with proper clip fasteners rather than the plastic push-on one used on later portable Teks. If not quite the 'battleship' style of the 500 valve series (it can be carried without risking a visit to A&E) it was certainly a 'cruiser'.

Yes you have a truly excellent piece of equipment which should still outlast most modern stuff as well as feeling better to use.

Edward

[Colin]

That's a nice scope and a great find. Well done on sorting it out too.

Even if it wasn't serviceable this sort of kit provides a treasure trove of spares. Not just the components and valves that are still within spec, but the hardware too. BA nuts, bolts and screws and all sorts of tag strips and connectors etc. Buying it all in seperate batches would cost a fortune. So, saved from the skip and put to good use is ideal but a fiver well spent whatever the outcome.

[Mike-repairman]

Hi Edward; I have detachable front panel with the flap for the probes and it came with 3 probes as well; although I had to fit a new BNC to the x1/x10 one; no problem.

Colin; There are no valves in this model, but quite a few dozen transistors; and the other components used are of a very high quality, especially the calibration presets which are the all-enclosed type. It was obviously made to last; I would be interested to know what this model cost when new; not cheap I suspect.

Mike.

[ppppenguin]

I have the 1967 Tek catalogue. This has the 454 on the cover. This is the 150MHz version of the 453 and is marked as "new". The same catalogue also lists all the traditional 500 series scopes, which were obviously heading rapidly for obsolescence.

In the April 1967 list, the 453 was £801. Must have been made in Guernsey as there was no Purchase Tax. The 454 was £1045+ £211/7/0 PT. In May 1968 the 453 had gone up to £864 and the 454 to £1266+£251/16/0 PT.

By comparison, a 585A with 82 plug in, giving 85MHz dual trace cost £1061 in May 1968. A 547 with 1A2 plug in would be the nearest 500 series equivalent to the 453 and cost £951.

[jjl]

I have a couple of examples of the very similar 454. One was made in the USA, the other in Guernsey. The 454 boards and front panel look almost exactly the same as the 453. The 454 uses 6 nuvistor valves in the input amplifiers and timebases.
Both of my 454s had power supply faults when I obtained them. The first one had a low value high voltage electrolytic which had leaked its contents causing one of the leads to corrode right through. The other had a poor socket contact to one of the low power transistors in the regulator circuitry. This caused one of the higher voltage supply rails to go very high and took out both of the Y deflection transistors. All very fixable but things to watch out for.

John

[Mike-repairman]

Thanks Jeffrey, around £1000 then. Quite a lot of money in those days.

John, the 453 is all transistor; I wonder why they used nuvistor valves for the amps, higher input impedance perhaps?

Mike.

[XTC]

This was a very high bandwidth scope for the day.

Jeffrey mentions the 1967 catalogue, which must be about when it hit the market. It would have been in development for a year or two before. I recall another thread where it was said the commercial FET production started around 1962. When design on this scope started, FETs hadn't been around for more than two or three years, probably didn't have the specification and they were an unproven technology. They knew nuvistors worked.

Once they had a high performance design which worked reliably with nuvistors, they'd be inclined to stick to it, rather than go to the effort of redesigning it with new FET types, for little advantage and possibly, endless problems.

Pete.

[Mike-repairman]

Correction...

Pete, just checked the circuit of the 453 and the scope certainly does have 6 x 8393 and 2 x 5642 nuvistors in the unit (one 8393 in each channel input). Also has 82 transistors listed as well.

Nuvistors seem to be still available; just a few dollars from the States; not sure about UK though. Unlikely to be needed unless they failed completely, as the gain can be adjusted on the front panel.

Mike.

[Brased]

I have two of them. The later one was made in Guernsey and uses fets whilst the other was made in the US and uses nuvistors. Both are ex IBM and it is possible that the first one was imported to the UK before production started in Guernsey. Actually I bought the second one as 'non-working' to provide spares for the first one but found that it was fine. The seller clearly had 'finger trouble'.

Yours looks like the later version with fets Mike. I'm glad to hear that the cover was with the scope. These metal covers do seem to survive much better than the plastic ones fitted to later models. The only snag is that the foam interior always seems to disintegrate but this is easily replaced.

Edward

[Mike-repairman]

Edward, the foam interior has long gone and the clip that holds the flap in place has also gone; but no problem as the unit sits in the rack with the front off, with the clip off front on top to hold the probes.

Just looked at the manual for the 453A scope and that appears to be the updated model with FETs in the channel inputs. The earlier 453 model has the nuvistors.

Mike.