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Old 15th Feb 2018, 9:38 pm   #21
Brettski
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Default Re: Oscilloscope not used in years

Hi Alan , thanks for that. I’m staying with battery powered sets as I’m happier being able to experiment without getting a 240v (or more) zap. However I can see externally the I will need to replace the mains flex. This should be no problem . But I am not confident enough to run the scope without the lid on. So it’s going to spend a bit longer drying out yet. I reckon I will be able to knock a limiter up as I have all the parts knocking about in the garage.

Let’s see what happens in a few weeks.

Brett.
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Old 21st Feb 2018, 12:54 pm   #22
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Default Re: Oscilloscope not used in years

Had two of these scopes, first one died after it was in my boot during a crash, had a heater go o/c on an ECC88 if I recall. A few weeks later I was down the tip and saw one more or less the same so gave a quid for it with the intention of pulling a valve from it. Well took the covers off and it was all solid state, was going to rip it apart but thought I'd plug it in before ripping it to bits. Low and behold it worked, gave it to a friend when I got my Hitachi. As far as I know it.s still going, that must have been 10 years ago.
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Old 21st Feb 2018, 11:13 pm   #23
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Default Re: Oscilloscope not used in years

For the avoidance of confusion I don't think there was a solid state version of the S51A. The later S54A was a solid state scope with similar spec. I stand to be corrected of course.

Alan
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Old 22nd Feb 2018, 9:44 pm   #24
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Default Re: Oscilloscope not used in years

I took a chance and powered it up tonight. It works! Took a while to come to life . I had the cover off and all valves were glowing. So power off,lid back on and then put a signal through. Itís been on for three hours and all seems well.

Picture in my photoís if you care to look.

Thanks everyone, I ve just to learn how to use it now.

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Old 22nd Feb 2018, 11:14 pm   #25
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Default Re: Oscilloscope not used in years

Excellent. Have fun.

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Old 23rd Feb 2018, 11:00 am   #26
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Default Re: Oscilloscope not used in years

Great news! A good, neat 'scope. We had one when I was at school in the late 60's early 70's.
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Old 25th Feb 2018, 4:14 pm   #27
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Default Re: Oscilloscope not used in years

The simple answer is NO! don't 'power it up'. A spell in the airing cupboard will do no use at all. After this amount of time (15 years) used or not, the equipment will have to be re-capped. That is to say that all electrolytic's will have to be replaced - at least. If you power it up at the stage the chances are that at some time soon, one or more elec. caps will burst, spraying electrolyte everywhere.
If you power it up, it may work for a while,but at some stage fail.
Hope this helps.
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Old 25th Feb 2018, 4:40 pm   #28
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Default Re: Oscilloscope not used in years

Thanks for the warning. I will put a re cap on the to do list.

Cheers. Brett.
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Old 27th Feb 2018, 5:17 pm   #29
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Default Re: Oscilloscope not used in years

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Originally Posted by Brettski View Post
I took a chance and powered it up tonight. It works! Took a while to come to life . I had the cover off and all valves were glowing. So power off,lid back on and then put a signal through. It’s been on for three hours and all seems well.
Good news- and 3 hours functioning is most encouraging. "Took a while to come to life"- 'scopes are very dependent (more so than many other electronic devices) on having their operating voltages pretty close to spec. with lots of cascaded DC-coupled stages that can wander cumulatively off and result in a big offset at the plates. Leaky capacitors can shift bias points, also hinder the operation of blanking circuits and timebases. With some old, complex valve 'scopes, there can be a bit of a pantomime of traces wandering one way, then the other, sporadically vanishing etc. before everything finally settles down.
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Old 1st Mar 2018, 11:19 am   #30
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Default Re: Oscilloscope not used in years

I wouldn't go changing capasitors without good reason. It might be worth checking the temperature of any large 'cans' (smoothing capasitors) after operating for a while, but do this with the power OFF and not forgetting that the device can still be holding enough charge / energy for it to REALLY hurt if you touch the wrong thing !

Maybe someone (Les?) can advise if there are any must replace parts in this specific scope

dc
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Old 1st Mar 2018, 11:46 am   #31
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Default Re: Oscilloscope not used in years

I totally agree, I would not go on a mass change of all the caps.
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Old 1st Mar 2018, 1:15 pm   #32
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Default Re: Oscilloscope not used in years

Just a point on reformed capacitors, 12 hours seems to be slap bang in the middle of the "failure window" after the false confidence has kicked in. I've had that on a couple of tek scopes. Looks fine, then the capacitors starts to fail at around 10h and the bridge rectifier leaves the building.
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Old 1st Mar 2018, 10:53 pm   #33
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Default Re: Oscilloscope not used in years

OK Dave, my observations:-- With most of these older valved TQ scopes (all of which I would repair and fully calibrate before sale) a few had occasional low EHT (HV rectifiers going resistive) which if they failed my relaxation oscillator test, would be replaced by B&W TV EHT diodes. A very few needed one of the 100Ufd caps in the HT doubler circuit replacing. Quite a few resistors going high value. Only the very old S31 and D31 had brown German capacitors (Wima) already dead or dying -- replace on sight. I did have a very few transformers with O/C or shorted turns.
Obviously calibration showed a few valves that needed replacing, though I generally tested all of them (I had an Avo Mk.IV) and either replaced or moved to a less important location. I was lucky having a big stock of ECF80 and ECC88 which fitted most sockets. Anything else was the odd thing you just have to trace out using logic. I had very few TEK valved scopes, and quickly learned that apart from TQ and TEK, very few valved scopes were worth touching. I had a couple of Marconis (2200/2200A) but so many valves you were likely to hit faults, plus dozens of not very reliable carbon resistors causing uncontrollable free running or other problems (but they must have been fantastic scopes when new). Big solatron, like the Marconis, Advance, poor, Hartley, terrible. I found I could make some money from TQ scopes, but obviously the later solid state ones were better.
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Last edited by MotorBikeLes; 1st Mar 2018 at 10:55 pm. Reason: added Wima
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Old 6th Mar 2018, 5:48 pm   #34
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Default Re: Oscilloscope not used in years

Quote:
Originally Posted by ajgriff View Post
For the avoidance of confusion I don't think there was a solid state version of the S51A. The later S54A was a solid state scope with similar spec. I stand to be corrected of course.

Alan
here is a S51B at home
also a very glowing little scope. There will not be a lot of differents to a S51A.

greetings
Martin
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Old 6th Mar 2018, 10:18 pm   #35
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Default Re: Oscilloscope not used in years

Quote:
Originally Posted by 6AL5W-Martin View Post
Quote:
Originally Posted by ajgriff View Post
For the avoidance of confusion I don't think there was a solid state version of the S51A. The later S54A was a solid state scope with similar spec. I stand to be corrected of course.

Alan
here is a S51B at home
also a very glowing little scope. There will not be a lot of differents to a S51A.

greetings
Martin
Nearly identical.

Thanks everyone itís been an interesting thread.

Brett.
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Old 6th Mar 2018, 11:10 pm   #36
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Default Re: Oscilloscope not used in years

The S51B was an updated valve (not solid state) version of the S51A introduced after the takeover by Tektronix I believe. Overall it is very similar allthough the CRT circuit is slightly different in that it uses neon voltage stabilisers. The pcb was competely redesigned however.

I still think that the S54A was the first basic Telequipment single beam transistorised scope and that it superceded the S51 (A, B, E & T) series.

Alan
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Old 7th Mar 2018, 1:53 am   #37
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Default Re: Oscilloscope not used in years

Thinking about it there was probably a solid state S54 which didn't last long before being updated to the 'A' version. Will have been offered alongside the S51 for a year or two I guess.

Sorry for wandering off topic.

Alan
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Old 7th Mar 2018, 8:21 am   #38
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Default Re: Oscilloscope not used in years

Had a few of these Telequipment scopes including a S51A, all the caps re-formed ok. Did you power it up Brett through a LL? If you power it up and leave it on with an AC ammeter clipped on to the fuse (fuse out) in the plug to monitor it's current consumption, you should be fine. If current draw goes up, switch off and check the caps.

One of those plug in "watt meter's" is handy for this sort of thing.

Andy.
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Old 7th Mar 2018, 9:41 pm   #39
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Default Re: Oscilloscope not used in years

The S54A was preceded by an S54, very similar circuitry, except for a nuvistor in each Y channel, and another in the timebase. The transistors were "earlier" versions with odd numbers, and I recall the sweep on the fastest T/B speed on one I had was completely blanked. I replaced the unblank transistor with a CTV video output type (BF259 probably) - complete cure. Either the Y bandwidth was only 6MHz, compared with the 10MHz of the S54A, or it may have been 10HHz, but none achieved it.
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Old 12th Mar 2018, 11:22 pm   #40
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Default Re: Oscilloscope not used in years

Quote:
Originally Posted by Diabolical Artificer View Post
Had a few of these Telequipment scopes including a S51A, all the caps re-formed ok. Did you power it up Brett through a LL? If you power it up and leave it on with an AC ammeter clipped on to the fuse (fuse out) in the plug to monitor it's current consumption, you should be fine. If current draw goes up, switch off and check the caps.

One of those plug in "watt meter's" is handy for this sort of thing.

Andy.
I got impatient and powered up without a lamp . I figured if it went bang, i donít know enough to do a repair myself, I would just wait for something to come up on paybay.

Itís still working
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