Tektronix 214 - It won't Store! - UK Vintage Radio Repair and Restoration Discussion Forum

jamesinnewcastl · 30th May 2021, 6:20 pm

Hi All

I have a Tek 214 Dual Beam Portable Storage Scope. The non-store part works mostly OK but the storage part doesn't! The video here shows the problem, my video camera has made the trace look choppy but in reality it is normal - please ignore that effect.

https://youtu.be/Hl-mq09-G2c

Anyone have any experience with these? I have the manual and all the voltages seem OK but something is up! In the last part of the video I am pressing the STORE button repeatedly sort of half-way and I get sort of what I expect to see - namely a flooded screen and a stored line. OK out of focus, etc but stored.

Cheers
James

Chris55000 · 1st Jun 2021, 8:10 pm

Hi!

Follow the CRT storage setting–up procedure on pages 22 to 24 of the manual, but by the looks of the video, I reckon you'll be on a loser as this looks like loss of emission of the flood–gun of the CRT I'm afraid!

These minature storage CRTs use 0.6V 400mA directly–heated cathode filaments for both the "writing" gun and the "flood" gun, and these filamentary cathodes have very little spare emission over what's needed for the design of the tube!

If the +65V, +5.6V and –5.6V supplies are low, check the power–supply oscillator circuit on sheet 4 – there are voltages marked on it you can check, but if these test OK I fear you're looking at a defective CRT I'm afraid – the overall "flash" of green as you flood the storage mesh during the erase procedure is much less bright than I normally see with this type of bistable tube, implying lack of flood–gun electrons!

If your meter doesn't give you an accurate reading of the 0.6V CRT filament supplies, you can do a rough comparison by lighting up a small 2.5V torch–bulb with 0.6V from a bench supply and then seeing it the 'scope transformer lights up the bulb at similar brightness!

(Use the flood gun filament supply as this supply is not at a high potential below earth!)

Chris Williams

jamesinnewcastl · 2nd Jun 2021, 6:53 pm

Hi Chris

Thanks for your reply. I have tried to follow the manual but I could not get a trace and the manual assumes that the scope is actually working! I've not found any incorrect voltages so far.

A nice chap on the Tek.io site made the following videos for me of the scope in action:

https://www.youtube.com/watch?v=R0ozSOYHqqc

Nice snappy storage! However his second one taught me an important lesson:

https://www.youtube.com/watch?v=3zLCN68xtTI

It seems that the way to use these scopes is to switch to STORE and let the screen flood, then you press ERASE. This sets the screen up for the subsequent storage operation. I have been assuming that pressing STORE is all you need to do to get the scope ready. You can imagine my disappointment! The method of use is not mentioned in the manual (I claim 'man look' if it is...... mind you, I have seen the phase 'write ready' somewhere in my reading around the subject)

So, I tried the right method and:

https://www.youtube.com/watch?v=IzpO_wvN4Og

Fiddled with the focus and intensity - previously the intensity was near max - adjusting the grid voltage the brilliance pot can be reduced but focus cannot be achieved, but now I get what I think is quite a nice 'ready' screen:

This result would be great if not for the fact it is out of focus!

https://www.youtube.com/watch?v=HxzWbg9lGx8

I need to have another crack at the beast - I may start from the out of focus point. The procedure looks convoluted but it may result in correct operation - I hope!

Cheers
James

jamesinnewcastl · 3rd Sep 2021, 5:26 pm

Hi All

Well it didn't store but I quickly cured it by leaving it alone on the bench and passing it every day for a couple of months thinking "I should pack it all away, mmm no, I won't be beaten!"

That seems to have cured it as when I finally got around to turning it back on - it worked! It still has many small faults, the focus is suspect, the triggering only free runs at certain rates, the X-shift pot is noisy. I haven't checked the Y amps yet.

Here are links to videos of it working. In one I just jiggle the Y position but in the other I finally realise an electronic version of etch-a-sketch while in X-Y mode. Note the noisy X-shift.

The thing I like about the storage feature is its bistable nature. Having fiddled endlessly with my Marconi spectrum analysers ability to either bloom out or just not appear this little item just writes and that is it. I've not timed how long it stays visible but it is certainly enough time to have a good look at the trace.

https://youtu.be/TvV5-HKe7ek

https://youtu.be/3LTqru1bq_E

Cheers
James

30th May 2021, 6:20 pm	#1
jamesinnewcastl Heptode Join Date: Jul 2009 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 722	Tektronix 214 - It won't Store! Hi All I have a Tek 214 Dual Beam Portable Storage Scope. The non-store part works mostly OK but the storage part doesn't! The video here shows the problem, my video camera has made the trace look choppy but in reality it is normal - please ignore that effect. https://youtu.be/Hl-mq09-G2c Anyone have any experience with these? I have the manual and all the voltages seem OK but something is up! In the last part of the video I am pressing the STORE button repeatedly sort of half-way and I get sort of what I expect to see - namely a flooded screen and a stored line. OK out of focus, etc but stored. Cheers James

1st Jun 2021, 8:10 pm	#2
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,864	Re: Tektronix 214 - It won't Store! Hi! Follow the CRT storage setting–up procedure on pages 22 to 24 of the manual, but by the looks of the video, I reckon you'll be on a loser as this looks like loss of emission of the flood–gun of the CRT I'm afraid! These minature storage CRTs use 0.6V 400mA directly–heated cathode filaments for both the "writing" gun and the "flood" gun, and these filamentary cathodes have very little spare emission over what's needed for the design of the tube! If the +65V, +5.6V and –5.6V supplies are low, check the power–supply oscillator circuit on sheet 4 – there are voltages marked on it you can check, but if these test OK I fear you're looking at a defective CRT I'm afraid – the overall "flash" of green as you flood the storage mesh during the erase procedure is much less bright than I normally see with this type of bistable tube, implying lack of flood–gun electrons! If your meter doesn't give you an accurate reading of the 0.6V CRT filament supplies, you can do a rough comparison by lighting up a small 2.5V torch–bulb with 0.6V from a bench supply and then seeing it the 'scope transformer lights up the bulb at similar brightness! (Use the flood gun filament supply as this supply is not at a high potential below earth!) Chris Williams __________________ It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed! Last edited by Chris55000; 1st Jun 2021 at 8:25 pm.

2nd Jun 2021, 6:53 pm	#3
jamesinnewcastl Heptode Join Date: Jul 2009 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 722	Re: Tektronix 214 - It won't Store! Hi Chris Thanks for your reply. I have tried to follow the manual but I could not get a trace and the manual assumes that the scope is actually working! I've not found any incorrect voltages so far. A nice chap on the Tek.io site made the following videos for me of the scope in action: https://www.youtube.com/watch?v=R0ozSOYHqqc Nice snappy storage! However his second one taught me an important lesson: https://www.youtube.com/watch?v=3zLCN68xtTI It seems that the way to use these scopes is to switch to STORE and let the screen flood, then you press ERASE. This sets the screen up for the subsequent storage operation. I have been assuming that pressing STORE is all you need to do to get the scope ready. You can imagine my disappointment! The method of use is not mentioned in the manual (I claim 'man look' if it is...... mind you, I have seen the phase 'write ready' somewhere in my reading around the subject) So, I tried the right method and: https://www.youtube.com/watch?v=IzpO_wvN4Og Fiddled with the focus and intensity - previously the intensity was near max - adjusting the grid voltage the brilliance pot can be reduced but focus cannot be achieved, but now I get what I think is quite a nice 'ready' screen: This result would be great if not for the fact it is out of focus! https://www.youtube.com/watch?v=HxzWbg9lGx8 I need to have another crack at the beast - I may start from the out of focus point. The procedure looks convoluted but it may result in correct operation - I hope! Cheers James

3rd Sep 2021, 5:26 pm	#4
jamesinnewcastl Heptode Join Date: Jul 2009 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 722	Re: Tektronix 214 - It won't Store! Hi All Well it didn't store but I quickly cured it by leaving it alone on the bench and passing it every day for a couple of months thinking "I should pack it all away, mmm no, I won't be beaten!" That seems to have cured it as when I finally got around to turning it back on - it worked! It still has many small faults, the focus is suspect, the triggering only free runs at certain rates, the X-shift pot is noisy. I haven't checked the Y amps yet. Here are links to videos of it working. In one I just jiggle the Y position but in the other I finally realise an electronic version of etch-a-sketch while in X-Y mode. Note the noisy X-shift. The thing I like about the storage feature is its bistable nature. Having fiddled endlessly with my Marconi spectrum analysers ability to either bloom out or just not appear this little item just writes and that is it. I've not timed how long it stays visible but it is certainly enough time to have a good look at the trace. https://youtu.be/TvV5-HKe7ek https://youtu.be/3LTqru1bq_E Cheers James