Telequipment D1011 scope - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Chris55000 · 17th Mar 2024, 3:09 am

. . .I've still not come across my incomplete T.Q. one yet despite a lot of searching!

. . .I've got to confess I haven't come across a CRT fault where deflection plates ended up shorting across internally, without there also being more major damage that would be obvious upon inspection!

. . .The D14–250 is a mono–accelerator CRT so there will be no internal spiral p.d.a. to obscure where the deflection plates are, and it is a B14G base with all pins brought out to the rear – pins 4 and 6 are the X–plates, pin 6 is X1 and pin 4 is X2!

Have you checked across the tube pins themselves with the base connector removed from the tube in case there's a short in the wiring?

D14–250 etc., pinout :–

1 :– h
2 :– i.c.
3 :– G1
4 :– X2
5 :– i.c.
6 :– X1
7 :– K
8 :– G3 (focus anode)
9 :– G2, G4 and I.P.S.
10 :– Y1
11 :– i.c.
12 :– Y2
13 :– n.c.
14 :– h

. . .I've got a few Oscilloscope Remains with that 14 pin type of CRT but they're all of the PDA type, so wouldn't go in your T Q.!

. . .I would remove your CRT and examine it very carefully at its base end – there is no e.h.t. cap or side–pins to worry about!

Chris Williams

PS!

An LCD conversion isn't really a practical proposition for this type of Oscilloscope!

Diabolical Artificer · 18th Mar 2024, 11:28 am

Is the CRT round or rectangular faced? I might have something. Andy.

Diabolical Artificer · 18th Mar 2024, 2:50 pm

Dug a CRT out of a Crotech 3132 scope. It's not a Mullard & it doesn't have a makers ID only "Type ~ C5S74P31B" It's 12 1/2" long, 5" round display. Base is 14 pin.

If that ones no good I do have some older Mullard TQ CRT's but these are out of valved scopes.

Andy.

Chris55000 · 19th Mar 2024, 8:36 pm

. . .Another tip you can try :–

. . .Try charging up an electrolytic capacitor of about 100–200 microfarads (e.g., smoothing can from an old valve TV chassis) to about 100 to 200 V and see if you can "flash out" the particles, etc., that may have lodged between the CRT pns – a low–resistance short will produce a very large spark but as the shorting particles burn away the spark will diminish in intensity and eventually disappear, at which point you will have cleared the short!

Try across pins 4 and 6 first, then link 4 and 6 together and "flashing" between 4+6 and 9!

Chris Williams

17th Mar 2024, 3:09 am	#21
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,874	Re: Telequipment D1011 scope . . .I've still not come across my incomplete T.Q. one yet despite a lot of searching! . . .I've got to confess I haven't come across a CRT fault where deflection plates ended up shorting across internally, without there also being more major damage that would be obvious upon inspection! . . .The D14–250 is a mono–accelerator CRT so there will be no internal spiral p.d.a. to obscure where the deflection plates are, and it is a B14G base with all pins brought out to the rear – pins 4 and 6 are the X–plates, pin 6 is X1 and pin 4 is X2! Have you checked across the tube pins themselves with the base connector removed from the tube in case there's a short in the wiring? D14–250 etc., pinout :– 1 :– h 2 :– i.c. 3 :– G1 4 :– X2 5 :– i.c. 6 :– X1 7 :– K 8 :– G3 (focus anode) 9 :– G2, G4 and I.P.S. 10 :– Y1 11 :– i.c. 12 :– Y2 13 :– n.c. 14 :– h . . .I've got a few Oscilloscope Remains with that 14 pin type of CRT but they're all of the PDA type, so wouldn't go in your T Q.! . . .I would remove your CRT and examine it very carefully at its base end – there is no e.h.t. cap or side–pins to worry about! Chris Williams PS! An LCD conversion isn't really a practical proposition for this type of Oscilloscope! __________________ It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!

18th Mar 2024, 11:28 am	#22
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,676	Re: Telequipment D1011 scope Is the CRT round or rectangular faced? I might have something. Andy. __________________ Curiosity hasn't killed this cat...so far.

18th Mar 2024, 2:50 pm	#23
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,676	Re: Telequipment D1011 scope Dug a CRT out of a Crotech 3132 scope. It's not a Mullard & it doesn't have a makers ID only "Type ~ C5S74P31B" It's 12 1/2" long, 5" round display. Base is 14 pin. If that ones no good I do have some older Mullard TQ CRT's but these are out of valved scopes. Andy. __________________ Curiosity hasn't killed this cat...so far.

19th Mar 2024, 8:36 pm	#24
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,874	Re: Telequipment D1011 scope . . .Another tip you can try :– . . .Try charging up an electrolytic capacitor of about 100–200 microfarads (e.g., smoothing can from an old valve TV chassis) to about 100 to 200 V and see if you can "flash out" the particles, etc., that may have lodged between the CRT pns – a low–resistance short will produce a very large spark but as the shorting particles burn away the spark will diminish in intensity and eventually disappear, at which point you will have cleared the short! Try across pins 4 and 6 first, then link 4 and 6 together and "flashing" between 4+6 and 9! Chris Williams __________________ It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!