Tv62 - Page 17 - UK Vintage Radio Repair and Restoration Discussion Forum

Top Cap · 11th Apr 2010, 4:47 pm

Looking back on some of the photos, I am worried about the location of C16?
Should it go from the Red asterisk to the Green one?
Les

oldticktock · 11th Apr 2010, 4:53 pm

already corrected that yesterday, thought nobody had spotted

But it's good that you did the reason I keep posting pics is to provide other eyes with evidence other than my own to verify, so at least it proves it works.

PJL · 11th Apr 2010, 5:00 pm

Disconnect C13 and measure the resistance again.

If it measures around 1M then switch on and measure pin 1 volts with C13 disconnected.

Station X · 11th Apr 2010, 5:14 pm

PJL. Won't the resistance reading on PCL83 (V3A) pin 2 to chassis depend on the setting of VR2 the Frame Speed control? It could be anything between 680K and 1.68M depending on where the control is set.

My understanding is that C13 has been changed, but it's obviously worth a check.

oldticktock · 11th Apr 2010, 5:15 pm

742k...

Station X · 11th Apr 2010, 5:19 pm

In that case R20 or VR2 is faulty. Try measuring each on its own. No need to snip anything. Even if the wiper of VR2 isn't touching the track it should still measure 2M.

PJL · 11th Apr 2010, 5:19 pm

Fix it...must be the pot as I think you already changed R20. If you haven't got a 2M pot then put a 1M resistor in it's place for the time being.

oldticktock · 11th Apr 2010, 5:21 pm

just to be clear 742K on pin 2
R20 is fine at 682K

Station X · 11th Apr 2010, 5:24 pm

Check the reading from pin 2 with VR2 at both extremes of travel.

PJL · 11th Apr 2010, 5:28 pm

You cheated and edited your post! In which case power it up with C13 disconnected and measure PCL83 pin 1, pin 2 and pin 3 voltages.

oldticktock · 11th Apr 2010, 5:30 pm

probe to clipped to chassis, probe clipped to pin2 (v3 half frame osc) VR2 rotated reads 749K whatever

Station X · 11th Apr 2010, 5:38 pm

In that case VR2 is short circuit or possibly the knob isn't actually moving the wiper. If you can't fix it replace with a fixed 1M resistor for the moment.

PJL · 11th Apr 2010, 5:38 pm

Check your wiring...R20 is wired to the wrong place.

Boom · 11th Apr 2010, 5:41 pm

Chris said he can measure 768k from pin 2 to deck so it wouldn't stop the oscillator working though even if the pot was shorting. It would just result in the frame speed being wrong.

oldticktock · 11th Apr 2010, 5:46 pm

Quote:

Originally Posted by PJL

Check your wiring...R20 is wired to the wrong place.

one end on pin 2 of V3 the other to bottom tag 4th in from right is that not correct then?

PJL · 11th Apr 2010, 5:46 pm

If you look at the picture, R20 is wired in parallel with C13 which would explain everything.

Edit: I can't really tell from the picture but I think this goes to pin 6 of the ECC8*. It is supposed to go to the frame speed control VR2.

oldticktock · 11th Apr 2010, 5:48 pm

please please tell me where it should go

it should hit a rail going to VR2 but i cannot workout from the schematic where that pickup point is in the real

PJL · 11th Apr 2010, 5:50 pm

Did you take any pictures before you started? I exoect it is tag 3 but you will need to follow the wire back to check it goes to VR2. Nearly fixed that fault...then on to the next

Top Cap · 11th Apr 2010, 5:52 pm

Maybe the tag to the right?

LOL! All you fella's spotted it while I was doing the picture Haa Haa Good Fun.

oldticktock · 11th Apr 2010, 5:53 pm

OK flipped back through my photo records ( thank god i take them ) tag 3 is the point

Phew.
PJL Thank you, thank you, that was yesterday brain melt.

TopCap as usual you are right

rectifiying faults as we speak

11th Apr 2010, 4:47 pm	#321
Top Cap Octode Join Date: Mar 2006 Location: Watford, Hertfordshire, UK. Posts: 1,270	Re: Tv62 Looking back on some of the photos, I am worried about the location of C16? Should it go from the Red asterisk to the Green one? Les Attached Thumbnails __________________ Whether the Top Cap is Grid or Anode - touching it will give you a buzz either way!

11th Apr 2010, 4:53 pm	#322
oldticktock Retired Dormant Member Join Date: Nov 2009 Location: Weardale, UK. Posts: 1,981	Re: Tv62 already corrected that yesterday, thought nobody had spotted But it's good that you did the reason I keep posting pics is to provide other eyes with evidence other than my own to verify, so at least it proves it works.

11th Apr 2010, 5:00 pm	#323
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Tv62 Disconnect C13 and measure the resistance again. If it measures around 1M then switch on and measure pin 1 volts with C13 disconnected.

11th Apr 2010, 5:14 pm	#324
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Tv62 PJL. Won't the resistance reading on PCL83 (V3A) pin 2 to chassis depend on the setting of VR2 the Frame Speed control? It could be anything between 680K and 1.68M depending on where the control is set. My understanding is that C13 has been changed, but it's obviously worth a check. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

11th Apr 2010, 5:15 pm	#325
oldticktock Retired Dormant Member Join Date: Nov 2009 Location: Weardale, UK. Posts: 1,981	Re: Tv62 742k...

11th Apr 2010, 5:19 pm	#326
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Tv62 In that case R20 or VR2 is faulty. Try measuring each on its own. No need to snip anything. Even if the wiper of VR2 isn't touching the track it should still measure 2M. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

11th Apr 2010, 5:19 pm	#327
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Tv62 Fix it...must be the pot as I think you already changed R20. If you haven't got a 2M pot then put a 1M resistor in it's place for the time being.

11th Apr 2010, 5:21 pm	#328
oldticktock Retired Dormant Member Join Date: Nov 2009 Location: Weardale, UK. Posts: 1,981	Re: Tv62 just to be clear 742K on pin 2 R20 is fine at 682K

11th Apr 2010, 5:24 pm	#329
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Tv62 Check the reading from pin 2 with VR2 at both extremes of travel. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

11th Apr 2010, 5:28 pm	#330
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Tv62 You cheated and edited your post! In which case power it up with C13 disconnected and measure PCL83 pin 1, pin 2 and pin 3 voltages.

11th Apr 2010, 5:30 pm	#331
oldticktock Retired Dormant Member Join Date: Nov 2009 Location: Weardale, UK. Posts: 1,981	Re: Tv62 probe to clipped to chassis, probe clipped to pin2 (v3 half frame osc) VR2 rotated reads 749K whatever

11th Apr 2010, 5:38 pm	#332
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Tv62 In that case VR2 is short circuit or possibly the knob isn't actually moving the wiper. If you can't fix it replace with a fixed 1M resistor for the moment. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

11th Apr 2010, 5:38 pm	#333
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Tv62 Check your wiring...R20 is wired to the wrong place.

11th Apr 2010, 5:41 pm	#334
Boom Retired Dormant Member Join Date: Jan 2007 Location: Westbury, Wiltshire, UK. Posts: 2,451	Re: Tv62 Chris said he can measure 768k from pin 2 to deck so it wouldn't stop the oscillator working though even if the pot was shorting. It would just result in the frame speed being wrong.

11th Apr 2010, 5:46 pm	#336
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Tv62 If you look at the picture, R20 is wired in parallel with C13 which would explain everything. Edit: I can't really tell from the picture but I think this goes to pin 6 of the ECC8*. It is supposed to go to the frame speed control VR2.

11th Apr 2010, 5:48 pm	#337
oldticktock Retired Dormant Member Join Date: Nov 2009 Location: Weardale, UK. Posts: 1,981	Re: Tv62 please please tell me where it should go it should hit a rail going to VR2 but i cannot workout from the schematic where that pickup point is in the real

11th Apr 2010, 5:50 pm	#338
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Tv62 Did you take any pictures before you started? I exoect it is tag 3 but you will need to follow the wire back to check it goes to VR2. Nearly fixed that fault...then on to the next

11th Apr 2010, 5:52 pm	#339
Top Cap Octode Join Date: Mar 2006 Location: Watford, Hertfordshire, UK. Posts: 1,270	Re: Tv62 Maybe the tag to the right? LOL! All you fella's spotted it while I was doing the picture Haa Haa Good Fun. Attached Thumbnails __________________ Whether the Top Cap is Grid or Anode - touching it will give you a buzz either way!

11th Apr 2010, 5:53 pm	#340
oldticktock Retired Dormant Member Join Date: Nov 2009 Location: Weardale, UK. Posts: 1,981	Re: Tv62 OK flipped back through my photo records ( thank god i take them ) tag 3 is the point Phew. PJL Thank you, thank you, that was yesterday brain melt. TopCap as usual you are right rectifiying faults as we speak