Decca CTV problem - UK Vintage Radio Repair and Restoration Discussion Forum

stuie319 · 17th Oct 2009, 5:28 pm

Hello Folks

My Decca console set has developed a problem and i'm hoping some of you
knowledgable chaps may be able to point me in the right direction.
I can only describe it as vertical 'cogging' as you'll see from the attached pic.
Started off as intermittant but is now there all the time to one degree or other.
Problem is i'm not sure really where to start looking

My first thought was noise on the supply to the line osc,
but then i wondered if it could be a sync problem, since i've seen
this effect in the past on sets that were marginally out of tune.
I have a manual for a 100 chassis but i'm led to believe this is a 110?
Any assistance would, as usual be very greatly received.

Regards,
Stu

Hybrid tellies · 21st Oct 2009, 11:28 am

Not to familiar with this chassis but I would check the supply line smoothing and decoupling. Does the effect vary with brightness levels, if so then check capacitors especially electrolytic ones around the power supply.

HamishBoxer · 21st Oct 2009, 11:45 am

Allsorts can cause this and the fact you say was intermitent,i would check an old favourite.CRT earthing.

David

stuie319 · 23rd Oct 2009, 7:32 pm

Chaps,

Thanks for the replies

Hopefully the weekend will allow me some time to get in amongst it.
I'll let you know how I fare

Thanks again,

Regards
Stu

Tazman1966 · 21st Dec 2009, 8:51 pm

Hi Stu.

How did you get on with this in the end?

Philips210 · 21st Dec 2009, 9:18 pm

Quote:

Originally Posted by stuie319

I have a manual for a 100 chassis but i'm led to believe this is a 110?
Any assistance would, as usual be very greatly received.

Regards,
Stu

Hi Stu.

If it is a Decca 100 then it will have a 20AX tube fitted.
The 110 chassis used the 30AX tube.

Regards
Symon.

stuie319 · 23rd Dec 2009, 7:03 pm

Hi Tas

Well the truth is the sheer volume of 'normal' work has meant I haven't had a sniff of a chance to play with it so far.
Its the living room set as well, so that gives you some idea of how much tv i've watched!
(Plus I need to buy a new digibox as my 2k one went off with the analogue change over

)

Symon - Thats useful information thanks very much

Hopefully sometime beetween Christmas and new year I'll find some time (I'm on call xmas and boxing day

)

As soon as I've some news, I'll report back.

All the best,

Stu

Hybrid tellies · 23rd Dec 2009, 7:37 pm

Hi Stu, I do feel for you because of the same reasons my Decca has been broke since the summer. I am hoping to get on with mine over the few days holiday coming up. Best of luck with your fault.

17th Oct 2009, 5:28 pm	#1
stuie319 Pentode Join Date: Jan 2007 Location: Stockport, Greater Manchester, UK. Posts: 229	Decca CTV problem Hello Folks My Decca console set has developed a problem and i'm hoping some of you knowledgable chaps may be able to point me in the right direction. I can only describe it as vertical 'cogging' as you'll see from the attached pic. Started off as intermittant but is now there all the time to one degree or other. Problem is i'm not sure really where to start looking My first thought was noise on the supply to the line osc, but then i wondered if it could be a sync problem, since i've seen this effect in the past on sets that were marginally out of tune. I have a manual for a 100 chassis but i'm led to believe this is a 110? Any assistance would, as usual be very greatly received. Regards, Stu Attached Thumbnails

21st Oct 2009, 11:28 am	#2
Hybrid tellies Nonode Join Date: Jan 2004 Location: 1966-1976 Coverack in Cornwall and Helston Cornwall. 1976-present Bristol/Bath area. Posts: 2,965	Re: Decca CTV problem Not to familiar with this chassis but I would check the supply line smoothing and decoupling. Does the effect vary with brightness levels, if so then check capacitors especially electrolytic ones around the power supply. __________________ Simon BVWS member

21st Oct 2009, 11:45 am	#3
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: Decca CTV problem Allsorts can cause this and the fact you say was intermitent,i would check an old favourite.CRT earthing. David

23rd Oct 2009, 7:32 pm	#4
stuie319 Pentode Join Date: Jan 2007 Location: Stockport, Greater Manchester, UK. Posts: 229	Re: Decca CTV problem Chaps, Thanks for the replies Hopefully the weekend will allow me some time to get in amongst it. I'll let you know how I fare Thanks again, Regards Stu

21st Dec 2009, 8:51 pm	#5
Tazman1966 Nonode Join Date: May 2006 Location: St Albans, Herts, UK. Posts: 2,193	Re: Decca CTV problem Hi Stu. How did you get on with this in the end? __________________ All the very best, Tas

23rd Dec 2009, 7:03 pm	#7
stuie319 Pentode Join Date: Jan 2007 Location: Stockport, Greater Manchester, UK. Posts: 229	Re: Decca CTV problem Hi Tas Well the truth is the sheer volume of 'normal' work has meant I haven't had a sniff of a chance to play with it so far. Its the living room set as well, so that gives you some idea of how much tv i've watched! (Plus I need to buy a new digibox as my 2k one went off with the analogue change over) Symon - Thats useful information thanks very much Hopefully sometime beetween Christmas and new year I'll find some time (I'm on call xmas and boxing day ) As soon as I've some news, I'll report back. All the best, Stu

23rd Dec 2009, 7:37 pm	#8
Hybrid tellies Nonode Join Date: Jan 2004 Location: 1966-1976 Coverack in Cornwall and Helston Cornwall. 1976-present Bristol/Bath area. Posts: 2,965	Re: Decca CTV problem Hi Stu, I do feel for you because of the same reasons my Decca has been broke since the summer. I am hoping to get on with mine over the few days holiday coming up. Best of luck with your fault. __________________ Simon BVWS member