BRC 3500 Convergence panel wanted - UK Vintage Radio Repair and Restoration Discussion Forum

yampy187 · 2nd Jul 2023, 8:21 pm

Looking for a complete BRC 3500 convergence panel for my HMV Colourmaster 2715.

The one in the set has many toasted crumbling pots and a melted transductor. Making it impossible to set the convergence/pincushion correctly.

If anyone has one available please let me know. Costs covered of course.

Cheers.

Jan

neil29 · 2nd Jul 2023, 8:52 pm

Hi Jan, Are the transductors anything like the ones used in the Decca bradford, bush A823, Philips G8 etc. if so i might be able to help.

Cheers
Neil.

yampy187 · 2nd Jul 2023, 9:39 pm

Hi Neil.
Yes, it does look the same as the one used in a Bradford. Do you know if they the same impedance/inductance?
If they are, I have a Bradford 30 in the loft, With a duff lopt I can pinch one from!

Cheers. Jan

Chris55000 · 2nd Jul 2023, 9:53 pm

All of the early 1970s delta–gun CTVs used the same pincushion–correction transductor, Mullard AT4041/07, with the two field–scan section windings connected in series or parallel and then in series with the field–deflection circuit, whilst the line scan windings are connected across the line deflection–coil circuit with a limiting resistor of between 120 Ω and 470 Ω.

The N/S phase correction inductor, where used, is usually connected across the field–scan section windings of the transductor with a tuning/shaping capacitor in series with one side of it!

The exact circuit details vary slightly from design to design, and also between valved and transistorised frame/line timebases, but they're all interchangeable!

Chris Williams

yampy187 · 2nd Jul 2023, 10:31 pm

Hi Chris. Thanks for that useful info! I did not know that they were all interchangeable!

I’ll create a thread in the television section when I get started on it.

Still looking for a convergence panel to scavenge some pots from

Cheers.
Jan

pastyboy · 4th Jul 2023, 4:13 pm

Mark Clinton may be able to help with a panel he had a set off me that could be a breaker. You might have to get him on the facebook group.

G6ONEDave · 5th Jul 2023, 12:44 pm

If you can't get a complete panel, post a pic of the actual parts you need and their values. I can then have a look through my drawer of convergence parts.

Dave

dazzlevision · 5th Jul 2023, 12:50 pm

You have a PM.

yampy187 · 6th Jul 2023, 4:21 pm

Thank you all for the replies.

Dazzlevision is kindly going to sort me out a complete board.

Mods, This thread can now be closed

Cheers. Jan

2nd Jul 2023, 8:21 pm	#1
yampy187 Hexode Join Date: May 2010 Location: Coventry, Warwickshire, UK Posts: 374	BRC 3500 Convergence panel wanted Looking for a complete BRC 3500 convergence panel for my HMV Colourmaster 2715. The one in the set has many toasted crumbling pots and a melted transductor. Making it impossible to set the convergence/pincushion correctly. If anyone has one available please let me know. Costs covered of course. Cheers. Jan

2nd Jul 2023, 8:52 pm	#2
neil29 Heptode Join Date: Dec 2004 Location: Newport, Gwent, UK. Posts: 962	Re: BRC 3500 Convergence panel wanted Hi Jan, Are the transductors anything like the ones used in the Decca bradford, bush A823, Philips G8 etc. if so i might be able to help. Cheers Neil.

2nd Jul 2023, 9:39 pm	#3
yampy187 Hexode Join Date: May 2010 Location: Coventry, Warwickshire, UK Posts: 374	Re: BRC 3500 Convergence panel wanted Hi Neil. Yes, it does look the same as the one used in a Bradford. Do you know if they the same impedance/inductance? If they are, I have a Bradford 30 in the loft, With a duff lopt I can pinch one from! Cheers. Jan

2nd Jul 2023, 9:53 pm	#4
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,874	Re: BRC 3500 Convergence panel wanted All of the early 1970s delta–gun CTVs used the same pincushion–correction transductor, Mullard AT4041/07, with the two field–scan section windings connected in series or parallel and then in series with the field–deflection circuit, whilst the line scan windings are connected across the line deflection–coil circuit with a limiting resistor of between 120 Ω and 470 Ω. The N/S phase correction inductor, where used, is usually connected across the field–scan section windings of the transductor with a tuning/shaping capacitor in series with one side of it! The exact circuit details vary slightly from design to design, and also between valved and transistorised frame/line timebases, but they're all interchangeable! Chris Williams __________________ It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!

2nd Jul 2023, 10:31 pm	#5
yampy187 Hexode Join Date: May 2010 Location: Coventry, Warwickshire, UK Posts: 374	Re: BRC 3500 Convergence panel wanted Hi Chris. Thanks for that useful info! I did not know that they were all interchangeable! I’ll create a thread in the television section when I get started on it. Still looking for a convergence panel to scavenge some pots from Cheers. Jan

4th Jul 2023, 4:13 pm	#6
pastyboy Hexode Join Date: Nov 2015 Location: Cornwall, UK. Posts: 270	Re: BRC 3500 Convergence panel wanted Mark Clinton may be able to help with a panel he had a set off me that could be a breaker. You might have to get him on the facebook group. __________________ I'm a callins, get me outta here ! (I am also an erie but it's my day off)

5th Jul 2023, 12:44 pm	#7
G6ONEDave Octode Join Date: Dec 2019 Location: Owston Ferry, North Lincolnshire, UK. Posts: 1,704	Re: BRC 3500 Convergence panel wanted If you can't get a complete panel, post a pic of the actual parts you need and their values. I can then have a look through my drawer of convergence parts. Dave __________________ Quote "All is hyperthetical, until it isn't!" (President Laura Roslin, Battlestar Galactica)

5th Jul 2023, 12:50 pm	#8
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,629	Re: BRC 3500 Convergence panel wanted You have a PM.

6th Jul 2023, 4:21 pm	#9
yampy187 Hexode Join Date: May 2010 Location: Coventry, Warwickshire, UK Posts: 374	Re: BRC 3500 Convergence panel wanted Thank you all for the replies. Dazzlevision is kindly going to sort me out a complete board. Mods, This thread can now be closed Cheers. Jan