Roband Power Supply - UK Vintage Radio Repair and Restoration Discussion Forum

ZL1TQT_John · 1st Mar 2013, 1:56 am

Is anyone able to provide a schematic or manual for a Roband V50/50 adjustable regulated power supply please? It is 0-500Vdc, 500mA, made at a guess in the early 1960's. Uses a multi-tap, multi winding transformer, semiconductor diode bridge and a valve series pass regulator. Information on anything similar (V50/25, V25/x, etc) would likely assist. Thanks.

woodchips · 1st Mar 2013, 1:30 pm

Wow, some power supply! Unfortunately can't help, is this the one that was on the trade Me website?

As a silly question, do the valves act as series pass elements over the whole 0-500V, or are transformer windings switched in and out so it only regulates over, say, 50V? The reason for asking is I have a 0-350V PSU that is stepped in 50V. Not yet tried it, needs checking out first, just in case!

Boi

ZL1TQT_John · 4th Mar 2013, 6:58 am

Yes it's quite clever. There are three settings switches. Hundreds of volts, tens and units. One sets the required output on these switches. Not only is the transformer tapped, but the reference voltage to the regulator amp is switched by the settings switches so the "dialled-in" setting results. Now I've got it repaired it seems to be pretty much accurate to a volt or so over the whole 499V range. The regulator itself is very stiff (although slow) and once settled shifts only negligibly from about 10% load to full load.

glowinganode · 21st Dec 2013, 5:18 pm

I have just acquired one of these and would appreciate any info available.

Regards,
Rob.

1st Mar 2013, 1:56 am	#1
ZL1TQT_John Diode Join Date: Mar 2010 Location: Tauranga, New Zealand Posts: 4	Roband Power Supply Is anyone able to provide a schematic or manual for a Roband V50/50 adjustable regulated power supply please? It is 0-500Vdc, 500mA, made at a guess in the early 1960's. Uses a multi-tap, multi winding transformer, semiconductor diode bridge and a valve series pass regulator. Information on anything similar (V50/25, V25/x, etc) would likely assist. Thanks.

1st Mar 2013, 1:30 pm	#2
woodchips Octode Join Date: May 2010 Location: Grantham, Lincolnshire, UK. Posts: 1,174	Re: Roband Power Supply Wow, some power supply! Unfortunately can't help, is this the one that was on the trade Me website? As a silly question, do the valves act as series pass elements over the whole 0-500V, or are transformer windings switched in and out so it only regulates over, say, 50V? The reason for asking is I have a 0-350V PSU that is stepped in 50V. Not yet tried it, needs checking out first, just in case! Boi

4th Mar 2013, 6:58 am	#3
ZL1TQT_John Diode Join Date: Mar 2010 Location: Tauranga, New Zealand Posts: 4	Re: Roband Power Supply Yes it's quite clever. There are three settings switches. Hundreds of volts, tens and units. One sets the required output on these switches. Not only is the transformer tapped, but the reference voltage to the regulator amp is switched by the settings switches so the "dialled-in" setting results. Now I've got it repaired it seems to be pretty much accurate to a volt or so over the whole 499V range. The regulator itself is very stiff (although slow) and once settled shifts only negligibly from about 10% load to full load.

21st Dec 2013, 5:18 pm	#4
glowinganode Octode Join Date: Apr 2009 Location: Aylesbury, Buckinghamshire, UK. Posts: 1,522	Re: Roband Power Supply I have just acquired one of these and would appreciate any info available. Regards, Rob. __________________ We have done so much, for so long, with so little, we are now qualified to do anything with nothing.