Quad 33 help - UK Vintage Radio Repair and Restoration Discussion Forum

vampyretim · 12th Nov 2019, 4:25 pm

Hi all,

I'm repairing a quad 33 which won't power on. I've had a look inside and the cap and resistor across the mains switch has blown apart. The double pole switch is only working on one half.
I was thinking of joining the neutral conductors together and leaving the working half of the switch for the live side. Does anyone know where I can get a modern equivalent of the damaged part? Is it absolutely essential?

Many thanks.

Radio Wrangler · 12th Nov 2019, 4:54 pm

Capacitors and resistors are stocked all over the place, but a call to Quad might be your best bet for a replacement switch.

Those golden cased Rifa capacitors are notorious for doing that and they stink awful too. No surprise!

Across the mains it needs to have a Class-X safety classification.

David

vampyretim · 12th Nov 2019, 5:06 pm

Quote:

Originally Posted by Radio Wrangler

Across the mains it needs to have a Class-X safety classification.

David

Just put a resistor in series too?

alanworland · 12th Nov 2019, 5:19 pm

The original Rifa component was a cap and resistor in series in the one case. As said best place for the switch/pot is Quad, failing that Dada.

Alan

nutteronthebus · 13th Nov 2019, 10:32 am

Hi what upgrades are you doing to the 33 as I have done 15 of them in the DADA style see http://www.dadaelectronics.eu/shop/q...er-with-switch for the switch at 13.80 euros

also upgrade the power supply to 16v to give more headroom the DADA site has all the info . The cap is a RIFA type and RS do them ( it's to stop the switch from burning out )

Dave

alanworland · 13th Nov 2019, 12:34 pm

I have carried out the Dada upgrades on a couple of 33's and found it well worthwhile. Components deteriorate so gradually it can go unnoticed but restoring things back as they should be (or better) you really appreciate what fine units these are.
On one of these there was a low level hum not altered by any switches/controls, one was an early unit, the other was much later and had an earth connection between power supply centre and mains earth socket.
A similar connection was made to the early humming one which totally cured it.

Alan

Craig Sawyers · 13th Nov 2019, 12:54 pm

The switch failed on mine, and I bought a replacement from Quad. The track/track matching was truly dreadful, and returned it to them for a refund with the measurements.

I checked the track/track matching on the original and it was very, very close. So I lurked on eBay until I spotted a NOS single gang but with the same switch. So I transplanted a NOS switch onto the original QUAD pot.

And used a non-RIFA capacitor/resistor snubber instead.

Craig

12th Nov 2019, 4:25 pm	#1
vampyretim Heptode Join Date: Aug 2011 Location: Bristol, UK. Posts: 538	Quad 33 help Hi all, I'm repairing a quad 33 which won't power on. I've had a look inside and the cap and resistor across the mains switch has blown apart. The double pole switch is only working on one half. I was thinking of joining the neutral conductors together and leaving the working half of the switch for the live side. Does anyone know where I can get a modern equivalent of the damaged part? Is it absolutely essential? Many thanks. Attached Thumbnails

12th Nov 2019, 4:54 pm	#2
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,876	Re: Quad 33 help Capacitors and resistors are stocked all over the place, but a call to Quad might be your best bet for a replacement switch. Those golden cased Rifa capacitors are notorious for doing that and they stink awful too. No surprise! Across the mains it needs to have a Class-X safety classification. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

12th Nov 2019, 5:19 pm	#4
alanworland Heptode Join Date: Feb 2011 Location: Southend, Essex, UK. Posts: 802	Re: Quad 33 help The original Rifa component was a cap and resistor in series in the one case. As said best place for the switch/pot is Quad, failing that Dada. Alan

13th Nov 2019, 10:32 am	#5
nutteronthebus Hexode Join Date: Jun 2011 Location: Glossop, Derbyshire, UK. Posts: 487	Re: Quad 33 help Hi what upgrades are you doing to the 33 as I have done 15 of them in the DADA style see http://www.dadaelectronics.eu/shop/q...er-with-switch for the switch at 13.80 euros also upgrade the power supply to 16v to give more headroom the DADA site has all the info . The cap is a RIFA type and RS do them ( it's to stop the switch from burning out ) Dave __________________ Any tool can be used as a hammer but a screwdriver makes the best chisel

13th Nov 2019, 12:34 pm	#6
alanworland Heptode Join Date: Feb 2011 Location: Southend, Essex, UK. Posts: 802	Re: Quad 33 help I have carried out the Dada upgrades on a couple of 33's and found it well worthwhile. Components deteriorate so gradually it can go unnoticed but restoring things back as they should be (or better) you really appreciate what fine units these are. On one of these there was a low level hum not altered by any switches/controls, one was an early unit, the other was much later and had an earth connection between power supply centre and mains earth socket. A similar connection was made to the early humming one which totally cured it. Alan

13th Nov 2019, 12:54 pm	#7
Craig Sawyers Dekatron Join Date: Nov 2010 Location: Oxford, UK. Posts: 4,984	Re: Quad 33 help The switch failed on mine, and I bought a replacement from Quad. The track/track matching was truly dreadful, and returned it to them for a refund with the measurements. I checked the track/track matching on the original and it was very, very close. So I lurked on eBay until I spotted a NOS single gang but with the same switch. So I transplanted a NOS switch onto the original QUAD pot. And used a non-RIFA capacitor/resistor snubber instead. Craig