QUAD II mains at 240VAC instead of 220VAC?

Zombie · 20th February 2003, 02:05 PM

Hello!

My Quad II's go awfully hot and the xformer pit is flowing. The voltages at the measuring points are 10-15% higher than the nominal.
Would connecting the mains to the 240V (ca. 10% decrease in the voltage input) tap make the amps run less warm?
Any hazards?
Cheers,
Tom

EC8010 · 20th February 2003, 04:03 PM

Quad IIs always run rather hot, but they shouldn't be melting their pitch! There is no hazard at all in setting them to the 240V tapping rather than 220V - quite the reverse. And yes, it should make them run cooler.

Once done, check the HT voltage to the output stage against the specified voltage, and check that the 180R cathode resistor isn't on the verge of dying.

Zombie · 20th February 2003, 04:08 PM

Hello!
Thanx for the reply.
I just switched them on (some other people assured me it's OK to change taps) and here's what I've got:
323V before the choke
316V after the choke
24V on the 180R
All other voltages as before.
Do you see anything potentially damaging here? Or (even worse) sonically deteriorating?
Btw, I had 360V at the choke before...
Cheers,
Tom

EC8010 · 20th February 2003, 04:28 PM

Your voltages are all 5% down on the Quad specified values, but that's unlikely to cause an audible problem, and your mains voltage variation might be as much as that anyway.

If it hasn't been done already, it's a good idea to replace the 180R 3W resistor with a 5W type, and also replace its parallel capacitor (the heat shortens its life).

Keep an eye on transformer temperature, although replacements can be had, they are expensive. I assume that you have left plenty of room around the amplifiers for cooling...

Zombie · 20th February 2003, 04:59 PM

Yup, I have a 5W 180R now, and a 47uF in paralell.
Seems it doesn't go that hot anymore, but I'll let it run the rest of the evening. No change in sound though...
Tom

20th February 2003, 02:05 PM	#1
Zombie diyAudio Member Join Date: Feb 2003 Location: At home	QUAD II mains at 240VAC instead of 220VAC? Hello! My Quad II's go awfully hot and the xformer pit is flowing. The voltages at the measuring points are 10-15% higher than the nominal. Would connecting the mains to the 240V (ca. 10% decrease in the voltage input) tap make the amps run less warm? Any hazards? Cheers, Tom

20th February 2003, 04:03 PM	#2
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Hot Quads Quad IIs always run rather hot, but they shouldn't be melting their pitch! There is no hazard at all in setting them to the 240V tapping rather than 220V - quite the reverse. And yes, it should make them run cooler. Once done, check the HT voltage to the output stage against the specified voltage, and check that the 180R cathode resistor isn't on the verge of dying. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

20th February 2003, 04:08 PM	#3
Zombie diyAudio Member Join Date: Feb 2003 Location: At home	Voltages Hello! Thanx for the reply. I just switched them on (some other people assured me it's OK to change taps) and here's what I've got: 323V before the choke 316V after the choke 24V on the 180R All other voltages as before. Do you see anything potentially damaging here? Or (even worse) sonically deteriorating? Btw, I had 360V at the choke before... Cheers, Tom

20th February 2003, 04:28 PM	#4
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Your voltages are all 5% down on the Quad specified values, but that's unlikely to cause an audible problem, and your mains voltage variation might be as much as that anyway. If it hasn't been done already, it's a good idea to replace the 180R 3W resistor with a 5W type, and also replace its parallel capacitor (the heat shortens its life). Keep an eye on transformer temperature, although replacements can be had, they are expensive. I assume that you have left plenty of room around the amplifiers for cooling... __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

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20th February 2003, 04:59 PM	#5
Zombie diyAudio Member Join Date: Feb 2003 Location: At home	Yup, I have a 5W 180R now, and a 47uF in paralell. Seems it doesn't go that hot anymore, but I'll let it run the rest of the evening. No change in sound though... Tom

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