Hi to all Quad lovers.

Anyone know why a DC voltage of 7.3 volts approx is present on pin 4 of
DIN output socket of Quad 33s ?

It is derived from the dial lamp supply.

Quad label it with the letter " P " .

Goes nowhere on a Quad 303 power amp.

http://www.geocities.com/quad_esl63/...atic/pre33.jpg

http://www.geocities.com/quad_esl63/...c/power303.jpg



....... Phil

Phil Allison wrote:
Hi to all Quad lovers.

Anyone know why a DC voltage of 7.3 volts approx is present on pin 4 of
DIN output socket of Quad 33s ?

It is derived from the dial lamp supply.

Quad label it with the letter " P " .

Goes nowhere on a Quad 303 power amp.

http://www.geocities.com/quad_esl63/...atic/pre33.jpg

http://www.geocities.com/quad_esl63/...c/power303.jpg


Presumably so you could have a relay in your power amp to turn on the power,
a feature not found in Quad power amps.
http://groups.google.com/group/uk.re...6ce82af8aa0b6e

That pre33.jpg diagram is missing the earth connection on pin 2

--
Eiron.

"Eiron"
Phil Allison wrote:
Hi to all Quad lovers.

Anyone know why a DC voltage of 7.3 volts approx is present on pin 4 of
DIN output socket of Quad 33s ?

It is derived from the dial lamp supply.

Quad label it with the letter " P " .

Goes nowhere on a Quad 303 power amp.

http://www.geocities.com/quad_esl63/...atic/pre33.jpg

http://www.geocities.com/quad_esl63/...c/power303.jpg


Presumably so you could have a relay in your power amp to turn on the
power,
a feature not found in Quad power amps.
http://groups.google.com/group/uk.re...6ce82af8aa0b6e



** Thanks for that quote - I had figured as much but the absence of any
comment in the operator's handbook made me curious to find out.


That pre33.jpg diagram is missing the earth connection on pin 2


** :-0 !!!!!



......... Phil

Eiron wrote:
Phil Allison wrote:
Hi to all Quad lovers.

Anyone know why a DC voltage of 7.3 volts approx is present on pin 4
of DIN output socket of Quad 33s ?

It is derived from the dial lamp supply.

Quad label it with the letter " P " .

Goes nowhere on a Quad 303 power amp.

http://www.geocities.com/quad_esl63/...atic/pre33.jpg


http://www.geocities.com/quad_esl63/...c/power303.jpg


Presumably so you could have a relay in your power amp to turn on the
power,
a feature not found in Quad power amps.
http://groups.google.com/group/uk.re...6ce82af8aa0b6e

That pre33.jpg diagram is missing the earth connection on pin 2

I suspect that diagram was "re-created", as the original official circuits don't look anything like that. Hence the earth
connection was lost in the process. Interestingly the same re-created circuit appears on the Quad World website so one or t'other
has just perpetuated the error.
For the real circuit layout see: http://www.flashbacksales.co.uk/manu...rcuit%2033.pdf
This one IS the real deal.

With regard to the DC supply on Pin 4 of the 33, the Quad Service Manual states........

"The DC supply provided on Pin 4 of the output plug, derived from diode MR503, is used only as a switching supply for special
installations. Its regulation is poor and is nominally 7-8 volts at 1 ma maximum, intermittent rating. The DC supply is omitted on
sets after S/N 80000."

Here endeth the lesson

"Mike Coatham"

For the real circuit layout see:
http://www.flashbacksales.co.uk/manu...rcuit%2033.pdf
This one IS the real deal.


** Thanks for that schem link - far easier to read an interpret than that
horrible re-drawn one.

The particular Quad 33 in question was picked up recently from the USA via
eBay by a friend of mine.

http://cgi.ebay.com.au/Quad-model-33...QQcmdZViewItem


The only defects found were a missing fuse top ( by luck I had the exact one
needed on hand ) the use of a US 2 pin plug on the AC lead and a few
slightly noisy switches and balance pot.

Plus the internal tranny was linked for 127 volts AC - contrary to the eBay
blurb !

BTW

Quad 33s are very "green", drawing only 1.6 watts of AC power and most of
that is used to operate the dial light !!



....... Phil

In article , Phil Allison
scribeth thus

"Mike Coatham"

For the real circuit layout see:
http://www.flashbacksales.co.uk/manu...rcuit%2033.pdf
This one IS the real deal.


** Thanks for that schem link - far easier to read an interpret than that
horrible re-drawn one.

The particular Quad 33 in question was picked up recently from the USA via
eBay by a friend of mine.

http://cgi.ebay.com.au/Quad-model-33...QQitemZ2301675
81036QQihZ013QQcategoryZ67807QQssPageNameZWDVWQQr dZ1QQcmdZViewItem


The only defects found were a missing fuse top ( by luck I had the exact one
needed on hand ) the use of a US 2 pin plug on the AC lead and a few
slightly noisy switches and balance pot.

Plus the internal tranny was linked for 127 volts AC - contrary to the eBay
blurb !

BTW

Quad 33s are very "green", drawing only 1.6 watts of AC power and most of
that is used to operate the dial light !!



...... Phil




Its very worthwhile changing the capacitors at that age, the original
cap makers weren't much cop!.

IIRC somewhere there is a mod to -improve- the power supply, bigger
cap/s there too I think, and I don't reckon it'd have PW doing
16 2/3 RPM either..
--
Tony Sayer

"tony sayer"

Its very worthwhile changing the capacitors at that age, the original
cap makers weren't much cop!.


** All electro caps tested AOK on my Bob Parker ESR meter.

Only 405s were affected by badly made Kraut electros.



IIRC somewhere there is a mod to -improve- the power supply, bigger
cap/s there too I think,


** Yawn.

Not interested in any " bigger = better " ********.


....... Phil