It is currently Fri Dec 15, 2017 7:36 am

Quad 66 Pre-amp stuck in standby

 
Posts: 1450
Joined: Wed Jul 27, 2011 10:14 am
Location: gloucestershire

Re: Quad 66 Pre-amp stuck in standby

Post by rob t » Sun Jul 31, 2016 5:56 pm

hi Mark the fuses that feed the bridge look like small caps in the one i repaired they were brown but i think they come in other colours .
Rob T

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Quad 66 Pre-amp stuck in standby

Post by marc » Sun Jul 31, 2016 6:03 pm

Cathovisor wrote:Okay; what about between 0v and mains earth?

0v to mains earth have full continuity.

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Quad 66 Pre-amp stuck in standby

Post by marc » Sun Jul 31, 2016 6:07 pm

rob t wrote:hi Mark the fuses that feed the bridge look like small caps in the one i repaired they were brown but i think they come in other colours .
Rob T

Hi Rob,
No this one doesn't have fuses, AC from the transformer is direct to the bridge on the PCB and there is 21v ac reaching the bridge. I think this is a series 2 pre-amp and according to the service data fuses are fitted from series 4 onward.

Marc.

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Quad 66 Pre-amp stuck in standby

Post by marc » Sun Jul 31, 2016 6:09 pm

PYE625 wrote:"In the amp, a common cause of problems are dry joints, in particular on the through-pcb pin connections."

As I said at the start.

I would carefully re-solder them all and at least you will know they are not playing silly buggers lol.

That's where I'm going next, Honest ! :qq1

 
Posts: 715
Joined: Tue Jan 27, 2015 2:02 pm
Location: Chatteris, Cambs

Re: Quad 66 Pre-amp stuck in standby

Post by PYE625 » Sun Jul 31, 2016 6:19 pm

Lol, they surely can have you chasing all over the place as voltages and symptoms come and go :bba

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Quad 66 Pre-amp stuck in standby

Post by marc » Sun Jul 31, 2016 7:56 pm

Hi all,

We have lift off ! :bba

It was indeed (as Andrew suspected) the through-PCB pin connections that were causing the trouble.
The PSU is now standing at -12.1v / 0v / +12.3v which I suspect is near enough.

Actually it was a good thing to delve a little more deeply as I have also replaced some caps that were looking rather sorry for themselves, they were working but not for much longer judging by the bulging tops.

Another thing that seems to have changed is that on switch on there is now a delay before the volume gently increases to it's previously set level, before the it used to come straight up immediately so I have a feeling this old pre-amp has had some undetected issues for many years.

Thanks for all your input guys, it's appreciated :aad
Happy days ! :)

Marc.

 
Posts: 715
Joined: Tue Jan 27, 2015 2:02 pm
Location: Chatteris, Cambs

Re: Quad 66 Pre-amp stuck in standby

Post by PYE625 » Sun Jul 31, 2016 8:04 pm

Glad to be of help Marc. :aad

 
Posts: 706
Joined: Sat Jan 07, 2012 10:21 am
Location: Sleaford lincs

Re: Quad 66 Pre-amp stuck in standby

Post by Dr Wobble » Wed Aug 03, 2016 1:23 pm

Has this got a protection circuit? On some amps they wont come out of standby if there's DC on the output. I know it's not a power amp but it might have some form of protective circuit that stops it powering on.

Andy.

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Quad 66 Pre-amp stuck in standby

Post by marc » Wed Aug 03, 2016 5:05 pm

Dr Wobble wrote:Has this got a protection circuit? On some amps they wont come out of standby if there's DC on the output. I know it's not a power amp but it might have some form of protective circuit that stops it powering on.

Andy.

Hi Andy,

No, it was just one (or more :cch ) of the 'link throughs' on the double sided PCB that had gone O/C, the Quad has been working a treat since Sunday in fact I'm listening to the dulcet tones of radio Leeds as I type :)

Marc.

Previous

Return to Radio & Audio



Who is online

Users browsing this forum: No registered users and 2 guests