+ Reply to Thread
Results 1 to 10 of 10

Thread: Quad II monoblocks

  1. #1
    Join Date: Mar 2009

    Location: Cork, Ireland

    Posts: 652
    I'm Nathan.

    Default Quad II monoblocks

    Hi,

    I've too many projects on the go at the moment, but I've had a set of Quad IIs in a box in my study for a while now. Apparently one of them is fully working, but the other is a little temperamental. Is there any resource on the web that supplies directions on how to overhaul these amps.

    Any pointers would be appreciated.

    Regards,

    Nathan
    DIY is fine and dandy, but just try selling it on!

    Nathan.

  2. #2
    Join Date: Feb 2008

    Location: South Wales

    Posts: 9,151
    I'm NotTakingLifeTooSeriouslyTheseDays.

    Default

    hi Nathan,
    these amps are relitively simple to service/repair etc.
    here are some pointers.
    Cathode resistors tend to fall off or fail if output valves have drawn excesive current etc. Interstage coupling caps are almost always a failier in these amps, so change them without question, if you dont and you fit a new set of output valves then dont be surprised if they fail again within the first hour or so of firing them up!
    Mains transformers are prone to failing on one of a pair as Quad decided it was a good idea to run the preamp, plus the tuner of one power amp only hence the one transformer has a harder life than the other which can lead to premature failer.
    It goes without saying that all valves will need to be fully checked and tested before asuming the amp on initial inspection dosent work.
    i hope this helps.
    regards,Anthony,TD...
    "Today scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality"
    Nikola Tesla



    Its now a conspiracy theory to believe that the Immune system is capable of doing the job it was designed to do.
    A fish is only as healthy as the water its swimming in ! [Dr Robert Young]


    www.tubedistinctions.co.uk

    Matthew 5:10

  3. #3
    Join Date: Feb 2010

    Location: Plymouth, UK

    Posts: 458
    I'm invisible.

    Default

    Have a look here....loads of info....you may need to ask but you should be set.....
    http://tech.groups.yahoo.com/group/quadhifi/
    If only it was that simple

    Main System :
    Quad II/40 amps, Music First passive pre, Tannoy Stirling SE speakers, Technics 1200 + RB301, V-LPS, digital streaming from Mac mini via Lifatec Toslink to Moon 300D. Meier Corda Arietta headphone amp, Sennheiser HD650 Phones. Mark Grant i/c cables. Speaker cables, Audioquest Rocket 44 BiWire.


    Ray.

  4. #4
    Join Date: Mar 2009

    Location: Cork, Ireland

    Posts: 652
    I'm Nathan.

    Default

    Quote Originally Posted by anthonyTD View Post
    Mains transformers are prone to failing on one of a pair as Quad decided it was a good idea to run the preamp, plus the tuner of one power amp only hence the one transformer has a harder life than the other which can lead to premature failer.
    Hi Anthony,

    If I recall correctly I think my friend mentioned something about the transformer on one of them causing a problem. So once the transformer is fixed, I assume this reliance on one poweramp would be overcome by simply using a different preamp than the original Quad?

    Nathan
    DIY is fine and dandy, but just try selling it on!

    Nathan.

  5. #5
    Join Date: Mar 2009

    Location: Cork, Ireland

    Posts: 652
    I'm Nathan.

    Default

    Quote Originally Posted by jantheman View Post
    Have a look here....loads of info....you may need to ask but you should be set.....
    http://tech.groups.yahoo.com/group/quadhifi/
    Thanks Ray,

    I will have plenty of food for thought here, I am sure.

    Nathan
    DIY is fine and dandy, but just try selling it on!

    Nathan.

  6. #6
    Join Date: Feb 2008

    Location: South Wales

    Posts: 9,151
    I'm NotTakingLifeTooSeriouslyTheseDays.

    Default

    Quote Originally Posted by RochaCullen View Post
    Hi Anthony,

    If I recall correctly I think my friend mentioned something about the transformer on one of them causing a problem. So once the transformer is fixed, I assume this reliance on one poweramp would be overcome by simply using a different preamp than the original Quad?

    Nathan
    Correct!
    Anthony,TD...
    "Today scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality"
    Nikola Tesla



    Its now a conspiracy theory to believe that the Immune system is capable of doing the job it was designed to do.
    A fish is only as healthy as the water its swimming in ! [Dr Robert Young]


    www.tubedistinctions.co.uk

    Matthew 5:10

  7. #7
    Join Date: Dec 2008

    Location: Yorks

    Posts: 16,643
    I'm Nobody.

    Default

    I agree with Anthony, so simple.

    Just rebuild but don't be tempted with silly mods or flashy parts

  8. #8
    Join Date: Jan 2011

    Location: Kent

    Posts: 1,357
    I'm Clark.

    Default

    Quote Originally Posted by RochaCullen View Post
    Hi Anthony,

    If I recall correctly I think my friend mentioned something about the transformer on one of them causing a problem. So once the transformer is fixed, I assume this reliance on one poweramp would be overcome by simply using a different preamp than the original Quad?

    Nathan
    Just remember the Quads are earthed via the preamp.

  9. #9
    Join Date: May 2008

    Location: A Strangely Isolated Place in Suffolk with Far Away Trains Passing By...

    Posts: 14,535
    I'm David.

    Default

    A quicky here...

    It always seems to be one of the pair that gives the most trouble and it's usually the one which fed the preamp and tuners...... The potted chockes used to be set in tar and if this assembly became hot over many years, the choke could work its way down the molten or softened tar compound and eventually short on the terminals . A suggestion has been to remove the chokes and oven bake them at low heat with the terminals uppermost, returning them to the top of the cans and away from the terminals.

    Have a look here as well - http://www.dc-daylight.ltd.uk/the-Hi-Fi-stuff.html
    Tear down these walls; Cut the ties that held me
    Crying out at the top of my voice; Tell me now if you can hear me

  10. #10
    Join Date: Feb 2008

    Location: South Wales

    Posts: 9,151
    I'm NotTakingLifeTooSeriouslyTheseDays.

    Default

    Quote Originally Posted by BTH K10A View Post
    Just remember the Quads are earthed via the preamp.
    Good point!
    when i alter them to be run without the original preamp i usualy keep the two pin mains sockets but run a three core cable with the earth fitted with a soldered or crimped tag that i fit under one of the screws nearest the plug.
    this ensures that you are not reliant on the preamp or source output connectors being earthed.
    Dave's point about the chokes is also a valid one.
    Anthony,TD...
    "Today scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality"
    Nikola Tesla



    Its now a conspiracy theory to believe that the Immune system is capable of doing the job it was designed to do.
    A fish is only as healthy as the water its swimming in ! [Dr Robert Young]


    www.tubedistinctions.co.uk

    Matthew 5:10

+ Reply to Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •