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Green Wagon

Cambridge audio 640a

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I promise, you will NEVER see me touch another audio partner (cambridge) product as long as I live.

nad has been replaced by cambridge as my new champion of rubbish.

They are the worst product I have ever had the misfortune of experiencing.

 

This particular dung bucket came in with intermittent channel loss and distortion.

If I remember correctly, one repairer couldn't fault it, another couldn't give a solid diagnoses (I don't blame them - see my statement above).

 

 

 

post-106429-0-63507800-1443488124_thumb.

 

I know it's blurry, but have a look at the stupid non conformist speaker connections.

Yeah thats not going to confuse anyone is it...

 

post-106429-0-11281700-1443488134_thumb.

 

post-106429-0-13074700-1443488146_thumb.

 

 

It looses channels with movement of the volume pot shaft.

A replacement volume pot was the first step.

Owner wanted a blue alps, I managed to find one with remote motor to replicate old one.

Easiest to remove the front assy to get at the volume pot.

 

post-106429-0-01265100-1443488161_thumb.

 

Then shove the iron between the bottom and board to remove the old volume pot.

Yeah a real quality item here. *Vomit*

 

post-106429-0-87996800-1443488169_thumb.

 

New pot assembly being bigger, meant removal of some top mounted components (yellow lines).

Also installed some ribbon cable to connect to the new pot which will be turned upside down to get it to fit.

 

post-106429-0-99793600-1443488194_thumb.

 

These were relocated to the bottom of the board.

 

post-106429-0-48682200-1443488204_thumb.

 

Attach new pot to front panel, this meant re-drilling the front panel for the larger shaft bushing and new position of the locating pin.

Then shoe horn the whole lot into place.

 

post-106429-0-84758900-1443488212_thumb.

 

But wait. Thats not the end of the story. Nooooooo that would be too easy.

On test the loss of channels was fixed, but it still had the distortion issue.

Ended up being a mix of the speaker relays (2 off them) and also stinkingly poor soldering of the speaker relay/output board.

Amazing that even though lead free solder has been out for decades that this unit still has issues with it.

Obviously poor preclean tech at the production stage.

 

Todays lesson.

Don't buy cambridge audio or any other audio partner products.

 

Oh yes, final note, also reset bias to the correct levels.........................................

 

 

 

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Good work and sorry to have inflicted this on you but it was crying out to be saved ; )

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At least Nigel already had the relays in stock John.

My 740 is still a prospective boat anchor at this point!

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At least Nigel already had the relays in stock John.

My 740 is still a prospective boat anchor at this point!

Yes, the irony of your situation isn't lost on me.

Btw, I am blaming you for Nigel's loathing of the brand ; )

Edited by Telecine

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@@Green Wagon,

The owner doesn't deserve to have an "Alps" pot fitted, should have just painted the old one blue and be done with it....:D :d :D

What a waste of a quality pot....:P

Edited by Addicted to music

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Should have contracted sna member ,"decky" to fix/mod it,

I have the same amp thats had the decky magic and I can tell you it's WAy better than any nad iv heard and or owned,

It's a cracker

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Should have contracted sna member ,"decky" to fix/mod it,

I have the same amp thats had the decky magic and I can tell you it's WAy better than any nad iv heard and or owned,

It's a cracker

In Nigel's defence, he did offer to mod it, I declined. Now that it is working, I might consider some mods down the track.

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Good work and sorry to have inflicted this on you but it was crying out to be saved ; )

 

You havent seen the bill yet :P

 

 

Should've taken a hammer to it.

 

Yes, hammer is looking lonely at the moment.

 

 

Yes, the irony of your situation isn't lost on me.

Btw, I am blaming you for Nigel's loathing of the brand ; )

 

Oh don't worry, I have a bile duct full of loathing and hate to cover all eventualities :D

 

 

Nice work, GW :cool:

 

Ta.

 

 

@@Green Wagon,

The owner doesn't deserve to have an "Alps" pot fitted, should have just painted the old one blue and be done with it.... :D :D :D

What a waste of a quality pot.... :P

 

As I understand it, A true alps pot is a super rare item, so even though this one came from a reputable source, I can only wonder if it really is a genuine blue velvet pot.

Certainly has to be many many levels above what ca would ever dream about ;)

 

 

Should have contracted sna member ,"decky" to fix/mod it,

I have the same amp thats had the decky magic and I can tell you it's WAy better than any nad iv heard and or owned,

It's a cracker

 

Um.

nad - ca - cow dung - only difference to me is that cow dung is useful and doesn't try to disguise itself as anything but dung.

No I'm not referring to how it sounds.

My feelings are based purely on my experience of physically working on them.

 

As I said in the 740a thread, the board and parts used are so substandard it makes me wanna puke.

The mechanical design aspect is the final nail in their coffin.

 

I managed to find a thread from a guy that actually did design work for ca at one stage.

He wasn't impressed with ca's ideas.

They took a good design, then pushed it to its limits.

For some reason it ended up a model that just keeps burning out and failing.................( This is not in reference to the 740/640, but an earlier model )

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In Nigel's defence, he did offer to mod it, I declined. Now that it is working, I might consider some mods down the track.

 

Wait.

What.

I did.

I mean I did ????????

 

The old grey mare aint what he used to be. :D

 

And um, Now thats it's fixed, who says anything about ever allowing it back into the suburb ?? :huh:

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Interestingly I have exactly the same model in my bedroom setup, and it seems to be playing pretty well. I got mine from a guy who had brought it with him from London, but had to let it go when he returned. Don't know if I just fluked a good one or what, but I figure for $200.00 my risk exposure is acceptable. I guess if something does go pear shaped with it, I now know enough not to bother trying to get it fixed.

 

I also have a Cambridge 'One' system and have already noticed a few reliability issues with that. On the other hand, Cambridge CD players seem to be quite OK. Don't know if they're all made in the same factory or what.

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Should have contracted sna member ,"decky" to fix/mod it,

I have the same amp thats had the decky magic and I can tell you it's WAy better than any nad iv heard and or owned,

It's a cracker

Decky might have gutted it and slotted class D modules in it, now that will vastly improve reliability and SQ.....:P

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Interestingly I have exactly the same model in my bedroom setup, and it seems to be playing pretty well. I got mine from a guy who had brought it with him from London, but had to let it go when he returned. Don't know if I just fluked a good one or what, but I figure for $200.00 my risk exposure is acceptable. I guess if something does go pear shaped with it, I now know enough not to bother trying to get it fixed.

I am not surprised, no one sets out to make something unreliable. My observation is that the problems with this amp were in two areas:

1. The volume pot. This is a wear and tear item that will wear out on any amp.

2. The speaker output board. This seems to be a quality control issue and may be isolated to this amp.

Edited by Telecine

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I am not surprised, no one sets out to make something unreliable. My observation is that the problems with this amp were in two areas:

 

 

 

Um. Sorry in advance for what I'm about to type....

Buuuuuuuuuuut.

 

Planned obsolescence is a well known 'feature'.

It came about back when light bulbs started being mass produced.

It actually was invented BY those making light bulbs...

 

Been many tv shows about it. ( I have no life ;) )

 

Look at most cheaper items these days.

How many last just outside of the warranty period before failing.

How many car warranty claims are rejected until its no longer in warranty, then suddenly its a case of, 'oh this is broken and needs to be replaced at great cost'.........

 

Members of the jury, how find you ?

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Should've put in an RK50 potentiometer in there.

Well I would like to but it might be overcapitalising on the amp.

Got one going cheap?

Edited by Telecine

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Should've put in an RK50 potentiometer in there.

Well I would like too but it might be overcapitalising on the amp.Got one going cheap?

Yeah $750

Sent from my LG-D855 using Tapatalk

What the.......???

@@Telecine,

This is starting to have the same theme as @@djb maggies thread.....:P

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Yeah $750

Sent from my LG-D855 using Tapatalk

Might be overcapitalising.

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In case some onlookers don't know....

 

The RK50AX2 is a $600-800USD pot (brand new, the quad AX4 version for balanced circuitry is even more expensive) and is the best potentiometer money can buy in the world and has been since ALPS released it back in the late 80's only used in a the TOTL preamps and amplifiers by Sony and the like of the 80's and 90's golden age of audio.

 

Of course one can argue the best pot is no pot, like best capacitor is no cap. But that's a different story. If your application requires a pot, has the space then the RK50 is the best money can buy. It's also rare as schit due to limited production. The Khozmo crap doesn't even compare.

Edited by DefQon

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From what I have seen inside CA components, their designs are not that bad but I suspect the bean counters dumb down everything to be as cheap as possible.

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