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A&R Cambridge A60 tidy up

First listen has presented a couple small issues, the remaining pots are a bit noisy so I have ordered some 22k linear ones to replace them, also I get a hum when touching the volume knob, is this just a matter of earthing the pot housing?

Other than those couple things it is sounding very good so far.
 
I had that problem when replacing the volume pot with an ALPS on one of mine - in fact it also picked up radio until additional earth was run back to the board. I trapped an earth cable to the volume locking nut, soldered it to all the other (old) pots and then crimped it back to a ring tag and screwed to earth. The earth cable is a bit chunky as that is all I had at the time. It solved the problem.

The balance and tone controls are not really worth changing and hard to find a same value match. Have a few goes at contact cleaner and settle for that.

lets see if I can add a link to a photo.
https://www.flickr.com/photos/158915456@N07/37999589696/in/dateposted-public/


Happy listening
Julian
 
Awesome, thanks Julian. My fix will probably look much the same as I only have 10A automotive wire at the moment.
 
I think earthing wire over pots body's was standart on later models, at least thats what I have seen on one I worked on.
 
My new cover is almost finished, here it is mocked up.
I just need to seal the underside and glue in the brackets for the screws.

K1c9vgD.jpg


A bit unusual but I'm a big fan of brutalist architecture and it was easy to make.
 
:D

Until I saw this I thought nothing could outdo either the teak or rimu covers.

Yours has to be the most original and striking amplifier casing I've seen. Might even make it sound better, too ;)

I love it. It's from a concrete block, right? Again, well done.
 
Cheers!
It turned out more or less as I was hoping. It's a cast piece, I just made a basic mold to suit the amplifier much the same as the wood cover but thicker and missing the channel the front and rear panels sit in.
 
Guitarist 28 said:
Hi Kicker
I'm just about to buy another A60 to upgrade the one I already have. I bought my original one in the knowledge that it had a channel fault but at the moment it appears to be working well although after 30+ years a recap will be an improvement. I have reviewing http://www.decdun.me.uk/a60mods.html although I am not sure about upgrading the power supply via a separate case.

Please keep us posted of your work and I hope it goes well for you.

Rob
Click to expand...
hi. I'm about to begin the job on an A60. Did you ever get round to doing an external power supply?
 
Hi, all.
I have a 1986 a60+ which looks and sounds great with one exception. Over the last few years I have noticed I have to turn bass and treble up when listening to vinyl. Looking at C3 and C4 (and C1) in the pre amp section they are white translucent caps, possibly showing their age visibly.
If these are failing will that account for what I am hearing and would replacing them restore the correct riaa curve?
 
I've not been inside my A60 for years but ISTR that C3/C4 (and others) in the phono stage were film or polystyrene. They are under almost zero stress/voltage and will not have drifted. There is a 10uF electrolytic on the output though. C7/C107. How does that look? Also C2/C102
 
Typically, only the electrolytic capacitors will degrade over time as they dry out.
Most of the others will keep their value forever so no need to be replaced.
If the translucent capacitor you talk about is similar to the picture below, this is a polystyrene and never have to be replaced.

 
Yes, similar but both wires come out of one end. The electrolytics generally look ok. But, after 35 years continuous service it sounds like replacing the electrolytics is now due. As mine is an A60+, are the caps the same?
 
Caps are the same. I had a chance to listen to some non vinyl sources today. The sound is generally lacking in top end, space and sparkle. Turning the treble up restores some brittle sounding top end but it still sounds generally poor. Time for a re cap, I think.
 
Thanks, Julian.
I have those circuit diagrams relevant to my serial number (27390) and I so far have found no difference in the values of the capacitors.
 
Operajulian said:
Andrew: There were some changes to the components that A&R used over the years. If you search there is a much longer A&R thread or two on PFM.

For the A&R A60 plus they made some other changes to resistor values etc and changed to AUX to CD input.
The later Service Manuals have a page of A6o + changes.
Can all be found in this Google Drive.
https://drive.google.com/drive/u/0/folders/1XNnKH3W4y1hxG3aUwMVq9pqaMn3V3uK8
Click to expand...
Hi, Julian.
I am just working through the PF article you quoted.
In it there seem to be some capacitors added -
“Large capacity reservoir capacitors can be expensive with 10000uf types often costing £12+ each. In this instance we are going to use the Vishay 056 PSM SI long life part at £6 each and bypass with a Panasonic 330uf FC. Because the Vishay parts are shorter than the original LCR capacitors we can use the original solder point on the pcb for the new Panasonic caps and connect the Vishay to the previously concealed points as shown here - fig 4.”
Is that necessary? I have replaced the old 10000uf caps with almost identical ones. Thanks.
 
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