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Foothillphile 12th February 2013 12:01 AM

CAS-1 Repair
Hi Folks, I'm new here and looking for advice on replacing the bridge rectifiers on my CAS-1. I've read on here about some newer types but haven't found any current or voltage values so I know what to use, I could guess, but that's not good science. I've found only one schematic on here for a 240v power supply (not that it makes a difference) but alas, no values on it. Any help would be appreciated.


Zen Mod 12th February 2013 12:19 AM

pics , pretty please ?

even if I'm sure that generic 35A/400V Graetzs will do the job

Foothillphile 12th February 2013 05:03 AM

The graetz do look generic. I have no pics, but mine look like every old bridge rectifier I've seen over the last 40 yrs. They produce 49 volt rails.

I'm looking to use the newer high speed soft recovery type, but I don't know the value of the ones I'm replacing. It's not clear at all.

Anyone else out there know what these new ones are all about, and what values I need in a CAS-1 without going to far over rated? Now if the new tech can be found in the old center hole four tab block type, all the better for a clean swap.

JamesBrennan4 19th February 2013 12:49 AM

I had one of the diode bridges fail on my CAS-1 a few years ago. Just replace with one of the same type, same size, same mounting that has high enough voltage and current ratings. Don't worry about high speed diodes - you'll never hear or measure any improvement.

Foothillphile 19th February 2013 05:14 AM

Hi, thanks for the input. I've heard pros and cons and bought the Hype I guess. I found a distributor that has them in chassis style mount 35A 600V <100 Ns, so I went for them, no diff in price. I needed to change them out (30 yrs is a long time) while I was in there to replace the PS caps, which was another story for sizing vs values. I found some same diameter slightly shorter versions @ 11,000 mfd 75 V. Just arrived today.

BTW, how's you power switch doing? getting crunchy yet?

I also plan to change out the tantalum electrolytics with the Silks. Once you dust off the soldering iron, it's hard to put it down.;)


Foothillphile 3rd March 2013 05:20 AM

My CAS-1 is making music again! Thanks to all for the various inputs and posts that lead me to the sucessful Repair and Upgrade of this vintage amp I've owned for 30+ yrs.

Special shout-out to Jon Soderberg of Vintage Amp Repair in Sacramento, Ca. for the helpful tips.


regas99 24th May 2013 02:11 AM

I am also trying to resurrect my old CAS-1. The thermistor in the Vbe multipler on one channel failed. I pulled the other one to measure its characteristics, but managed to misplace it.

The schematic I have seen simply says 1k. Can anyone provide more information on the specs for this device?

Thanks! Tom

Zen Mod 24th May 2013 07:38 AM

no need

1K is enough info

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