Cary SLP-74 Preamp

[cms2469]

I have Cary Audio SLP-74 tube preamp that uses (2)12AT7 tubes and (2)12AU7 tubes but I forgot which tube goes in which socket.
Sockets are V1,V2,V3 and V4. I can't find anything in the owner's manual or on the circuit board that tells me. Any help much appreciated.

 

[cms2469]

I just found out from a very old email that the 12AT7s go in V2 and V4.

 

[Palmas0]

CMS2469, I can see you've already figured it out (valve position).
I'm repairing a Cary Audio SLP-74 and I believe it has been tampered with in the PSU.
would it be possible to send me some info and/or photos of the PSU?

Those bigger caps in the photo they are 4x47uF/350V and 2x100uF/350V? when in stand-by those caps get about 400V, and thats not heathy! either the PSU is not OK or I need to replace those caps with 450V ones.

Can you help me in any way to get this preamp into original shape?

Thanks

 

[cms2469]

Hi
I got a reading of 230-250 volts going to those caps.I now have a low hiss coming from mine and have a feeling it's old caps and not tubes.
Have to put my ear up to speakers to hear it.

 

[Palmas0]

230-250V when in operation mode? how about in stand-by mode? could you check?

A hiss must be the tubes. Humm can be the electrolitic caps and pops can be leakage in the interconnecting caps...

 

[cms2469]

Same voltage in each mode.

 

[Palmas0]

thanks, 🙂

that is not what i'm reading...
Could you chaeck in the PSU, the HV you have 2x22k in parallel between first and second 100uF cap and 2x 210k in parallel bleeding resistors (parallel to the first 100uF cap)?

 

[cms2469]

I probably can't find that.I'm not an ET.

 

[Palmas0]

👍 thanks for your help anyway, it was very usefull.