Sony TC-500A - Tube "tone" from AUX Source?

[IanMcI]

I picked up a Sony TC-500A (c 1964) from an estate sale and will be bringing it up on a VARIAC after a simple lube and mechanics check (all looks very good in that department).

Can I expect any worthwhile use as an amplifier for auxiliary sources (CD, turntable, etc.) for that "tube tone"?

https://imgur.com/gallery/kELjE

I brought this up on a variac and the results were less than impressive: the motor is remarkably loud; just sounds like a laboring, clunky beast. I doubt that it's a candidate for a restore, but my hope is to not just give up.

I'd like, if I can, to line-in a source that will use the tube amplifier section of the machine for reasonably pleasant audio output. Can this even be done?

I'd have to deactivate the motor drive system.

Thing is, as far as I can tell, this machine doesn't have a source monitoring mode, as does my Sony TC-651, though the outer rings of the volume knobs are labeled AUX (inner are labeled MIC PLAY).

Ian
SF Bay Area

 

[Tinkerbelle]

Are you thinking to remove the amp from the unit or just leave it there but not use the tape section? This looks to have a single-ended 6AQ5 amp and does have aux/line-in so you should be able to make a low power amp use out of it. The Servicing Guide available from HiFiEngine has a schematic.

 

[IanMcI]

Thanks for the response, Tinkerbelle! At the moment, I'm not thinking so much of separating the amplifier section from the tape section, as much as I am interested in being able to make use of the amp section, while pretty much thinking of the tape section as "toast". Maybe if I had some cool source player out of it, I'd remove the mechanics, which would have, at least, the benefit of lighting its considerable weight. And then, only if it all strikes me as worthwhile, as I have other projects to get to.

Yes, it does have an AUX/line in, so I know I can use an outboard source, but I'm not sure I can listen to that source, as I can through the source-monitoring feature on other R2Rs (like my TC-651). I haven't delved into things to a degree that suggests it's an easy thing to do (no source monitoring capability apparent).

If I heard that machines like this could be easily modified and the results were as promising as "tube tone" might suggest, I might go that road. But, if I were to hear that it really isn't worth the trouble, I'd continue with a posting in my local CL - hoping to re-home the unit with someone who would appreciate the challenge of getting this machine up and running (such a nice, clean package).

Ian
SF Bay Area

 

[BinaryMike]

The TC-500A has pretty good output transformers, if I recall correctly. I ordered several from Sony's parts department for projects of my own back in the day. 6AQ5 finals won't get you as much audio power as the 6BQ5 finals that Akai used, but I believe you have the makings of a great little flea-power amplifier there. If it was up to me, I would scrap the mechanicals, salvage the tubes and transformers, and then rebuild the amp section alone on a new chassis with reference to the original schematic.

 

[Tinkerbelle]

Making a stand-alone would probably be the best option as suggested above unless you plan to later try to restore the tape functions. It looks like you could test it out as-is but it would probably need some component refresh to bring it into spec so you might have to take the amp out anyway for that. The Aux volume controls are there and there are speaker On/Off & Record/Playback switches plus speaker outs (according to service manual these are 8 Ohm for external speaker or low impedance earphones). However, for reference, check the manual and take a look at the schematic.

 

[IanMcI]

Thanks for the continued input and advice! I did find someone with whom I've "re-homed" this machine. He is very tube oriented and knows much more about how best to get the most out of it.

Ian
SF Bay Area

 

[Lou F Quincy]

Ian, I realize this thread is a year old but I'm curious if your Sony TC-500A buyer ever got back to you with the results. I have a newly acquired TC-500 and am debating whether to gut it or not.
Thanks, Lou Fred Quincy of St. Johns, Oregon

 

[FlaCharlie]

Ian, I realize this thread is a year old but I'm curious if your Sony TC-500A buyer ever got back to you with the results. I have a newly acquired TC-500 and am debating whether to gut it or not.
Thanks, Lou Fred Quincy of St. Johns, Oregon

Here's a recent thread started by another member who's working on building an amp using parts from the Sony:

http://www.audiokarma.org/forums/index.php?threads/sony-tc500a-teardown-questions.852596/

You can definitely build a nice amp using the Sony transformers and some of the other parts.