Is my Dynaco Stereo 400 worth repairing for resale?

@curiousjim 

I get there is little room inside, however, all new caps of the same value will be much smaller. At times I have had to check the values again, they are less then 1/2 the old caps size for the same value. In fact have gone up in voltage on a lot of caps, they are sill much smaller. 

Point it, there should be a lot more room, after you swap out a few caps. 

Yes, do not purchase any "kits" get the service manual, it should have a parts list, with that, put together an order with mouser or digikey.

I built the Ampzilla in 1975. I paid for a rebuild 12 years ago after a 2 hour conversation with Mr. Bongiorno months before he died. I subsequently used it until I finally replaced it with a Spread Spectrum Analysis (SSA) Son of Ampzilla II amplifier, circuitry designed by Jim and finished in partnership with Jim by Wyred for Sound who physically built it and designed the beefy power supply.

A note about his name: I have only seen references to “James” Bongiorno in the last 25 years, with pictures of him usually wearing a wild colored suit with an extravagant shirt. When I met him as an 18 year old in late December 1984, he introduced himself to me as Jim and was wearing a white T shirt with a leather jacket, very biker like.

The original Ampzilla had a “dual-differential input” and had completely complimentary symmetry from input to output. I think the SWTP Tigersaurus had a complentary output stage with differential input. Others may know better, but the lineage of the Ampzilla runs through the Dyna400 to SAE 4 to Marantz 500 chain most directly. I think that the Marantz 500 was the first to use both high powered PNP and NPN transistors in its output stage.

@mswale 

Did you use fancy dancy caps and could you hear a big difference in the sound? If so, was it a good or bad difference?  I’m still trying to decide whether I want to keep the 400 or hopefully sell it.

Likely not very helpful, but I had a few Dyna 400s in my day, with and without meters. I found them to be ok sounding, but that was with analog only sources, different rooms and so on. I cannot speak for today if I would enjoy listening to one. I have a very large amp collection, and I enjoy many of them, as my speakers are very easy to drive. My best, MrD.

@curiousjim 

LOL, fancy caps. Well, I used audio caps (Nichicon Muse ES, Gold) for the signal path, and regular caps for everything else. Also replaced all carbon comp, and fuse resistors with metal film. 

Yes, it made a very noticeable improvement, everywhere! Bigger sound  stage, lower noise floor, cleaner sound, more bass, more high, cleaner mids, more dynamics. Like a vale was lifted. 

Also have a spare pre-power amp set as a backup, switched it back to back with refreshed vs original. The refreshed is just so much better. 

Like I said, cost was nominal, my time was vast. Think my pre-amp took 12 hours over a couple of days. Power amp was like 18 hours over a few days. Replaced over 100 parts (caps, resistors, diodes) in both units.