Dynaco Stereo 400

Joined
May 4, 2016
Messages
60
Location
Northeast Iowa
Tagline
Love great audio, beermaking and pyrotechnics
#22
I have a couple 150's. One has the Van Alstine mods. Great sounding unit. Always wanted to figure out just what the mods were and do the other one. Anyone have info?
 

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
2,175
Location
Connecticut
#24
I just dragged it into the workspace here at work. It's EASILY half the weight of the Counterpoint. A couple more caps and some tubes and I think we'd be there.

Appears to be from 1974, based on a sticker I found inside. 200WPC in 1974 was significant, as you PL fans know. It also has esoteric knobs and buttons on the front I have no hope of ever understanding. Inside, it's a bit of a mess! I guess this is how things were done in 1974, but by 70's vintage Japanese stuff is a LOT nicer inside.

The gentleman I got it from is quite nice. He's "in the business" so I'll have to follow up with him again. He bought a truckload of gear from a deceased audio engineer. I think he said he got six Revox tape decks, and at least one Otari. (maybe two). I didn't have time to chat further, as it was late, but he's sitting on some good stuff it seems. He paid zero for this amp in that deal, so he made his money back.

Anyway, all the fuses are good, and I don't see anything obvious, other than it appears the transistors (I guess- not the power transistors, which are carefully placed to overheat the speaker binding posts) on the left hand board appear to have gotten much hotter than those on the right side board. Check the pictures:

IMG_3272[1].JPG
IMG_3274[1].JPG
IMG_3275[1].JPG
IMG_3276[1].JPG
 

George S.

Chief Journeyman
Joined
Feb 18, 2020
Messages
1,044
#26
I built a complete Dynaco system back in the day. Screws held the phono jacks. I've heard that factory wired units used rivets. Screws or rivets on the back panel?
 

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
2,175
Location
Connecticut
#27
I’ll have to check tomorrow. I put it under the bench for now.

Based on the markings on the plate over the caps, at least one person has been in there.
 

nakdoc

Chief Journeyman
Joined
May 11, 2011
Messages
532
Location
Nashville, TN Music City
Tagline
highly biased
#29
It looks like it is kit built, and someone did a sucky job recapping. To cure the distortion, resolder the driver boards around the differential pair.
I used one of these for years on Dahlquist DQ10s, and was very happy.
 

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
2,175
Location
Connecticut
#30
The rear tags appear to be "factory" installed, but I'm not sure how the kits looked externally.

The inner frame seems to have cut outs for VU meters on the front, in the center. I have to check the inputs to see if they are rivets or screws...

But it is messy inside. Everything is flying up off the board (which may be by design?) and some masking tape labelling a wire or two, so either you are correct, it's a kit build, or it has been "worked" by someone. Low priority at the moment.

I am planning to go through the Pioneer today.
 
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