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I was hoping someone could tell me the function of a box that plugs into the back of a Dynaco PAT-5 preamp. There's an umbilibal type cord that goes to a silver box, and within the box is a transformer, and that's it. Optional? Required? I dunno...
HELP! - John
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is a Frank Alstine-like mod to beef up the power supply. He frequently outboarded certain components to add larger capacitors in the main chassis.Even to this day, his PAS-3 flavor has the transformer hanging out the back for that reason.
jms130,Several years ago a friend gave me the PAS3 and ST70 he had built from kits in 1964. These were two very high mileage pieces of gear. By the way, he purchased the kits from a shop on "Radio Row" in NYC that was demolished to make way for the World Trade Center buildings. Think of those piles of new $4.50 Telefunken ECC803S you might have picked up on that street at the time.
In the box that came with the PAS was a small device like you describe but about which I never asked. This was built in the same off grey/ green/ goldish paint, was marked as Dynaco, and had a partial cage/cover on it like the ST70. Unfortunately, this is packed away in a mystery location in storage, a pity because I know it had the instruction book with it.
My memory of this box is that the plug that resembles a socket took a special cord that ran to those same receptacle/sockets on the ST70 and -I could be completely wrong on this as I don't know if it's the same box - when you turned on the PAS, it triggered the ST70 to turn on-. I can't remember if it also had a couple of conventional sockets to plug other components into. Of course, now I wish I'd paid more attention about 8 years ago when I saw it the last time! Oddly, since I have one of these mystery boxes with the book, it's still a mystery to me as well!
I'll wager the Dynaco fanatics over on "Dynaco Doctor" forum will know all about your box. Perhaps they actually converted stereo to mono during an age when people wre suspicious of two channel,...
Cheers,
Bambi B
Cortlandt Street what a great place! Block after block of electronics and each trying to undercut the other. Not only could you find almost anything there, you would also find the best price. My dad was a Radio Row veteran and the first time he took me there I thought I had died and gone to heaven.
Anyway could this be the box? (see link) If so it's for PAM-1s.
- http://cgi.ebay.com/Dynakit-Dynaco-PS-1-PreAmp-Power-Supply-Mullard-Tube_W0QQitemZ180090417765QQcategoryZ3284QQssPageNameZWDVWQQrdZ1QQcmdZViewItem (Open in New Window)
I owned both a PAS-3X and a PAT-5. (Built 'em both.) Both had AC outlets on the rear (like a power strip) for powering other electronics. Some outlets were switched with the main power switch on the preamp; others were live all of the time.In fact, the PAT-5 generated all kinds of nasty transients when powered up (or powered down; can't remember which) so Dynaco wired that unit to be on all of the time to avoid destroying speakers when it was feeding a powerful amplifer (like the Stereo 400). The PAT 5 "power switch" (a heavy-duty job) actually switched only the outlets on the rear.
Bruce from DC,Yes, I'm a bit vague on this one- you're right, the extra outlets don't make sense given the onboard ones. I'm still thinking the function of the mystery box is more along the lines of being a trigger to turn on the ST70. It's also the only thing I can think of as use for those odd tube socket-like receptacles on the ST70 since there are separate RCA jacks.
I'll have to dig that box out one of these days.
Cheers,
I used to know what the tube socket receptacles on the front of the ST-70 were, but now I forgot. It may have been that Dynaco had a previous model preamplifier that actually took its B+ and 6.3V filament supply from the ST-70. I'm just not sure.I built one of them - in 1969 - too. I know that one function of the tube sockets was to make the connection to your voltmeter for setting bias. It was 1.56 V.
Certainly not required. Does the mystery box plug into the wall???
Nope, doesn't plug into the wall... on the preamp, between the two switched outlets, there is an unmarked plug that resembles one used for a vacuum tube. No other power source, however the unit seems to be dependent on it as it doesn't function with out it. I might take a look-see inside and see if this was some sort of home-made mod...
I am looking at my unmodified Pat-5, circa 1975. There is nothing like what you mentioned on it, and no mention of anything like it in the instructions, which I also have.
Seems as though the power transformer was located outside the chassis. Some type of home brew, not bad... almost looks factory. I wonder if the purpose was to reduce hum? hmmmmm.....
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