Dynaco PAS (3?)

[Fast_Eddie]

Well, it's rough. But I did just find a Dynaco PAS pre amp for $2.99. It actually may clean up ok. Some of the pots and switches are iffy and it looks to have spent some time in a damp environment. Not like it was underwater, but like I said... it's rough.

I just picked it up on my lunch break and haven't had a chance to even look it over really. All the same, pretty cool.

Oddly, I got a Dynaco PAT2 along with it. They were both at the thrift store, but no sign of a power amp anywhere. The PAT looks a little better, but still not 100%. We'll see.

[SpruceMoose]

brass or aluminum faceplate on the PAS?

[Fast_Eddie]

It's an aluminum faceplate. I've been looking at pictures on the internet and can't really tell which it is. I'll have to get a closer look at it after work.

[Fast_Eddie]

Couldn't take it any more. Ran out to the car and brought it into the office.

My initial impression was far, far too harsh. It's actually not bad. Lots of oxidation on the knobs and such, but I think once it's cleaned up it will be good. Not sure where I got the water damage idea. I popped off the top and it's like new in there. Amazing. Sitll has the Dynaco tubes in it. I'll recap it and I think it will sing some sweet songs.

The iffy switch turned out to be a lose set screw.

[Fast_Eddie]

This is a web pic- but this is what it looks like. PAS3?

[salb203]

Nice score for $2.99. You have either a PAS-3 or a PAS-3X preamp. The way you can tell is to rotate the bass/treble knobs, if they have a shorter rotation than usual (compare to the volume control) then it is a PAS-3X.

Sal

[Fast_Eddie]

Nice score for $2.99. You have either a PAS-3 or a PAS-3X preamp. The way you can tell is to rotate the bass/treble knobs, if they have a shorter rotation than usual (compare to the volume control) then it is a PAS-3X.

Sal

Hum, thanks for the info! From "lock to lock" they turn just over 180 degrees. You think that makes is a 3X? What's the difference? I mean besides the pots on the tone controls?

[SpruceMoose]

could be a PAS2 with the -3 faceplate. check the label on the back.

[Fast_Eddie]

The label on the back simply says DYNA PAS

[Brian]

I'll bite. What is a PAT2? I know of the PAT4, PAT5 and PAT5bi-fet but never heard of a PAT2. These was a PAS2.

[Fast_Eddie]

I'll bite. What is a PAT2? I know of the PAT4, PAT5 and PAT5bi-fet but never heard of a PAT2. These was a PAS2.

A PAT2 is what you get when you mean to type PAT4 but mess up.

[salb203]

Hum, thanks for the info! From "lock to lock" they turn just over 180 degrees. You think that makes is a 3X? What's the difference? I mean besides the pots on the tone controls?

I would say it is a PAS-3X. When you open it up look behind the treble and bass controls, if you see 1uf capacitors (I think there are 2 1uf caps) soldered from the potentiometers to the printed circuit board, its a PAS-3X which will "electrically" remove the tone controls from the circuit when the controls are set at the center.

Again, great score at $2.99, I am never that lucky.

Sal

[analog addict]

Are most likely Telefunkens.....:thmbsp:

The quad of 12AX7's in and of themselves, with a decent amount of life left in them are prolly worth at least a Benny.....:banana:

[Fast_Eddie]

...if you see 1uf capacitors (I think there are 2 1uf caps) soldered from the potentiometers to the printed circuit board, its a PAS-3X

Yes, there are. Thanks!

I was looking and see quite a few of these selling on e bay that appear to be original, as in old caps, solenium rectifier in place, original tubes.

It seems that you would need to replace the electrolytics at least, doesn't it? I almost affraid to plug it in witout doing that. Looks to be worth a few bucks though, so I hate to do anything that might diminish it's value.

[analog addict]

Do yourself a favor and get a variac. It's worth the investment. :yes:

I also have a capacitance meter, which is extremely handy for sorting out all the old caps. :thmbsp:


Before you plug anything in, read this (http://audiokarma.org/forums/showthread.php?t=778).....

[Fast_Eddie]

Do yourself a favor and get a variac.

Yup, ok. This thing looks pretty nice and appears to be worth enough to justify getting a variac. I looked on e bay and it's pretty confusing for those of us who are new to this. Seems there are several different types and the prices are all over the place.

I'm selling some speakers right now so I'll have some cash that I can put against this.

[analog addict]

Once you get bitten by the toob bug, you'll never look at your SS gear in quite the same way....:no:

Get a Variac that is rated for 5 Amps or better. That will give you some flexibility. Meters are nice, but all you really have to do is once you first get it, use a DVM and measure the VAC against the dial markings.....:thmbsp:

[Fast_Eddie]

Thanks- I'll need some help, but I'll get this all sorted. I'm working on restoring a Motorola tube amp right now. (another thread going on that one already) So once this is all sorted out I'll have a nice little tube system to get me started.

Thanks,

Ed

[salb203]

Yes, there are. Thanks!

I was looking and see quite a few of these selling on e bay that appear to be original, as in old caps, selenium rectifier in place, original tubes.

It seems that you would need to replace the electrolytics at least, doesn't it? I almost affraid to plug it in witout doing that. Looks to be worth a few bucks though, so I hate to do anything that might diminish it's value.

I own 2 PAS-3 and 1 PAS-3X and the electrolytic's were good in all 3, I replace the selenium rectifiers as the DC voltage going to 12AX7's were low.

I also cleaned up another PAS-3 for someone and the caps were good in that one too.

I did replace the voltage doubler capacitors on my first preamp but the caps were good when I checked them out of the circuit.

Sal

[Fast_Eddie]

I own 2 PAS-3 and 1 PAS-3X and the electrolytic's were good in all 3, I replace the selenium rectifiers as the DC voltage going to 12AX7's were low.

I also cleaned up another PAS-3 for someone and the caps were good in that one too.

I did replace the voltage doubler capacitors on my first preamp but the caps were good when I checked them out of the circuit.

Sal

Great! I'm gonna get a variac and get this puppy going! I'm pretty excited- I'm gonna have a pretty cool tube rig!

[Fast_Eddie]

Sorry for the poor quality. Camera batteries died and I couldn't take any more. And the macro on this thing! Grrr. It sucks!

[Fast_Eddie]

You can sorta make out how badly coroded the knobs and face are. Any suggestions for cleaning that up? But look inside- like new. Amazing.

[Russellc]

Are most likely Telefunkens.....:thmbsp:

The quad of 12AX7's in and of themselves, with a decent amount of life left in them are prolly worth at least a Benny.....:banana:

Yes, those should be tele flat plates. Turn them upside down and look for the diamond imprint. Once in a while I've found tele ridge plates, likely where someone changed one out? I have bunches of pairs of these things I've gotten from dyna stuff, and most of them test quite strong. Not exactly my favorite tube sonically, but good 12ax7a are harder and harder to find. See FM-3 zone for new faceplates with or without tone controls, various colors as well.

Russellc

[Russellc]

Selenium rectifier likely needs to go. Measure your filamanet voltage and see where you are. As these die they allow less and less voltage through. A couple of caps and diodes will fix you right up.

Russellc

[Fast_Eddie]

Thanks Russellc

Found this re: Selenium rectifier replacement:

http://www.curcioaudio.com/PAS2-3X%20Fil%20Rect%20Replacement.pdf

[salb203]

Wow, the inside is very clean, you might be able to use a brass wire brush to clean the outer edge of the knobs.

Since you don't have a variac, you can wire a 15-30 watt light bulb in series with the line cord. If the bulb light up bright, then you might have a problem but if it lights up dimly and the filaments light up dimly, keep it that way for a while and if the power transformer stays cool I would give it a try at full power.

Sal

[Fast_Eddie]

It's remarkable isn't it? It looks so rough outside, but dang, it's not even dusty inside!

[DaWoofer]

Fabulously clean inside, what a steal! I payed the going price and then put in the SDS board and the bass tightened right up. It was a tad flabby in the bass until that mod. I'm not sure if just changing the selenium rectifier to diodes will help in that regard. You should up the capacitance for that to help. Good luck with your new gear.

[Fast_Eddie]

Thanks DaWoofer

Well, I have good news. I pulled the knobs and face plate off. The face cleaned up pretty dog gone well! Looks more than presentable. The knobs are badly pitted, but I put a bit of work against them and polished them with Semichrome. They at least have some shine to them now and it makes a big, big difference. If you looked at it now you wouldn't assume it was trash as I almost did when I saw it.

Cooooool!

[Fast_Eddie]

Some pictures of it now that its clean!

[Fast_Eddie]

Wish me luck. The pre amp is cooking at 30 volts on the variac I got today. So I should know if it works soon. The good news is the PAT-4 I got with it is working perfectly, so that gives me some hope for this little guy.

Take care,

Ed

[worldoftone]

NICE! And great deal. I have a PAS-2 with the PAS-3 faceplate that dad built in '66.

- WOT

[simplynuts]

I have a dyna and that I believe is the original preamp manufacture plant

[Fast_Eddie]

Woo hoo! I brought it up really slowly. Still on the Variac, but at 110v. I hooked it up to my T Amp and a portable CD player. It works really, really well! I shot the pots quickly with Radio Shack cleaner and everything is working great. Even the switches that I didn't clean work just fine! No odd noises or anything, so I think everything is in order! I'll let it cook for an hour or so at 110v. and then move it into the main system!

Cool!

[clydeselsor]

Nice preamp!