How to Replace filter capacitors Dynaco PAS 3 Tube type Preamp amplifier D-lab Electronics

Step by step procedure for the Dynaco PAS series tube preamp, utilizing the SDS Audio Labs Capacitor replacement board. Sometimes when you do this type work, modern components may be necessary. Others may have a difference of opinion. However, do as you see fit. The Dynaco's are sought after, great performers, well worth the effort of restoration. Taking a little poke at the social responses on KZbin. Hope this is of value to you.

[@donmoore7785]

That unit is in amazing condition, inside and out.

[@joeyvanostrand3655]

I just got a kick ass set of Dynaco speakers. 2 2-10's and 2 1-8's w/ a tweeter. They are wonderful!

[@orresearch007]

Amazing, I have a Beckman 310 exactly the one on your desk, and I used it when I was restoring my PAS a few years ago. Your video is detailed and excellent.

[@74dartman13]

Nice job as always Terry. I always learn something from your videos!

[@allanjohnston8049]

You have such an awesome way of making a repair look so easy!!! I know how to solder etc but knowing the right type of repair is so important You amaze me every time I see you in operation You make it look so easy Thanks for another great video!!

[@keithnelson5605]

I saw that on the shelf about a week ago. Glad you made a video. I have one waiting for some love.

[@kane100574]

Thanks, man! I love your channel!

[@barrychristiansen4579]

very cool work Terry . well done @! Cheers!

[@jjiacobucci]

Awesome demonstration, Terry!

[@d-labelectronics]

Thanks, Great project, more to do before the final test

[@edvaioli7340]

Next PAS you do make sure to video. The board has been redesigned for right side up mounting and elimination of the rectifier tube if desired. Also no instruction sheet is included.

[@crbielert]

2 of these on my bench right now.

[@jcmcclain57]

Terry, thank you for the detail and explanations in this and your other instructional videos. Good job! 👍👍

[@johnbellas490]

Those PAS units were real nice!! Had one myself and it was hooked up to 2 EICO 50 WATT amps with the EL34 output tubes.It was a real good system, wished I still had it today, but sold it about 20 years ago! John Bellas KC2UVN

[@garysmith8455]

I kept ALL my Dynaco gear.... PAS-2 (those same original tubes still there too!) with all new caps and elimination of the selenium rectifier. Mark 3 amps have all new caps including quad cap with 650v. rating and new diode rectifier for filaments... All made at the factory assembled in 1965 as stamped by the same tech... These run into a pair of 1967 Klipschorns (UNaltered)... Heck of a sound considering the year.... (O:

[@swinde]

You bastard ... I had four of the Dynaco Mark III amps, three Kits I built and one factory assembled. I foolishly traded them in for later models of Marantz equipment. The Marantz stuff still works great with some TLC from me, a tech, but I wish I had kept them. I still have a Dynakit PAT-4 and a Stereo 120, but I miss the tube amps.

[@georgethomas9436]

A great how to video. I like it how you showed how to use upgrades. Again love your channel. Well worth subscibing.

[@d-labelectronics]

Thank you my friend. Hopefully more this weekend

[@MichaelLloyd]

Excellent video as always. I've updated a few Dynaco Pre-amps with parts from a place called UpdateMy Dynaco. I haven't restored my tube preamp yet. Too many irons in the fire for now. 73 NE5U Mike

[@timothyharris7017]

terry you rock man........love your video........

[@harryconover289]

Before you mount the replacement supply board I recommend a foam insulation tape on the chassis and have the board seal on that it would be a much stronger assembly one Screw mount for that size board is marginal at best by adding the support below it makes it easier to do and stronger to

[@DeadKoby]

If their board is priced competitively, it's a good solution. I'm sure you could also do the job manually with generic caps and fuse parts.

[@zipstuff]

Great video! Question, you did not show the wiring on how to get power to the board? Can you share how that was accomplished?

[@RobertKohut]

This certainly a very nice example of a PAS pre, looks almost new!!

[@d-labelectronics]

Good thing Dynaco used the A instead of an O in that model, the reputation may have suffered

[@RobertKohut]

LOL...too true!!

[@willrobbinson1]

Replacing the selenium rec with silicon is a must BUT it may increase the heater volts on tubes without correcting

[@treed873]

So what happens if you blow that fuse? Wouldn't have been better to mount that board right side up?

[@TheGalaxyhopper]

you rock, big daddy, you had me toe tappin, friend'

[@LOLAAUM]

Thanks for the great video! Thanks to you, I have done this upgrade and for the most part, everything is functioning properly. But now I have audible hum (which I did have before upgrade but it was very slight). Only connection is preamp to power amp. Not affected by volume. I don't experience it with other preamps that I have. Thanks in advance for any insight!

[@Dutchamp]

Terry, I admire your repair work. Real good work., but I have a little comment on one thing, I think your a more RF repair guy, no offense ment what criticism I make. I see you ground parts and wires where ever you can, normally and especially in RF it is required, a must have course of ossilation problems. But in audio it can be tricky try to lead all ground to a star point or even better to the input ground terminal. Then you never get 60hz hummm. I ones took a ground from point to point a lead from 2" underneath a pcb board and the Amp was bussing loud in my case 50hz (Holland) that's what I wanted to say. The rest you do top work I like it a lot.

[@richardweinberger6302]

Why did they put the fuse on the bottom?

[@jordanch68]

I need to get one of those boards from SDS for my PAS2. :)

[@d-labelectronics]

It is the way to go!

[@scottonnob]

Instead of 13 ohms, I'm getting 7. Is something wrong? I don't want to put power to it if there's a problem.

[@kenhancock8931]

first cheers terry ;-) thx 4 tha video

[@edvaioli7340]

Excellent video, Terry. To be clear, does the board come populated or do I have to provide my own components? Thank you.

[@gerardcarriera7052]

Great video! Years ago, my Dad gave me his PAS-3 as well as his ST-70. I have not been able to use it as the dual 750K balance control pot is seized and he broke it trying to use a pair of pliers trying to free it. I have searched everywhere and cannot find a replacement. Any ideas as to where I can find one? I replaced for him that exact same filter can back in '74 as the same thing happened. At the time, I got the same multisection one cheap. Of course if I can ever find that pot, I will install that new board.

[@kanuckbrewero6118]

Nice work on the project. I see the new board uses 5% resistors.

[@MikeTheGreatOne99]

Dammit your awesome!!

[@jefffree6990]

Nice job Terry! But Dick from the internet is saying He woulda left the original can in, for vintage cosmetics sake. What prevented the new board from being flipped to a more normal and convenient orientation?

[@robertporter1429]

Help Y'all - I just purchased and received a new SDS Pas Kit....one BIG question...there are 4 "diodes" in my kit...All the videos I see from Terry and others show this PAS kit exactly as I have BUT...his version clearly does not have any Diodes....I'm not totally smart about this...but can anyone explain what AND why they now send U the 4 diodes?? Many Thanks!!!!!!!!

[@kylenovak97]

I’m installing this exact same kit. I have a PAS2. My board is about 50% stuffed. I’m a solder newbie. The resistors I could bend the leads taught and then solder. The 4 large caps didn’t have much lead/prong to work with. They were short. I was a little queasy to have the 4 largest caps held in place by only solder. Am I just a worry wart? 🤖☠️

[@8xlaxx]

Looks like a PAS -3X ?,....as I see the small black caps coming up to the tone controls from the board. Very nice! You should do an Eico vs Dynaco shootout!

[@zurdoremi]

Hi, do you.only work on amplifiers?? No Linear Tracking tturntables?? Thanks

[@edvaioli7340]

I ordered and received a board but not instructions with it, Do you have a link to yours?

[@roberthurless4615]

Another good vid, However, I noticed that the wire hole did not have a rubber grommet in it. Did that concern you at all? Also, at the start of the vid, what is that piece of gear behind the Dynaco? An old O'scope perhaps?

[@d-labelectronics]

Hello, That instrument is my Wavetek audio generator.

[@RobertKohut]

Nice!! Glad I didn't 'Pas' on this vid!! Is this for your Dynaco mono blocks?

[@d-labelectronics]

This PAS is for a friends Dynaco set. I run a homebrew tube pre-amp on mine. Better that you watched the PAS rather that letting it blow in the wind!

[@waynepollard6879]

I'd like to see the work !

[@xmenken1]

How much did you charge for this pre-amp upgrade?

[@motorheadbanger7720]

Why did not they include no fuse at all back in time?

[@TheCondoInRedondo]

Wait. That was you. I saw your lips move when the troll was talking.

[@rciancia]

Really nice job Terry. That board is perfect and is the only way to do it. Glad you sent Dick from the internet packing.... the motto for those who post KZbin comments... don't be dick. Nice job as usual... Ron

[@d-labelectronics]

Roger that man, Glad you like!

[@lawrencehudlin]

Nice video... and it's a thumbs up from me for sure...BUT... I would have left the large filter cap in place, snipped all wires and leave it covering that hole now left behind. And the fuse and holder would have to be moved from the top of the board to the bottom side facing up for easy access should it ever blow.

[@dhpbear2]

I would've flip the capacitor board so the components were on the top.

[@gonzo11213]

Hi there, this is a great video! Thanks for that. I have what I believe is a PAS 3. The problem is when I turn it on, it does power up, the 12ax7's are very low but do light, the 12x4 is nice and bright...but no sound, through my Marantz. I tested the two transformer leads to the 12x4 with the AC side while plugged in, and nothing registers on my meter. There also is a weird low level crackling sound coming from the transformer, weird glue smell, but no smoke. The caps are original with no visible leakage. What is your assessment and thanks for saving my butt with this video by the way.

[@swinde]

I am going to go out on a limb and speculate that you have a bad power transformer. Be sure to add a fuse on the primary side.

[@gonzo11213]

@@swinde Right on! I did end up purchasing a new transformer, haven't put it in yet, the fuse is next then possibly a couple of tubes and the power supply caps there isn't any leakage but I may just change em out just to be safe not ro hurt the transformer.

[@Barracuda48082]

A decent capacitor checker with value readout would help..

[@Barracuda48082]

Nine thumbs down? Wth You are local to me..less postal. I have a fellow ham I gave a hb100, 200 10-80 m set to re cap..he could use some help..He has had it for a year but still not on the air.. Kd8tbc Lee . He is on the Hazel Park 2m net 6.640 on Sunday. There is a echolink also. Surprise him..ha. 73, KB8QLZ Gary

[@dhpbear2]

07:35 - HOLD IT! That sounded like many empty BEER CANS! Are you a 'closet' beer drinker, Terry? :)

[@d-labelectronics]

Haha, you caught that! Well, my wife only drinks beer out of a bottle, so I used La-criox sparkling water cans. Wanted some type of crash during the troll's forced exit. Maybe next time I will try a stack of bottles. TD

[@soupalex]

[looking at the scope] so all in all, that's a really good _sine…_

[@soupalex]

i must be the first person in the history of the world to make or notice a sign/sine gag when sending a test signal through an audio amplifier /s

[@remley8877]

Cool video as always. Totally wish i had chosen " Dick from the internet" for my KZbin name. I'm still laughing at that.

[@dhpbear2]

Interesting that Dynaco had 2 different styles for this preamp (07:35)

[@swinde]

Yes, the smaller picture is the PAS-2 which I think is very similar except for the new front panel and knobs.

[@zulumax1]

The other one is a PAS-2 which had a different fascia and plastic knobs, other than that same innerds. Not sure if they were both were made at the same time, I think it was a cosmetic update.

[@fredflintstone8048]

Nice upgrade, thanks for sharing... hmmm dick on the internet.. I've seen those.

[@andershammer9307]

Don't change the tubes ! Unless you want to spend a ton of money on audiophile approved tubes. Those original tubes were Telefunkens and they last forever.

[@FluxCondenser]

The original tubes are all shot on the one I’m restoring now. Preamp must have gotten plenty of use so I’ll be replacing them.

[@raimondoconcepcion6142]

Hey anyway or form of contacting you personally. Maybe an email or phone number. Interested with your videos.

[@justsumguy2u]

I always referred to the PAS series as the "Piece A Sh*t" series by Dynaco. I mean no disrespect at all to your video, it's just that I've owned two of them, and they sound truly horrific. The best adjective I can use to describe the way they sound is "woolly"....no high end whatsoever

[@Barracuda48082]

Filters, filters

[@johnsimms3957]

Yeah get rid of those old filer caps.

[@edvaioli7340]

Sorry, I can't recommend this board. Board is poorly marked with zero documentation. look elsewhere.