Capacitor board for PAS 3

I have an original PAS 3 that of course needs new capacitors. I saw the SDS Labs capacitor board, which Triode Electronics sells:

http://www.triodeelectronics.com/sdslacabofor1.html

I asked Triode whether this replaces everything that needs replacement because of age, but haven't heard from them. Has anyone tried this board?

Thanks,
John R.

Here’s another alternative.

http://www.curcioaudio.com/dynadr_3.htm#DYNACO%20PAS%20PREAMP%20%28Models%202,%203,%20and%203X%29

jrethorst wrote:I have an original PAS 3 that of course needs new capacitors. I saw the SDS Labs capacitor board, which Triode Electronics sells:

http://www.triodeelectronics.com/sdslacabofor1.html

I asked Triode whether this replaces everything that needs replacement because of age, but haven't heard from them. Has anyone tried this board?

Thanks,
John R.

Yes, i sell it. It replaces both the filament and B+ caps and the Se rectifier.
Here is the documentation : http://n.manet.nu/tubedoc/PASboardnewins-1.pdf

jrethorst wrote:I have an original PAS 3 that of course needs new capacitors. I saw the SDS Labs capacitor board, which Triode Electronics sells:

http://www.triodeelectronics.com/sdslacabofor1.html

I asked Triode whether this replaces everything that needs replacement because of age, but haven't heard from them. Has anyone tried this board?

Thanks,
John R.

The under powered transformer needs to be replaced as well jrethorst. Back in the day some of the PAS 3's received an update to replace the bad transformers. So you might also want to look and see if your model received the update.

Tom Pickett wrote:

jrethorst wrote:I have an original PAS 3 that of course needs new capacitors. I saw the SDS Labs capacitor board, which Triode Electronics sells:

http://www.triodeelectronics.com/sdslacabofor1.html

I asked Triode whether this replaces everything that needs replacement because of age, but haven't heard from them. Has anyone tried this board?

Thanks,
John R.

The under powered transformer needs to be replaced as well jrethorst.  Back in the day some of the PAS 3's received an update to replace the bad transformers. So you might also want to look and see if your model received the update.  

Please spread no unfounded rumors.
The transformer is small, yes, but so is the power consumption.
One can reduce this additionally by replacing the pilote lamp with a LED ( dynakitparts has a complete kit if you like).Adding more tubes is a secure way of killing the transformer.
The other reason transformer blows is most likely bad capacitors combined with the fact that PAS don't have a fuse.
The SDS cap board has a fuse that will be incorporated with the primary.

peterh wrote:

Tom Pickett wrote:

jrethorst wrote:I have an original PAS 3 that of course needs new capacitors. I saw the SDS Labs capacitor board, which Triode Electronics sells:

http://www.triodeelectronics.com/sdslacabofor1.html

I asked Triode whether this replaces everything that needs replacement because of age, but haven't heard from them. Has anyone tried this board?

Thanks,
John R.

The under powered transformer needs to be replaced as well jrethorst.  Back in the day some of the PAS 3's received an update to replace the bad transformers. So you might also want to look and see if your model received the update.  

Please spread no unfounded rumors.
The transformer is small, yes, but so is the power consumption.
One can reduce this additionally by replacing the pilote lamp with a LED ( dynakitparts has a complete kit if you like).Adding more tubes is a secure way of killing the transformer.
The other reason transformer blows is most likely bad capacitors combined with the fact that PAS don't have a fuse.
The SDS cap board has a fuse that will be incorporated with the primary.

I mean no disrespect.... This is not an unfounded rumor. I have worked on many of these PAS 3's throughout the years and have had to replace many of these transformers due to failure. I have been servicing and repairing tube equipment for over 38 years since 1983 after receiving my Masters in electronics and computer science and have owned and operated my own repair shop for many years.

I once started with a completely stock PAS and gradually upgraded it, evaluating marginal changes as I went.

The power supply of the original PAS was not exactly robust, and old ones are of course much worse. The incandescent pilot lamp is a huge drain on the power supply. I started by replacing it with the LED, and right away noticed a big improvement. The bass wasn't sloppy any more, but it was still saggy.

I did a lot of research on various upgrades (there were a few more choices back then), and wanted a solution that would work with the original audio boards as well as upgrades. For this reason I chose a regulated board from Dynaco Designs, as the Tubes4Hifi power supply (now Erhard-Audio) didn't work with the original audio boards. The DD board kept the original transformer for the filament circuit and added another for the B+ circuit. (It is no longer available, or not shown on their web site. It was adaptable - could use the rectifier tube or not, bit it wasn't documented and required much communication with DD to configure it.)

I was surprised to hear less of an improvement with this step than I did with the pilot lamp replacement. The bass was a bit tighter, but the sound was kind of lackluster or flat, not very dynamic.

Next I disconnected the tone controls, loudness and filter. Negligible improvement.

My next step was to upgrade the audio boards, and here I hit a home run. I used the Akaido board now sold by Erhard-Audio. Imaging became holographic. Dynamics improved markedly. Detail improved, the mids and highs sweetened, the bass punchy and well integrated. The phono board (I think it was a PH-10) was also pretty good.

I replaced the selector switch, the balance and volume controls (used a stepped attenuator for volume - meh?) and the jack panel. And the face plate. Buy this time the only original parts were the chassis and the transformer.

While it was a good education, it was an expensive way to upgrade a PAS. But the end result sounds much better than a Van Alstine mod that was even more expensive.

daveshel wrote:I once started with a completely stock PAS and gradually upgraded it, evaluating marginal changes as I went.

The power supply of the original PAS was not exactly robust, and old ones are of course much worse. The incandescent pilot lamp is a huge drain on the power supply. I started by replacing it with the LED, and right away noticed a big improvement. The bass wasn't sloppy any more, but it was still saggy.

I did a lot of research on various upgrades (there were a few more choices back then), and wanted a solution that would work with the original audio boards as well as upgrades. For this reason I chose a regulated board from Dynaco Designs, as the Tubes4Hifi power supply (now Erhard-Audio) didn't work with the original audio boards. The DD board kept the original transformer for the filament circuit and added another for the B+ circuit. (It is no longer available, or not shown on their web site. It was adaptable - could use the rectifier tube or not, bit it wasn't documented and required much communication with DD to configure it.)

I was surprised to hear less of an improvement with this step than I did with the pilot lamp replacement. The bass was a bit tighter, but the sound was kind of lackluster or flat, not very dynamic.

Next I disconnected the tone controls, loudness and filter. Negligible improvement.

My next step was to upgrade the audio boards, and here I hit a home run. I used the Akaido board now sold by Erhard-Audio. Imaging became holographic. Dynamics improved markedly. Detail improved, the mids and highs sweetened, the bass punchy and well integrated. The phono board (I think it was a PH-10) was also pretty good.

I replaced the selector switch, the balance and volume controls (used a stepped attenuator for volume - meh?) and the jack panel. And the face plate. Buy this time the only original parts were the chassis and the transformer.

While it was a good education, it was an expensive way to upgrade a PAS. But the end result sounds much better than a Van Alstine mod that was even more expensive.

Very nice and detailed post daveshel....