Pioneer SM-83 restoration

[jrme]

Hi,

I have bought a tube integrated amplifier, Pioneer SM-83, with the idea of restoring it.

Since this is at least a 40 years old amp, I was expecting something worst when I found it in Internet, but when I received it, I had the nice surprise that not only it was in good cosmetic shape, but also it worked relatively well. Only the support for the fuse at the back was broken.

I opened it to check the different electronic parts and then it was different. Even if the look of these electronic parts is good, their values are far from what it was supposed to be at the beginning.

So I have decided to restore and share the experience with any other person who could be interested or who has already restored such an amp.

From those who have already the experience of this amp, I would appreciate their advise on particular things or behaviour of this amp, please.

In advance thanks.

Best Regards.

José

[LinuksGuru]

Hi!

Here you can find a detailed walk-through of restoration process and parts used. I ordered almost all parts from Digikey USA. You have to select electrolytic can caps so they can fit clamps and limited height of chassis.

MacGuru HQ: Vacuum Tube Amplifier Pioneer SM-83 Restoration
MacGuru HQ: Pioneer SM-83 Vacuum Tube Amplifier Tests & Measurements

[jrme]

Hi,

Thanks you for your answer, I have visited the links you posted and I think that you have done a wonderful work there. I am using it contents as a guide for my own restoration. Really very, very well done.

My first step, already done, has been to check the values of parts. The next, on the way, is to make a list os components and find what goes the best for rhem. I will visit the Digikey USA to check what can I find there and try to group my purchase.

Regards.

José

[LinuksGuru]

I have BOM somewhere on my HD, it lists SM-83 parts as well as few others for another project. Its impossible to to sort out them apart since a lot of time have passed. I can find and upload it if you wish.

[jrme]

Hi LinuksGuru,

Yes please, you can upload the parts, it will help a lot.

Regards.

José

[LinuksGuru]

I can do it on Monday when will be back home.

[jrme]

Great, it will make me the task easier.

In the mean time, I can tell you, even with its old parts, this amp sounds wonderful. Just a little bit of distorsion at high volume; probably because I have the use to listen to transistor's amps.

Regards.

José

[LinuksGuru]

Hi, Jose,

You can download list of spare parts here (OpenOffice spreadsheet). Please read notes, there are some items for another projects.

http://www.vacuum-tube.eu/files/pion...neer_sm_83.sxc

[John L]

I'm glad I discovered this thread. I bought a Pioneer SM-83 about four years ago, on e-bay, when I was going through one of my "gotta have this, gotta have that" phase. And one of the things I picked up for an extremely good price, was this little fellow. I promptly put it away, in my stack of vintage gear, that fills up my unused upstairs bedroom.

Well, I am finally deciding to do something about all this 'stuff' and want to repair/construct/create something of my own. And naturally the first thing to come to mind is a tube amplifier. I have lots of them lying around, including 'pulls' from Magnavox, Motorola, RCA, and my favorite from nostalgia, Voice-of-Music. As a kid I had a new V-M record player in Alaska, and a V-M tape recorder, so I am naturally 'sweet' on those old critters.

But before I can create my first amplifier, I need two things: one, some expertise on what I am doing; and two, a preamplifier. I have lots of them, but really want a tube preamplifier.

I have a good number of tube receivers, but they are just a bit too big for my needs, and I need something that looks nice, will do the job as preamplifier, and will pass along that nice mellow sound of tubes from the amplifier.

So I started rummaging around, and there sat that cute little Pioneer. And knowing that I can bypass the amplifier circuit, I pulled it out and dusted it off. And here I am, having taken some very quick and dirty pictures, and wondering if this little baby will work for me without having to do major surgery.

Here are some shots. First off, you can tell that someone has already done some reconditioning work on the amp. The knobs stick out first, and they really look modern and profession. The person before me had a pretty good artistic sense, and those knobs make the unit look more modern than it really is.

And note the replacement of speaker terminals. They are now banana clip friendly. Joy! And I also note now that he has definitely replaced some of the caps, expecially two of the electrolytics. The other two look original.













Oh shucks, I forgot to take a picture of the inside of the top of the amplifier. I'll have to lug it back down and remove the cover in a little while.

[jrme]

Hi,

Your amp looks very clean and in very good shape.

What about the tubes ? Personaly, I am experiencing some difficulties to find them for replacement.

In any case this amp is really wonderful. The quality of the music throught it.

Congratulations.

Regards.

Jose