Pilot 248 Amplifier

[idadude]

Anyone ever worked on/upgraded one of these integrated amps? Just wondering what I could do to make it better. Looks like one of the bias pots may be cooked too. I will do a re-cap for sure, along with replacing the diodes. The tubes tested good, though one 7591 had been replaced. Would be nice to hear this one sing.

Larry D.

 

[derekva]

I haven't found a schematic, but that's got some *serious* iron. I'll bet it would sound amazing with just a general cleanup and recap.

-D

 

[idadude]

I haven't found a schematic, but that's got some *serious* iron. I'll bet it would sound amazing with just a general cleanup and recap.

-D

Yes, I bet it will sound great too. I have a similar 246 and it is one of the best sounding vintage pieces I have. There were not many made, so I'm not surprised that there was only your response so far. The 'serious' iron was what got me interested in these Pilot pieces and once I heard them I was hooked.

I've done a little searching and found that the 5 meg 1/2 W DC Balance pot will not be too difficult to find a replacement for. I do have a schematic for the 248, so that's a big help. I'll re-stuff the cans, change out all the small caps, and take the ceramics out of the tone controls and put in silver micas and/or polystyrenes. There's just a LOT of caps to replace. I had a Pilot 602 receiver and tested all the kidney bean caps and found that 90% of them were leaky, so I don't trust these in the 248 either. It will take a bit of work, but should be worth it.

Larry D.

 

[kmolles]

I have one too. It's on the "need to inspect and test shelf", so I have no insight for you (yet). They look well built, so I'm eager to discover how it performs myself.

 

[multichamp12]

Agreed Pilot gear is my favorite. The 248 is pretty rare, you don't see them come up for sale too often. I started with a Pilot 240 and it's still one of the best sounding amps I have,

 

[idadude]

Well I took off the 'cooked' looking pot and it was fine inside. I looks as if the 20 ohm resistor going to ground may have cooked the wiring next to the pot and had given it the smoked appearance. That may have happened when one of the original Westinghouse 7591s went bad.

Anyway, I brought it up slowly on the variac and got music equally out of both channels at 50-60 volts. Good enough for me. Now I know it's ready for a cleaning and re-cap. The volume control is terribly scratchy and cuts out a lot when you turn it, so it will get attention first.

Larry D.

 

[idadude]

I have one too. It's on the "need to inspect and test shelf", so I have no insight for you (yet). They look well built, so I'm eager to discover how it performs myself.

What kind of shape is your's in cosmetically? Mine is all there, but was in a heavy smoker's house. I'll definitely put in a lot of time to get this one fixed up to where I'm happy with it. After rebuilding my 246 I can say that they're absolutely worth the time and money you put into them.

Larry D.

 

[multichamp12]

Post some pics of the rebuild if you can!

 

[gadget73]

Leaky caps can make pots act even worse than they are, so check that too.

I dig my Pilot gear.

 

[darkblue94]

My SA232 amp is suh-weeet!!!

 

[Leland47]

I've got a 248B sitting on a shelf, awaiting restoration. Here are some spec below.
I believe I read somewhere that the 248 weighted in at 34lbs? I can't remember where I got that info....

 

[Theron D]

I've got a 248B sitting on a shelf, awaiting restoration. Here are some spec below.
I believe I read somewhere that the 248 weighted in at 34lbs? I can't remember where I got that info....View attachment 720890

View attachment 720891

Was wondering if you ever restored your 248B? I recently purchased a beautiful 248B but will need a restoration as well most likely. Any input appreciated. Thanks

 

[Leland47]

Hey Theron D

No, still sitting on shelf....waiting.
Yours sounds nice.
If you decide to do a basic rebuild, caps and such, start a thread and I’m sure AKers will help you along. Great bunch here!

Post some pics, I’d like to see it.
Lee

 

[Theron D]

Hey Theron D

No, still sitting on shelf....waiting.
Yours sounds nice.
If you decide to do a basic rebuild, caps and such, start a thread and I’m sure AKers will help you along. Great bunch here!

Post some pics, I’d like to see it.
Lee

thanks Lee I will!

I did start a thread on this particukar amp but was only in refernce to speaker hookup and looking for user manual.

 

[Leland47]

For some reason....there doesn’t seem
To be a schematic or Photofac for this Pilot model. At least I’ve never found one. But you’re right....there should be a user manual out there somewhere.

I’d try to find a plain 248 manual and see how that works.

 

[Leland47]

Hey, I found this over on HiFi Engine....Looks like a Photofax for the 248.

Its too big to upload here. Shoot me your Email in a "conversation" here....and I'll send it to you.

Or just register on HiFi Engine and download it.

Best
Lee

 

[Theron D]

For some reason....there doesn’t seem
To be a schematic or Photofac for this Pilot model. At least I’ve never found one. But you’re right....there should be a user manual out there somewhere.

I’d try to find a plain 248 manual and see how that works.

I have someone sending me a copy of the 248 manual. Listening to it right now, super sweet mid range. Doesnt have the low end power of say a Rogue Cronus Magnum, but that's comparing apples to orange!

 

[kmolles]

Well, I finally pulled mine out and messed around with it. It's amazing how this thing could sit unused for so long and still work! (Yes, i brought her up slowly on a variac....started playing at about 70 volts). I'm not going to b put it back in storage and no need for it. I am just using amps I've built myself now. Off to ebay this goes!