Fender Bassman 50

[labb]

anyone have a layout drawing for the Bassman 50 that they can share, thanks

[Latole]

IMO layout is not available

Bassman 50 Schematic is 99% ( if not 100 %)  same as Bassman AA371 and layout is available here:

https://el34world.com/charts/Schematics/files/Fender/Fender_bassman_aa371_schem.pdf

I do 5 minutes search, can you find better with more time ?

[labb]

Thanks for the info. I compared the two item to item and they are identical.

[PRR]

Line switch moved to other line, thermal switch added.

[labb]

Thanks. I didn't pay much attention to the mains end. This thing showed up at my door with a note that said, if you fix it, you can have it. Don't know from who.  It looks like it has been in the barn for several years. Quick check of the transformers with Fluke show that they are a go. Don't know what happened with it. looks to have the original tubes.. one of the 6L6 missing. The fuse looks to be original and is not blown. Caps look to be all original. Wish I had some history on it. Well, will find out when I get into it. If anyone is interested in seeing the guts of it I could take pic and post. Thanks for the replies.

[bmccowan]

This thing showed up at my door with a note that said, if you fix it, you can have it.

Reminds me of how I got one of my favorite dogs. A little girl came up my driveway - tiny puppy in her arms. "Hey mister, do you know who's puppy this is?"
I'd like to see pics - I bet others too. I have a Bassman 50 that had been modded and then trashed when the PT died. I have used it to experiment with different Bassman circuits. It now has two different Bassman circuits in it. Its a fun and easy chassis to work on - no pesky reverb or tremolo

[Latole]

It's helpful to know it's for a repair. A schematic would be more useful.

The problems that this amp can have are very numerous.

The principal
1- Oxidized lamp bases, to be replaced
2- The 2 transformers possibly defective; To measure
3- The filtering capacitors to be replaced.
4- Cleaning all pots with Deoxit contact cleaner

Good luck

[Latole]

Fender Bassman 50 revival

https://myweb.uiowa.edu/berkwitz/bassman50revival.html

[labb]

Hope pic work

[sluckey]

Judging by those postage size pics I'd definitely say that's some kind of Fender amp.   

We need to see some big uns.

[labb]

Ok. Here comes bigger ones. You know I don’t know how to do this.

[labb]

A couple of things: all of the filter caps are bad. The amp has a humdinger and the balancing system. Visual inspection appears that several of the caps on the board are bad. The few resistors I checked were good (PS dropping resistors.) I would think that most of the cc resistors have drifted up out of spec.  Not really sure how many $ I want to pour into this thing. Just retubing is a load.

[Yeatzee]

Looks like it's one of those weird master volume ones like I just finished working on recently.

https://youtube.com/playlist?list=PLxuLEzgnah7gWiy5LNovUouiJbdqIeLN_&si=Go_DdyznLfPhWq1d

They're weird, different layout than the regular Bassman 50 without the MV and no official layout exists to my knowledge.

[sluckey]

Hey, I built a similar bench around a 30" diameter oak tree 35 years ago. The oak is now about 42" and what's left of the bench is not safe to sit on.   

[labb]

Yes on the master vol. I haven’t found a schematic that it shows up on. Kinda puts you in the guess to mate mode. Did you ever find any thing else. Fender repair and parts sells a repair kit(caps, resistors and don’t know what else) they say schematic and layout provided. I’m tempted to call and order and ask what they are providing for schematic and layout. Last I saw it was $185

[Yeatzee]

Yes on the master vol. I haven’t found a schematic that it shows up on. Kinda puts you in the guess to mate mode. Did you ever find any thing else. Fender repair and parts sells a repair kit(caps, resistors and don’t know what else) they say schematic and layout provided. I’m tempted to call and order and ask what they are providing for schematic and layout. Last I saw it was $185

Nope, it doesn't exist. It's from what I understand partially a mix between the Bassman 50 and Bassman 70 with the MV which does have more info. If you check out that series I linked to I go over everything in that amp and it was all original. Many of the values used are not readily available, I opted to swap in Bypass caps that are more standard values and it sounded great after. All covered in the series :)

[bmccowan]

I do not think the bones of that amp are that bad. But, I also would not try to restore it. If it was a car, it could be a restomod.
I would rebuild it to play it. The chassis can be cleaned. The faceplate can maybe (need to measure) be replaced with a repo blackface (not to fool anyone, but that faceplate looks a goner.) The repo will not have the MV - no great loss. The iron, pots and tube sockets will likely work out. Build what you wish in the guts. Use the existing board, or not.
$? Don't count - its easier that way.
Or - I can send you directions to my doorstep. Or as we say in Maine, my dooryard.

[Latole]

Worst than I think

My answer no 6

Plus ; need new face plate

If you are not a pro with amp repair, leave it,
Sell it for parts.
Don't waiste you money and you time

[bmccowan]

If you are not a pro with amp repair, leave it,
Sell it for parts.
Don't waiste you money and you time

I think it depends on how the word "pro" is being used. If it means experienced or knowledgeable, then I think its a good point - its a lot of work.
But if it means professional amp tech that is trying to make a profit; I do not think there is money to be made building up this amp. So I think its the pro that should probably hand the project off.
But many here are hobbyists. And some hobbyists enjoy a challenge and don't keep an accounting of our losses. Its the same with any hobby.
I would enjoy the challenge of doing something fun with what is left of this amp. My trashed Bassman 50: new layout, new turret board, new PT, new faceplate. What $ did I spend? time?   Did I have fun coming up with a plan and building it - yes. I play it and it sounds good. Is it worth much money - Hell no.
I know from previous threads that Labb has built a number of amps. But I also know that, like me, he is getting up in years and some tasks can be a struggle. So I do not think its a financial decision. 

[Latole]

If money doesn't matter and time is pleasure, why not !

[sluckey]

If that amp showed up at my door I'd fix it ***IF*** the transformers are good. Probably be less than $100.

I added the MV pot to the schematic. Should be able to fix the amp using this modified schematic...

[Latole]

If that amp showed up at my door I'd fix it ***IF*** the transformers are good. Probably be less than $100.

I added the MV pot to the schematic. Should be able to fix the amp using this modified schematic...

I agree.

1- You are a pro
2- And "IF" the transformers are good

[sluckey]

Not a pro. Just a hobbyist. Never had a single customer and never will. Some customers take the fun out of my hobby. Don't want the aggravation and don't need the money.

[Latole]

Not a pro. Just a hobbyist. Never had a single customer and never will. Some customers take the fun out of my hobby. Don't want the aggravation and don't need the money.

Not a pro in the sense of a businessman but in the sense that you know amps very well

[labb]

I talked with my financial advisor (wife) and she said go for it. I once saved a Crate Blue Voodoo from a dumpster so I kinda know what I am up against. Will build it back to original. Steve thanks for the marked up schematic showing the MV. I’ll probably have to call on you folks for advice before it is done. And Steve, the bench around the tree (Pecan) serves as my part time work bench. Don’t think I have enough time left to see the tree grow into it.

[shooter]

Not a pro. Just a hobbyist.

my camper-building hobby has brought a few folks to the door, helping one now, knows NOTHING of AC - DC circuits, wanted to hire me, I laughed n told him that would ruin the fun.  I did add a footnote that if he managed to fry everything after I wired it, I charge $50/hr to fix stupid 

[bmccowan]

Bravo! Go for it and have fun.
psionicaudio has a recent YouTube rebuilding a rusty cruddy Bassman - worth a look.
Yeatzee's is worth a look too, but read the comments as they clear some things up.
 

[sluckey]

And Steve, the bench around the tree (Pecan) serves as my part time work bench. Don’t think I have enough time left to see the tree grow into it.

My bench had about 2' clearance all the way around the tree. I figured the treated pine would rot away long before the tree grew into it. I didn't count on the tree roots growing. They buckled my bench and literally pushed one side out of the ground. I guess if you want something to last forever you should build it out of stone. 

[labb]

Or concrete

[PRR]

Neither stone nor concrete lasts forever here. We had a place with garage, the floor and foundation buckled by frost and undermined by woodchucks. Most stone splits-off layers every winter. Even the good granite they sold to Boston, the scraps we use as steps spall.

[shooter]

want something to last forever you should build it out of stone.

thought the folks that weighed things in stones was an odd choice, now that i've moved tons it makes complete sense 


got the same problem here, frost, woodchucks, the 80yr old silver maple roots and the garage floor have become one! fortunately it's a 2 car so Pam can park on one side during the winter months, the other bay has been parsed off to catch things that don't need level floors