1968 Bassman project

[sonicmojo]

I've always wanted a Bassman but never found one for the right price. Now I have one to mess with. I just picked up this very rough (non working) Bassman. It's no BF gem like Tonemerc's recent find but I'm guessing it is a 1968. I have not opened it yet to verify dates or see what circuit. That will have to wait a few days. I figure it was worth the $125 for the transformers and tubes for some other project if I can't get it going again. I'll update this thread with any progress.

[img1488]http://www.sonicmojo.com/bassman/3.jpg[/img]
[img1319]http://www.sonicmojo.com/bassman/2.jpg[/img]
[img1885]http://www.sonicmojo.com/bassman/1.jpg[/img]

[sonicmojo]

So after drilling out one of the rusted bolts on the head I opened it up before I have to fly out tomorrow. It is an AB165 as I was hoping. It looks mostly stock except for a few caps and probably that coax.

It obviously needs filter replacements. Now we know why Fender puts these on the bottom.

[img1286]http://www.sonicmojo.com/bassman/6.jpg[/img]
[img1840]http://www.sonicmojo.com/bassman/4.jpg[/img]
[img1783]http://www.sonicmojo.com/bassman/5.jpg[/img]

[ToneMerc]

Drip edge model, excellent score Bryan and it came with tubes.

TM

[crbowman]

I play steel guitar in a band in which our lead guitarist plays through an old drip edge bassman exactly like this one. Same year and everything. You would expect it to sound good, but I'm constantly surprised. It sounds REALLY good.

[groovtubin]

I play steel guitar in a band in which our lead guitarist plays through an old drip edge bassman exactly like this one. Same year and everything. You would expect it to sound good, but I'm constantly surprised. It sounds REALLY good.

My BEST D sounds came from those trannies! A 70`s is ridiculous!

ijm@Omegaamps

[sonicmojo]

I ordered new electrolytics and a couple of .022 caps to replace those orange drops (which are .1) before I left for the airport this morning. One of the rectifier diodes tested shorted so I'm going to replace all of them. Hopefully those parts and careful cleaning will bring it to life again. I'm going to treat it as a new amp build and bring it up very carefully.

[crbowman]

I ordered new electrolytics and a couple of .022 caps to replace those orange drops (which are .1) before I left for the airport this morning. One of the rectifier diodes tested shorted so I'm going to replace all of them. Hopefully those parts and careful cleaning will bring it to life again. I'm going to treat it as a new amp build and bring it up very carefully.

Sounds like you've got the right idea. I think I'd also rebuild the bias supply circuit just to be on the safe side.

[sonicmojo]

I replaced the electrolytics, fuse, power cord, and one of the diodes. I sprayed the pots and got them turning well, cleaned jacks, and tidied up the coax. I turned her on without tubes and the voltages actually looked okay so in went the tubes. The tubes all worked and it sounds great with much chime! The bright switch wasn't working so I took it apart and cleaned it and it works now. Luckily I had some identical handle hardware and kept the strap but replaced the rusty parts. I have some chassis straps in the mail to replace the rusted ones. I'm still less than $200 all in on it now and probably no reason to go further except fine tune, maybe re-tolex, make a back panel, and perhaps keep an eye out for a less corroded black line faceplate.


[img700]http://www.sonicmojo.com/bassman/7.jpg[/img]

[ToneMerc]

Gotta love cheap and it works. I received the dual 25uF caps the other day and I picked up a 3 conductor cord. So when I'm feeling it, I will recap mine and upgrade the cord.

TM

[billyz]

Rewire the power amp to any AB763 circuit and you will really hear it come alive.

[ampmike]

Awesome find,Love it.So much you can do with a bassman for mods.I would love to find one for that,Great Job on the repairs!!!Mikey

[sonicmojo]

I'm still working on this one. One weird thing happens. If I don't play it for a few days and turn it on, sometimes I get barely any volume for a little while on either channel. Today it seemed extra long. I wiggled tubes, checked the speaker cable, and finally when I twiddled the volume knob on the normal channel, it ramped back up. It can't be that pot because it was the same on the other channel but I wonder what is happening........

It is hard to retest because I would have to turn it off and unplug it for about 3 days to get it to happen again.

[sonicmojo]

Thank you Taylor (amplifiednation) for the piece of tolex. If anyone around here gutted a '68 Bassman and still has the old faceplate laying around that is in fairly good condition, let me know.

[img1168]http://www.sonicmojo.com/bassman/sisters.jpg[/img]