Question: 3 Prong for a Bassman

[lakehaus]

I recently picked up a '68 Fender Bassman. Great amp for my needs. But, I'm tired of this sucker shocking me! So I bought a grounded 3 prong cord to wire in, thinking "just put white to white, black to black, and ground to PT post." Well, yeah, not so simple for this techno-boob.

Below is a pic of it's guts, and the cord that it came with, which obviously is not stock... no white, both black, I dunno.

Can someone tell me where the new cord's white wire goes? I have a multi-meter, and I'm not afraid to use it (just don't know what/where to measure). Thanks

[img:640:480]http://i256.photobucket.com/albums/hh17 ... G_1352.jpg[/img]

[jaysg]

Look for the schematic I attached to this thread:

https://tubeamparchive.com/viewtopic.ph ... light=fuse

Imo, you should get rid of the 0.047uF and the polarity switch it's attached to.

I can't recall whether the AC recepticle on the back of a '68 has same-size blade holes, or is set up for to two different sizes. According to this article:

http://en.wikipedia.org/wiki/Domestic_A ... nd_sockets

the bigger prong is Neutral(white).

[Kregg]

Have you ever seen the circuit tester pens that light up? You only need to touch the wire jacket. Very handy around the house! If it lights up that's the hot side. Or, you could turn on your meter, attach one (-) probe to ground and touch the other (+) probe wire to find the hot lead.

[lakehaus]

Thanks for the advice and guidance guys! I'll give it a try this weekend...

[Kregg]

In looking closer at the photograph, it appears you have a brass set screw and a zinc screw. Black to Brass is the proper wiring for electrical receptacles.

[billyz]

Here is a good diagram to follow.

[davemccarthy707]

Look for the schematic I attached to this thread:

https://tubeamparchive.com/viewtopic.ph ... light=fuse

Imo, you should get rid of the 0.047uF and the polarity switch it's attached to.

I can't recall whether the AC recepticle on the back of a '68 has same-size blade holes, or is set up for to two different sizes. According to this article:

http://en.wikipedia.org/wiki/Domestic_A ... nd_sockets

the bigger prong is Neutral(white).

+1 on the schematic. The main thing is dont fuse the neutral!. Its pretty simple. First remove your old cord and all the wiring to the power switch, the accessory plug, the fuse holder and the ground switch. Now put the black to fuse holder inside lug. Next run from the tip of the fuse holder to the close side of the switch, next attach the transformer lead to the other side of the switch (if it isnt already there) Next take the other transformer wire and splice it (with solder or a butt splice and heat shrink) to the white wire. Lastly attach a ring terminal to your ground wire and attach it to a transformer bolt. (Hint: this should be your longest wire in case someone pulls out the cord at least you will be grounded till the end. ) That's it.

[davemccarthy707]

Look for the schematic I attached to this thread:

https://tubeamparchive.com/viewtopic.ph ... light=fuse

Imo, you should get rid of the 0.047uF and the polarity switch it's attached to.

I can't recall whether the AC recepticle on the back of a '68 has same-size blade holes, or is set up for to two different sizes. According to this article:

http://en.wikipedia.org/wiki/Domestic_A ... nd_sockets

the bigger prong is Neutral(white).

+1 on the schematic. The main thing is dont fuse the neutral!. Its pretty simple. First remove your old cord and all the wiring to the power switch, the accessory plug, the fuse holder and the ground switch. Now put the black to fuse holder inside lug. Next run from the tip of the fuse holder to the close side of the switch, next attach the transformer lead to the other side of the switch (if it isnt already there) Next take the other transformer wire and splice it (with solder or a butt splice and heat shrink) to the white wire. Lastly attach a ring terminal to your ground wire and attach it to a transformer bolt. (Hint: this should be your longest wire in case someone pulls out the cord at least you will be grounded till the end. ) That's it.

[solderstain]

Since I did something similar, I thought some visuals would be useful. These pictures are actually of my 'Bassman Combo' (formerly a Pro Reverb), but I did the same thing with my '66 Bassman.

Oh, by the way, jaysg's suggestion about losing the 'Ground' switch and its capacitor? I strongly agree! Toss that crap in the nearest dumpster. Doing that opens up a very useful hole in the back panel, which I made use of by moving the bias pot to a more accessible position. You'll see it in the pictures.

Since you're putting a three-conductor cable in, go all the way and replace the two-conductor convenience outlet with a modern three-conductor version while you have the soldering iron hot.

[img:640:480]http://www.doctorvintage.com/amps/bassm ... power1.jpg[/img]

[img:640:480]http://www.doctorvintage.com/amps/bassm ... power2.jpg[/img]

[lakehaus]

I did the conversion last night, and it works like a Champ (no pun!). I kept the ground switch and lost the death cap, but I like the bias relocation mod solderstain mentions above. Next time I pull the chassis I'll likely do that.

Thanks again. These forums are great!!