The Steel Guitar Forum

My Dickerson arrived today. It plays amazing (although I don’t yet). I was stunned it made the trip from Massachusetts and was IN TUNE. .

I haven’t done anything with the amp tonight. The cord is rotted and has a lamp cord taped to it so I need to replace that before I can test it.

I'll try to post pictures once I take some.

K

Congrats! My Stringmaster arrived yesterday (my first "serious" steel guitar purchase) and it was also a surprise to me that it was pretty consistently in tune! A good solid plank of wood perhaps is hard to throw out of tune.

Good luck with the two of them...will be interesting if you can revive that amp. Without any kind of schematic or documentation, I wonder if you could even know if the tubes that are in it are even the appropriate kind?

There is a site called "schematic Heaven" which may have a schematic of that old amp.
Another place is EL34.com, which is a forum devoted to building and working on tube type amps..

Hope this helps !!

Some of those old small amps had no power transformer, and had the tubes wired in series, to use line voltage.
Problem was, that one side of the power cord was wired to the chassis, which means that the input jack for the cord, might be hot (along with the guitar !)
Look for a brand/serial number/model number on that amp, so you can get the info you need...

I opened up the amp. I’m SOOOOOOOOOOOO stoked it’s really clean and looks original except the tubes. I’m not so thrilled that there are broken solder joints.

It DOES have a transformer. It also has readable markings on everything and a recent make fuse still in place. Heading to the sites Mr Creller suggested to see what I can see. Maybe pick a brain or two.

I took pictures of the amp and the guitar, and am resizing them now. I should have them up soon.

K

Maie sure you replace the electrolytic capacitors before turning it on. The old ones are decades past their service life end.

Bill Creller wrote:Some of those old small amps had no power transformer, and had the tubes wired in series, to use line voltage. Problem was, that one side of the power cord was wired to the chassis, which means that the input jack for the cord, might be hot (along with the guitar !)

For when you need that extra "spark" in your playing...yikes!

Reminds me of a saying I've read, originally about mushroom hunters: there are old amp technicians, and there are bold amp technicians...but there are no old, bold amp technicians.

If you do try powering up with the original electrolytic filter caps, check that they're not getting too hot by frequently touching the can at first. Sometimes they short, get hot and burst! What a mess! It would also buzz and not play, but some would keep messing with it.

X2 on the filter caps. If one shorts out, it can do damaged to the power transformer.
Under the chassis, new caps can be wired in, after removing the wires on the old filter can terminals, to keep the original appearance of the filter cans if it has those..
How about a list of the tubes ? Did you determine what brand the amp is ?
Finding a schematic will require some info on who built it etc..

Hey, sorry for the delay. Also tried to do some research myself - let me know what I got wrong... Lots of pix, long post!



1. Not sure yet who actually made the amp. It has a Fators Mfg decal from 1944-1947, between Dickerson himself and Magnatone. There is a bit of an Oahu Publishing label on the back (sold from their catalog?). It doesn't have tone or volume controls, and has the Dickerson logo on the front with the rounded cabinet like earlier models. Maybe it was re-labelled leftover stock?

2. I also found this at http://www.magnatoneamps.com/dickerson.html:

"The smallest and lowest price amplifier was the S6. The 3 tube circuit produced 3 watts and drove a 6" speaker. A few different preamp tubes were used in these including a 6SF5 and a 6C5. The power tube was a 6F6 and the rectifier was a full wave rectifier tube, like an 83V, 5V4, or a 5Y3. On some early models, a small battery bias cell was used to apply a negative bias to the preamp."

I have a picture of the battery bias cell and another article link further down the post.

No joy on finding a schematic yet.



3. Mr Creller, the tubes are L to R:

KEN-RAD > only markings are KEN-RAD MADE IN USA 6-43 188-5 on the base, no glass etch (made in Owensboro, and maybe before GE if it is original to the amp)

Realistic 6V6GT Made in USA

Sylvania > metal base, only markings are Sylvania Made in USA For Replacement Use Only T3R and a leaf logo (looked up the date code, T3R is Nov '42-Jan '43. ) no glass etch



Here are pics of the amp's guts:



The green and white thing is a battery bias cell. I found an article about an earlier model Dickerson with this component here: http://www.charlestonarea.com/Dickerson/







Here is the guitar. Electronics work perfectly. It needs some new tuner knobs ('40s plastic disease!) and probably string hole grommets, but it is otherwise in great shape! Even the flocking on the bottom is clean and undamaged. No idea what the little holes with the circle are from.















I have more pix if anyone wants to see something closer, or I can take one if I missed something.

K

Nice stuff, thanks.

I noticed the amp has one of the speakers with an electromagnet. Talk about vintage!

X3 on the electrolytics. I would not power it up until you change those. All the other paper and wax caps should be changed as well because by this time they're performing more like resistors than capacitors due to leakage. That means that in addition to passing the ac signal to the next stage, they're also allowing dc to pass to the grids as well, screwing up the works. Some of the resistors look toasty and would disconnect one end, measure, and replace as necessary.

i have a friend who purchased a dickerson amp. yours looks to be a 1947 whereas the one i worked on was a 48. his had a 6l6 instead of the 6v6 and it turned out to be a wonderful sounding amp once i repaired it with the valuable direction of blake hawkins who is a member here.

i replaced all of the caps and a few resistors. i'd still like to build my own based upon the single 6l6.

i'm enclosing the link to my thread in the hope that it could help you.

play music!

http://bb.steelguitarforum.com/viewtopi ... kerson+amp

Really cool combo !! At least the caps are sort of out in the open, for fairly easy replacement !!
Tuner knobs from Stewart-MacDonald will fix that part..!

I have a lot of tubes, if you need some...

Yours looks to be a 1947 vintage, I have 2 or 3 of them. I'll have to look at them and see what I can come up with in the way of schematics, etc. The speaker is not a field coil type that's the output transformer mounted on the speaker frame instead of on the chassis. The bias battery mentioned in the referenced article is there to set a reference point on the preamp grid tube. If it doesn't work I am certain there are work-arounds (a 1.5v battery, etc.) that can be used and would accomplish the same thing.
The guitar looks to be a ca. '47 student model as well. That's not to say it won't be cool to play and it probably will sound just like all the other Magnatone/ Dickerson guitars of the 40s thru mid 50s era.
Good projects.

Good pictures. Especially the fuse. That will bring you to grief! SFE 14 is a 14 Amp, 32 volt automotive fuse. The power transformer will burn before that fuse will blow.

The Dickerson Schematic that I got from
Mike Butler does not show a value.

Typical would be an AGC 2 or AGC 3 for this size
Amp.

Thanks for the info on the fuse. I had not looked it up yet.

This amp is waaaay older than the one I fixed before. That one just had a cracked tube, a few bad caps and the speaker wiring was bad. I also had the schematic.

I was going to write down all of the caps etc figuring it worked before, but now I'm not so sure. I know what assuming means in most cases, and with that oversized fuse, I wonder if everything in it really is correct, or if it was prone to blowing fuses because something else is the wrong part.

It is certainly worth a trip to an amp tech you trust. It should not costs that much to check out and it is a nice amp. I have the same guitar (green MOT).
regards, lefty