Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => EZ Board postings => Topic started by: Geezer on June 17, 2005, 09:46:25 pm
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Hoffman Amplifiers
> Tube Amp Building - Tweaks - Repairs
> Alamo amp service, pt. III
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stratavox
Junior tube assistant
Posts: 25
(2/12/04 8:34 pm)
Alamo amp service, pt. III
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So, replaced every cap in the amp, 3 wire power cord, installed an internal fuse, new tubes (5y3, 1@ 6V6, 1@ 12ax7 and 1@ 6av6). Still no trem...next step is swapping out the resistors in the trem portion of the circuit (for starters). Any other suggestions? TIA-
GroundhogKen
Forum Moderator
Posts: 2262
(2/12/04 8:51 pm)
Re: Alamo amp service, pt. III
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Part III? Did I miss I and II?
Got a scheme?
Is a footswitch ( a short ) required for trem operation?
Ken
stratavox
Junior tube assistant
Posts: 26
(2/12/04 9:20 pm)
Re: Alamo amp service, pt. III
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Hi Ken, glad to hear from you again (and SEE you finally!) - hope this finds you and yours well. The Alamo is one I posted about several months ago- flea market find, here in Pittsburgh PA for $20.00. No handle, the emblem missing, but you see the tube compliment. It had the Alamo 10" speaker (swapped out now for a Jensen) and it appeared to have all original parts internally. The tube chart had been damaged to the extent the model number was missing (post #1), and the Mallory cap can surely needed replaced after 40 to 50 years out there (post #2), so here we are. Yes, there is a 1/4 plug fs jack on the froint panel for the trem, and I have tried a shorted plug). No schem, after every Web search I can come up with, so...just to look at it, it seems somewhat like a number of others of the day, no roach, and as I pointed out, I just replaced EVERY cap in it (again, after all these years...) so I'm looking at the resistors next. It also occurs to me that while the 6av6 has been twice swapped, it STILL could be a bad tube. What are your thoughts? Thanks Ken, and again, good to hear from you.
Zedhead
Junior tube assistant
Posts: 1
(2/29/04 10:22 am)
Maybe I can help...
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I am brand spanking new (oops, that would be a different forum altogether, wouldn't it?) to this whole thing. Please be patient if I commit a cyber faux pas!
I just acquired a similar sounding 1966 Alamo combo--looks VERY original--and the tremelo DOES work. I could trace out the tremelo part of the circuit for you, if you think that would help.
I have been seaching for a week for any info or schematics on this amp, without success. I know it is based on a Western Electric/AT&T patent...but I haven't found anything exactly like it. I've joined this site to get some help on this, my first journey INSIDE the world of tube amps--but if I can be of some help first, great.
JP
stratavox
Junior tube assistant
Posts: 30
(2/29/04 2:26 pm)
Re: Maybe I can help...
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Hi Zed, and welcome. I looked long and hard for a schem, but wasn't able to find this particular circuit. Thanks for the offer, but I think I just need to swap out the tube again until I find a good one, and I haven't yet had the chance to replace the resistors in that part of the circuit. Where are you, and would you care to tell how you came to have your piece of Texas?
Zedhead
Junior tube assistant
Posts: 2
(2/29/04 3:37 pm)
Dismember the Alamo!
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Howdy, pardner! How did I get the Alamo? you ask...Well, I am another victim of E-bay. It looked too unique to pass on...turns out it might be a little TOO unique! Could it be that the Alamo amp is the last bit of nostalgia that doesn't have a web page or magazine devoted to it?
It looks very nearly original (I don't think this has even had a cap job!). I see you've already done some of the mods that were at the top of my list: add a fuse, a grounded AC cord.
I know how to solder, but not a whole lot more--but I think this will be a good project to learn on.
How did you install your fuse?
I tested the speaker at 1.8 ohms...was yours a 2 ohm speaker?! (or did I do something silly already?)
The chassis is on my kitchen table right now.
The kitchen table is in Harbor Springs, Michigan...up near the tip of the mitt.
How 'bout you?
If I can be of any help matching parts or whatever, feel free to let me know.
Peace, JP
Edited by: Zedhead at: 2/29/04 6:26 pm
stratavox
Junior tube assistant
Posts: 31
(3/2/04 6:11 am)
Re: Dismember the Alamo!
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Hi Zed- I replied offline, but maybe you didn't get it, so...the fuse is just the board-mount type from Radio Shack, mounted inside the chassis in some empty space near the P/T. My Alamo speaker was an 8 ohm, but the O/T, which appears original (based on photos pf other Alamo's and it's condition) is a multi-tap, so your 2 ohm may be correct...I'm sitting in Pittsburgh, PA as we speak, getting ready for another day at work, and waiting for some Ebay parts to show up for the next project, a tweed Deluxe with a Tremolux trem circuit in it. Enjoy your day-
Zedhead
Posts: 3
(3/2/04 8:10 am)
stratavox
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THANKS for welcoming me and for your help! I'll obviously have other questions--but I'll post them in the larger forum so as not to be a nuisance!
I didn't want to drill a new hole for the fuse, so your method is the one I'll use.
The OT is original--but it does have 3 taps. The center tap is empty now, but HAD a wire soldered to it at some time. (Can the taps be tested with a meter?) I am debating whether or not to have the original Alamo speaker reconed or buy a new one.
Maybe you can answer one more for me? My amp (model info is scratched off) has a Mallory multi-can filter cap that I haven't found anywhere else: 20 @ 450v, 20 @ 450v, 20 @ 25v. Sound familiar? Did you replace yours?
The Deluxe with a Trem circuit sounds cool--is this a modification to an existing amp, or a build?
Thanks again, good luck and peace, JP
stratavox
Junior tube assistant
Posts: 32
(3/3/04 9:09 pm)
Alamo service
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Hi Zed- I figured the 40+ years the Mallory cap can was in there was long enough, so I replaced it, but with several individual caps of the appropriate ratings. There was a good bit of space available near the power transformer, so ....I had a 10" Jenson on hand, and it was a very nice sounding replacement for the Alamo 10. Again, it wasn't blown, but it sure was dry...as to finding the output at each terminal of the tranny, maybe someone more "in the know" than I can chime in. Thanks for the conversation- I like these little amps!
Zedhead
Posts: 4
(3/4/04 8:15 am)
Thanks, Stratavox
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THANKS for your help!
Good luck on your project. JP
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