Remember the Alamo

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dintymoore

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I have an Alamo guitar amp I got dirt cheap awhile back. It's a Made in the USA tube amp. I like the sound but could use some help getting it right. Anybody that has knowledge in this department please help! :)

here's the symptoms: when I insert a guitar cable in, it makes an incredible amount of noise - cracks and pops. But once the plug is plugged in, the amp is fairly quiet (as tube amps go) and sounds great.

If I tap on the front of the amp around where the input jacks are the amp picks up the sound like a microphone.

My first thoughts were that the capacitors that are on the input jacks need replaced, and also that maybe the tubes are bad.

? any ideas

thealamo.jpg
 
dintymoore said:
If I tap on the front of the amp around where the input jacks are the amp picks up the sound like a microphone.
Click to expand...

That would be a microphonic preamp tube. You should clean all of the jacks and sockets with Deoxit before you start replacing any components.
 
ocnor said:
That would be a microphonic preamp tube. You should clean all of the jacks and sockets with Deoxit before you start replacing any components.
Click to expand...

Thanks, I did the jacks with Deoxit and I'll try cleaning the tube sockets.
 
BEWARE There are LETHAL VOLTAGES in there even when it's unplugged. If you aren't familiar with safe practices You could be electrocuted.
 
JCH said:
BEWARE There are LETHAL VOLTAGES in there even when it's unplugged. If you aren't familiar with safe practices You could be electrocuted.
Click to expand...
This. My Ampeg V4 almost killed me. Not fun.
 
thanx for the replies and the warnings! :)

I'll try carefully pulling the tubes and wiping a Deoxit soaked Q-tip on the contacts.
 
What are you saying ? that the tube carries a voltage when not pluged in the a socket and power switch is in the off position?



:cool:
 
moresound said:
What are you saying ? that the tube carries a voltage when not pluged in the a socket and power switch is in the off position?



:cool:
Click to expand...

No, it powers off fine and actually works well other than:

when you tap anywhere near the input jack it sounds like you're tapping a microphone, and when you plug or unplug a guitar plug from it there's a huge amount of snap/crackle/pop!

I just took a plastic pen and lightly tapped around... there's no sound when I tap any of the tubes but there's what I'm guessing is a large plug in capacitor (has MFD on it with other markings) and when I tap on that there's cracking type sounds, but no where is it as loud as when I tap right by the input jacks.
 
It's a fairly easy fix I would guess, either touch up the solder on the jacks, or the plating on the jack might be worn down and you should replace it with a switchcraft jack (don't go the cheap route on jacks!)

Related, Alamos were always kind of neat, I've had a couple of them. What's the tube compliment in yours?
 
moresound said:
What are you saying ? that the tube carries a voltage when not pluged in the a socket and power switch is in the off position?



:cool:
Click to expand...

Nope, not the tubes. Sneaky, innocuous-looking (even pretty- some have a nice baby-blue plastic covering- the same shade of blue as a portuguese man-o-war- that can't possibly be a coincidence) little things called capacitors, which can knock you on your ass, or KILL you, if you don't treat 'em with due respect.

Basically, they store up an electrical charge, and then turn it loose all at once. Think of a battery that releases ALL it's charge in a fraction of a second (it's no accident that a battery and a capacitor have similar schematic symbols.) You have no doubt seen an electronic flash on a camera- if you listen carefully when the flash is turned on, you can hear the capacitor charging up, it makes a faint, high-pitched whine. Then, when the switch is thrown, it discharges NOW, and that fires off the strobe light. Now, imagine that current going through YOU, instead of the strobe. Get it?

You have to discharge them to a ground, before working on the amp. Google it for a how-to- I am not going to tell you how, lest I forget something and your estate decides to sue me...
 
I think I got it. :)

I took the cover off and used Deoxit on all the pots and jacks... took out the tubes and used some on the contacts... still had the problem.

Then I noticed that the nut on the input jack was loose and tightened it... hard to believe (for me anyways) but that appears to have been the problem. The microphonic problem is gone (!).

I'm blown away that something that minor seems to have been the problem, but I used it for several hours and it sounds great - much clearer than before probably due to cleaning the pots.

Thanks everyone for your comments!
 
I had an Alamo Montclair Reverb amp (copy of the Fender Deluxe 'verb). I purchased it in 1976. The tube compliment was a 12AX7 for the tremolo, and 2 6V6 tubes on the power amp. I forget what tube it used for the rectifier, but I replaced it with a solid state module that plugged into the rectifier tube socket when that tube burnt out.
From some of the symptoms you're describing, it could be the rectifier going bad. As I recall, it's not an expensive component to replace.
 
Except for the logo on the grill cloth, that looks a lot like a Montclair 'verb. The one I used to own had a Script logo that looked so much like the Fender script logo, Alamo could have been sued for trademark infringement [except for the fact that the word "Alamo" clearly does not even remotely resemble the word "Fender"].
:laughings:
 
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