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New Tech needs help with Alamo Galaxie tube amp

Mr.Brian

Mr.Brian

New Member
Hey fellas, hope I am posting this in the correct place. Just need a little help if possible. I have not been able to find a schematic for the Alamo Galaxie anywhere. I have heard one does not exist but I do have the Montclaire schematic which I have also been told is very close to the Galaxie and should be fine to work from. Does anyone have any experience working on them or maybe have some information on these amps? Im just learning electronics repair (I am a recording engineer) and any help would be very much appreciated. Thanks in advance.
-Brian
 
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Dswankey said:
While it is a tube amp it's a guitar amp. I would suggest editing your thread title to include guitar so that you'll attract some of the guitar folks here at AK also edit your inital post to include what it is you're trying to do with the amp, repair? modify? etc

Also you might try the "Musicians Forum here at AK

https://www.audiokarma.org/forums/index.php?forums/musical-instruments.83/
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Oh yes right sorry. I am new to forums and still learning the ropes. Thank you for the tip, much appreciated.
 
Mr.Brian said:
Hey fellas, hope I am posting this in the correct place. Just need a little help if possible. I have not been able to find a schematic for the Alamo Galaxie anywhere. I have heard one does not exist but I do have the Montclaire schematic which I have also been told is very close to the Galaxie and should be fine to work from. Does anyone have any experience working on them or maybe have some information on these amps? Im just learning electronics repair (I am a recording engineer) and any help would be very much appreciated. Thanks in advance.
-Brian
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Alamo_electra.gif



I believe that the Galaxie has a tremolo circuit which the Electra does not. Check your tube chart and see if the above tubes appear to match. :idea:
 
Mr Boochie said:
Alamo_electra.gif



I believe that the Galaxie has a tremolo circuit which the Electra does not. Check your tube chart and see if the above tubes appear to match. :idea:
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Thanks for the reply! Much appreciated. I posted a picture of the tube chart and will take some more photos to post here. There is something not normal going on with the transformers, you'll see what I mean in the photos. Something many of you guys have likely seen before, but I haven't a clue. Thank again for the help
 
cademan said:
What seems to be the problem? :idea:
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The first time powering it up there was a burning smell and some smoke coming from the transformer, I think. I powered it down and unplugged it and when I took a look inside I noticed that one of the 7591 tubes had a broken guide pin and eventually came to find that it had been turned around and plugged in the wring way. I am somewhat new to this but know that surely cannot be good for the amp. I marked the correct way to plug it in and put it back in correctly. How do I test the transformer(s?) to see if its toasted or if its still ok? It doesn't look the best, but it doesn't smell burnt really either.
 
You can open it up and take a look at the components connected with that 7591 tube socket. It's quite possible you could have just fried a resistor but you will need to look.

The power transformer may be fine. Those things are pretty rugged but a simple test would be to remove all tubes and power it up and carefully observe it for a few seconds to see or hear what happens.

If you can, take some pics of the area concerning that one tube.
 
cademan said:
You can open it up and take a look at the components connected with that 7591 tube socket. It's quite possible you could have just fried a resistor but you will need to look.

The power transformer may be fine. Those things are pretty rugged but a simple test would be to remove all tubes and power it up and carefully observe it for a few seconds to see or hear what happens.

If you can, take some pics of the area concerning that one tube.
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There was actually a blackened resistor but not at the tube socket, it was connected to two different legs of the multi-capacitor can. I found the same exact and replaced it. Does that resistor being burnt mean the capacitors in the can have gone bad? or does that indicate something else?
I am going to do the test you suggested now, do I remove every tube? I have a 16ohm dummy load for connected to the output, from what I understand that is the correct thing to do, is this a situation where I should use it instead of a speaker? Or do I intentionally want to have no load connected at all?
 
No need for a dummy load if there are no tubes. The can capacitor may be fine but you will just have to test it. A simple volt/ohm meter will suffice.

Can't tell without any pics but that burnt resistor could have been a result of the tube put in wrong.

Years ago I broke the guide pin to a 5Y3 rectifier tube for a hi fi amp. It smoked something awful but only burnt up the power resistor. I still have the amp and it is still working today.

Make sure that amp has a fuse.
 
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Can you take some photos of the circuit wiring? Maybe, a couple two or three close-ups?

This may help the diagnosis. :thumbsup: :)
 
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