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  1. #1
    Les Paul Forum Member j45's Avatar
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    HELP! Alamo Scematics

    I have a pair of pristine late 1950's Alamo Model 6 amps, the big ones in the beautiful wood "A" cabinets with P15N powered by two 6L6's.....somewhat similar to a tweed Pro. Both need some repair, have very complex tone circuits, and are true point to point without any turret boards. I desperately need schematics and have had no luck finding anything for the Alamo Model 6.

    If anyone knows where I might find or can help me locate schematics I would be forever grateful. Either that or if somebody knows a tech very familiar with this particular circuit (it's a real nightmare if not) I would be happy to ship them. I've owned these for many years... one was just awesome before it went down and the other, although cosmetically pristine, needs work as well. I would be thrilled to have them working again....they've been sitting for way too long. Any help would be greatly appreciated.

    oops *schematics" (title)

  2. #2
    Les Paul Forum Member MapleFlame's Avatar
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    Re: HELP! Alamo Scematics

    Kerry, shoot a pic of the innards and post it. Lotta these amps had the multi wire filter caps.
    Top carves are sexy

  3. #3
    Les Paul Forum Member j45's Avatar
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    Re: HELP! Alamo Scematics

    I'll get pics. The tone section is a series of push buttons that boost or cut selected frequencies, kind of a half a$$ varitone/parametric EQ and being true PTP it adds the equivalent of four or five bird's nest thrown in the mix. Hard to see anything but capacitor soldered to resistor upon capacitor soldered to resistor upon more and more of the same all swirled around in a big whirlwind of components. Never seen anything like it.

  4. #4
    Les Paul Forum Member
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    Re: HELP! Alamo Scematics

    I repaired an odd amp that was point to point wired with no schematic. It takes a little patience. You could draw up your own schematic by tracing wires and making measurements with a DVM. A good technician should be able to repair it, but finding a good technician may be a problem.

  5. #5
    Les Paul Forum Member roadrunner's Avatar
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    Re: HELP! Alamo Scematics

    I've got the same amp I've been wanting to work on for years... went looking for a schematic and... nada.

    Hopefully, there's something out there.

    What's wrong with your Kerry? Are they making sound?
    Achieve the Possible!


  6. #6
    Les Paul Forum Member j45's Avatar
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    Re: HELP! Alamo Scematics

    It's been so long it's hard to remember what each is doing. I do know one was playing just fine...amazing, actually. I think I remember it just kinda a blew out and got softer and rough sounding...I believe. The other needed work, can't remember what but seems it made sound.

    Do you think there are techs out there that could look at that circuit and figure it out? I'd be willing to send them off.

  7. #7
    Les Paul Forum Member roadrunner's Avatar
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by j45 View Post
    It's been so long it's hard to remember what each is doing. I do know one was playing just fine...amazing, actually. I think I remember it just kinda a blew out and got softer and rough sounding...I believe. The other needed work, can't remember what but seems it made sound.

    Do you think there are techs out there that could look at that circuit and figure it out? I'd be willing to send them off.

    You've done the obvious thing, replaced the tubes, cleaned the tube sockets, checked the filter caps, checked for cold (or broken) solder joints?
    If it's not the tubes, and all the electrolytics are ok, it might be an output transformer... hopefully not. That "getting softer" thing does happen when an output transformer starts to go south.

    I've found, over the years, that tube amp problems are almost always tube related. I'd start there.

    I got my amp up and running by retubing it, I had to replace the filters too, they were leaking badly. Ran great after that.

    Make sure you run that old beauty on a variac, 115 volts or a little less... those old amps definitely don't like modern wall voltage, it's way too high for the design of those circuits and their components.
    Achieve the Possible!


  8. #8
    Les Paul Forum Member
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    Re: HELP! Alamo Scematics

    Hey J45, where are you located?
    If you are near Chicago, you could drop the amp off with me.
    I'm not a pro, but I bet I can fix it.

  9. #9
    Les Paul Forum Member j45's Avatar
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by Diablo1 View Post
    Hey J45, where are you located?
    If you are near Chicago, you could drop the amp off with me.
    I'm not a pro, but I bet I can fix it.
    I'm in Baton Rouge, La. Not close but I'd be willing to ship it if you'd like to give it a shot. If you will send an email to krhys at cox.net, I will send a note with details of what I know about the amp so far.

  10. #10

    Re: HELP! Alamo Scematics

    Quote Originally Posted by Diablo1 View Post
    Hey J45, where are you located?
    If you are near Chicago, you could drop the amp off with me.
    I'm not a pro, but I bet I can fix it.
    Seems solid.
    .
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    My Mileage Does Not Vary

  11. #11
    Les Paul Forum Member
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    Re: HELP! Alamo Scematics

    Say J45, can you post up some gut shots of the amp?
    I'd like to see some close ups of the caps and resistors.
    I want to make sure I can read the values by eyeball since there is no schematic. I saw a pic of an old Alamo on the Music Electronics Forum and it was near impossible to read the values because of the deterioration. I don't want you to ship the amp unless I'm sure I can do you some good.

  12. #12
    Les Paul Forum Member j45's Avatar
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    Re: HELP! Alamo Scematics

    Will do...it may take a few days. The amps aren't here at home but I'll go get pics ASAP. Thanks.

  13. #13
    Les Paul Forum Member
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    Re: HELP! Alamo Scematics

    I have one of those, too, j45. I am in the process of recapping it. My components' values are readable. Contact me if I can help with it.
    I have worked thruogh a number of these older Alamos...and even a more 'modern' one from the mid-60's...without a schematic. I had a friend/customer who played harp and was into the smaller Alamo's that were the little brothers to this Model 6....same cab design just smaller.
    "As soon as man does not take his existence for granted, but beholds it as something unfathomably mysterious, thought begins." Albert Schweitzer

  14. #14
    Les Paul Forum Member j45's Avatar
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by Wally View Post
    .....same cab design just smaller.
    Except for the tone section which seems to complicate things, right?

  15. #15
    Les Paul Forum Member
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    Re: HELP! Alamo Scematics

    Hey J45, I'd send it to Wally, since he has a working amp to verify voltages and component values. That's a lot less sleuthing than I'd have to do.

  16. #16

    Re: HELP! Alamo Scematics

    Quote Originally Posted by Diablo1 View Post
    Hey J45, I'd send it to Wally, since he has a working amp to verify voltages and component values. That's a lot less sleuthing than I'd have to do.
    You really don't need a schematic to work on an amp. This sounds like a puss-out. I enjoyed your bet of being able to fix it, and personally, I'd like to see what you can do.

    Get an RCA handbook and compare voltages to what you find in the amp. Dump a seperate preamp signal into the power section to quickly see if the problem is with that satellite tone section. Prior to digging in, you need to trust most wax caps will be drifted while drop-style caps will probably be OK. Most of the resistors are probably OK. Cap values shouldn't be much of a mystery.
    .
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    My Mileage Does Not Vary

  17. #17
    Les Paul Forum Member
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    Re: HELP! Alamo Scematics

    j45, I was meaning to say that the cosmetic look of the cabs are the same...the stylized 'A' in plywood. Yes, the tone section/schematic is necessarily a bit more convoluted in the big Md. 6. Those push buttons remind me of the push button auto transmission in my first car...a 1960 Plymouth station wagon that would haul all of the equipment a young guitarist could need back in 1966.
    "As soon as man does not take his existence for granted, but beholds it as something unfathomably mysterious, thought begins." Albert Schweitzer

  18. #18
    Les Paul Forum Member
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by cryptozoo View Post
    You really don't need a schematic to work on an amp. This sounds like a puss-out. I enjoyed your bet of being able to fix it, and personally, I'd like to see what you can do.

    Get an RCA handbook and compare voltages to what you find in the amp. Dump a seperate preamp signal into the power section to quickly see if the problem is with that satellite tone section. Prior to digging in, you need to trust most wax caps will be drifted while drop-style caps will probably be OK. Most of the resistors are probably OK. Cap values shouldn't be much of a mystery.
    Puss-out? Maybe.
    If it was my amp, I'd have a go at it for sure. I just think Wally is a safer bet because he has a working amp and knows the cap and resistor values by either measuring or reading the codes/labels. He also can measure the voltages at every socket pin on his working amp, so he can quickly tell where the problems are in the one that needs repair. What if it needs a new PT? Wally can figure out the requirements based on his working amp. How the heck could I possibly guess the right B+ voltage to spec? Sure I could get a transformer that would work, but I couldn't match an unknown B+. Here's one of mine that I fixed up without a schematic, the Capitol:



  19. #19
    Les Paul Forum Member MapleFlame's Avatar
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    Re: HELP! Alamo Scematics

    Ahh I know this company. They made amps for everyone. Lemme look to find the schematic.

    Lectrolab was a name for them too.

    Try this and match the tube chart.
    http://lectrolab.wordpress.com/category/lectrolab-r600/
    Top carves are sexy

  20. #20
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by MapleFlame View Post
    Ahh I know this company. They made amps for everyone. Lemme look to find the schematic.

    Lectrolab was a name for them too.

    Try this and match the tube chart.
    http://lectrolab.wordpress.com/category/lectrolab-r600/
    I do believe you are right about Lectrolab building my Capitol amp. However, it doesn't match any Lectrolab schematic or tube complement.
    The Capitol has six 6EU7 tubes, four 7591 tubes and a GZ34 rectifier. It is a stereo amp with two output transformers. It is cathode biased, has a tube tremolo (cap and resistor network), grid leak bias for the input triodes, and a cathodyne phase inverter. The transformers are labeled "Tranco" and are dated to 1961. It has two Jensen C12R speakers that also date to 1961. My amp cabinet is also made of real wood, not press board like most other Lectrolabs.

  21. #21
    Les Paul Forum Member MapleFlame's Avatar
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by Diablo1 View Post
    I do believe you are right about Lectrolab building my Capitol amp. However, it doesn't match any Lectrolab schematic or tube complement.
    The Capitol has six 6EU7 tubes, four 7591 tubes and a GZ34 rectifier. It is a stereo amp with two output transformers. It is cathode biased, has a tube tremolo (cap and resistor network), grid leak bias for the input triodes, and a cathodyne phase inverter. The transformers are labeled "Tranco" and are dated to 1961. It has two Jensen C12R speakers that also date to 1961. My amp cabinet is also made of real wood, not press board like most other Lectrolabs.
    Sound Projects Co.
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  22. #22
    Les Paul Forum Member MapleFlame's Avatar
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    Re: HELP! Alamo Scematics

    Top carves are sexy

  23. #23
    Les Paul Forum Member j45's Avatar
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by cryptozoo View Post
    You really don't need a schematic to work on an amp. This sounds like a puss-out. I enjoyed your bet of being able to fix it, and personally, I'd like to see what you can do.

    Get an RCA handbook and compare voltages to what you find in the amp. Dump a seperate preamp signal into the power section to quickly see if the problem is with that satellite tone section. Prior to digging in, you need to trust most wax caps will be drifted while drop-style caps will probably be OK. Most of the resistors are probably OK. Cap values shouldn't be much of a mystery.
    I don't know anything about amps other than how to turn them on a play but this looks pretty intimidating to try and tackle without a schematic. It may not be as bad as it looks to a good tech, maybe it's because it's a lot more stuff crammed in than I'm used to seeing and I don't know what I'm looking at. Let's just say it looks nothing at all like the simple layout in the amp that Diablo1 posted. I still haven't had the chance to get a gut shot pic but will get to it after my weekend work ends.

  24. #24
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    Re: HELP! Alamo Scematics

    THanks for the 'push' to get j45 to let me work on that amp, Diablo. However, my amp doesn't have its original PT, so I could not be sure that my voltages would be 'correct'. In any case, unless one runs a VAriac or some sort of voltage control, these old amps are not functioning at 'correct' votlages anyway. And....lowering voltages for these vintage amps makes a world of difference in how they sound, ime.
    So, j45, my amp's resitors and caps have readble values on them...but that is the extent of my being able to ascertain 'original' specs. The PT that is there is huge and has a homemade bracket supporting it. A different PT might be one thing on the list in putting this one back into action...although it was working when I pulled the speaker for a recone....and a recap for the circuit.
    j45, if you have the orignal PT, it would be of great interst to know the specs on that one...or to have it here side by side with my amp in order that both of them could return to 'original' specs.
    IF anyone ever takes measurements of the voltage on that PT....without tubes installed., that would be of great interest to me.
    "As soon as man does not take his existence for granted, but beholds it as something unfathomably mysterious, thought begins." Albert Schweitzer

  25. #25
    Les Paul Forum Member
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by MapleFlame View Post
    That little sucker sounds gooooood!
    53 LP, 74 Black Beauty, 09 50th R9 LP, 06 R6, 63 SG Special, 62 & 64 SG juniors, 60 Double Six, 1947 L7 and 1937-41 L30 archtops and a few Fenders, Voxs and Hagstroms,
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  26. #26

    Re: HELP! Alamo Scematics

    Here's a photo of an Alamo 6 I saved from somewhere a few years ago.... maybe it will help while J45 gets some shots of his. I almost bought one of these and would love a chance to hear one in person some day.



  27. #27
    Les Paul Forum Member MapleFlame's Avatar
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    Re: HELP! Alamo Scematics

    Thanks for posting pics.
    #1 Get some electronics cleaner spray and spray the hell out of it or use an air compressor and blow all the dust out. Dust/cat hair etc... in these amps with spaghetti wire mess will be greatly affected.
    #2 Far right is the electrolytics, replace them.
    #3 All those other caps, diodes, etc.. just need to be checked to see if they are still in spec. Any good amp tech can figure out Power section etc... and do a process of elimination to find where things are at.
    Top carves are sexy

  28. #28

    Re: HELP! Alamo Scematics

    Kerry, I just spoke with my friend and amp guy, Skip Simmons. He doesn't have a schematic for the Model 6 Alamo, however, he said that he has worked on a couple of them and did use the term "rat's nest" when describing them. You might contact him about having your amp serviced. He is located here in Northern California.

  29. #29
    Les Paul Forum Member j45's Avatar
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by Brown Recluse View Post
    Kerry, I just spoke with my friend and amp guy, Skip Simmons. He doesn't have a schematic for the Model 6 Alamo, however, he said that he has worked on a couple of them and did use the term "rat's nest" when describing them. You might contact him about having your amp serviced. He is located here in Northern California.
    This is awesome...yes I'd love to contact him if you would tell me how. I'll ship them in a heartbeat.

  30. #30
    Les Paul Forum Member j45's Avatar
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by valcotone View Post
    Here's a photo of an Alamo 6 I saved from somewhere a few years ago.... maybe it will help while J45 gets some shots of his. I almost bought one of these and would love a chance to hear one in person some day.


    !!! This looks like both of my amps. Identical in all ways as far as I can see. If I'm not mistaken the speaker is not a field coil like it appears to be.... I believe that's the output tranny mounted on the side. Anybody know? Thanks for the pic. I almost have to wonder if this may not be one of mine before I got it. Can't be that many around, especially this clean. I recall perfectly that I was in absolute heaven that last day I was playing mine. I was deep in a zone just digging how awesome the sound was when my "good one" failed. These photos really inspire me to get mine going again. These are just killer amps. Thanks again for the pics!

  31. #31

    Re: HELP! Alamo Scematics

    Quote Originally Posted by j45 View Post
    This is awesome...yes I'd love to contact him if you would tell me how. I'll ship them in a heartbeat.
    Send an email to me at: brown hyphen recluse at comcast dot net and I'll get you his info.

  32. #32

    Re: HELP! Alamo Scematics

    Quote Originally Posted by Diablo1 View Post
    Puss-out? Maybe.
    If it was my amp, I'd have a go at it for sure. I just think Wally is a safer bet because he has a working amp and knows the cap and resistor values by either measuring or reading the codes/labels. He also can measure the voltages at every socket pin on his working amp, so he can quickly tell where the problems are in the one that needs repair. What if it needs a new PT? Wally can figure out the requirements based on his working amp. How the heck could I possibly guess the right B+ voltage to spec? Sure I could get a transformer that would work, but I couldn't match an unknown B+.
    That was sarcasm from the start, sorry it went over your head -- why anyone would blindly ship an amp to a stranger on the internet who bets they can 'fix it' because they got lucky on theirs is beyond me.

    http://www.skipsimmonsamps.com/
    Skip Simmons Amp Repair
    4824 Bevan Road
    Loma Rica, CA 95901
    530-771-7345 • 707.678.5705
    skip@skipsimmonsamps.com
    .
    .
    My Mileage Does Not Vary

  33. #33
    Les Paul Forum Member
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by cryptozoo View Post
    That was sarcasm from the start, sorry it went over your head -- why anyone would blindly ship an amp to a stranger on the internet who bets they can 'fix it' because they got lucky on theirs is beyond me.

    http://www.skipsimmonsamps.com/
    Skip Simmons Amp Repair
    4824 Bevan Road
    Loma Rica, CA 95901
    530-771-7345 • 707.678.5705
    skip@skipsimmonsamps.com
    Sarcasm is hard to pick up on the internet. You don't know me and I don't know you. That's sounds like a good deal for me. You don't know what skills I have or don't have, but you have a business fixing amps, so I'm certain that an amateur like me rubs you the wrong way....good. The only reason I started into amp repairs/building as a hobby is because I have an amp that I took to three professionals, and none of them fixed it, but they did charge me, and tell me, "nothing is wrong". They weren't crooks, just incompetent or too lazy to do the job right. I did my research on the internet, studied the schematic, and learned exactly how every circuit worked on that amp. I also found out the common failure points for the amp. Then I fixed it. I checked the value of every resistor and cap to make certain they were within spec or replaced. The amp sounds good as new, and I've owned it since new 42 years ago. I didn't get lucky, I'm persistent and know that the information is available to fix or build nearly anything if you have some intelligence and can read.....it's an engineer thing.

  34. #34

    Re: HELP! Alamo Scematics

    Quote Originally Posted by Diablo1 View Post
    Sarcasm is hard to pick up on the internet. You don't know me and I don't know you. That's sounds like a good deal for me. You don't know what skills I have or don't have, but you have a business fixing amps, so I'm certain that an amateur like me rubs you the wrong way....good. The only reason I started into amp repairs/building as a hobby is because I have an amp that I took to three professionals, and none of them fixed it, but they did charge me, and tell me, "nothing is wrong". They weren't crooks, just incompetent or too lazy to do the job right. I did my research on the internet, studied the schematic, and learned exactly how every circuit worked on that amp. I also found out the common failure points for the amp. Then I fixed it. I checked the value of every resistor and cap to make certain they were within spec or replaced. The amp sounds good as new, and I've owned it since new 42 years ago. I didn't get lucky, I'm persistent and know that the information is available to fix or build nearly anything if you have some intelligence and can read.....it's an engineer thing.
    Diablo1, I don't know if cryptozoo has an amplifier repair business, however, I just wanted to make it clear that he isn't Skip Simmons.

  35. #35
    Administrator MikeSlub's Avatar
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by j45 View Post
    !!! This looks like both of my amps. Identical in all ways as far as I can see. If I'm not mistaken the speaker is not a field coil like it appears to be.... I believe that's the output tranny mounted on the side. Anybody know? Thanks for the pic. I almost have to wonder if this may not be one of mine before I got it. Can't be that many around, especially this clean. I recall perfectly that I was in absolute heaven that last day I was playing mine. I was deep in a zone just digging how awesome the sound was when my "good one" failed. These photos really inspire me to get mine going again. These are just killer amps. Thanks again for the pics!
    Yes, that is an output tranny mounted on the speaker. Not a field coil.
    Mike Slubowski

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  36. #36
    Les Paul Forum Member
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    Re: HELP! Alamo Scematics

    Quote Originally Posted by Brown Recluse View Post
    Diablo1, I don't know if cryptozoo has an amplifier repair business, however, I just wanted to make it clear that he isn't Skip Simmons.
    Thanks Brown Recluse. You're right, I thought that was Skip Simmons posting from the ad in the signature. I owe an apology to Skip for my wrong assumption.

  37. #37
    Les Paul Forum Member 67FlyingV's Avatar
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    Re: HELP! Alamo Scematics

    These guys are very good tube amp repair specialist. If you want to contact them.

    http://chromedomeaudio.com/home

  38. #38
    Les Paul Forum Member Patrick Ginnaty's Avatar
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    Re: HELP! Alamo Scematics

    Sorry to go a wee bit off topic, but I *just* got my Alamo Twin Ten back yesterday. The tech had to draw his own schematic to figure it out.

    What a tone monster.

  39. #39
    Les Paul Forum Member j45's Avatar
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    Re: HELP! Alamo Scematics

    Finally a gut shot:


  40. #40
    Les Paul Forum Member latestarter's Avatar
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    Re: HELP! Alamo Scematics

    wow, looks great with the pine cab. crypto, not everyone is a crook man. chill sometimes.
    Otherwise known as Grant.

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