Vintage Jtm45 With A Bit Of Extra "hair"???

Discussion in 'Let's Talk Vintage' started by pleximaster, Jan 30, 2017.

  1. pleximaster

    pleximaster Well-Known Member

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    I just found this on the "Blocket" (Swedish Craigslist sort of) and I it was sold as an "Old 50´s JTM45 in non working condition. Refurbished with faux fur and used by the Cover Hair Band the Dirty Hairies. Main transformer probably shot. No valves. Not working."

    I have no idea what it really is (i initially ask for pictures but had to go fast as the seller got a crowd of calls and emails. I "swished" him the 4500 kr (About 450 euros - 500 dollars). Gonna pick it up later. It can turn out to be waste or a treasure!

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    plexi
     
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  2. neikeel

    neikeel Well-Known Member

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    Looks like a 64 JTM45 with RS trannies, possibly a PA model originally, wonder if the serial is in the 1000 bracket. The octal sockets are clearly new as I would expect hem to have been Cinch ceramics.
    Sounds like a good deal if the OT works. You know that Majestic can rewind the PT for you if you ask nicely?
     
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  3. tomsvintage

    tomsvintage Active Member

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    Excellent find ;):agreed: !!

    Looking forward to seeing the progress !!

    Maybe close to my # PA 1009 :woot:

    Congratulations !! :yesway:
     
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  4. pleximaster

    pleximaster Well-Known Member

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    Got the amp before the weekend.

    The bo was in terrible condition filled with nails, crews and extrasuport wood and rotten in the edges and filled with mould!!! Smells horrible! Probably only good for measurements but perhaps not even that. Unfortunately I had to bring my kids with me to pick the amp up and the youngest reacted with asthma when we drove back home.

    In side the amp things was much better. However I don´t really know what I have what it is and what it was! :) I guess it is like Neil said a PA model. Backpanel is all sandpapered and polished and no markings, You can still see a bit of a serial number as those were ingrained and not silkscreen on the plastic probably 1000series I have to check with a blacklight and see if I can make out all numbers.

    The amp came with plastic cast RS 0.022 grey and 0.1 light grey caps and carbon comp resistors. It had a few replaced and some added caps and resistors that I did´nt bother to figure out what they did, I tried to make it "stock" again.

    The MT was´t shot as I measured it so I reinstalled it. All wires were cut to length for the amp but it is not a regular RS unit you'd find for a JTM45. I think it is an older replacement. It is labeled "Heavy Duty Mains Trans - International Exp. Model" and is much taller than an old regular RS transformer. It has also 110-120 voltage taps in addition. Any one seen one before?

    Then things got interesting...
    Fire in it up it literally burst into flames. I have had smoke before but not fire! Took down the fuses in my variac and the whole house! I had check and double checked all wiring as components and replaced bad ones. WTF! I rechecked again and again using up fuses as there was no tomorrow!

    Late late night i found the problem. Two of the octal (Cinch black bakelite valve sockets, I think they are original, I have seen them on a couple of old amps now, same as the ceramic cinch but bakelite) were looking fine but had random shortage between the pins. I guess this is due to two factors the amp looks as it have had a Cap blowout that stuff is sticky and very hard to remove part of it is conductive. Then the apparent storage in a damp environment probably made it worse and it somehow created an invisible conducive film in various places. I could not get it out of the sockets without removing it and literally bath it en electric cleaner and deoxit. I Only done one so far and I with do the other two. I really think I have to take this amp into bits and clean all parts more or less. It was really moody when I measured the components I got various results from time to time and this conductive film is probably dropping in and out in more places than just the sockets. To bad and boring restoration work. Cleaning is no fun - ever!

    Interesting to see PARK knobs on this one, They are exactly the same as on the orange 67 Park in my avatar. Also probably replacement... the mystery is to be unfold... :)

    plexi

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  5. neikeel

    neikeel Well-Known Member

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    Very interesting! Still looks very much like '64 era with the trafelite engraved front panel. Do you see signs of the head cab ever having Vynair (grey or split front?). Might be worth a bit of archaeology (in the fresh air!).
    Do you have any board pics of before you did your work?
    It is an 8 hole circuit board so certainly not offset era (which had some grey Dubilier caps and carbon comps). The internal fuse fits more like '65.
    I would have expected ceramic sockets in 64. Black octals crop up again in mid 65 from amps I have/have had.
    I am surprised you kept that non-stock filter cap up top bearing in mind the new screens/PI cap.
    What exactly smoked?

    Is your circuit board fixed like that?
     
  6. pleximaster

    pleximaster Well-Known Member

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    Cab has not been investigated fully it is in a plastic bag i the attic of the garage...

    but I did pull off all the "fur", It got me sick all night... But i looks as it did not have Vinair but was a sold smooth black front with piping close to the edges.

    The internal fuse is my doing hard to see but its not the "right" one and I just glued it there I kind of like having the extra fuse. I had to trim one of the sides to make it fit and not interfere with one of the sockets.

    Sorry I didn´t get the before picture I am an impatient person. I did´t men to start fixing the amp the same night I got it. However It smelled so bad I did´t want to bring it inside the house. The aluminium chassis was covered in a "frosting" of mould and aloud making it all powdery dusty looking. So I started in the cold garage first just cleaning it of with naphtha and so... Then I started to remove knobs and controls to get in everywhere and the loosen the board and other parts and finally i Got the solder iron out and ditched most of the wrong crappy stuff. After that I ripped the fur of the cab... Then I realised I was had my new pants on I just bought and they did not look brand new anymore.... That is me in a nutshell! Impulsive for sure! I even got a diagnose! LOL :D:D:D:fever::lol::lol::lol::nuts::nuts::nuts::nutkick::nutkick::nutkick:

    Regarding filtercaps and such I have learned the hard to use salvable ones until the amp is running reliable. These filter caps and the bias caps were all checked and work perfectly in my latest restoration

    The parts that smoked were the non original 8.2K big piher resistor and the non original (wrong value) green coloured screen resistors. The fire and flames started in the then empty rectifier socket. It might have been naphtha left somehow after my cleaning the night before, however I dried it out with a hairdryier to get the naptha before I took it in the house. However the shortened sockets were the main reason for the spark that egnited what ever burned.

    Added Edit:
    The board it not fixed in the pictures it is more straight when mounted, However only 4 screws not five as usual. As I told TomV it is strange this one does´t have any extra holes drilled in the chassis when you consider all thats been done with it! :)

    plexi
     
    Last edited: Feb 3, 2017
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  7. BanditPanda

    BanditPanda Well-Known Member

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    I got queasy reading this while eating my lunch lol
     
  8. pleximaster

    pleximaster Well-Known Member

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    I got super frustrated about the shootings in the sockets. So I spend almost all night up amping in this sucker. (The family thinks I do too much amping and they were asleep.)

    I removed all three sockets and cleaned the them they. They all tested ok I installed them again but then a new shortage between other pins appeared. So I decided to ditch all three old bakelite Cinch octal valve sockets.

    I had some old ceramic sockets but not Cinch that are smaller in size. I did´t want to top mount the sockets (that would have worked without enlarging the holes) since it would not have looked right. So I removed the mounting base of the sockets putting them underneath making it look "right" from that side and the top mounting the ceramic part from the top securing it with a few drops of super glue. If I find the right sockets I could (And time and enthusiasm to replace tube sockets :) ) I could just heat the chassis with the solder iron and remove them.

    After I installed "new" sockets I could finally work on the amp finding some other issues and fix those. The amp had a pretty high B+ so I (for the first time) used zener diods to knock it down to acceptable levels 420 Volt. I eventually made one quick and dirty sound clip on the amp as the family woke up this morning. Really cool and aggressive tone.

    The backpanel had been painted and the sanded so it was all blank. I wet sanded most part of it to get a even shiny look on it again. The serial number are engraved on these panels and you could see 10XX... Under a black light I could make out the last two numbers 28 so the serial had been probably 1028 (PA series I think due to the amps features) I used a exacto knife to deepen the numbers but I distorted the font. I filled it with som gold power as it had originally. Then I just used a gold pen and wrote SPEAKER PA MAINS and FUSE 2 AMP by hand. After I finished I realised I was tiered and had written SPEAERS without a K. Remove with some gasoline and rewrite. After that I polished som of the writing of making it look a bit scruffy. It wont fool anyone at close inspection but it looks better than just a blank white panel.

    Later I´ll see what vintage parts I have lying around changing out the modern ones like the filters, valves and some resistors. Ill also try some lacing on the wires. BUT not today!!!! :)

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  9. neikeel

    neikeel Well-Known Member

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    Glad you got it up and running, how high was the plate voltage without the Zeners?
     
  10. pleximaster

    pleximaster Well-Known Member

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    Around 470-480v without...

    It is totally reversible mod, I just thought I finally try it as I was doing so much sh@t to this amp anyway!!
     
  11. neikeel

    neikeel Well-Known Member

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    That voltage does not sound far off for an early amp. Your mod looks quite neat tho':)
     
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  12. tomsvintage

    tomsvintage Active Member

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    Excellent job !! Thanks for sharing !!
     
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  13. danfrank

    danfrank Active Member

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    I've never seen where shorted out sockets could be "revived" and used again. When the arc occurs, the conductive carbon trace gets etched into the socket material and is nearly impossible to fully remove. Maybe it could be removed by a Dremel type tool used to "dig out" the conductive trace, but then the strength of the socket would be compromised with the removal of the material.
    Replacing the shorted sockets is the way to go.
    I find your restorations amazing, Pleximaster. You do excellent, excellent work! Beautiful!
     
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  14. neikeel

    neikeel Well-Known Member

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    +1
     
  15. pleximaster

    pleximaster Well-Known Member

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    Restored cab! Less hair! Recovered repro logo and 35% new wood... :) The Smooth tolex is from my grandfathers old rain coat!!!!! :) :) :)

    Missing the metal fascia strip, just a white string there so far...

    plexi
     
  16. neikeel

    neikeel Well-Known Member

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    Love the smooth material idea, I presume your grandfather no longer needs his coat:(
    I think chunky bass fret wire might worth for the front strip (not sure of the gauge or profile). I have one original strip saved for one of my restos and someone sent me some metal strip that does feel like fret wire! I salvaged some thin white piping from a PA cab soft cover to use on the front lip.
     
  17. pleximaster

    pleximaster Well-Known Member

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    No my grandfather passed away a few years back 104 years old and I think this raincoat dated back to the 50s-60´s so its time period correct!

    The fascia strip.

    Tom vintage hooked me up with a terrific guy, Ray in the US that has a very nice T shaped fascia strip that I have ordered. I think it is made for tile decorations nowadays.

    Best plexi
     
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  18. tomsvintage

    tomsvintage Active Member

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    Beautiful restoration Plexi !! Thanks for sharing !!:agreed::applause::dude::eek::bowdown:

    I had to save those latest pictures to my Dirty Hairies file !!
     
  19. strato2009

    strato2009 Active Member

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    great work
     
  20. clutch71

    clutch71 Well-Known Member

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    Quite a read! Sorry I missed the early versions of the story. Before the smell and the reaction to it, I would have called for keeping the hairy version. Great work!
     

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