I bought a tube combo amp.

Discussion in 'The Backstage' started by kevinpaul, Nov 2, 2015.

  1. jep1210

    jep1210 Senior Member

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    I looked there too and there's nothing. Is it different than what was posted a few times in this thread?
     
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  2. pinkjimiphoton

    pinkjimiphoton Senior Member

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    all the stuff is in this thread just a couple pages back
     

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  3. jep1210

    jep1210 Senior Member

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    Thanks Jimi
     
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  4. pinkjimiphoton

    pinkjimiphoton Senior Member

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    ok, i got the right filter caps this time, the last link to mouser i posted is right. also got my new variac... man i never thought i'd use one again when i gave all my tube crap away 10 years ago.
    so tomorrow, provided the little woman doesn't go quasar on my ass, i will begin the process of frankensteining my silkyn back to life, with pictures every step i think of.
    don't fret, and stay tuned. errr... you know what i mean ;)
     
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  5. Believer

    Believer Junior Member

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    Can't fool me...I see what you did there!;)
     
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  6. pinkjimiphoton

    pinkjimiphoton Senior Member

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    amp disassembled, pt disconnected, first 4 of the filter caps in, and an ass load of pics where i can which will follow. i gotta gig in a couple hours, so hopefully can button it up today in one shot.

    BEWARE. they used snap in caps for the filter caps, not thru holes and soldered them in. the solder they used appears to be that lead free crap which contaminates fuckin everything it touches. i damaged the cap side pads on each one. luckily, they aren't neccessary to the circuit operating thank jebus. beware. crappy solder = tough reworking. even GOOD solder gets contaminated with this shit.

    so if ya tread where i have trodden (?) and do the filters, beware of this. this crappy solder made it so literally pulling the iron away it would solidify before i sucked it. had to suck repeatedly (somewhere someones laughing and i hope not getting wood) before it came clean enough to manhandle the leads outta the holes. but its done.

    kicking my own ass for misreading 22000uF as 2200. tht cap appears fine so its gonna stay.

    next will be the 33u@400v caps. then the rectifiers just to be safe... then i mark and drill for the new pt and bolt it in.

    onwards n Upwards
     
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  7. ultra80096

    ultra80096 Senior Member

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    ahh, snap ins. I was originally looking for caps & wondered if they were snaps or radials, especially those 220's. Was going to pull the board out & make sure before I ordered, Glad to know.. they seem to be the most popular in that range, even 400V's are cheap. Think I'm going to stay with them. Got me in the mood to get going & pull my board tonight.

    When I did the basic mods on two amps, about 1/2 way through the first one, I just melted, & either solder sucked or wicked before pulling components. Worked really swell & no resulting damage.
     
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  8. pinkjimiphoton

    pinkjimiphoton Senior Member

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    go with normal thru holes bro. the snap ins were NOT what it was designed for, probably all they could find that would fit in the limited space of the chassis. but they are literaally carved down and jammed into the board. even with a 40 watt iron and solder pump (a big long one) getting them clear without pulling the "top" pads was impossible. out of the 4 220's, i got ONE where it didn't fuck up. that said, the top pads weren't necessary for circuit integrity. but yeah, if ya get 'em out, go with normal ones. you and the amp will be happier. the only way to get them out is to literally bend and pry them off the board which to me is a potential doomsday for the pcb.

    they have to be 40mm high or less. 44 mm will not fit in the board. i posted the right sized ones from mouser the other day if ya scroll back some, they are the exact size fit with thru holes, and nichicon instead of the chinese garbage that the amp came with. not worth damaging the amp.

    man, mine looks like the pics you posted now. messy ;)

    i REALLY hate this lead free solder crap. yech. almost wanna redo the entire board with real old school solder.

    all but one of the caps was popped. i ended up changing everything but the 22000uF cap cuz i fucked up and got 2200 instead. vent on that one seemed fine, i'll desolder it and test it before i button stuff up.

    also guys, change the 2 bias filters, 22uf. you can go up to 100uF if ya want to there, keep the voltage rating around 100v. these can take a hit too and are cheap. if ya fire it up and get a hum you can't get rid of, suspect them.

    all the silicon rectifiers seem to have survived so i'm not fucking with them.

    i did the first half of the reverb mod yesterday, took the resistor down to 820r as i felt the reverb was deficient before.

    also swapped out the mid pots to 50k from their stock 25k... will give a bit more mid bite. i use a lot of mids generally so for me should be fun. surprisingly, the marshall side was 25k too, i expected to see 50k. you could go to 100 but the amp may get unstable,

    gonna add the cap to the reverb mod, and change out the resistor to give the preamp a bit more headroom, then start doing the transformer. i drank wayyyy too much whiskey after the gig last nite to wanna fuck with a 700vct transformer when i got home ;)

    more later. need to 420 out and grab some brunch (can't believe i slept til noon) and have at it.

    newbs take note please: you do NOT wanna rush this process. make yourself take the time to do it safely. seriously. this shit can KILL you. so please be careful!! check everything twice, then put it aside til the next day and check again with fresh eyes before firing up. seriously.
     
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  9. pinkjimiphoton

    pinkjimiphoton Senior Member

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    I HAVE ATTAINED LIVING SILKYN!!! TOTALLY DIFFERENT BEAST WITH THE PROPER POWER SUPPLY HOLY SHIT!!!
    NOTHING LIKE IT WAS!!!
    reading around 502vdc now, when i got this thing it was about 380. surprised it was even running!!
    i DID do the reverb mod. distinct improvement, useable reverb now about 1/2 way up instead of full blast like before.
    also did the mod to raise the preamp voltage, totally brings the stock circuit to life. channel volumes match well, improved presence and note definition. you could actually fool yourself into thinking the clean channel is a fender, and the dirt channel a tweaked in jcm800.
    i DID double the midrange pots to 50k as well. i like 'em pegged. that also made a huge diff in the tonal range of the amp.

    this thing has way fuckin' more balls now than it had when i got it. jesus, i bet it was only putting out about 15 watts before, now it will tear your head right off.

    i used to have to run it wide open!! not anymore.

    my humble suggestion is to replace the transformer first before modding the amp tonally. you may find its just right once the thing has proper voltage fed to it.

    HATS OFF TO JOHN AND BUD PURVIS FOR MAKING THIS HAPPEN!!!!

    ok.. some dissasembly hints.
    unplug the speaker

    unscrew the two screws to secure the reverb leads. remove the leads, put them screws right back in, and tight... they go into standoffs that hold the pcb in place. you don't need to remove any of the screws on the bottom of the chassis to dissasemble the amp.

    there are 4 plastic plugs on the top of the amp, remove them and you'll find bolts and washers. remove the bolts and washers. the amp should settle down right into the cab as you do it.

    pull the chassis.

    you need a small flat screwdriver to remove the knobs. take 'em all off.

    next, remove the nuts and washers for the pots.


    remove the input jack nut thing. once ya get it apart, put it back in so ya don't lose the washers.

    draw a picture of the wiring. label fucking everything... the switches, where the wires go, colors etc etc. trust me on this.

    if you're gonna add inline fuses like i did, the 6.3 input on the circuit board is a good place to solder one in. you want 4 amps for the fuse. that should cover the 6 12a_7's and 6l6's... .9 amp per 6l6, .3 amp per preamp tube.

    i put the b+ fuses in line with the switch.

    anyways.. sorry..

    connect a roach clip with a 1 watt 100k -ish resistor to another roach clip on a bit of wire. with one hand in back pocket, clip roach clip to b+ point on board. connect other side to ground. leave it there. you may or may not get a hell of a spark.


    NEXT unscrew the gazillion little phillips heads that hold the board in place, including the one securing the reverb cable to the board. i find wiping my screwdriver in one direction on the back of the speaker magnet to be a handy way to magnetize the driver, which makes it easier to handle the screws and little washers.

    once a have all them undone, unscrew the nuts for the 4 jacks on the back of the amp and pull the daughter board out some. now, with a little finagling, you can slide out the circuit board, still attached to the transformer.

    you DID draw out the wiring and color code, right? ;)

    take the time to look at your shit. some wires don't need to be messed with, so unplug them from the switches on the front. push 'em out of the way. cut off all the wires except the screen and b+ terminals about an inch from the board . now flip the board over and desolder the black wire marked screen that goes to the choke, and the red and yellow wire that goes to b+

    you don't wanna have to splice on to those two wires like the others.


    you'll need a nut driver inside the chassis and a phillips head outside to unscrew the 4 bolts for the xformer. once unscrewed, ease the tranny out and pull the wires thru the hole. admire your handiwork. you're part way there.

    measure the holes where the wires come out on bud's transformers, and go center to center.

    measure inside the chassis, and center punch the spot ya wanna drill. harbor freight has centerpunch, drill bits etc.
    i advise getting the 3 pack, and start small and work your way up. i ended up going a good half inch or so, and stuffing a grommet that fit in.

    carefully feeed your wires thru the holes. twist the green and blue wires together. they carry ac and can make the amp noisy.


    you may want a helper for mounting the tranny, its a pain in the ass but doable if all ya got is you.

    i actually stood the transformer on its end and pushed the screws up thru with a screwdriver and caught the locking nuts, then tightened everything down.


    if you're gonna do some of the immortal mods, nows the time to figure 'em out.

    one fuse on the heater supply, like i said, 4 amps slow blo is about right. doesn't matter which one. you only need one. i was stoned so i put two in (rolls eyes)

    for the b+ fuses, i put two inline fuse holders to the switch with a spade connector, then soldered that to the two red wires with the fuse holder in the middle. shrink wrapped the solder connections.
    1 amp slo blows here seem to be ok, and is where RG Keen suggests to start.


    twist the primarys together real fuckin tight, and stick 'em in a nice insulated spade connector.. you can kinda "screw" 'em in to it. get it in good and tight, and crimp the hell out of them. shrink wrap reccomended.


    now solder all relevant wires to where they gotta go. the color code matches the original, which makes it easy.

    don't worry about clipping the leads and shit. just tuck 'em all in the side over there, you'll be fine.

    solder the 12v(10v) taps, the grounds (black and white, red and white you can connect to the star ground near the power jack on the back of the amp) resolder your screen and b+ connections.

    if ya wanna make any mods, now is the time to do it.

    carefully slide the pcb back into place, so all the pots poke out. tighten all the washers and nuts, and replace the input jack nut. also reinstall the switching and speaker out daughter board.


    screw that fucking board back down. all of 'em. make 'em tite!


    hook up the wires that go from the power socket to the switches, and your primarys and b+ wires.

    connect a speaker load to it, and the reverb as well (and footswitch)


    if ya use a variac (i did) bring it up a little at a time till ya hit 110. monitor your voltages on th epower tubes, and make sure nothing explodes or smells funny. power down.


    install tubes. again, if ya have the variac, bring it up a couple volts at a time til ya hit your target voltage, monitoring the plate and grid to make sure your voltages are in the ballpark.

    once ya hit 110, let it cook for a few. go burn one. have a beer. whatever.

    check your voltages, adjust bias if necessary, turn it off. discconnect the variac, hook up whatever is left and congratulations, you should be good to go.

    too tired, too late... many pics to come.


    again, thanks to all who made this possible!! 3 cheers!

    hopefully i left nothing important out. be careful, there's really lethal voltages in there. check thrice, always insulate if in doubt and take your time. this took me a couple days to get to this point.

    good luck my friends. hope this helps someone a little bit.

    peace out
     
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  10. pinkjimiphoton

    pinkjimiphoton Senior Member

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    ok gang as promised pictures. i couldn't get any cool "action " shots cuz it was me by my lonesome. but there's 39 pics total i remembered to take. hopefully they're in sequence.
    1.jpg 2.jpg 3.jpg 4.jpg 5.jpg 4.jpg 4.jpg 5.jpg
     
  11. pinkjimiphoton

    pinkjimiphoton Senior Member

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  12. pinkjimiphoton

    pinkjimiphoton Senior Member

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  13. pinkjimiphoton

    pinkjimiphoton Senior Member

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  14. pinkjimiphoton

    pinkjimiphoton Senior Member

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  15. pinkjimiphoton

    pinkjimiphoton Senior Member

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  16. pinkjimiphoton

    pinkjimiphoton Senior Member

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  17. pinkjimiphoton

    pinkjimiphoton Senior Member

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    36.jpg 37.jpg 38.jpg 39.jpg



    th th th that's all folks!!

     
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  18. ultra80096

    ultra80096 Senior Member

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    Good job Jimi!. Wow, only 380v on the plates? It must have been sick. All four of mine had no less than 490. Considering possibly the electro's, did your amp have a lot of hum? They say that can be one of the symptoms of them dying. My four amps are all dead silent.
     
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  19. kevinpaul

    kevinpaul Premium Member

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    I might do the caps one day. I am go to Paris and Berlin for a speaking thing. I and going to study these photos and thank our main guy Jim. Thanks man that is so cool of you to help us like this.
     
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  20. pinkjimiphoton

    pinkjimiphoton Senior Member

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    ultra, yeah it will hum bad with bad caps, sometimes like if ya bend a note up, you'll hear a ring modish kinda weird thing where ya hear a sub harmonic kinda bending down opposite what you play.
    i'm glad i changed 'em out, now it will probably out live me ;)

    kevin, honored, doc. rock on!
     
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