Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com

After much trepidation... 5E3

Discussion in 'Shock Brother's DIY Amps' started by Preacher, Oct 15, 2017.

  1. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D
    So I ordered a Boothill partial kit a few months ago. Dave was nice enough to get me what I needed as I had accumulated some miscellaneous parts on my own.

    After months of on again off again soldering, rewiring and lead dressing I finally got to the point three weeks ago where I wired up the two transformers and had it ready to test and for some reason I did not. Not sure if I was scared I had messed something up or that it might be a failure. So yesterday I decided I would forgo football and test the amp.

    Got my light bulb limiter ready, safety glasses on and plugged it in. I went and grabbed my multimeter and when I turned around the pilot light was glowing. That thing is on! Yep my switches are upside down and it was ready to go when I plugged it in. Whew, glad there was not any issues. Light bulb was dark so I went onto RobRob's start up.

    Everything looks good, I have 6.2 (should be 6.3 though) at the pilot and heaters on the pre amp. And I have 325V at each of the two rectifier pins.

    All I need now is some tubes to move onto the next step.

    IMG_1305.JPG
    IMG_1304.JPG
    IMG_1303.JPG

    See anything to worry about? And I have woke up with wood for the last year and a half so as soon as this is done it is time to take care of that and build a cab.
     

  2. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D
    Oh and the wire nuts were there for the test run. Once it is up and ready to go, I will solder them and shrink wrap them. I don't want them coming loose in transit.
     

  3. Old Tele man

    Old Tele man Tele-Afflicted

    May 10, 2017
    Tucson, AZ
    I just thought you were a lineman electrician by trade (ha,ha).
     

  4. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D
    Father in law is a master electrician. We have wire nuts everywhere in every size lol
     
    dan40 likes this.

  5. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D
    Is there a way to check voltages without tubes? I will get some tubes ordered soon but would like to make sure my wiring is good.
     

  6. Old Tele man

    Old Tele man Tele-Afflicted

    May 10, 2017
    Tucson, AZ
    With all tubes (except the rectifier) removed, you can probe the sockets to verify the HIGH voltages are where they should be and the bias voltage is adjustable.

    And, remember, without the other tubes installed, no cathode-bias readings can be made as they exist only when the tube conducts current through its cathode resistor...no tube = no current = no cathode bias voltage.
     

  7. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D
    That's what I thought. Will start my cab since I will have to wait on tubes. So far everything looks good.
     

  8. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Great story -- startup 3 weeks later but also 1 minute earlier than planned. :)

    Let me say your wiring (OK, minus the wire nuts!) looks pretty darn tidy for a first build. Nice job.

    Rob's startup steps are great. EL34 guru Sluckey also has a very readable, useful startup procedure where you'll note that a number of steps, like 3 thru 6, are basically done prior to inserting all the tubes.

    And anytime you start up without tubes, recall the one hope to discharge filter caps spontaneously (hot tubes draining them) is absent, so a bleeder resistor, or at least a snubber, is literally a lifesaver.
     

  9. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D
    Thanks, yeah the wire nuts were a quick change choice. The PT was a pickup from an overstock company so it was a little suspect. It was rated exactly like a standard 5E3 so for a few bucks was well worth it if it worked at all The OT was new so I was confident in its ability to do what it needed so it is hard wired. Once I get the tubes in and give it a go I will finish solder those and cut off the excess.

    And on the filter caps. Noted!! I actually had modified a Valve Jr a few years ago and was warned of my impending death if I did not discharge those caps!!
     

  10. robrob

    robrob Poster Extraordinaire Ad Free Member

    Dec 29, 2012
    United States
    Your amp looks really good. Yes, you should check voltages with just the rectifier. The DC voltages will be much higher than normal with no current use. You should have rectifier voltage at all the tube plates because there will be no voltage drop through the B+2 and B+3 dropping resistors and across the plate load resistors with no current flow.

    Make sure you have heater voltage on the preamp tubes at pins 4 to 9 and 5 to 9.

    And as warned above, the caps will hold their charge for a long time with no tubes installed.
     
    Preacher likes this.

  11. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D
    Robrob, thank you for your time to look over all of our builds. You are a wealth of information.

    I do have one issue, I went to your website and got distracted from amps by jets, helos, motorcycles and sports cars... you need a disclaimer for guys like me who get lost in things like that.

    So in high school I was planning on going to USAFA in Colorado Springs to become a pilot, even did ROTC. Had the recruiting office, the senator and everything lined up and the grades and math skills to go to the academy and then grew about six inches over the summer. So my dreams of being an F15 or F16 jockey were over (my dad always wanted me to go be an aviator in the navy so I checked that out but the Tomcat doesn't have much leg room either). My recruiter said C130s were still in the mix though... so I bailed on that dream.

    Then later in life I bought a couple of motorcycles to scratch that itch and finally a '91 Miata turbo that was just missing the turbo (someone sold it for quick cash). Rebuilt that car and it put a lot of smiles on my face till my brother in law bought it, now he is the one smiling. I had my eye on a newer RX7 that was just setting in someone's yard down the road, I thought a V8 swap might be the cat's meow so now you have me looking at the older RXs too....

    So I will definitely be looking for Captain RobRob on my next flight with the airline with a heart!
     
    speedy mcfeely likes this.

  12. robrob

    robrob Poster Extraordinaire Ad Free Member

    Dec 29, 2012
    United States
    Preacher, I'm 6' 2" and was within a 1/4 inch of having too much seating height. I don't know why the Air Force is so restrictive though. I had to run the seat in the F-15 up quite a bit to maximize visibility. I know the F-16 cockpit is tighter but the Air Force limits seem almost arbitrary.

    I have also lusted for a V8 Miata. I'm seriously considering putting a supercharger in mine.

    [​IMG]
     

  13. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D
    A scotch over 6’3” and long bodied. That was the issue with me, same issue I had with this little triumph convertible I was buying. Was great with the top down, went to put the top up and almost scalped myself. I had to lobotomize my Miata seat to get the top up in it.
    A Miata with a supercharger is fun to, power at the ready. The turbo has a little lag but when it hits it is fun. A Monster Miata, yes please. A guy had one for sale here in DFW for like $8k. Seemed done right too, was a bargain at that number. It was a ‘96 I think so a good year ad well.

    My wife started her own business 18 months ago so no toys for me for a little while. But when she starts cash flowing well a sporty is on the list.
     
    robrob likes this.

  14. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D
    So I fired it up to do some voltage checks and it was humming pretty good. So I started to check voltages and when I put my negative probe on the grounding point on the large capacitors where the bus starts the board pushed down just a bit and the hum went away. I lifted the negative probe and the hum comes back. Push back on the eyelet and the hum goes away. Lift the probe hum comes back.
    Ground loop or is there an open ground to chassis that is under the board. I don’t want to have to pull the board if it may just be a bad ground.
    I had a video but can’t upload it.
     

  15. jhundt

    jhundt Poster Extraordinaire

    Age:
    63
    Mar 23, 2003
    Netherlands
    Remember this: if you are plugged in to the light-bulb limiter, all your voltages will be off. You can't accurately measure voltages with the light-bulb limiter in place. You CAN check if the voltages are 'in the ballpark', and if high and low voltages are in the right places. But once you have established those things - and nothing blows up - you have to remove the current limiter before proceeding.
     

  16. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D
    After nothing blew up with the limiter. I checked all the tubes and fired it up without the limiter.
    I think it is just a bad ground and it may be right around the tone pot as it has a direct impact on the level of hummmmmmmm.

    I also checked voltages today and some seemed high. I will post those later to get some feedback. I am almost wondering if I have my rectifier wired correctly.
    IMG_1304.JPG

    Seems in looking at a couple of schematic pins 4&6 are to get voltage from the tranny, but I think my schematic called for 3&5. I will check that tomorrow as well.
     

  17. arcticbreaze

    arcticbreaze Tele-Meister

    106
    Aug 2, 2014
    Oamaru NZ
    which rectifier did you buy not all the new 5Y3's have the correct 50 volt drop.
     

  18. rocksmoot

    rocksmoot Tele-Meister

    159
    May 6, 2012
    Rogers, Arkansas
    You sure have a nice, clean build there. Should be up an running in no time at all.
     

  19. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D
    Voltage readings - no limiter

    12AX7 -
    Pin 1 - 143
    Pin 3 - 1.12
    Pin 6 -137
    pin 8 - 1.1

    12AU7
    Pin 1 - 66
    Pin 3 - 1.2
    Pin 6 - 127
    Pin 8 -76

    6V6GT
    Pin 3 - 343
    Pin 4 - 303
    Pin 8 - 17.1

    6V6GT
    Pin 3 - 339
    Pin 4 - 302
    Pin 8 -17.1

    5Y3GT
    Pin 2 & 8 - 347
    Pin 4 & 6 - 1.2? I cant read my own writing

    I still have not figured out the ground hum either. I have continuity from the chassis to the ground buss and to each of my grounding points on the large caps and the input jacks. However I have an orange drop capacitor on the tone control going to my ground bus. Would it be better to ground that cap to the back of the pot? Am I creating a ground loop with a pot that is grounded to the chassis and then running the cap to the ground bus?
     

  20. Preacher

    Preacher Tele-Afflicted

    Apr 17, 2007
    Big D

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