Page 2 of 2 FirstFirst 12
Results 36 to 57 of 57
Like Tree54Likes

Thread: 5150 hideous death

  1. #36
    Supporting Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    11,658
    Quote Originally Posted by Gingertube View Post
    I do airborne electronics PCB's for a Laser Airborne Depth Sounder survey system - 2 examples: Q-Switch Driver boards for the laser at 4.5kV and Photomultiplier Power Supply (for the Laser Receiver) at 2.5kV.

    FR4 boards are fine - get the layout right, clean bare boards thouroughly before loading, again after loading and then finally spray with Conformal Coating. The last step (conformal coating) is paramount for reliability. I would suggest that this should be standard practice for tube amp boards.

    Cheers,
    Ian
    Ian,
    What is the purpose conformal coating? I'm not unfamiliar with it, it's just that I usually see it used as a means of controlling moisture infiltration (which shouldn't be a problem with FR4) or squelching the growth of tin whiskers with lead free solder (which isn't a problem with most small operation built tube amps). It there is another good reason? I'd be interested.
    "I've heard magic defined as "a technology you don't understand". By that aphorism, the folks in this forum are practicing wizards, able to summon AND control the lightning demon, and make charms to allow others to use the demon in certain ways." R.G.

    "...less ear-friendly but handy for jazz." Leo_Gnardo

  2. #37
    Old Timer
    Join Date
    May 2006
    Location
    Chill-Ville, VA
    Posts
    2,029
    Quote Originally Posted by The Dude View Post
    It might have been a good idea to measure the original caps and replace them with something that would fit into the amp.
    <BEFORE> cutting out the old parts...

    Justin
    "When receiving a shock I emit a strange loud high pitched girlish squeak." - Alex R -
    "Sort of like not checking for toilet paper before taking a dump. ." - Chuck H -
    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

  3. #38
    Supporting Member Jazz P Bass's Avatar
    Join Date
    Dec 2008
    Location
    Wernersville, PA
    Posts
    11,671
    My take on 'conformal coating'?

    It's a bitch to get off if you want to rework the pcb.

    conformal_coating_removal_techiques.pdf

  4. #39
    Supporting Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    11,658
    I got through a good bit of it. What a PITA. I agree that conformal coatings have benefits. Probably an improvement for factory built amps. Especially those with a high DNR probability, as many are now. I certainly don't think conformal coatings have any place in cottage industry amps though.
    "I've heard magic defined as "a technology you don't understand". By that aphorism, the folks in this forum are practicing wizards, able to summon AND control the lightning demon, and make charms to allow others to use the demon in certain ways." R.G.

    "...less ear-friendly but handy for jazz." Leo_Gnardo

  5. #40
    Supporting Member Jazz P Bass's Avatar
    Join Date
    Dec 2008
    Location
    Wernersville, PA
    Posts
    11,671
    Conformal coating is not needed in a guitar amp.

    For what purpose?

    Military, marine, aerospace, welding equipment, yes.

    The gunk is made to isolate the PCB from the environment.

    Well, I guess it would keep beer spills off the PCB.
    The Dude likes this.

  6. #41
    Lifetime Member
    Join Date
    Jan 2007
    Posts
    157
    Quote Originally Posted by Jazz P Bass View Post
    Conformal coating is not needed in a guitar amp.

    For what purpose?

    Military, marine, aerospace, welding equipment, yes.

    The gunk is made to isolate the PCB from the environment.

    Well, I guess it would keep beer spills off the PCB.
    It also greatly increases the dielectric strength of traces and pins, and changes the minimum required spacing for a given voltage. It is a good idea for PC-mounted power tube sockets.

    For example, according to the IPC-2221A spec, a 32mil spacing on a component lead termination with conformal coating is good for over 500V, while the same component lead termination uncoated is only good for 300V max.
    Last edited by raiken; 02-02-2016 at 06:26 PM.
    nickb likes this.

  7. #42
    Senior Member
    Join Date
    Jul 2011
    Location
    Adelaide, South Oz
    Posts
    635
    Chuck H,
    I was a liitle loose in my language. Specifically, I use Anti-Corona Conformal Coating on these boards. It prevents build up of grunge and moisture on the board which may lead to arcing problems but its main benefit is that it has a dielectric strength of 48kV/mm compared to the dielectric strength of air of approx. 3kV/mm. This means that for a given track separation then a coated board can have 16 times higher voltage between those tracks before arcing.
    Cheers,
    Ian

  8. #43
    Supporting Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    11,658
    Yeah, those things don't occur to me in idle thought because I still build eyelet boards. Spacing isn't an issue and a new board can be expected to last the buyers lifetime without any coating. But with new lead free solders and SMD boards that sometimes have close tolerance (and these are the amps most likely to be considered DNR if they fail) a conformal coating could add some reliability with added insulator resistance and tin whisker prevention. It might be a small benefit, but how much could the stuff cost per unit? Literally a few pennies if you're Berringer or Loud.
    "I've heard magic defined as "a technology you don't understand". By that aphorism, the folks in this forum are practicing wizards, able to summon AND control the lightning demon, and make charms to allow others to use the demon in certain ways." R.G.

    "...less ear-friendly but handy for jazz." Leo_Gnardo

  9. #44
    Senior Member Enzo's Avatar
    Join Date
    May 2006
    Location
    Lansing, Michigan, USA
    Posts
    27,829
    And since most of us still use one sided boards, the difference is having to run a trace around something and maybe use a jumper, rather than thread a tiny trace between socket pins on the board.
    Education is what you're left with after you have forgotten what you have learned.

  10. #45
    Old Timer tedmich's Avatar
    Join Date
    Apr 2008
    Location
    Sonoma CA
    Posts
    3,088
    Well the OP is gonna unload a few polished PV Turds, Clist LOOK OUT!



    The 5150 cleaned up pretty well, the graphics are just printed as the badges are long gone...



    I though this way funny

    The 6505+ looks AOK considering the guy had spray painted it entirely neon green...
    Last edited by tedmich; 02-03-2016 at 05:30 PM.
    Chuck H and g1 like this.

  11. #46
    Old Timer tedmich's Avatar
    Join Date
    Apr 2008
    Location
    Sonoma CA
    Posts
    3,088
    I just got my first offer to trade dope for my 6505+

    "Trade for ommp?"

    Oregon medical Marijua..?
    NONONONONONONONONONONONONONONONONONONONONO

    amp was spray painted bright GREEN when I bought it...coincidence???
    Last edited by tedmich; 02-14-2016 at 09:22 PM.

  12. #47
    Old Timer tedmich's Avatar
    Join Date
    Apr 2008
    Location
    Sonoma CA
    Posts
    3,088
    SOLD all the amps!

    Down to Ultra+ 212, Bravo and Ultra 120 head

    so I sold 1/2 my amps really...
    Last edited by tedmich; 03-10-2016 at 11:58 PM.
    Chuck H likes this.

  13. #48
    Junior Member
    Join Date
    Aug 2017
    Posts
    14
    Hi
    My 5150 have this problem too.
    My friend can make a pcb to me. But how can I remove the original board turret and pin. And how to install it to the new pcb?
    mikepukmel likes this.

  14. #49
    Supporting Member Jazz P Bass's Avatar
    Join Date
    Dec 2008
    Location
    Wernersville, PA
    Posts
    11,671
    If I am not mistaken, the sockets are held in by pop rivets.
    In that case you must use a drill to remove the rivet head.
    mikepukmel likes this.

  15. #50
    Senior Member
    Join Date
    Mar 2017
    Location
    Massachusetts, USA
    Posts
    357
    Quote Originally Posted by tedmich View Post
    working on my 5150 again, found this modded board pic online

    Attachment 37458

    LOL!!
    Ooooo! Niiiice.

  16. #51
    Old Timer tedmich's Avatar
    Join Date
    Apr 2008
    Location
    Sonoma CA
    Posts
    3,088
    Quote Originally Posted by Kwm488 View Post
    Hi
    My 5150 have this problem too.
    My friend can make a pcb to me. But how can I remove the original board turret and pin. And how to install it to the new pcb?
    JPB is correct, rivets hold the tube sockets onto the chassis, drill them out and take extra care to remove metal shavings. A cheap harbor freight rivet gun will reinstall.

    The pins come loose wit a big ~50w solder iron and fit back nicely with the right sized hole in the new PCB, or you can solder the ribbon cable direct to the board (many do).

    I did a solder flood on the traces that PV had, figuring they carry more current.

    I let the pierced dude who bought the 5150 know that while it was 100% stock electrically it didn't have a PV board . He wasn't a collector so didn't mind but as a final test totally dimed it through the 2 x 12" Ultra 212

    it felt like the apt complex was falling down...good times!
    Justin Thomas and g1 like this.

  17. #52
    "Thermionic Apocalypse" -JT nickb's Avatar
    Join Date
    Dec 2009
    Location
    Devon, UK
    Posts
    2,275
    Thread creep alert. This arrived on my bench a couple of weeks ago.

    badcaps.jpg

    The cap at the bottom was just hanging on its leads. Yikes!
    The Dude, DrGonz78 and mikepukmel like this.
    Experience is something you get, just after you really needed it.

  18. #53
    Supporting Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    11,658
    That's not a hack job* per se. That's a straight up amateur job. Clearly done by someone who doesn't understand the dangers or consequences.

    * If I may define a "hack job" as one done by a bad tech rather than an amateur. You can sort of tell the difference.
    The Dude and mikepukmel like this.
    "I've heard magic defined as "a technology you don't understand". By that aphorism, the folks in this forum are practicing wizards, able to summon AND control the lightning demon, and make charms to allow others to use the demon in certain ways." R.G.

    "...less ear-friendly but handy for jazz." Leo_Gnardo

  19. #54
    Stray Cap DrGonz78's Avatar
    Join Date
    Oct 2011
    Location
    Scottsdale, AZ
    Posts
    1,618
    Quote Originally Posted by nickb View Post
    Thread creep alert. This arrived on my bench a couple of weeks ago.

    Click image for larger version. 

Name:	BadCaps.jpg 
Views:	42 
Size:	110.3 KB 
ID:	44813

    The cap at the bottom was just hanging on its leads. Yikes!
    Not only is that cap hanging by the leads, it is also hovering right over a pair of cement resistors that no doubt heat up nice and hot!! I would think exposing the filters caps to that kind of heat is just asking for trouble.
    The Dude and mikepukmel like this.
    When the going gets weird... The weird turn pro!

  20. #55
    Senior Member Enzo's Avatar
    Join Date
    May 2006
    Location
    Lansing, Michigan, USA
    Posts
    27,829
    I'm with CHuck, this is total amateur work. Note that not only did he stuff radials in where readily available axials belong, but he snipped off the old leads and soldered the new to the little remaining stubs, instead of soldering the new leads to the board. The clumsy wire splice to extend the cap leads. In general approaching this like it is just a pile of parts to replace - no concern over stability, heat, or anything else.
    mikepukmel likes this.
    Education is what you're left with after you have forgotten what you have learned.

  21. #56
    Junior Member
    Join Date
    Aug 2017
    Posts
    14
    Hi

    I want to mod my 5150 combo. I find out the schematic is different with 5150 amp head.

    Please see the schematic, is this 47k a bias resistor?
    If yes, I should choose 22k or 47k trimmer? And what value resistor ? 10k?

    And I want to add 1ohm resistor to the power tube pin, to check the ma. I did it for vintage Marshall. How can I do it?

    Thank you

    Is img_8451.jpg

  22. #57
    Old Timer
    Join Date
    May 2006
    Location
    Chill-Ville, VA
    Posts
    2,029
    Hi Kwm488,

    Just fyi, you'll probably get better responses and faster by starting your own new thread instead of piggybacking off of this one.

    Justin
    DrGonz78 and mikepukmel like this.
    "When receiving a shock I emit a strange loud high pitched girlish squeak." - Alex R -
    "Sort of like not checking for toilet paper before taking a dump. ." - Chuck H -
    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

Page 2 of 2 FirstFirst 12

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Death cap
    By cowboy in forum Maintenance, Troubleshooting & Repair
    Replies: 12
    Last Post: 03-03-2014, 11:55 PM
  2. 5150 II to orgininal 5150 spec mistake
    By damus in forum Maintenance, Troubleshooting & Repair
    Replies: 4
    Last Post: 04-04-2013, 09:00 AM
  3. Sorry, no Death Star
    By g1 in forum Lobby
    Replies: 9
    Last Post: 01-15-2013, 02:54 PM
  4. Convert 5150-II lead channel to original 5150 spec.
    By hourglass in forum Mods & Tweaks
    Replies: 5
    Last Post: 07-29-2009, 01:57 PM
  5. Difference between 5150 and 5150 II?
    By Gregg in forum Theory & Design
    Replies: 2
    Last Post: 01-29-2007, 09:25 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •