Anyone else not fond of working on PCB amps?

Discussion in 'Amp Tech Center' started by dougstrum, Nov 29, 2017.

  1. dougstrum

    dougstrum Tele-Holic

    Posts:
    960
    Joined:
    Oct 6, 2015
    Location:
    blu ridge mtn cabin
    Just got my Pro Jr back in good order:) Did some mods years ago and it's a fine sounding
    little amp!

    It started making some glichy noises and was also sounding dirty. It's a '93~so I replaced
    the filter caps and tubes. Didn't help~so I cleaned and tensioned sockets. Noticed the
    amp would cut in and out when pushing up on tubes. Then noticed pushing on the chassis
    also caused cutting in and out...time to pull out the PCB's.

    What I found was a trace that had lifted off the board where I had changed a coupling cap
    about 5yrs ago~fixed it by replacing the trace with solid wire, all done...

    Put it all back together only to find input jack had gone dodgy. Upon disassembly I found a couple of the jacks solder connections were loose on the board, resoldered and finally all is working properly.

    I definitely think stuff I build with terminal strips is better, much more solid!
     
    OneHenry and moosie like this.
  2. Jeru

    Jeru Tele-Holic

    Posts:
    623
    Joined:
    Nov 17, 2006
    Location:
    Chicago
    Agreed. Good job keeping the thing going. Basically, do that until you’re sick of disassembling and limping along, then gut it and build something cool into the chassis..!
     
    dan1952 likes this.
  3. Andy B

    Andy B Friend of Leo's Ad Free Member

    Posts:
    2,078
    Joined:
    Mar 16, 2003
    Location:
    Colorado
    I have serviced all sorts of amps for many years. Every type of construction has good and bad points. If you use the proper equipment and the correct technique PCB amps are no big deal. The majority of what ‘s out there is PCB based.
     
    JD0x0 and corliss1 like this.
  4. Wally

    Wally Telefied Ad Free Member

    Posts:
    33,195
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    Kudos on the good work. Ime, not all PCB amps are created equally. There are PCBs that are built to demanding standards and there are PCBs that are built less expensively. The Blues/Hot Rods are in the latter category. One should always double check the traces anytime one has to heat up a connection. The Fender RI PCbs are better PCBs. The Fender Pro Sonic is another step up from the Reissues in PCB amplifier quality.
     
    Thin69, Bill Moore and SheldonP like this.
  5. Thin69

    Thin69 Friend of Leo's

    Posts:
    2,915
    Joined:
    Oct 28, 2009
    Location:
    Galveston, TX
    Just bought a couple AC4's that are my first PCB amps. Hope to heck the tube sockets are attached to the chassis. They are great sounding amps inside a small house. Spent my career in electronics with a large share in PCB. They were pretty stout. Hope the AC's are the same or better yet, hope I never need to find out. In the mean time I'll just play the heck out of them.
     
  6. VintageSG

    VintageSG Friend of Leo's Ad Free Member

    Posts:
    3,309
    Joined:
    Mar 31, 2016
    Location:
    Yorkshire
    There are PCBs and PCBs. I prefer the former :)
    Seriously, there are some exceptionally well manufactured circuit boards that can withstand component replacement without issue, then there are boards that seem to have a couple of microns of poorly attached copper like substance that lifts like a hookers skirt at the first provocation with the iron. You only know which is which when it comes to rework time.
    A good iron with a substantial tip body is a must. The shorter time needed with the iron in contact, the better. A weighty tip body holds far more heat than some spindly POS. Wattage is no guarantee. Keep the slimline, spindlies for working on classic 8-bit micros. get some heft in that tip!.
    I really don't mind PCB stuff.

    As to the AC4, sorry, sockets direct on floppy boards with micron thick traces, held together by stubbornness.
     
    Andy B and Wally like this.
  7. ranjam

    ranjam Tele-Holic

    Posts:
    635
    Joined:
    Dec 29, 2015
    Location:
    Canada
     
  8. BryMelvin

    BryMelvin Tele-Afflicted

    Age:
    67
    Posts:
    1,962
    Joined:
    Jan 4, 2014
    Location:
    Arivaca AZ
    I work on just about anything. However current surface mount stuff is often impossible to fix.
     
  9. Wally

    Wally Telefied Ad Free Member

    Posts:
    33,195
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    there are modern Marshall PCB amps that have no more production value than do the BLues/Hot Rod amps, ime. There are certain post-1990 Marshalls on which I do not work....I have no interest of any kind in them at all....whether they work or not does not involve me.
     
    OneHenry and bparnell57 like this.
  10. DavidP

    DavidP Friend of Leo's

    Posts:
    2,489
    Joined:
    Mar 16, 2003
    Location:
    Vancouver, BC
    I replaced all the electrolytic caps on an old Music Man RD65 and that had a military-grade board and traces --no issues at all with de/re-soldering. I wish all PCB amps were built like that, but dream on...
     
    Wally likes this.
  11. Wally

    Wally Telefied Ad Free Member

    Posts:
    33,195
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    There are higher-quality PCB amps out in the market, but they are not priced to the general consumer market. That is why one of those Blues/HOT Rod amps is the biggest selling Fender amp of all time....it is very affordable compared to high quality current market or what vintage amps cost in today's dollars.
    I haven't heard of Fender replacing the Blues/Hot Rod/ Pro Jr. amps instead of fixing them. Now, all of the digital effects with power tube outputs....yeah, disposable quantities.
     
  12. ranjam

    ranjam Tele-Holic

    Posts:
    635
    Joined:
    Dec 29, 2015
    Location:
    Canada
    When you've worked on Fender, or even Peavey, warranty, as I have, you get a 'DNR' list. Now, this isn't like the 'Do Not Resuscitate' paper I signed, but a 'Do Not Repair' list. Under the five year warranty? Straight exchange. We keep the cadaver for parts, and after 90 days the serial number is on the 'black list', meaning I can't fix it and sell it to someone who takes it to another Fender depot. It is supposed to go in the garbage. That's why my basement jamming is all done on blacklisted Fender or Peavey gear. :rolleyes:
    A lot of Fender parts are no longer available. Those garbage pots Fender uses in the Blues Junior? Not available. I use ones from a cadaver. If a tube blows, and scorches the board? In the garbage. Those junk plastic board mounted 1/4" jacks? If you can't rob Peter to repair Paul, it's in the garbage. Seriously. I just replaced the output IC on a DNR Line 6 Spyder. I shouldn't have, but for a basement jam it's actually pretty cool. In the garbage? Nope, it's mine now.
    It's not so much that Fender has lousy production values, but they add insult to injury and use bottom-of-the-barrel parts. Even a Blues Junior, or a Hot Rod Deluxe, that has the awful ribbon cable that I take out and replace with shielded cable. Really? That's not quality, that's a quick buck, and ruining the name.
    Now as soon as I can find an IC for this free G-Dec........... ;)
     
  13. corliss1

    corliss1 Friend of Leo's

    Posts:
    3,428
    Joined:
    Sep 13, 2008
    Location:
    Lansing, MI
    Yup, and the new updates this year make it so that anything not made in North America is DNR, so there's a few tube products on the list now even.
     
    bparnell57 likes this.
  14. alnicopu

    alnicopu Friend of Leo's

    Posts:
    3,810
    Joined:
    Oct 3, 2009
    Location:
    The city
    Depends. Ive flipped and worked on stuff that was so cheaply made you had to be quick with an iron to keep from lifting traces. I also worked on a Sundowner 100w head that was so hefty I could unsolder and replace components from the top of the board without having to remove anything. Either way, it comes down to technique.
     
  15. dougstrum

    dougstrum Tele-Holic

    Posts:
    960
    Joined:
    Oct 6, 2015
    Location:
    blu ridge mtn cabin
    I must admit the thought of doing that very thing crossed my mind!
     
  16. Wally

    Wally Telefied Ad Free Member

    Posts:
    33,195
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    Thanks, ranjam. Now I have heard of this relating to the Blues/HotRod Amps. I appreciate the revelation, and point taken. Fwiw, I ran into the problem of certain parts not being available for a Fender about 20 years ago...with a Red Knob Twin. A certain push/pull switching pot was not available. I know more now and might be able to find it today, but this was before the ‘net access around here. Anyway, that amp sat for a few months while I frustratingly tried to find that part through the channels at my disposal. No luck.....since the switching aspect of the part was what was broken, I took apart a brand new push/pull in order to repair that pot in the Red Knob. Oddly, when the amp was dropped off, the owner asked: “This won’t take long since it is a newer amp, right?” I chuckled and told him that if it were an old BFTR, I would have it ready for him tomorrow...but that I could not guarantee anything with the Red Knob.
     
  17. Andy B

    Andy B Friend of Leo's Ad Free Member

    Posts:
    2,078
    Joined:
    Mar 16, 2003
    Location:
    Colorado
    I've got 2 Champion 600 DNR amps here. Most of the others I was able to get my hands on got fixed and donated to Blue Star Connection. IME the amps on the DNR list are built by subcontractors and Fender, Peavey, etc. never had a source of parts for them. In the long run it being cheaper to repalce defective amps than maintain a parts supply.
    In 2001 while attending authorized service training, I was told by the Service Manager of Fuji Film USA that if it wasn't for the (then) laws in this country, Fuji would not have a service department. It was more cost effective back then to replace defective units rather than service them.
     
  18. ranjam

    ranjam Tele-Holic

    Posts:
    635
    Joined:
    Dec 29, 2015
    Location:
    Canada
    Sadly, I only had the one given to me.;)
    It had a blown and smokey charred (like a burnt marshmallow) circuit board, but the transformers were fine, so I gutted the chassis and put a Hoffman 5F1 board in there. Works like a charm, and I have a cool recording 'Champ' that I shelled out $8.40 to have. :D
    I have a few older SS Fender amps sitting under my bench, waiting for 'parts no longer available' to fall in my lap. One of the last ones is an older Deluxe 900. It's the darn FX control (16-position 'encoder'). The rest of the amp works fine, if I want to play it drier than dry. Heck, the 100-watt Celestion in there is worth keeping it, right? It's a free 90-watt solid state Fender, so who am I to complain? ;)
     
    corliss1 likes this.
  19. jsnwhite619

    jsnwhite619 Friend of Leo's

    Age:
    35
    Posts:
    2,476
    Joined:
    Sep 10, 2013
    Location:
    Georgia
    First off, I am not a tech, just have learned to do my own stuff. But, I've had friends ask me to help with their PCB stuff and I've never even taken a look at it. I just explain that I don't feel like buying them a new amp if I let the iron sit in one spot too long. I've built my collection of Tweed clones, and I still love my Pro Jr. But, at this point, I don't see myself ever buying another factory amp unless it's a vintage one. I enjoy the building process, but I love the idea of having something I can rely on and maintain myself for the rest of my life.

    Here is a single input, 2 knob, 2 power tube Pro Jr board.
    Pro jr board.png

    And here is a 2 input, 2 knob, 2 power tube Harvard board
    24209949_10104156873938431_2090566303_o.jpg

    I'm gonna stick to my fiberboards.
     
  20. Platefire

    Platefire Friend of Leo's

    Age:
    71
    Posts:
    3,402
    Joined:
    Nov 3, 2003
    Location:
    North Louisiana around Many
    I got into amp repair when I retired. The PCB board amps caused me to resign:>) Repairing an old fender with an eyelet board is just like eating ice cream, love
    it! but when someone would bring in a Peavey or similar---boy! by the time I got r dun and had put too much time in it to charge what I actually had in it.

    Like ranjam---it you do it everyday(a lot) and familiar---not so much a problem but for me---I had to do major research every time. I managed to get all the pcb amps fixed but for me was like pulling teeth.

    So now I just work on all my personal DIY point to point's and turret board amps. Out of the 17 tube amps I now have, the only pcb amp I still have is a Pignose G40V. Platefire
     
    jsnwhite619 likes this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.