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NEWBIE WITH A QUESTION ABOUT A RANDALL RG100ES??

Started by RandallRG, February 11, 2013, 06:03:45 AM

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RandallRG

Hey Guys hows it going? I just found this site & it's Awesome! It looks like the place to be if your in to S/S Amps LOL! Anyway I have a question...I FINALLY found a RG100ES! I have been wanting one for awhile because these To me are one of if not the BEST S/S Amps period & I play Metal so it's a "No-Brainer"! I needed to replace a pot (for my Mids) no problem I got the pot from Mouser took the amp apart & realized that one of the three wires that go to the pot has come off @ the board. Everything else looks perfect on the Amp. It has been taken care of very well since the 80's! What can I do to fix this? I can provide a pic if you need one. Thanks again for any help Steve.

DrGonz78

Nice congrats on the amp dude :tu: Welcome to the site too!! It's a good one!

I say post the pics so we have some form of reference here... I may not be much help but others will know I am sure of it.
"A person who never made a mistake never tried anything new." -Albert Einstein

g1

  Looks to be very straightforward as far as where the wires go.
If you haven't done something like this before, the trick will be to get the board loose so you can turn it over to solder the wire back to it. 

RandallRG

Quote from: g1 on February 11, 2013, 11:16:56 AM
  Looks to be very straightforward as far as where the wires go.
If you haven't done something like this before, the trick will be to get the board loose so you can turn it over to solder the wire back to it.

No there is no issue where the wire goes..It's getting it back on. It broke off right @ the board. There is really nothing coming out of the board to grab on to...No I have not had the Board out before...Thanks!

Enzo

That is what you have to do.  A proper repair would not be to try to solder a wire to some little scap sticking out from the board.  You turn the board over, or at least free it enough to get at the underside, clear any remaing bits of wire and old solder from the hole where the wire goes.  Trim off some insulation from th wire to expose the conductor, put the conductor through the hole, and solder it to the board.

RandallRG

#5
Quote from: Enzo on February 11, 2013, 05:29:09 PM
That is what you have to do.  A proper repair would not be to try to solder a wire to some little scap sticking out from the board.  You turn the board over, or at least free it enough to get at the underside, clear any remaing bits of wire and old solder from the hole where the wire goes.  Trim off some insulation from th wire to expose the conductor, put the conductor through the hole, and solder it to the board.

Nah I would NEVER repair something like that ever! Im sure alot of people would try to get away with soldering a little piece of wire to the "Non-Exisiting" piece of wire that's not even there! LOL! Anyway I figured the proper way to fix this was to remove the board & solder it from the other side. I wanted to see if you guys the "Pros" had any other ideas to run by me or let me try etc??? I appreciate your Help Guys! Here is a pic of the issue...

DrGonz78

#6
Yeah actually I did work on an RG80 before and removing all the pots was the way to go for me. Sometimes other wires can come loose while getting to the underside of the board to do the soldering. Double check all other wires before putting it all back together or you could end up repeating this if you notice a loose wire later. When you don't free up the pots the three wires to the board can get loosened. I also found it much easier soldering on the board with it freed up. I actually replaced all the wires that were on all the pots as the wire was old and needed it. The older wiring in these amps tends to break off at the board pretty easy. Good luck :tu:

Edit: I was posting just as you were and was mentioning the old wires on the pots... Either way you go about this those wires may break off...
"A person who never made a mistake never tried anything new." -Albert Einstein

RandallRG

#7
Quote from: DrGonz78 on February 11, 2013, 06:23:20 PM
Yeah actually I did work on an RG80 before and removing all the pots was the way to go for me. Sometimes other wires can come loose while getting to the underside of the board to do the soldering. Double check all other wires before putting it all back together or you could end up repeating this if you notice a loose wire later. When you don't free up the pots the three wires to the board can get loosened. I also found it much easier soldering on the board with it freed up. I actually replaced all the wires that were on all the pots as the wire was old and needed it. The older wiring in these amps tends to break off at the board pretty easy. Good luck :tu:

Edit: I was posting just as you were and was mentioning the old wires on the pots... Either way you go about this those wires may break off...

Yeah the only way to do it....Is EXACTLY the way you described it! The wires seem to be very frail after all these years. Wish back in the day they did the routing of the wires a little different etc? I mean c'mon 25+ years I think they did (& still are) doing a great job! Removing the board & "De-soldering" all the wires from the pots is the only way to go about this. I was looking @ it today & realized that this was the only way for it to be fixed properly...Thanks for the reply! 

RandallRG

#8
Quote from: g1 on February 11, 2013, 11:16:56 AM
  Looks to be very straightforward as far as where the wires go.
If you haven't done something like this before, the trick will be to get the board loose so you can turn it over to solder the wire back to it.


I like the way that the wires from the pots are run "Under & Over" on this Board. Im sure they are much Stronger this way! They are just on top on my Board straight from the pot. Which to me seems like a "Weak" link..

g1

  It is not necessary to desolder the wires from all the pots.  You can remove the knobs and the nuts holding the pots to the chassis.  Then push the pots into the amp.  If you are careful you will be able to flip the board without breaking more wires.
  If the wire is solid core, you may want to use stranded wire for replacement as it will probably take more flexing before it breaks.

RandallRG

#10
Quote from: g1 on February 12, 2013, 08:48:35 PM
  It is not necessary to desolder the wires from all the pots.  You can remove the knobs and the nuts holding the pots to the chassis.  Then push the pots into the amp.  If you are careful you will be able to flip the board without breaking more wires.
  If the wire is solid core, you may want to use stranded wire for replacement as it will probably take more flexing before it breaks.

Yeah i am with ya! The only problem I see doing it this way (Which is a great idea) is I think the wires (most or maybe all) are going to be very "Temperamental" as far as them "holding" on to the pot's etc when the board is removed. I would like to just take it out & take off all of the white wires to the pots & replace all of them with some new longer wires so this will not be an issue down the road! The board in the other pic up top looks like it would hold much better because the wires are run 'under & over" for strength. Thanks for your input! I appreciate it! \m/

Roly

Quote from: g1If the wire is solid core, you may want to use stranded wire for replacement as it will probably take more flexing before it breaks.

Utterly.  :dbtu:

They should never have used single core in the first place, that's the basic cause of the problem, and they are bound to give similar trouble in the future.  That's also why they have done the 'up and down' at the board end, stranded wire generally wouldn't need that treatment.  The fail here is that there is no way to do something similar at the pot ends.  If you replace them all with stranded, and they won't go through the anchor holes, don't worry about it, just go direct from pot to PCB.

A good source of free stranded hookup wire (in a range of colours) is from dead computer power supplies.  I find the computer shops here are only too willing for you to take some of their junk off their hands, free for the asking.

Personally, in this case I'd leave the pots and unsolder them all and replace all the connecting wires.  What goes where looks pretty obvious from the pic.
If you say theory and practice don't agree you haven't applied enough theory.

g1

  It looks like the board with the "over and under" wiring is a newer version with extra holes drilled.  Your board does not appear to have the extra holes so you won't be able to do that.  What you can do is add a bit of support where the wires meet the board by using some silicone or hot glue.  At least that will keep them from flexing right where they meet the board.
 

DrGonz78

Also, to note is that the board you have is a bit different than the board w/ the under over wiring. It is like someone modified the board by use of a drill right through the main ground trace on the board. On your board that same trace appears to be not as wide and I would not recommend ever drilling through a trace in the first place, especially on your board revision.

@G1 >>> I like the idea of adding glue at the end to ensure that the wires stay in for a long time.

@Roly >>> I don't think it is solid core wires... I remember the wiring on these was stranded but just lifeless copper due to age. The wiring was not the best quality IMHO. Also, great idea about getting good hook up wire from dead computer power supplies!! I got about three that I will gut soon. I will have to revisit a post that you had too about building a dummy load using a power supply enclosure. That was a great idea too!
"A person who never made a mistake never tried anything new." -Albert Einstein

Roly

I do some of my best shopping at the tip.  :dbtu:  (nuthin' if not cheap)  I've got about 30 computers, half a dozen flat screens, a few printers, and all sorts of 'puter related ephemera, plus digital STB's, a HDD/DVD TV recorder, 5.1 sound system, &c&c&c all in PWO, just for the taking - not to mention about half a dozen console organs (told you not to mention those!).  It is a constant amazement to me what good stuff people just throw out.  I have a stack of multi-gig HDD's and heaps of RAM ex-'puters that weren't worth taking whole.

Stripped computer power supply cases make good general project cases.  I scored a box full of ded PSU's frm a local repairer a while back, and out of curiosity costed just the most useable bits out of one, and it came to $80 to buy new EIA connectors, project case, optocoupler, 7805 regulator, high voltage caps, fan, hookup wire... and that was ignoring most of the stuff on the PCB.

Also: photo processors throw out disposable cameras with a good high voltage cap, LED or neon, near-new AA battery, not to mention an inverter and xenon flashtube, again free for the asking.

You have to put up with people thinking you're nuts; and you should take everything they offer (which means knowing where a receptive dumpster is for the dross).

Talking of which, dumpster diving, hard rubbish collections, and the aftermath of Trash & Treasure markets have produced entire going computer systems including laser printers and a sack full of network cables.  In fact I'm quite picky these days and turn my nose up at CRT-anything, 'puters with fewer than 4 USB ports or earlier than P4/XP, and even then...  The only rule is don't make a mess, try to leave it tidier than you found it; don't cruel the pitch.

A notable score was a box with an untouched Ubuntu install.

My favorite acoustic guitar is a 12-string restrung as a six which I intercepted on its way to the dumpster because of a cosmetic blemish, but it has a lovely full tone.
If you say theory and practice don't agree you haven't applied enough theory.