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Rivera Boost Mods - R55

Discussion in 'Amp Tech Center' started by soundchaser59, Jan 12, 2014.

  1. soundchaser59

    soundchaser59 Tele-Afflicted

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    I found a great site for doing the channel 2 Ninja Boost mod HERE Looks pretty darn simple!

    But I "neeeed" to mod the channel 1 boost, and I can't find anything on that side. I prefer using channel 1 for my lead sounds, and the fixed boost is just too over the top to be usable.

    Anybody know anything about this? Even just a modded schematic would help. What are the chances that both boosts work and are wired the same way?
     
  2. Ike286

    Ike286 Tele-Holic

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    Contact the guy who does the ninja boost. I could help if I had a schematic, but I can't find one, otherwise, hope you figure it out.
     
  3. soundchaser59

    soundchaser59 Tele-Afflicted

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    Here is one "R" Series schematic. I'll try and contact the other guy. Thanks!

    http://www.freeinfosociety.com/electronics/schematics/audio/riverarseries.pdf


    Apparently the Ninja mod guy does not have any contact info on his web page. I did leave a comment asking for the new info, and I see I'm not the only one who wants to mod both channels. The last comments were only a few weeks old, so maybe the guy is checking back now and then.
     
  4. Ike286

    Ike286 Tele-Holic

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    Well, I have had such a time trying my best to figure out that schematic, it's so hard to follow, and read in general.... Anyway, I think what the thing is, is that there is a high value resistor in the signal path (2.2M) and I think what happens is that when you engage the boost, it bypasses that resistor with another resistor (721K) to lower the value to about 550k, so instead of being a high value resistor which blocks a lot of signal it makes it smaller for more signal. On the other channel, it looks as if it's a similar boost circuit, just it bypasses the 2.2M completely.

    So you want to do that mod for both channels...

    My first idea, is, you could replace R116, and R130 with 2M trim pots wired as variable resistors (two lugs of the pot only). This way you would be changing the level of boost when the boost is OFF, so when the boost is turned ON, it wouldn't be so big. And it would most likely make your amp a little more dynamic with it OFF. The thing with this is that, your amp would have slightly more gain than before, so you may have to turn the gain down a teency bit. You could also use two regular size pots on teh back panel in place of the trim pots I mentioned, this way would be like the mod you posted about, using some shielded wires running to a pot on the back panel.

    PLEASE, just in case I'm wrong, it's probably because it's so hard to read that schematic, so please don't blame me.... ;)

    And if you need more explanation, be specific with what you don't understand, and I'll try to help more.
     
  5. soundchaser59

    soundchaser59 Tele-Afflicted

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    Thank You. I will review the schematics again and see if I can decipher what you suggest. The original mod article I linked to is a huge clue, and I think it allows us to infer that the other channel can be modded in a similar fashion.
     
  6. soundchaser59

    soundchaser59 Tele-Afflicted

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    Sorry to jog your memory after all this time, but I have finally gotten up the courage (and the free time) to take another look at doing this mod on both channels of my R55.

    Admittedly, those schematics are very, very poor. I have tried to get Rivera to send me something more legible, but they won't. (or they can't)

    But using the photos as a guide from the article I link to above, in the fourth photo down in that article it's possible to see a close up of the mod. It appears he has modded R117, not R116. R116 appears to be in its original place. R117 is the 221k resistor that has been lifted on one end and had the 1M ohm pot inserted in series. (linear taper, I assume it's rated for at least a half watt? since it looks like the resistors are 1/4 or 1/2 watt) It seems to be somewhere between pin 8 V2 and pin 2 V3.

    On the schematic there is another 221k resistor, I think it's R122, tied to the Ch.1 boost, and seems to be connected roughly between pin 1 V2 and pin 7 V3. I tried to mark these things in red on my own screen shot from the schematic, hope that makes sense in the jpg. I believe these would both be red-red-brown-orange resistors, and the article author does say in the comments that he used a 1Meg ohm pot.

    [​IMG]

    I'll have to open up my R55 and get my magnifying glass out again to be sure of my interpretation here. But if the author says he got the Ninja boost to be variable, it seems to make sense that a similar R value would control the Ch. 1 boost as well.

    The 4th photo down in the article is good, but the 3rd photo might actually be easier to see the R117 resistor lifted where it says 221k on the board.
    http://ivanrichards.files.wordpress.com/2011/12/ninja-boost-003.jpg

    In the 4th photo you can see R122 the light blue red-red-brown-orange resistor near the top left, just above the red and green shielded wire. I believe that is the other 221k resistor that controls the CH. 1 boost.
    http://ivanrichards.files.wordpress.com/2011/12/ninja-boost-004.jpg
     
  7. Bendyha

    Bendyha Friend of Leo's Silver Supporter

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    Hi soundchaser,
    Not quiet right what you've got there.
    Your red circle marked ch 1 boost R122 is around R152 - the diode ampre setting resistor in the Vactrol. Next to it is R122, indeed 221k, but it's function is along with R120 joined to it, to form a voltage divider and as grid leak with C130 parallel acting as a tuned treble bleed. A poti here will vari gain, but not in the way you want, so leave it alone. There is a different set up as on the ninja boost mod where the resistor in question to be replaced with a poti is in parallel with R118 when the vactrol is on. To imitate this setup would be a better idea. So where the Ch1 boost vactrol joins R130, this is the point to split, and insert the poti for variable gain.
    Ben.
     
  8. johnb

    johnb Tele-Meister

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    I had the mods done by a Rivera service center to a Suprema I owned a while. Rivera supplied the schematic to them. The option was to send the chassis to Rivera.
    That said, it was great being able to "dial in" the right amount of gain for both the boost circuit.
    See if there is someone in your area that works on Rivera and they may have the correct schematic.
     
  9. soundchaser59

    soundchaser59 Tele-Afflicted

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    That makes sense. Ike286 above also said to mod R130 the 2.2M resistor for the Ch.1 boost, and I see now that is the one that's in parallel with the Ch. 1 boost.

    No auth'd Rivera servicers in my area, shipping would be required no matter what. I asked Rivera (can't remember the guy I spoke with, it wasn't Paul) on the phone and they flat out refused, said they don't do mods like this any more, and said they do not have a schematic for this particular mod. Maybe if I get the real Paul on the phone he will send me the schem? Do you remember the name of the place you took yours?

    If I had a correct schematic for the mod, or written instructions that are known correct, I can do the work. I'm just not sure enough of my schematic reading chops to know if I'm modding the correct component. But if I were told what to mod, I can easily correlate my schematic with what I see on the actual board inside the amp.

    Having both of these boosts at least tamed down, or variable, would make them usable. The way they are now they are completely over the top and not usable for me at all.
     
  10. Bendyha

    Bendyha Friend of Leo's Silver Supporter

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    so

    [​IMG]
    For the american Ch1 boost
    The circle is around the same part in photo and schem, the four legged black thing. One leg on each end will be conected to either end of the 2M2 resistor.
    It doesn't matter which end, but unsolder and lift one of these legs - if you remove the whole circuit board to get underneath as it should be done, or just snip it in half if you want to do it all from the top, and in this gap put in your 1 Meg linear poti with the one side to the middle tag, and the other to either the left or right tag, depending if you want to turn it up or turn it down clockways.
    For the Ninja boost it is like you said
    "R117 is the 221k resistor that has been lifted on one end and had the 1M ohm pot inserted in series."
    Here it is also just snipped through on the top.
    Lots of fun with modding.
    Ben
     
  11. johnb

    johnb Tele-Meister

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    Sorry but it was so long ago that his name escapes me. He did work for Atlanta Music Brokers in Roswell, GA. Worked out of his house and taught guitar lessons as well. Wish I could be more helpful.
    If you get it done you'll like it for exactly the reasons you stated.
     
  12. soundchaser59

    soundchaser59 Tele-Afflicted

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    HOLY COW!!! THANK YOU! That is awesome! :eek: :D :cool: WOW! I wish I could send you a couple of juicy grilled hamburgers and a large pizza!

    Looks like pretty tight quarters for my cheap soldering iron to get into, but I've made it this far replacing screen and grid resistors and fx loop pots on this amp. This variable boost mod would be the frosting on the Rivera cake if I can do it! I just hope I can get my tool in there without accidentally touching and melting some other component! :lol:

    (I saved the photo to my own drive, so if you ever remove it on your end I won't lose it. Thanks again!)

    The next hardest part is finding a pair of 1M ohm linear 1/2 watt pots small enough to fit on the leftover space on the back panel of the chassis. Sure as heck don't have any here in my town!
     
  13. soundchaser59

    soundchaser59 Tele-Afflicted

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    Does it have to be one leg of the vactrol that is in series with the new pot?

    Will it have the same effect if I put the pot in series with the 2M2 resistor?

    I looked at the board tonight. It is waaaayyyy easier to get to the resistor than it is to pull one leg of the vactrol.

    I was also surprised to see that all of these resistors are the smaller 1/4 watt types. I was expecting to find 1/2 watt resistors in there.

    I only have one pot, so I'm tempted to make the Ninja boost a fixed but smaller boost by simply using a bigger resistor in place of the 221K. I think I would be ok if the CH.1 boost is the only one that is variable. I don't have much free space to work with on the back panel. I really don't want to make a hole where the serial number is. A decent alternative is to use the large (3 square inches) free space on the bottom of the chassis just behind the fx loop pots. The boost pot would face down toward the bottom of the cab, instead of sticking out the back of the amp.
     
  14. Bendyha

    Bendyha Friend of Leo's Silver Supporter

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    "Does it have to be one leg of the vactrol that is in series with the new pot?"

    If it is a variable boost that you want, then yes.

    "Will it have the same effect if I put the pot in series with the 2M2 resistor?"

    That will leave your boost at the same level as it is now, but you would be able to weaken the unboosted tone - not what you want.

    "I looked at the board tonight. It is waaaayyyy easier to get to the resistor than it is to pull one leg of the vactrol."

    Tja....thats the way it is. Check with a continuity tester that you have one of the legs that joins to the resistor, as I said before, both ends will have one that joins to either end of the resistor. the other two wires are for the LED part of the optoresistor. Avoid excessive over-heating with the soldering iron as well, these things can be rather heat sensitive.
     
  15. soundchaser59

    soundchaser59 Tele-Afflicted

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    Ok, Thank you! I guess it's true what they say.......nothing in life worth having comes easy. :eek: :lol: :( :cool:

    I am realizing now why the guy who wrote the article only did the Ninja boost mod and never did describe the CH.1 mod......the Ninja boost mod is much, much easier to do since R117 is in series with the vactrol, and it is a wide open work space. R130 and the Ch.1 vactrol is nested under a bundle of wires and will require much more precise work.

    I like to think I do things like this because nobody else can. I like being the one guy who can say, "I did it!" So I'm gonna try. The chassis is out of the cab right now, waiting for me. I'll start on it after work tonight.

    You did an excellent job describing and visualizing this mod for me. You would make a good teacher me thinks! Thank You!

    Thanks everyone who responded and helped. All of the tips together makes me believe I can do this. The only thing really giving me concerns is that I don't have real "professional" type tools designed specifically for this kind of work. Best advantage I have is putting a brand new tip on my soldering iron so that things happen quickly when I make contact! :lol:

    I do have the parts. I found the right parts in my plastic tub stash. I found a 1M linear taper pot (had to cut the shaft down to length) and several varieties of 5% 1/2 watt resistors to try on the Ninja side. The pot isn't perfectly linear. I turned it thru half of its range and it was already up to 800K, and the rest of the turn took it up to 1.2M total R.
     
  16. marshman

    marshman Poster Extraordinaire Silver Supporter

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    I have an old article on these mods saved on this ancient PC down in the mancave...I don't know if it's simply rehashing what you guys have already done, and it's geared to the "R-Series, Suprema, Quianna and Fandango", but if anyone wants it. PM me and I'll send it to you.
     
  17. Ike286

    Ike286 Tele-Holic

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    Just be very careful, and if you can't see stuff, make sure you have a good light, and even a magnifying glass. All you should need is a pair of pliers and your iron, so have at it, I'd love to see how this works out.
     
  18. soundchaser59

    soundchaser59 Tele-Afflicted

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    I need a little bit of shielded wire. And I always try to use shrink tubing to insulate and stabilize my connections.

    When I first start out, it seems a good solder wick braid is my best friend. And they are not all created equal. Some are called desoldering braid, some are called solder wick, and one works a lot better than the other. I forget which is which, but I think one of them already has flux in it, and that's why it works so well. (and that's the kind I have at home right now) I'm always very careful to completely desolder. I use a magnifying glass and make sure I can see the lead wiggling in the hole before I start tugging at it to pull it out. If it doesn't wiggle then it isn't completely desoldered yet. Careful desoldering makes it a lot easier to work on this thing from the top, cuz I really really don't want to take the board out of the chassis.

    One other thing I will do is get my wife to hold the end of the shop vac hose near the bit when I drill the hole for the pot shaft. Keeps small shavings from scattering around inside the chassis.
     
  19. Ike286

    Ike286 Tele-Holic

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    I always have had solder wick, and it works very well. So that may be the one you have and like so much. I have gone through rolls and rolls of that stuff while modding one super overdrive pedal... that was a fun project, long gone now. (will be starting a similar one soon, hopefully)
     
  20. soundchaser59

    soundchaser59 Tele-Afflicted

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    Any last minute tip for soldering the shield braid to the pot housing? I suppose I should use a spot of flux on that too?
     
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