Q418C jonnyscaramanga Rat clone

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Thanks to @Megii and a @marauder I'm now in business to build a Rat clone, so if I may be a late entry I'd like to get in on this challenge business. 

From Marauder I got an old LM308N op amp, and then from Megii I got a Fuzz Dog Rodent kit. LM308s are hard to get now, hence my buying Marauders, but actually Megii's kit has one, so if this goes well I'll be looking at building something else LM308-based. Maybe a Rat 2—I was interested by ICBM's comments that he prefers the Rat 2, so perhaps I'll compare them. I'd have to do that on veroboard though, because I'm not aware of anyone who makes a Rat 2 PCB.

If successful, this will be my first completed build. Years ago I bought an OCD kit off a fellow forumite (back in the MusicRadar days, I think) and I got most of the way through the (vero) circuit board before running into trouble with my soldering iron and getting a tech to finish it off. Hoping to manage the whole thing this time.

Question: I've got a 4-pot kit for incorporating the Ruetz mod into the pedal. I wouldn't have chosen this, and I'm thinking about just leaving it out (assuming I can find something not-unsightly to block the fourth hole in the enclosure). Does anyone know if there's anywhere on the Ruetz pot's travel that replicates a stock Rat? I've seen forum posts claiming that with a 1k pot, there's no way to get exactly the classic Rat sound. I only want the pedal for the Rat tone. If I can get the stock Rat tone AND some others, I might as well include the pot, but if I can't I'll leave it alone.

Here's a picture of my highly organised workspace, where I am currently re-learning how to read resistor codes while I wait for my Amazon Prime soldering mat to arrive. Pretty excited about the black case and neon orange knobs (don't know why my camera makes them yellow) —should be a cool looking pedal as long as you don't open up the case!





My YouTube channel, Half Speed Solos: classic guitar solos demonstrated at half speed with scrolling tab and no waffle.
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Comments

  • Got bored waiting for the post, started without the soldering mat.

    The first component goes on... great success!




    Then I did all the resistors except R4, which relates to the Ruetz mod and I haven't decided about it yet. I also added the IC socket since it had resistors either side and I was worried it might be fiddly.



    ... and the back, which... looks like a circuit board.



    Alright! So far this is highly rewarding and very moreish. Time for a lunch break (and to research how to to identify capacitors and diodes!). This is also much easier than making cables or replacing pickups, the soldering jobs I've attempted in the past.

    My YouTube channel, Half Speed Solos: classic guitar solos demonstrated at half speed with scrolling tab and no waffle.
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  • robertyroberty Frets: 10893
    edited October 2018
    I'm gonna say this cos I messed up slightly when building mine

    If you got the vertical mount pots that go straight into the board, mount them to the chassis before soldering them into the board otherwise they might be a bit wonky.

    Got some de-wonking to do later

    Good luck, mine sounds excellent and may even be knocking the 90s LM308 turbo rat off my board
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  • roberty said:
    I'm gonna say this cos I messed up slightly when building mine

    If you got the vertical mount pots that go straight into the board, mount them to the chassis before soldering them into the board otherwise they might be a bit wonky.

    Got some de-wonking to do later

    Good luck, mine sounds excellent and may even be knocking the 90s LM308 turbo rat off my board
    Thanks, that's a really useful tip. Hopefully my sieve-brain will retain it at the relevant moment! 
    My YouTube channel, Half Speed Solos: classic guitar solos demonstrated at half speed with scrolling tab and no waffle.
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  • I'm noticing a lot of differences between capacitor values in the kit and those on Rat schematics I've seen online. There are also some discrepancies between the photo of the completed board on the kit instructions and the components list inside. I'm gonna have to do some research to see what differences these make, but it's already worrying me that this might not be a true clone. Although it's also possible that the layout is what's different. So, for example, ElectroSmash thinks C3 is 30 pF and C4 100pF, while my kit has them as 100pF and 33pF. But maybe they're just using different numbering systems?
    My YouTube channel, Half Speed Solos: classic guitar solos demonstrated at half speed with scrolling tab and no waffle.
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  • %&^&&!!! I forgot diodes had polarity and I've put D3 in the wrong way round. And cut off the legs. Currently unsuccessfully attempting to get solder wick to come to my aid.
    My YouTube channel, Half Speed Solos: classic guitar solos demonstrated at half speed with scrolling tab and no waffle.
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  • robertyroberty Frets: 10893
    You'll need to resolder that 2K2 resistor if you're using the Optopus daughterboard btw. They don't say but best to read the Optopus guide before starting the main project 
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  • robertyroberty Frets: 10893
    I would email them if you have concerns about values etc. They are pretty hot on support
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  • robertyroberty Frets: 10893
    %&^&&!!! I forgot diodes had polarity and I've put D3 in the wrong way round. And cut off the legs. Currently unsuccessfully attempting to get solder wick to come to my aid.
    I'm not using the D2 and D3 diodes. I can send you mine of yours is damaged after this 
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  • robertyroberty Frets: 10893
    I had a few blunders on the way but it was alright in the end
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  • roberty said:
    %&^&&!!! I forgot diodes had polarity and I've put D3 in the wrong way round. And cut off the legs. Currently unsuccessfully attempting to get solder wick to come to my aid.
    I'm not using the D2 and D3 diodes. I can send you mine of yours is damaged after this 
    Thank you, that's a great offer and makes this operation less stressful! I've got one leg out (actually my girlfriend did), but the other one is still not coming. Curse my good soldering practice and efficient mechanical joints! I've got the board pretty warm a couple of times so I hope everything's OK.

    Later...

    OK, diode out. I think there's just enough length left on the legs but I can't get the holes in the board clear enough of solder to push them back through. Do I need to get some flux to put on my soldering braid? So far it seems very adept at soaking up the solder from the tinned tip of the iron but much less enthusiastic about taking it off the board. 

    Here's what the back of those joints look like now (sorry, couldn't get my phone camera to focus any better than this). Is it likely to be fried?


    My YouTube channel, Half Speed Solos: classic guitar solos demonstrated at half speed with scrolling tab and no waffle.
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  • Adam_MDAdam_MD Frets: 3420
    edited October 2018
    No it won’t be fried but you’ll be better off with a decent solder sucker to clear the holes.  I use one of these there are cheaper options but nothing as good for this money

    https://www.amazon.co.uk/Quality-Innovative-Silicone-Nozzle-Engineer/dp/B002MJMXD4/ref=mp_s_a_1_2?ie=UTF8&qid=1538836392&sr=8-2&pi=AC_SX236_SY340_QL65&keywords=engineer+solder+sucker&dpPl=1&dpID=41by8CVXglL&ref=plSrch

    If you want to try and MacGyver it today heat the pads until the solder melts then push a toothpick in the hole which should open it wide enough for you to get your diode in.  
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  • xscaramangaxscaramanga Frets: 436
    edited October 2018
    I've got a solder sucker too. I don't know if it's good or bad (although it was cheaper than that one) but it's not doing what I need it to do either. Gotta get ready for tonight's gig now, so I'll have to come back to this tomorrow.

    Out of interest, @roberty, how come you're not using D2 or D3? Did you just build a Turbo Rat?

    EDIT: I DID IT!!!!!! D3 is just about in situ now.
    My YouTube channel, Half Speed Solos: classic guitar solos demonstrated at half speed with scrolling tab and no waffle.
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  • robertyroberty Frets: 10893
    My settings are turbo and clean, these two are my faves

    I have four original rats of different varieties and a deucetone with LM308 mod

    I'll be gutted if I end up preferring the new op amp :-)
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  • MegiiMegii Frets: 1670
    Nice to see this in progress at last, looking good! :)
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  • OK, Sunday and back on it! (Spoiler: it doesn't work)

    Pots on board, mounted in case (cheers @roberty, I can see this would've been a pain if I hadn't done it your way!)



    See?



    Testing time! Regret not doing this in the enclosure. Wiring this was a faff.



    And... it's dead. I then realise that I had initially forgot to put the IC in the socket, and I hoped that would do it. Nope. It passes a signal, but the signal is about the same as going straight into the amp, possibly a little quieter and crappier sounding. Pots don't seem to have any effect (I tested it with gain and volume on max). I've (attempted to) wire the mini toggle for LED clipping and regular diode clipping; sound is the same in both toggle positions.

    So, off to google pedal troubleshooting I guess!

    Here's the full size image if anyone wants to play spot-the-noobie-error:




    My YouTube channel, Half Speed Solos: classic guitar solos demonstrated at half speed with scrolling tab and no waffle.
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  • robertyroberty Frets: 10893
    D'oh! Does it do the same with the switch in both positions? To rule out diode damage 

    Check the orientation of the op amp and polarised parts

    Also make sure the knobs are turned up!

    Sorry if you've already tried these

    Here's mine for reference: 
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  • So... I've wired it in true bypass, a suspicion I confirmed by disconnecting the battery and producing no difference to the tone whatsoever! I presume I've just misunderstood the wiring of the jacks and this should be a quick lead swap.
    My YouTube channel, Half Speed Solos: classic guitar solos demonstrated at half speed with scrolling tab and no waffle.
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  • Looks like you've jumpered one of the clipping diodes. Being hard clipping, you're shorting the signal to ground. Either replace the link with a diode or snip it out. That should do it.

    My wife asked me to stop singing Wonderwall.
    I said maybe.....
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  • robertyroberty Frets: 10893
    Looks like you've jumpered one of the clipping diodes. Being hard clipping, you're shorting the signal to ground. Either replace the link with a diode or snip it out. That should do it.

    D6 is an extra one wired in series with D3 for asymmetrical clipping options. So it needs to be jumpered if not used 
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  • Matt_McGMatt_McG Frets: 321
    @roberty ;'s doesn't have the diode jumpered top right. As @lasermonkey ; has already pointed out.
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