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The workbench thread
http://maplifiers.net/forum/viewtopic.php?f=7&t=122		 Page 1 of 18
Author:  Zozobra [ Tue Jul 13, 2010 4:27 pm ]
Post subject:  The workbench thread
So what have you fuckers got lying in pieces on your workbench right now?

I have this:
Attachment:
File comment: JMP 2098
JMP2098.jpg
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Marshall lead 100 2098. Marshalls 1st attempt at an SS head and by all accounts they got it very wrong. It looks like the preamp is fucked somewhere as it plays fine plugging into the loop (TRS to send and return on the same socket :facepalm:). I'm gonna poke about to see if I can get the bastard working again. If not then it'll do as a slave unit I guess. Its worth pretty much fuck all although the noise kids go nuts for them.

I have a RAT clone I started building ages ago but never finished too.
Author:  chris_d [ Tue Jul 13, 2010 5:21 pm ]
Post subject:  Re: The workbench thread
It is funny, my workspace usually just sits idle, a pile of coiled wires and soldering shizz.

I have a sort of mental block on leaving electroprojects unfinished, so it is rare that i start a pedal or amp and don't finish it over the course of a few hours, and so like, 90% of the time, my workspace is pretty barren/boring. Also, of late, this is due to the fact that i am too broke to buy parts and simply don't have any projects i can do with the random parts selection i have.

Though, occasionally, i will suddenly go nuts and build three things at a time, out of scavenged junk that i swore i would throw away months ago. :red:

But as it stands now, it is in its boring state, just a pile of tools and wire. :cry:
Author:  chris_d [ Tue Jul 13, 2010 5:25 pm ]
Post subject:  Re: The workbench thread
Oh also, that TRS loop style, is also how Matchless did their passive loops on the DC30. Pretty shitty arrangement, fo sho. I tried that out for kicks once and was not into it at all. :mad:
Author:  Zozobra [ Tue Jul 13, 2010 6:12 pm ]
Post subject:  Re: The workbench thread
Think I just fixed the problem with my RAT clone. Looks like I had a bit of solder crossing tracks that I misses that somehow caused it to pick up radio and be generally nasty in a bad way. It did short pin 1 to pins 2&3 on the filter pot so that would probably do wacky shit. Need to go pick up a 9V battery to test it as i cant find any :mad:
Author:  chris_d [ Tue Jul 13, 2010 7:58 pm ]
Post subject:  Re: The workbench thread
Haha, yeah, i was running into that every time i built something, for too long.

One day i got pissed that all i had were used 9volts that were all reading like 5 or 6v so i bodged this thing up out of an extra power supply i had lying around:
Image


I think it originally came from an answering machine or something, but it is rated for 9vdc @400mA, so it works fine for just abut any build.

Nowadays i also have a Visual Sound 1-Spot that has a 9v clip attachment i can use for the same purpose.

The only caveat, would be that sometimes you will get excess hum or noise when using it instead of a battery, basically same as any pedal, just exacerbated if you are testing a bare board with no enclosure or the shielding that said enclosure would provide. Also, if your build is really fucked, with a power supply short or something you can conceivably get into more trouble being plugged into the wall than you would be likely to with a battery.

That said, for me, the convenience of not having to locate a good 9v somewhere around the house every time i build something makes it very worth it.

Another option would be something like this thing i just found:
Image

Which is very similar to the adapter i have for my 1-Spot and would preclude any fiddly sorts of modification as in my wall wart above.

:idk:
Author:  Zozobra [ Thu Jul 15, 2010 12:56 pm ]
Post subject:  Re: The workbench thread
Gah, damn rat is still self oscillating somewhere. I build it round at a friends over beer and a few substitutions were made so I might just rebuild the fucker from scratch.
Author:  chris_d [ Thu Jul 15, 2010 1:32 pm ]
Post subject:  Re: The workbench thread
Zozobra wrote:
Gah, damn rat is still self oscillating somewhere. I build it round at a friends over beer and a few substitutions were made so I might just rebuild the fucker from scratch.


Is it a straight up rat, or did you mod it?

How did you build it? PCB? Or some form of protoboard?

Also, what subs did you make?

Can you take a picture of the build and post it?
Author:  Devtron [ Thu Jul 15, 2010 5:09 pm ]
Post subject:  Re: The workbench thread
I should have a couple of pedal kits sitting in my mailbox right now.

Also Chris, since TS is down I can't read those PMs you sent me with all the tools/supplies and such I will need for the builds. So, expect a PM shortly.
Author:  Zozobra [ Fri Jul 16, 2010 11:23 am ]
Post subject:  Re: The workbench thread
Its a stripboard build. Quite messy (piggy backed resistors and caps :facepalm: ) and for the time in debugging It's probably quicker to rebuild without the subbed parts as the resistors and caps come to only a few quid. Main sub was I couldnt find an LM308 so I used a TL071 which is verified as an acceptable sub on a few pedal forums.
Author:  Zozobra [ Fri Jul 16, 2010 11:26 am ]
Post subject:  Re: The workbench thread
Attachment:
Rat - Original ProCo Version.gif
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layout i'm using. My friend who I built it with has used this one before.
also I have a dpdt (on-off-on) switch to switch between diode and LED clipping with the off position for clean(ish) boost.
Author:  chris_d [ Fri Jul 16, 2010 11:51 am ]
Post subject:  Re: The workbench thread
The TL071 is a usable sub, and i have one of those in my latest rat build as well.

It works fine. BUT you have to be sure to leave out the 30pf cap that is supposed to sit between pins 1 and 8 (C6 on that Torchy layout), as that cap's purpose is not needed or utilized by the TL071 type IC.

I would also suggest double checking your subbed values, as it is also possible that you don't have what you think you have in some spot. I have done that before, swapping an orange band for a red one or something on a resistor in a piggyback and winding up with a total value much different than what i meant to achieve. If you do not already, it is a good idea to test the piggybacked values with a multimeter before you solder them in, to ensure that you haven't done anything silly with your eyes, or the math.

I would say that if you are passing sound(even if it has a pile of oscillation right now) it is probably an easy fix to get going right. :idk:

I assume you have looked over the thing with a magnifier or something to determine beyond the shadow of a doubt that you don't have any hairs of solder bridging the traces in any place?
Author:  Devtron [ Fri Jul 16, 2010 4:22 pm ]
Post subject:  Re: The workbench thread
My pedal kits came in today.

First off, GGG does a really good job separating everything into little bags. Each kit comes in a labeled bag, which contains all of the parts separated into even smaller labeled bags. Everything looks to be in order, and it comes with everything you need for the pedals (including wires) minus tools.

So now I just have to wait 6 days to get paid again, go buy up all the necessary little bits and start doing work.

Today ... I design the paint/stickers!
Author:  Zozobra [ Sat Jul 17, 2010 11:13 am ]
Post subject:  Re: The workbench thread
Ah didnt know about the 30p cap. I'll try taking it out. I'll double check the board but I'm pretty sure there arent any shorts. I rescore in between the traces with a knife anyway. Pretty certain we checked all the parts with a meter first but I'll have a look over it again to be sure.

cheers man!
Author:  Zozobra [ Wed Jul 28, 2010 6:30 pm ]
Post subject:  Re: The workbench thread
Modded my VK112 to have less gain and changes the tonestack a little while I was there.

A few piccies:
Image
Nice beefy OT there...

Image
The guts, pre mod.
Author:  Zozobra [ Mon Aug 02, 2010 7:18 pm ]
Post subject:  Re: The workbench thread
Wow, I'm getting something pretty close to deliverance era corrosion of conformity tone which is pretty impressive for a valveking running a pair of 5 year old, clapped out sovlek 6l6wxt+ toobs.
Author:  Zozobra [ Sun Aug 08, 2010 8:12 am ]
Post subject:  Re: The workbench thread
Added a bias pot yesterday. Not had the chance to play with it much since I installed it but it certainly seems to have improved the clean tones. The coldest tube was running at 12.6 mA at a B+ of 483 V clocking in at a massive 20% idle max dissipation haha. Granted that tube is probably fucked though. The other tube was at 19.6 mA (32% idle max). Thats the cathode current too so theres a few mA of that from the screens so the true plate dissipation is a bit lower. I'm surprised the amp would even output much because the crossover notch must be huge and the cold valve must have been in cut off for most of its cycle. Anyway its all biased up to 60/70% now although I should really get some new glass thrown in there.

I knew peavey biased cold but that is fucking nuts.
Author:  Zozobra [ Fri Aug 27, 2010 12:07 pm ]
Post subject:  Re: The workbench thread
Image

:D
Author:  metalfanat1c [ Fri Aug 27, 2010 1:14 pm ]
Post subject:  Re: The workbench thread
My JSX was on a tech's workbench until this morning. I went and picked it up and it sounds much better.

Apparently one of the filter caps was about to pop.
Author:  Zozobra [ Sat Aug 28, 2010 6:30 am ]
Post subject:  Re: The workbench thread
How old is that? JSX is fairly new in the scheme of things right?
Author:  metalfanat1c [ Sat Aug 28, 2010 1:29 pm ]
Post subject:  Re: The workbench thread
Yep. Mine was made in '09 I think.
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