FAILURE!!!!!!!!!!

  • Thread starter Thread starter Juggernaut
  • Start date Start date
Juggernaut":3e7a9 said:
Cool, I may try that in the morning, just out of curiosity. :D
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Yeah I can't quite make out all of the wiring there and it's really not needed to get that circuit to scream. Your problem could be there or it may still be elsewhere but it will at least rule out one more thing. You can always put it back in later after you get it crackin.
 
wow.. thats a rats nest! Ill post pics of mine when Im done.. im sure it will be worse :D
 
I just threw it together, I wasnt shooting for clean.......yet. I wanna get the circuit that I wanna use worked out, then I'll clean it up. :thumbsup:
 
also it looks like your negative feedback isn't hooked up (wire from the speaker jack to the negative feedback resistor) the amp will work without it but it would probably be unstable and sound bad. Some thing in the ballpark of 33k to 68k should sound good for that resistor.
 
Yo Mike, I gotta admit, those pictures and that process of frustration is giving me some GAS. How much do clones like that usually cost?
 
This one cost me $725.....my Sloclone will probably be in that range or a bit more.
 
Juggernaut":54aef said:
This one cost me $725.....my Sloclone will probably be in that range or a bit more.
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Where's the website/forum with all the information? The thought of the Sloclones got me itching :lol: :LOL:
 
Ok I keep scouring those pics and from what I can see the preamp looks like it should be functioning. I think I might be onto something though, your output grid wiring looks odd (pin 5 of the output tubes). I can't make out everything but you've got two red wires going from the output coupling caps to the ppimv pot and it looks like there's two more red wires going from those caps to some resistors over on the end of the board. Can you elaborate on what you've got there, are those 2 red wires tied together where those two resistors meet? It looks like those are your grid resistors for the power tubes, a more detailed shot of that part of the board could speak a thousand words. That part looks fishy, we might be onto it.
 
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I'll be back in a bit, got to go to work, but I'll get back on here as soon as I get there.


:D

Thanks, hope these help.
 
Okay it looks like you're getting a weirdo parallel load because of how you've got those output grids wired, they'll work fine like that without the ppimv but with that master you only feed pin 5 of the output tubes from the pot. Best thing to do would be to remove the ppimv, install bias feed resistors (100k-220k that I mentioned before) just like a stock marshall, and leave your output grid wiring the way it is.
 
ok, so will I be able to put a MV in it that way? I'm not real clear yet on the suggestion you gave.
 
You already have the pre pi master volume wired up in the preamp, it's just like the one in the jcm 800, as long as the taper of the pot is good it should work just fine, I like it much better than the ppimv for a circuit like you've got. The ppimv is better for 2 or 3 gain stage preamps imo, it's too over the top with a preamp that hot. So do this, I'll give you a step by step.

1. Disconnect the ppimv. Desolder the two green wires coming off the pot from the power tubes, desolder the two red wires coming off the pot from the output coupling caps, leave the other two red wires going to your output grid resistors on the end of the board in place. Disconnect the other red wire coming off the pot from the eyelet in between the output coupling caps, there should be another wire in that eyelet coming from the bias supply, leave it there. The ppimv should be completley disconnected now, go ahead and yank the pot and all of those pesky wires.

2. Time to add the bias feed resistors, if you've got some 220k thats the standard value, 150k also sounds good and you could even use 100k, anything in that ball park will get you up and running and you could tweak it later. So we'll say 220k for this. Take your first 220k and it goes from one of the output coupling caps to that center eyelet where the wire from the bias supply goes, now do the same with your other 220k , go from the end of the other output coupling cap to the eyelet with the bias supply connection. That area of the board should look like an X now with your bias feed resistors on the side of the board towards the pots and your pi plate resistors (82k and 100k) on the side of the board towards the back of the chassis. So the 220k resistors should meet at the middle eyelet with the wire from the bias supply, the other end of each 220k should connect to it's respective output coupling cap. Those red wires running to your a output grid resistors on the end of the board should still be connected where the bias feed resistors meet the output coupling caps.

That should do it. Good luck, I hope that fixes it for ya :thumbsup:
 
Juggernaut":8452f said:
Like this?

grg.jpg
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Yes sir, the dotted red and the dotted blue wires shown coming off the ends of the coupling caps would be the same as the two red wires that you have running to your output grid resistors on the end of your board. The dotted blue wire shown running to the center eyelet at the junction of the 220k resistors is the same as the one coming from your bias supply. Rock and roll man, hope it works :rock:
 
cool, I'll give it a go in the morning when I get home, I didnt bring it with me tonight. So I'm still gonna need a MV?
 
Juggernaut":9ac66 said:
cool, I'll give it a go in the morning when I get home, I didnt bring it with me tonight. So I'm still gonna need a MV?
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Your second pot from the input jack should be your MV.
 
cool, sorry for being so thick headed today, I'm swimming through a sea of NyQuil and Benadryl.......... :doh:
 
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