Chuck D. Bones
Circuit Wizard
I didn't get the resistor as planned, I've set the Pignose aside for a few days 'til the resistor gets here. Plenty of other pedal and home projects to keep me occupied.
72’ pignose
- Thread starter dlazzarini
- Start date
Couldn't you use 4 40 ohms (or 47r which is probably more common) 1/4 W resistors to make a 10 ohms 1 W resistor ? Or is it too dangerous on a amp circuit?
dlazzarini
Well-known member
I just placed an order with Mouser including that resistor. Should have it early next week
Chuck D. Bones
Circuit Wizard
Could, it's just a matter of space. I have some 10Ω 5W "sandstone" resistors, but no way one of those will fit.
dlazzarini
Well-known member
Hey Chuck I replaced that 1ohm resistor on that pignose and it fired right up. I did also order a 10 ohm resistor to try out that capacitor thingy you were talking about. What was the end goal of that
Chuck D. Bones
Circuit Wizard
I finally got my wirewound resistors. I replaced the 1Ω resistor with a 12Ω and a 100μF in parallel. I replaced the 680Ω resistor and thermistor with a 1N4004. The Pignose works, and it gets plenty loud, but above a certain volume there is a fair amount of crossover distortion. I'm thinking the 12Ω is too large, so next I'll try something around 3Ω. 1Ω is too low with a 12V power supply. If you're using batteries, the 1Ω is probably best.
To answer your question, the goal of increasing the 1Ω resistor was to stabilize the bias. It's very stable, but the consequence is too much crossover distortion. I need to find some middle ground.
To answer your question, the goal of increasing the 1Ω resistor was to stabilize the bias. It's very stable, but the consequence is too much crossover distortion. I need to find some middle ground.
dlazzarini
Well-known member
I see. I don’t really know what they’re supposed to sound like but it does start distorting once I get the volume up around half way or so
oldfuzzface
New member
Hello all,
Resurrecting this thread because I have a 7-100r that I am attempting to repair.
I searched the web to find out what type of transformers I can use for this project, but came up empty. Hoping one of the experts on here can help me out.
I'm retired and have to tinker with something over the winter so I dont go nuts! TIA
Resurrecting this thread because I have a 7-100r that I am attempting to repair.
I searched the web to find out what type of transformers I can use for this project, but came up empty. Hoping one of the experts on here can help me out.
I'm retired and have to tinker with something over the winter so I dont go nuts! TIA
oldfuzzface
New member
Chuck D. Bones
Circuit Wizard
I don't have specs on the transformers. Are you sure they need to be replaced?
oldfuzzface
New member
well, the legs are missing on the large one. The smaller one is still in the board, but I havent tested it yet. I dont mind if I have to replace parts, it will be a fun learning experiment for me as well, but I find nothing on transformers to use.
I do have another pignose here with numbers on the transformers but cant locate. Im probably not reading correctly since Im a greenhorn on electronics, but learning project by project.
On a side note, I have to delete a duplicate post. I didnt know this Forum heading still existed.
Thank you for your help!
I do have another pignose here with numbers on the transformers but cant locate. Im probably not reading correctly since Im a greenhorn on electronics, but learning project by project.
On a side note, I have to delete a duplicate post. I didnt know this Forum heading still existed.
Thank you for your help!
oldfuzzface
New member
here is the larger transformer. It does have legs, although 1 appears to be broken. Maybe I can solder a lead onto it ? I'll test them both first. I just assumed I'd end up replacing them.
Feral Feline
Well-known member
That's the way to go.
IF they're still operational (apart from broken legs), definitely go with rigging up some kind of fix for the broken legs — even if it means offboard wiring the entire thing (but then you have to figure out a way to secure it, and in a place that won't induce hum/noise/etc).
oldfuzzface
New member
Thanks for the info.
Yes this is the route Im going to go. The transformers tested good (ohms and continuity) and hopefully will work if I get a lead on it and go over the rest of the board.
I'm still determined to find something. lol There are many rabbit holes I've gone down. I am learning in the process, so all is not lost.
I didn't realize this little amp was so difficult for what seems like a simple pcb of parts. I would think that someone would have built one from scratch by now.
EarthCovenAudio
New member
Hey everyone reviving this post. I have this same pignose, at this point I've changed everything on the board except b172, b175, resistors, transformers and the cap labeled green .
Transformers seem to read okay but one of the output transistors (b324 on the top side of schematic) keeps going into thermal runoff. I'm unsure where to turn to next, logic tells me its the transformers or b172/175 transistors but looking for ideas.
Transformers seem to read okay but one of the output transistors (b324 on the top side of schematic) keeps going into thermal runoff. I'm unsure where to turn to next, logic tells me its the transformers or b172/175 transistors but looking for ideas.
Bricksnbeatles
Member known well
Definitely interested in this thread. I have a ~72 pignose that I think works but honestly can’t totally tell lol. I should pull it out and clean it up soon. The volume knob/power switch is super noisy, but don’t know yet if it’ll be okay with a quick cleaning or if it needs to be replaced. I’ll try to remember to check out of my transformers have a different part number.
I’ve always wanted to build a pignose from scratch with Zappa’s XLR mods and stuff, but those transformers are infamously hard to find.
I’ve always wanted to build a pignose from scratch with Zappa’s XLR mods and stuff, but those transformers are infamously hard to find.