Reverse engineering circuits

[notCardio]

Anybody here any good at it? and I'm talking about old school transistor stuff, not ICs.

I've got a super simple amp and a pedal that I'd like to try to make new copies of, just because they're old and I'd like to have reliable versions.

 

[ashcat_lt]

Have you searched for the schematics online? Damn near everything is out there somewhere.

 

[notCardio]

I'm sure there are a million out there for the pedal, but all different and how am I to know who's right?

But I doubt if I'd find anything for the amp. No name Japanese maybe 5W transistor that I bought in a GC Murphy dime store circa 1968-1970.

 

[pikingrin]

Cardio, you might want to check in to Getchell Amplifiers for that amp... Bobby is a genius with amp electronics and could probably figure it out fairly easily. He's done some great work on a few of my amps and I got one of his little 1x8 custom builds that sings - he used to work out of the back of Dave's place but now he's got his own shop in Brownsburg. I know it's not the most convenient since you're out west but you could probably just pack it up the next time you head to the Burg and stop by his shop. It's right off of 267 close to Marsh...

 

[ashcat_lt]

I'm thinking that if they're simple enough that you think you can build them, then they should be simple enough for you trace out. You could post it here or over at DIYSB and have some folks double check for you. The worst part is probably going to be reading the component values. I hate resistor colors!

If you've got the software, you could take reasonable photos of both sides of the board and then mirror the trace side, make it semi-transparent, and lay it over the component side. Might make it easier to sort out.

Be very careful with that amp, though. The output power is small, but the input power is still the wall and can fuck up your day pretty quick. Unless you really know what you're doing around high voltage and know the proper safety procedures without having to ask on a web forum, you should probably outsource that one to a pro.

 

[notCardio]

Cardio, you might want to check in to Getchell Amplifiers for that amp... Bobby is a genius with amp electronics and could probably figure it out fairly easily. He's done some great work on a few of my amps and I got one of his little 1x8 custom builds that sings - he used to work out of the back of Dave's place but now he's got his own shop in Brownsburg. I know it's not the most convenient since you're out west but you could probably just pack it up the next time you head to the Burg and stop by his shop. It's right off of 267 close to Marsh...

I've looked at his amps and thought they were cool designs (like the ammo box) and Dave said they were great, but I never actually played one or heard anybody there who was playing one. And I could never justify spending that kind of money on an amp unless it was a blackface Deluxe Reverb or maybe a Princeton. I did come close to buying Travis' head once, but I just couldn't come up with the money in time.

I didn't realize he worked on amps though, other than his own.

 

[notCardio]

I'm thinking that if they're simple enough that you think you can build them, then they should be simple enough for you trace out. You could post it here or over at DIYSB and have some folks double check for you. The worst part is probably going to be reading the component values. I hate resistor colors!

If you've got the software, you could take reasonable photos of both sides of the board and then mirror the trace side, make it semi-transparent, and lay it over the component side. Might make it easier to sort out.

Be very careful with that amp, though. The output power is small, but the input power is still the wall and can fuck up your day pretty quick. Unless you really know what you're doing around high voltage and know the proper safety procedures without having to ask on a web forum, you should probably outsource that one to a pro.

Yeah, I had a hard time in electronics class. I'd have to tell other people what colors to pick out for me because I'm color blind.

And I don't have that kind of graphics skills. I don't know why, I worked with enough professional graphic artists.

I don't really know why I'm asking this. There's nobody worse with a soldering iron than me, and as a result, I hate doing it. I don't handle frustration well. One of the few things I got from my dad. We like to throw tools and cuss.

 

[pikingrin]

I've looked at his amps and thought they were cool designs (like the ammo box) and Dave said they were great, but I never actually played one or heard anybody there who was playing one. And I could never justify spending that kind of money on an amp unless it was a blackface Deluxe Reverb or maybe a Princeton. I did come close to buying Travis' head once, but I just couldn't come up with the money in time.

I didn't realize he worked on amps though, other than his own.

He does make some pretty badass amps; I've got one he built into an old Crate combo cabinet that he named the blues king. It's a little 1 x 8" all hardwired (no PCB) 5 watt beast that fills a niche void in my collection. It gets played often... But, I digress...

He does work on other amps, too. He recapped and retubed my old Magnatone, fixed my Twin and modded my Blues Jr, too. The maggy and blues jr are both impressive pieces of gear now. If you're serious about having that old amp of yours duplicated he would definitely be able to figure it out and make it happen.