How to Fix dead Fender Champ 5F1 Mojotone Kit Missing Jumpers

Yep, another Mojotone.com kit comes to D-lab for repair. Yes, once again missing jumpers to the 12AX7, plus a ground runner. Therefore the amp was powered, but no sound. I reviewed the schematic + layout diagrams on Mojo's site, looks A-OK. My guess, just a miss/bobo. This amp will require more attention, plus the owner wants some additional updates, so I stopped there just to point out the major violator, missing jumpers. These kits are great and I am happy to see folks building rather than playing video games. Just take your time, give it a quality assurance check before powering. I am happy to help. I do feel bad when sometimes its just a missed jumper, then you are out shipping, plus a service charge to get the amp going. Thanks all for being part of D-Lab electronics. TD

[@budandbean1]

The real problem is that you fellas on KZbin make it look so easy to work on amplifiers and other electronic equipment, that everyone thinks it is so simple to do. It’s actually not quite as simple as it looks and that once someone has issues, troubleshooting can truly be an art in itself. One of the reason I enjoy this channel is, you do a nice job explaining your thoughts behind your troubleshooting.

[@sam127001]

I've built a few amps ( not from kits, but still...) and have found it useful to use a highlighter to mark the parts as i install them; if you mark consistently, anything you didn't install is easy to see. THanks for showing this troubleshooting process !

[@rciancia]

Terry, the other problem with that kit diagram is the dotted line means its supposed to be UNDER the turret board... Those kits are so small and hard to work on for novice builders.. DLAB can fix anything..... I know you'll nail it. Great Job Terry

[@DeadKoby]

My first amp kit build required help from a technician... eventually I got much better. The last amp build was gold from the first turn-on.

[@msmith2961]

The green dashed wires are supposed to be connected underneath the board. The photo of the finished board on their website doesn't show those connections, so if someone is working from the photo it would be easy to miss. I suspect the missing ground is the one from the input jack to the negative rail of the second 8uf cap - also the ground for the cathode resistor - also another green dashed line....

[@DennisMurphey]

Yes more how to test circuits before powering up with a VOM outstanding. I can do all those tests easily as my Eico 147 chassis is twice as big so lots of space. Except i cramped the 12AX7 and 6V6 all down at one end so with point to point it gets real crowded in a hurry. I did add a ground bus which helped a lot. Thank You I am so excited to get to fire this baby up and see what i did, no smoke please. Dennis

[@Echapm40]

You are the man Terry! I also enjoy all your videos. I have a homebrew 5E3 that I am building using scrounged parts, hope to have it done one of these days.

[@giovanni4070]

Built a Heathkit multi band receiver in 1965 and it worked. Built a 5f2 clone in 2018 and was scared shitless that I would screw the pooch. Followed directions, added in more caps, built my own voltage regulator for startup and it worked, lots of noise though. Went through it, watched Terry trouble shoot and changed a few things. fired it up again and lots of noise. Seems I had a bad input cable. Now I use it every day with a 12 inch Weber speaker. I compiled a thick notebook of diagrams and schematics before I started and it was worth it. Kit builders more power to you but pay attention and do some homework

[@teleguy2650]

I bought the 2013 version of the Mojotone 5F1 and it worked perfectly for the start. Hint for anyone building from a kit, when following the wiring diagram, use a highlighter to mark off the jumpers/components/wires as you install or solder.

[@audiotechlabs4650]

You are so right, Terry! The old saying rings true....haste makes waste! It will be great to see put. 2 the mods. Thanxz

[@zummliller]

Yeah!: ''Every STINKING wire!'' 3 simple words of great amp wisdom...thanks

[@sa8die]

take yer time!! always good advice ( and dont put electronic kits together and drink beer, unless ur really good ).

[@brich2929]

I don't think that's a Mojotone kit. The OT is a Classictone brand. Looking at Mojotone's website and having built their 5E3, I know that they use their own branded Transformers. Also, in my Tweed Deluxe, the kit came with the proper Carbon Comp resistors. Again, looking at their website, the Champ kit includes Carbon comps, not metal film resistors. This kit was likely some other manufacturer.

[@robertcalkjr.8325]

Thanks Terry!

[@electrolytics]

Dropping by for good content. Auto Thumbs up engaged!

[@natem8034]

I just put together a Mojotone Jtm45 kit last month and there were some errors in the wiring diagram that came with it. Missing a jumper from a 27k resistor to the impedance switch and wires to the cap can mislabeled. That was for the diagram dated 2017, the older diagram on their website dated 2005 was correct. The parts they gave me matched the older diagram so that’s what I ended up using. I contacted them and they said they would get it corrected

[@CC-te5zf]

I've built 3 amps from kits. They all had some inconsistency or something hard to understand in the instructions. You just have to dig in, trace schematics and ask allot of questions.

[@coldfinger459sub0]

Lesson learned guys when you want to buy these kits. Have them direct drop shipped to Terry unopened have him put them together, will be cheaper than having him take them apart and then put them back together correctly. 😂🤣

[@mikeburch2998]

It's actually pretty easy to make mistakes on things like this if one has no real experience with building. When I built my HW-101 back around 1983 I made several mistakes because I was really tired from work during assembly. Getting OCD with construction comes with experience. :-)

[@kenhancock8931]

neat? thats rewiring the whole thing!!!!!oh well more$ for you. have a great day terry