The real problem is that you fellas on RUclips 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.
As a tech myself.. I seen many many amps that folks just rush into.. Always start off ensuring the power supply works.. The move and long the chain.. And double check everything! Have to agree with Terry on this one.
A lot of these people, will build these kits over 3,4,5 nights or sessions and forget were they were or what step they were on! Like Terry said, pay attention and be meticulous!
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 !
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
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.
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.
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.... Thanks for another good video Terry.
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
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
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
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.
The Mojotone 12/04/2018 Tweed Champ layout image was missing the green jumper. The image dated 02/01/2019 has the green jumper added. The schematic shows it as circled C . I am getting ready to start one of these kits and you just saved me a serious headache. One other question, would a 470 ohm 5 watt resistor be an acceptable replacement for the 470 ohm 1 watt resistor?
In case he doesn't answer, yes. The wattage refers to the handling capability. The resistor will dissipate around .7 watts. A 1 watt-rated resistor would work but not for long, so 5 watts is plenty. At least 2 watts for that specific place in the circuit. General rule is to have the wattage rating be at least double the wattage being used. That way the resistor doesn't get too stressed. The voltage will fluctuate as signal is being amplified so you want some extra room, thats why I suggest minimum 2 watts. That 10W is overkill but 🤷🏻♂️. Here's some math. I = V/R = 18V/470Ω = .038A ------Voltage across resistor divided by resistance equals current passing thru resistor. P = I*V = .038A*18V = .69W ------ Find power dissipated (wattage) by multiplying current passing by voltage across.
I agree, 5 watt would be best, and yes,470 ohms is too low of a value. I have been installing between 750-1K depending on plate voltage see the weber bias calculator www.tedweber.com/webervst/tubes1/calcbias.htm
@@d-labelectronics Thanks to all for the information. Hopefully with the information in the two videos and the updated images on MojoTones site, future kit builders will have better luck with this kit.
Hi, Terry! Hmmm... from looking at the schematic on the screen, I noticed the dotted green leads are harder to see than the yellow ones. Wonder why they couldn't have used another color for the two jumpers? Well, as is said below, it's more $ for you. And it's not like most of us haven't left out a component or jumper in our past wiring!
Great video and very educational!! What is the FIRST book on Tube Amplifiers that you recommend reading and understanding prior to beginning any amp kit build?
Why are the jumpers on the back side? You have to gut the amp to fix it. I have built 2 of the 5f1 kits from different suppliers with success on both. I'm not an electronics guy but can follow directions. Would it cause issues ....noise and hum... if the jumpers were on the front side with the rest of the components?
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.
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. :-)
The HW-101 was a LOT more complicated than this little amp. IIRC Heathkit used to say something in their manuals like “don’t work on the kit if you’re tired” or words to that effect. It was good advice.
Maybe I'm just dumb or something but I would like to love to know where you get those kits point-to-point wiring kits if you could leave me a message as to where I can locate things like that I'm usually on eBay looking for crap like that I just maybe I'm hitting the wrong way not looking for the right things Lord knows it would be greatly appreciated 73
Everybody that builds their own amps has to start somewhere. Wiring off the layout diagram is not, to me, the best way to go. I always wire off the schematic and use a hi-liter to mark my progress marking through each component installed and each wire that is landed. This helps eliminate missing connections. I also ohm out my connections to make sure I have continuity through my solder joints, sockets, etc. I still find mistakes but it improves my chances of getting a good startup.
I've always gotten by with just the schematic on pedals but I always use the wiring diagram on amps because one wire or ground in the wrong place and you can have a hum that is a mess to find.
Bet that sucks for someone to purchase an amp kit , put it together , and still have to pay an electronics guy to fix it right, lol. At least when you fix it they'll know it's quality work.
After building a 5F1 a couple months ago I made a short video with a couple of helpful pointers. If anyone is building one or having trouble it's worth checking out. ruclips.net/video/4y7inUmcPzs/видео.html I also have a playlist called 5F1 which has this video along with a couple of mods you can do.
Those thing are simple but if you don,t know your doing you,re gonna goof it up. Study up . Stew mac are selling those with full step by step instructions.
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. 😂🤣
The real problem is that you fellas on RUclips 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.
As a tech myself.. I seen many many amps that folks just rush into.. Always start off ensuring the power supply works.. The move and long the chain.. And double check everything!
Have to agree with Terry on this one.
A lot of these people, will build these kits over 3,4,5 nights or sessions and forget were they were or what step they were on! Like Terry said, pay attention and be meticulous!
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 !
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
Correct! Ron rocks... seriously!
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.
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.
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.
It's been 5 years bud, did you finish it?
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....
Thanks for another good video Terry.
You are so right, Terry! The old saying rings true....haste makes waste! It will be great to see put. 2 the mods. Thanxz
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
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
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
Wow! miswiring a cap-can could cause it to explode!
take yer time!! always good advice ( and dont put electronic kits together and drink beer, unless ur really good ).
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.
The Mojotone 12/04/2018 Tweed Champ layout image was missing the green jumper. The image dated 02/01/2019 has the green jumper added. The schematic shows it as circled C . I am getting ready to start one of these kits and you just saved me a serious headache. One other question, would a 470 ohm 5 watt resistor be an acceptable replacement for the 470 ohm 1 watt resistor?
In case he doesn't answer, yes. The wattage refers to the handling capability. The resistor will dissipate around .7 watts. A 1 watt-rated resistor would work but not for long, so 5 watts is plenty. At least 2 watts for that specific place in the circuit. General rule is to have the wattage rating be at least double the wattage being used. That way the resistor doesn't get too stressed. The voltage will fluctuate as signal is being amplified so you want some extra room, thats why I suggest minimum 2 watts. That 10W is overkill but 🤷🏻♂️. Here's some math.
I = V/R = 18V/470Ω = .038A ------Voltage across resistor divided by resistance equals current passing thru resistor.
P = I*V = .038A*18V = .69W ------ Find power dissipated (wattage) by multiplying current passing by voltage across.
I agree, 5 watt would be best, and yes,470 ohms is too low of a value. I have been installing between 750-1K depending on plate voltage see the weber bias calculator www.tedweber.com/webervst/tubes1/calcbias.htm
@@d-labelectronics Thanks to all for the information. Hopefully with the information in the two videos and the updated images on MojoTones site, future kit builders will have better luck with this kit.
Yeah!: ''Every STINKING wire!'' 3 simple words of great amp wisdom...thanks
Hi, Terry!
Hmmm... from looking at the schematic on the screen, I noticed the dotted green leads are harder to see than the yellow ones. Wonder why they couldn't have used another color for the two jumpers?
Well, as is said below, it's more $ for you. And it's not like most of us haven't left out a component or jumper in our past wiring!
Great video and very educational!! What is the FIRST book on Tube Amplifiers that you recommend reading and understanding prior to beginning any amp kit build?
Watch Uncle Doug’s videos. He goes into great detail on tube basics.
Why are the jumpers on the back side? You have to gut the amp to fix it. I have built 2 of the 5f1 kits from different suppliers with success on both. I'm not an electronics guy but can follow directions. Would it cause issues ....noise and hum... if the jumpers were on the front side with the rest of the components?
hi mr lab i made a champ 5f1 clone i want to put a 6l6 instead of 6v6 can i keep the same cathode resistor value or i must change the value.thanks
neat? thats rewiring the whole thing!!!!!oh well more$ for you. have a great day terry
Dropping by for good content. Auto Thumbs up engaged!
How may commericals are you gonna stack on each video?
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.
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. :-)
The HW-101 was a LOT more complicated than this little amp. IIRC Heathkit used to say something in their manuals like “don’t work on the kit if you’re tired” or words to that effect. It was good advice.
Are the builders that have the issues colour blind? That schematic didn't have the best contrast...
Terry, are you still making opti-plexes?
If so, how much for one in today's money?
Love all your videos. Do you dislike JJ tubes ?
Yes, I prefer SovTek and Tung-Sol
Shop Rate: $50/hr
If you help: $75/hr
If you worked on it first: $100/hr
If your friend worked on it: $150/hr
Will you build one for me?
Maybe I'm just dumb or something but I would like to love to know where you get those kits point-to-point wiring kits if you could leave me a message as to where I can locate things like that I'm usually on eBay looking for crap like that I just maybe I'm hitting the wrong way not looking for the right things Lord knows it would be greatly appreciated 73
Thanks Terry!
Nice!! "every stinkin' wire"... :-)
Everybody that builds their own amps has to start somewhere. Wiring off the layout diagram is not, to me, the best way to go. I always wire off the schematic and use a hi-liter to mark my progress marking through each component installed and each wire that is landed. This helps eliminate missing connections. I also ohm out my connections to make sure I have continuity through my solder joints, sockets, etc. I still find mistakes but it improves my chances of getting a good startup.
I've always gotten by with just the schematic on pedals but I always use the wiring diagram on amps because one wire or ground in the wrong place and you can have a hum that is a mess to find.
Oh c'mon Terry, spoilers in the opening scene?
:D
Bet that sucks for someone to purchase an amp kit , put it together , and still have to pay an electronics guy to fix it right, lol. At least when you fix it they'll know it's quality work.
Are these kits from Tube Depot?
Terry , there's no amp for sale on your site,,,,,, at all . ?? :(
People just keep screwing these things up it seems. More work for you.
The jumpers were originally underneath per Fender. Status quo for all their eyelet boards. That was one messy build.
That’s why they are dashed!
Could it be something to do with colour blindness
That's what I thought too.
Jeepers hot to fuse ring again ! Ouch !
"Just a miss/bobo"? I think you meant boo-boo ! With a dashed line ( jumper?) in the middle of the "circuit"!
no wine ?
would have been easier if you built the whole thing.these go together pretty quick when you know what to do
After building a 5F1 a couple months ago I made a short video with a couple of helpful pointers. If anyone is building one or having trouble it's worth checking out.
ruclips.net/video/4y7inUmcPzs/видео.html
I also have a playlist called 5F1 which has this video along with a couple of mods you can do.
People that cant figure this out on their own probably shouldn't be messing with high voltage tube circuits in the first place
Who else would love to know how much this fellow dropped on his “cheap” amp kit repair?
Those thing are simple but if you don,t know your doing you,re gonna goof it up. Study up . Stew mac are selling those with full step by step instructions.
Too much wire in there...
😂 If you don’t want to spend the time learning to read a schematic and you can’t follow a layout then let someone else build it.
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. 😂🤣