I'm not familiar with that particular model but you basically want to measure the Plate, Cathode and the grid voltages on each half of the 12BH7. On the first triode, pin 1 is the plate and pin 3 is the cathode. On the second half, pin 6 is the plate and pin 8 is the cathode. The cathodes are joined together with one bias resistor so their voltages should be the same. You can measure the plate voltages to see if they are similar. The Test Points are actually measuring the grids, Pins 2 & 7. You adjust the balance pot until the Grid voltages and plate voltages are the close to each other. I doubt you can get them exactly the same since each triode are typically not 100% identical. I hope that helps? Cheers

@@MikeFreda Thanks a lot for the explanation! Much appreciated.

Glad to hear it worked out for you and you saved a bunch of money! Cheers.

Thanks! It sure harder than it should be! Cheers.

Thanks for watching! Glad you liked the video. Cheers.

Thanks for commenting. This amp can be wired SEP (Single End Pentode) or SET (Single End Triode) by strapiing the grid. Triode mode has less power but also sound good. Not much of a difference but it can be noticeable. When running in triode, I find the bass not as deep but the vocals/mid range a bit more pronounced. You really have to do quality listening and A/B them to really hear a difference. To be honest, EL84 are good tubes, they are affordable and widely available but if you are looking for that "tube" magic you may want to look at my 6DN7 SET amp build. It's a low cost tube that sounds amazing! If you are looking to take a big leap into SET, another great sounding tube is the 2A3. These tubes do cost a bit more and the build process is a bit more complex but they are magical when paired with a higher efficacy speakers. I will be doing a build video using a 2A3 tube. Cheers

Thanks for commenting. I can make this for people but they are labour intensive and a bit fragile to ship. That's why I created the build series of this start gate and timing system. Please have a look at all the other related video's. Cheers

Thanks for commenting, I really appreciate it! It was a fun build. I liked it so much I'm making a High Gain and a JTM version using this output section. Cheers.

​@@MikeFreda Don't laugh, but I got into fiddling with amps. I would find these old tube amps on eBay that didn't work. Through the grace of God and help from a guy I befriended, (Jon Besent, who was an amp builder that started "Austone"), I never blew myself up. I bought a tube PA amp at the swap meet for $5.00, and converted into a amp head. It had 2 EL-84s and 1 12AX7. Believe it or not it rocked.

We all have to start somewhere. I started building tube amps in my late 20's when I came across a Fender Amp book that had a Schematic of a Champ in it. I said to myself, "is that all it is?" I bought the book and took it to work. An old guy I worked with was into ham radios. He laughed when I showed him the book and told him I wanted to make this Champ amp. He then proceeded to educate me a bit. The one major thing he told me was to always keep on hand in my pocket when testing. I still do that today. Cheers

@@MikeFreda Very cool to have a mentor. The electronic guys are not around anymore, or at least in my neck of the woods. I live in the desert area of California, and when I was in high school we had electronics class. I wish I took it, but being a 16 year old kid with a 68 Dodge Super Bee, I dove into auto shop 100%, and we cruised the main drag in Palm Springs. It was a great time to be alive. Wish I would have picked up a guitar way back then too.

Thanks. With the new bushing and 1” spacer lift all I has to adjust was the fan shroud. I had to lower it a bit and clearance the bottom the bottom of the shroud a bit. That was it. If you go more the 1”, you will have to do a few other things to make it work. Cheers.

Thanks for commenting. Glad it worked out. You can also poke the check ball with a piece of wire to get it to move. The CV still may a small air leak if there is some left over residue. Keep a look out for that. If that is the case you may try the Carb Cleaner trick again but it's been my experience that the CV will need to be removed for a more aggressive approach to cleaning it. Cheers.

@@MikeFreda Thank for the tip. I did do a test fire of my lantern and didn't hear any hissing sounds before and after start up. But will keep my ears open...

Thanks for the comment! Cheers.

Awesome. Hope it works out for you. Cheers.

Thanks for commenting. Yes, they are relatively simple to make and perform well! Cheers

Thank you! Cheers!

Thanks. Planning another event with a proper light tree.

Thanks for commenting. I don't disagree due to the rectifier tube and moderate B+ voltage these amps use but it doesn't hurt things. The main reason for the video is to show people the unique dual function switch and as I mentioned, I like using the switch for switching leads. I don't like the POP sounds of the input jacks disengaging and engaging. Cheers

@@MikeFreda sorry i now see in the comments you addressed what i said already

Thanks for commenting. Yes, there is something about these older lanterns. Cheers.

@@MikeFreda I 💯 agree!

I can make some extra. Please PM me for details. Cheers.

Thanks for commenting. I have a new version of the tool. Please have a look at my new video of it and the reason why I developed it. cheers.

Thanks for commenting. I'm glad you sorted it out. Good reminder! Yes, you should always release the pressure and/or have to cap off when working on the CV. Cheers.

Glad you like! Cheers

Thanks for commenting. Yes, a cover is on my to-do list! Cheers

Thanks. It fits perfectly into my shop. I’m planning more amps in this sort of look. Cheers.

Thanks for commenting and for the feedback. It's always a fine line to what to focus on. If I make the video too long, people will not watch. I will keep it in mind though. My next tube amp video will be more about the circuit/wiring and less about the chassis. I figured that people who are watching my build videos know how to solder and install components, but I could be wrong. I guess I could do a seperate video just on that. Cheers.

Thanks for the feedback. My code reader and it shows nothing wrong. Most basic store bought code readers only typically show something when the engine light is on. I'm not sure if a high end / factory code reader would register anything. The method I show is just "tricking" the ECU with a "high pin" value. Cheers

Thanks for commenting. I’m glad you like the video. As for Coleman parts, I typically purchase from OCP and get it shipped to a mail box in Sumas Washington. I work near there and just drive across the border to pick it up. I also goto gatherings and obtain parts. What I’ve also done is find/buy beater lanterns and drive for parts. I have enough common parts to make things work. I hope that helps? Cheers.

Thanks Mike was wondering if they shipped to Canada, and couldn’t find any info

They do. Just give them all the shipping info up front and they can work out the costing. Rob is a good guy!

Thanks for the sub, I appreciate it! Cheers.

Let me track it down. My old server crashed and I lost a lot of file. I switched to Google docs. Stay tuned! Cheers.

Link is now fixed! Cheers

@@MikeFreda Excellent, I downloaded it. Thank you!

Oh, okay. That good to know. Cheers.

Thanks for commenting. The transformer I'm using in this preamp is actually used in a Fender Champ amp and its overkill for this circuit. This amp does not draw a lot of current, around 8-10ma. The tubes are bias very lightly to help minimize gain and distortion. The PT you quoted is rated to give 300-0-300 at 50ma of current draw. If you have small amount of current draw you will typically see the B+ voltage being a bit higher. Will it work in the circuit? Yes, it will. The 0D3 will cap the operating voltage at 150VDC but you may have to adjust the large dropping resistors that are placed right in front of the 0D3. Simple ohms law equation will get you in the ballpark. You "may" have to go slightly larger. Its hard to tell until you build and test it. I hope that helps?

@@MikeFredayes, that does help! I’ll do some more research in to a better suited transformer, but I’m finding some champ transformers that should work either way. I’ve built a few paint by numbers, high gain guitar amplifiers… but this will be my first hifi build! This looks like a great build! Thank you… I will post a video when I finish!

You're so welcome! Cheers.

Good to hear! Cheers.

Thanks and welcome. Check out my Short of Stave Falls Generation station. Just as cool.

Thanks for commenting. Glad you liked the video. Cheers.

Thanks for commenting. I typically order from Mouser and Antique Electronic Supply. For filter caps, there is a large selection of them. The main criteria is Voltage, heat range and life span so you have to pick wisely. Cheers.

@@MikeFreda I didn't see a chassis layout file, like dimensions(like you did for the 12AU7 linestage). Did you make one? totally cool, if not, i'm about to buy metal and just thought i'd ask. Thank you

No, I did not do a chassis layout. You could probably screen shot the chassis footage on the first video and draw it out by hand. I suspect most people would just do a large top plate so my layout probably wouldn’t work. If you want something, I could do a quick sketch for you. Cheers.

Of what? Just the axles? Outside drum face to outside drum face? Or Centerline of my tires?

Thanks for commenting. If you research, readup and start small, you could do something like this. Cheers

Thank you fo ryoru kind words! I'm glad you liek the build. It's a favorite of mine and I use it every day, Cheers

Yes, something like that! Cheers.

I can make some more if people like. Please send me a PM. You can do that by signing into RU-vid and going to my About section. Email address there. Thanks.

Please send me a PM and I can give you the details. Cheers.