Fender Blues Jr Common Problems, PCB Replacement & Upgrades

Рет қаралды 7,550

2 жыл бұрын

This one suffered a lot of damage from a shorted valve.
It appears the previous tech then attempted to repair it without replacing the problem EL84. Hilarity then ensued.

Пікірлер: 49

@goodun2974 2 жыл бұрын

In the US it would have been Wheaties cereal: the ad campaign billed it as "The Breakfast of Champions", and so it passed into popular culture, with working people about to do a hard job saying "I hope everybody ate their Wheaties this morning!", although scientific examination eventually determined that despite the claims of being fortified with vitamins and minerals, Wheaties was nothing special nutritionally or energy-wise. A bartender in one of Kurt Vonnegut's novels, however, referred to a *martini* as the Breakfast of Champions!

@weschilton 2 жыл бұрын

Really nice work on that little guy. Love your custom PCB, world's better than what Fender came up with.

@rgbplumbinghilton 2 жыл бұрын

Great vid of one of the best selling amps..... Obviously fender don't want to admit the issues with them. The new looks like it's well designed and made!

@scottyotoole6125 7 ай бұрын

In the States our wheat biscuit breakfast equivalent would be Wheaties. Just found your channel. Enjoying the repairs! Cheers!

@edwardhannigan6324 2 жыл бұрын

Super interesting Brad, love the walk thru and all your fab tips.. Learning all the time..Ed.uk😁

@BradsGuitarGarage 2 жыл бұрын

So am I, mate! Learning new things and watching out for new "gotchas" every day!

@goodun2974 2 жыл бұрын

Nice crimpers; I have a similar but less expensive set that requires removing a pair of bolts to change the crimping dies. However, this type of crimp fitting does not constitute a cold weld, and I really don't recommend these for high current or high voltage connections, including filament supplies, mains B+, or screen supplies. The spade connectors on Fenders are a known failure point; I know you've seen Lyle at Psionic Audio bypass the plug-in connectors on some models in favor of soldering direct to the board or the sockets. Anyway, if you absolutely must crimp a new connector on, you're better off to use a high quality electricians' grade connector like those made by Panduit, perhaps even the uninsulated type that you crimp first and then slip an insulator over. A $30 pair of Klein crimpers used on the right connector will give you a military-style cold weld that smooshes (technical term, ha ha!) the two metals together into a gas-tight connection. PS, I don't think those crimps you used are designed for anything other than stranded wire; probably not great for use on solid or tinned/solidified wire.

@axemonkey Жыл бұрын

How did you put a knife through your foot? Also, does your output pcb for the peavey classic 30 also work for the peavey classic 50 and if so, what is the price for one?

@theguitaramptech 2 жыл бұрын

I really like your new valve mount PCB, Brad. Trust an Aussie ☺️

@BradsGuitarGarage 2 жыл бұрын

Thanks mate, I've got plenty in stock so hit me up if you're in need.

@theguitaramptech 2 жыл бұрын

@@BradsGuitarGarage thanks mate. I had one last week with a buckled board.

@rjake61 2 жыл бұрын

There’s a black board version out there with a 2019 design copyright. It has all the BJ IV changes, plus cathode bias with dual 270 ohm resistors. Blues Jr. Lacquered Tweed LTD from 2021.

@BradsGuitarGarage 2 жыл бұрын

Haven't seen that one yet. I guess they're all still working then!

@goodun2974 2 жыл бұрын

Considering that the previous "tech" who worked on the amplifier probably charged the owner an hour and a 1/2 to build that stupid auxiliary output jack panel, the customer probably could have spent just a little bit more money and got a replacement output transformer with multiple impedance taps.

@montygore1200 Жыл бұрын

What the heck is a breakfast biscuit. I always heard to tighten those things till your eyes bug out..

@russellesimonetta3835 2 жыл бұрын

Lyle is a gem. Very ,very Vox expert.

@BradsGuitarGarage 2 жыл бұрын

Super very.

@goodun2974 2 жыл бұрын

Those are very nice looking boards. I like the isolating slots inbetween the ribbon-cable connections. Strictly for your own customers or are you going to sell them?

@BradsGuitarGarage 2 жыл бұрын

I sell them to other techs only at the moment. Can't deal time-wise with any support requests from inexperienced users attempting a DIY installation.

@shanedolman1368 2 жыл бұрын

@@BradsGuitarGarage They are very cool looking Brad, I'm a tech and builder here in the UK, would you be willing to send one over here if I needed one and if so how much would it cost me? Cheers mate👍

@tjminasi1442 2 жыл бұрын

Leave no traces, hilarious bud!

@robertoaranibar8829 2 жыл бұрын

Great fix and thank you for this video. The amp sounded great at the end of the video. I’m assuming the new caps you used made the difference. I wish I had a tech like you where I live. My blues jr stopped working a few months ago and I took it to a tech who did a terrible job. I had to take it back to him 3 times because it sounded terrible and rattled after he fixed it. Then it didn’t even work when I got home with it the last time. It was a 45-min drive to the tech, the “repair” had already cost a couple hundred bucks, and I wasn’t about to go out there again. Now I’d like to try to fix it but I’m concerned about the risks of dealing with such high voltages without enough knowledge of what I’m doing. Do you have any advice on how I could safely learn to fix my amp?

@BradsGuitarGarage 2 жыл бұрын

Where are you located, mate?

@BradsGuitarGarage 2 жыл бұрын

Unless you want to embark on a lifetime of electronics, I'd suggest just finding a better tech. If you just want your amp to work, that's the best option. If you want to get into electronics, forget KZfaq and buy books: Art Of Electronics, How to Fix Everything Electronic, Designing Valve Preamps for Guitar and Bass (Second Edition) and many others will get you started.

@robertoaranibar8829 2 жыл бұрын

@@BradsGuitarGarage Thanks for your response. I’m in the US (San Antonio, Texas). I will definitely look into the books you mentioned. Really enjoyed your video… lots of funny stuff with the education. Rock on my friend!

@BradsGuitarGarage 2 жыл бұрын

There are some guys I can recommend in Austin. Shoot me an email if you'd like more details. I hate to see incompetent techs destroying things and scamming money out of people.

@jackheinemann8780 Жыл бұрын

I started repairing Hifi amplifiers, they are much much safer, especially the small ones. I'm here because my original blues jr from the late 90s has (finally) started playing up. I've done alot of work on alot of stuff, but working on these things gives me the heebie jeebies

@nellayema2455 2 жыл бұрын

Is there any worthwhile benefit of doing the Fromel Standby Switch mod. on a Blues Jr.?

@BradsGuitarGarage 2 жыл бұрын

No. Standby switches are unnecessary on this model as there is enough margin in the voltage rating of the capacitors that the unloaded HT doesn't exceed it before the valves warm up enough to conduct and load it down.

@zbaby82 2 жыл бұрын

Could a bias pot be installed on this amp?

@retread1083 2 жыл бұрын

From an electrical perspective, yes. And the safest method would be to add a trimpot (I'm guessing 15k should get you there) connected as a rheostat in series with R52. Since the plate current is a bit too high in stock configuration, if some wanker blindly adjusts the pot to minimum resistance, the worst that will happen is that the plate current will be a bit too high. And if the wiper contact to the element becomes intermittent or fails entirely, the (-) bias voltage will go up to the 26v rail. That would mean the plate current would be very low. Definitely better than having the bias float and having way too much plate current. Of course when the plate current drops the plate voltage will increase a bit. And we're already above maximum voltage spec for these tubes. So saying this failure mode is "safe" is somewhat relative in this case. But coming up with a strategy to mechanically mount the trimpot to the printed board could be a bit tricky. So all things considered, finding a goldilocks value for the division ratio with fixed resistors and calling it a day is a pretty good plan.

@BradsGuitarGarage 2 жыл бұрын

YES! Rowan from Keld Ampworks sent me some little elevated adjustable bias PCBs (we all do a little trading of our wares!) for this amp, I forgot all about it. If I remembered, I would have installed it and given him a shoutout. Oh well, there's always next time.

@michaelwbuncher7599 2 жыл бұрын

@@BradsGuitarGarage There will always be another blues jr on the bench eh?

@mattgilbert7347 2 жыл бұрын

1:55 - 2:55 faarkin hell, mate! From the ridiculous to the even more ridiculous. Where are you located? My old tech is retired. I'm in Sydney.

@BradsGuitarGarage 2 жыл бұрын

Google the name and we'll pop up, mate.

@mattgilbert7347 2 жыл бұрын

Will do. Cheers.

@luthiervandros Жыл бұрын

Leave no trace 😂😂

@BradsGuitarGarage Жыл бұрын

HAHA! I didn't even think of that when I said it! Good one.

@luthiervandros Жыл бұрын

@@BradsGuitarGarage solid gold!😂

@THEQueeferSutherland 2 жыл бұрын

That hot glue tho..... Why?

@BradsGuitarGarage 2 жыл бұрын

42.

@richwallace6854 Жыл бұрын

You confused me, Brad. When you said the PCB was twice as thick, you DID mean twice the "weight" , right? You know, say from 1 oz copper to 2 oz copper. I watched other videos on Fender amp repaic and always felt that Fender used cheap- ass PCB materials, plus cheap components.

@BradsGuitarGarage Жыл бұрын

Yes, the copper is twice as thick, not the substrate. The substrate on the Fender ones was 1.6mm this one was 2mm. The manufacturer screwed up my last order and sent me 1.6mm but they're fine. I'll make sure they get me 2mm on the next order, though.

@tjminasi1442 2 жыл бұрын

Triple voltmeters. They only way to go.