Glad I found your channel! I just got done with about 12 Blues Junior resto’s. I did most of what you describe but great insights, great detail and some additional info that is fantastic. Thank you!
Also, you mentioned that blown out filter cap and you couldn’t understand why it was replaced before and it failed . I think that’s the cap that was labeled improperly on the first series of boards. I believe the board was marked with incorrect or reverse polarity and that created a lot of problems and I think it was corrected on later board versions.
Excellent instructional video. I’m just left wondering about the reverb op amp. Is the stock one noisier? I have some NE5532 and OPA2134's left over from another project. I wonder if they would sound better too??
Great question. For other applications the OPA2134 is fantastic and the 5532 is very good. For this application, noise is not the primary concern, it is the OPAMPS ability to source current to drive the reverb tank. The 4556 can source much more current than the 4558, 5532 and OPA2134. If you notice in the design the current is also limited by the 470R resistors after the half wave rectification. I recommend changing those resistors to 3W 220R and the zener diodes to 17V 5W and the filter caps to 470uF 25V. These changes along with the 4556 with drive the reverb tank much better. Email me at john@proampsolutions.com if you would like to discuss further, there are a few other tweaks that are germane to reverb improvement.
wow, great video, ive been looking into this amp as a main amp, as im downsizing, and im also an apprenticing amp tech and looking for a challenge. lots of good info here. thank you for doing what you do. cheers!
I have a couple of questions. First, I'm guessing that the power tubes run hotter as the amp is cranked up? So if someone used it in a low volume situation (small venues, Master all the way up & low gain, no cranked distortion), would it last longer) Second, would a cooling fan help alleviate tho problems? Thanks! Kevin
@@BCEpedals So, the second half of my question: I'm guessing that it gets hot because it's being pushed hard. I've been playing around 4 gigs a month with BJ's ever since they hit the market in '95, and the same one since the Cream Board came out in 2002, and have had no problems with heat at all. There is no visual evidence of overheating. The only explanation I can think of is, I don't try to get it loud or to breakup, so maybe??? I've used it in (early Chicago style) Blues bands (before they got loud and distorted), A nine piece Western Swing Band for ten years, small Jazz bands, Swing Bands, and Country Bands, but never needed to crank it up enough to distort it.
nice vid, thought I might try a question. Non running jr when I bought it. Had a broken tube so I replaced the tube board and tubes.. I did replace the output transformer but feel like I should have replaced the power transformer first instead. Anyways the main board is modded heavily but I'm not getting any power light. Is the power transformer the next best guess.. thanks
I'm so interested in absolutely everything going on so far in this video, but I'm at the part where the ceramic disk cap is being described as inferior to the silver mica, and I'm so curious about the legit reasons for this... like, the cap is a Z5U or something susceptible to temp, but like... what beyond that... scientifically speaking??
WOW! That's incredible detail. I have a new Blues Jr. IV and it sounds fine for my purposes. It has a black PC board, which I have never seen on any UA-cam feature. There is at least one difference I can see on the board: it does not have the bias resistor pair (I think that is the R51 R52 pair) that techs like yourself will modify. There is just one resistor in that location. I don't know what that means for the problem of overheating, but the amp sure runs hot. There may be other differences, but I wouldn't know enough to tell. Thanks for your video. Really appreciate it. Fascinating.
Thanks for your feedback. The black PC board Blues Jr IV is cathode biased, not fixed biased like the cream pcb. I've worked on a couple of these and even though they are cathode biased, they still seem to run too hot, but much improved. The last one I saw was right at 100% which does not leave any room for line voltage fluctuations. I like to see cathode biased amps run between 90-95% idle dissipation. If you are concerned, I recommend taking it to a qualified service tech. If it is too hot, the value of the cathode resistor can be changed to dial the idle dissipation it in where it needs to be.
I have a IV as well. It's a good sounding amp. My only wish it that it had an effects loop, but many Fender models don't. I have other amps that do, so it's not really a big deal to me.
That blue wire should be above the brown wire to help it clear the power section ribbon cable and reduce hum from capacitance coupling, just from my experience
I have a question I ask whoever may know. Amp hums. When I put my hand between the driver tube and first power tube next to it, the hum stops. At least mostly, and sometimes completely. Any ideas?
I have a few thoughts. The Blues Jr is very sensitive to lead dress especially the blue and brown plate wires. Secondly this amp is notorious for over dissipation, if the power tubes are out of balance it will induce hum and that is made worse by excessive dissipation. Thirdly you could elevate the heater supply, but that involves more work, but would likely solve your problem.
@@proampsolutions Thanks. I ran across someone on a forum that talked about elevating the heater supply. I'll have to look into what that involves. The same suggestion from multiple sources tells me to at least investigate it. These are great little amps when they work right. Thanks again
The blues junior is probably the worst of them all, but the other reissues would still benefit from a recap, different speaker, speaker jack, tightening of loose hardware, tone adjustments, and better input jacks.
How sad these popular amps seem doomed by design to fail. Really, Fender should have recalled them and sorted the overheating power tubes at the very least. These amps are not cheap... in the UK they retail well over £600 and I’m sure the repair work you have done is equivalent to a minimum 1/3rd of the cost of the amp. Throw in a speaker change and you are into 50% of new cost easily. I’d love to hear amp techs recommendations for affordable small tube combos that have been designed and built properly. I bet it would be a short list !
Fender should have. It's absolutely cynical- they figured out since they are and will continue moving the world's most popular amps there is no need to show any respect to the customer by improving their product.
I never had any Fender gear that did NOT needed extra pimping. That is why I don't buy anything of this brand anymore. The damage on the board is something I am aware of. The first series - made in USA - hums like sh.t when you turn the reverb on. What I find interesting is that people spend a lot of money for US equipment and have to modify it afterwards - in a way it should be already when you buy the product. And no one seems to find this awkward. Only US made weapons seem to do their job properly. I swapped my Blues de Luxe Reissue and my above mentioned 1995 bought BJ with Japanese stuff - great sound and reliability under ALL circumstances since then. Fender to me is at the very most "The brand that creates urban legends." All the hue and cry about Fender - and especially Gibson - is just hilarious.
They all do. Every amp company tries to get away with as much as possible to save a few bucks. Long gone are the days of companies over engineering products for the customers sake.
I was considering purchasing a Fender Blues Junior 3 or 4 but looking at the electronics build quality is absolutely shockingly shit. Cheap components and circuit board. Mass produced rubbish.
man thanks so much your a hidden jem of knowledge thanks for your kindness in sharing that i'm now a subscriber
I just got a new Fender “tweed” Blues Jr. Ltd. for Christmas and retired my Pro Jr. Love the tips and mods; Thanks!#Fender🎸❤️
Glad I found your channel! I just got done with about 12 Blues Junior resto’s. I did most of what you describe but great insights, great detail and some additional info that is fantastic. Thank you!
Thanks for your feedback, much appreciated!
What's the cost of all 3 mods ?
this dude is a genius. Can you do this to my Blues Jr Tweed?
Yes happy to help you with your Blues Jr Tweed. Email me... john@proampsolutions.com
Also, you mentioned that blown out filter cap and you couldn’t understand why it was replaced before and it failed . I think that’s the cap that was labeled improperly on the first series of boards. I believe the board was marked with incorrect or reverse polarity and that created a lot of problems and I think it was corrected on later board versions.
Excellent instructional video. I’m just left wondering about the reverb op amp. Is the stock one noisier? I have some NE5532 and OPA2134's left over from another project. I wonder if they would sound better too??
Great question. For other applications the OPA2134 is fantastic and the 5532 is very good. For this application, noise is not the primary concern, it is the OPAMPS ability to source current to drive the reverb tank. The 4556 can source much more current than the 4558, 5532 and OPA2134. If you notice in the design the current is also limited by the 470R resistors after the half wave rectification. I recommend changing those resistors to 3W 220R and the zener diodes to 17V 5W and the filter caps to 470uF 25V. These changes along with the 4556 with drive the reverb tank much better. Email me at john@proampsolutions.com if you would like to discuss further, there are a few other tweaks that are germane to reverb improvement.
wow, great video, ive been looking into this amp as a main amp, as im downsizing, and im also an apprenticing amp tech and looking for a challenge. lots of good info here. thank you for doing what you do. cheers!
The bipolar power supplies are always suspect in the Hotrod lineup. Great video.
I see alot of mods that change the transformer to a mercury, thoughts!
Great video - the weakest part is the sound tests... sound like they were recorded with a soup can and a string. But that's okay. Great great job.
Thank you for stimulating video.
What gear do you use in opening jingle?
Awesome!! love this! wish I had one! ha ha From mtw in L.,A.
Thanks 👍
I have a couple of questions. First, I'm guessing that the power tubes run hotter as the amp is cranked up? So if someone used it in a low volume situation (small venues, Master all the way up & low gain, no cranked distortion), would it last longer) Second, would a cooling fan help alleviate tho problems? Thanks! Kevin
No, the bias needs to be fixed regardless of the volume you play. And a fan won’t help enough. These get hot enough to melt PCB traces.
@@BCEpedals So, the second half of my question: I'm guessing that it gets hot because it's being pushed hard.
I've been playing around 4 gigs a month with BJ's ever since they hit the market in '95, and the same one since the Cream Board came out in 2002, and have had no problems with heat at all. There is no visual evidence of overheating.
The only explanation I can think of is, I don't try to get it loud or to breakup, so maybe??? I've used it in (early Chicago style) Blues bands (before they got loud and distorted), A nine piece Western Swing Band for ten years, small Jazz bands, Swing Bands, and Country Bands, but never needed to crank it up enough to distort it.
outstanding job!!!👍👌💯
nice vid, thought I might try a question. Non running jr when I bought it. Had a broken tube so I replaced the tube board and tubes.. I did replace the output transformer but feel like I should have replaced the power transformer first instead. Anyways the main board is modded heavily but I'm not getting any power light. Is the power transformer the next best guess.. thanks
I'm so interested in absolutely everything going on so far in this video, but I'm at the part where the ceramic disk cap is being described as inferior to the silver mica, and I'm so curious about the legit reasons for this... like, the cap is a Z5U or something susceptible to temp, but like... what beyond that... scientifically speaking??
I like the original sound, it seems more 3 dimensional and ambient and chimey, like I expect a Blues Jr to be : )
Do these updates apply to ALL versions of the Blues Jr.. I have one of the original early ones.
Looking for a good hand wired version of a Deluxe Reverb any option?
WOW! That's incredible detail. I have a new Blues Jr. IV and it sounds fine for my purposes. It has a black PC board, which I have never seen on any UA-cam feature. There is at least one difference I can see on the board: it does not have the bias resistor pair (I think that is the R51 R52 pair) that techs like yourself will modify. There is just one resistor in that location. I don't know what that means for the problem of overheating, but the amp sure runs hot. There may be other differences, but I wouldn't know enough to tell. Thanks for your video. Really appreciate it. Fascinating.
Thanks for your feedback. The black PC board Blues Jr IV is cathode biased, not fixed biased like the cream pcb. I've worked on a couple of these and even though they are cathode biased, they still seem to run too hot, but much improved. The last one I saw was right at 100% which does not leave any room for line voltage fluctuations. I like to see cathode biased amps run between 90-95% idle dissipation. If you are concerned, I recommend taking it to a qualified service tech. If it is too hot, the value of the cathode resistor can be changed to dial the idle dissipation it in where it needs to be.
I have a IV as well. It's a good sounding amp. My only wish it that it had an effects loop, but many Fender models don't. I have other amps that do, so it's not really a big deal to me.
@@proampsolutions Thank you!! I just confirmed I have a black board BJ IV and I was curious about the cathode bias.
That blue wire should be above the brown wire to help it clear the power section ribbon cable and reduce hum from capacitance coupling, just from my experience
I have a question I ask whoever may know. Amp hums. When I put my hand between the driver tube and first power tube next to it, the hum stops. At least mostly, and sometimes completely. Any ideas?
I have a few thoughts. The Blues Jr is very sensitive to lead dress especially the blue and brown plate wires. Secondly this amp is notorious for over dissipation, if the power tubes are out of balance it will induce hum and that is made worse by excessive dissipation. Thirdly you could elevate the heater supply, but that involves more work, but would likely solve your problem.
@@proampsolutions Thanks. I ran across someone on a forum that talked about elevating the heater supply. I'll have to look into what that involves. The same suggestion from multiple sources tells me to at least investigate it.
These are great little amps when they work right.
Thanks again
What amp would you recommend for around 1500 or less,thanks.
Question. How does a BF Princeton Reverb RI compare in reliability? Will it have all these problems?
The blues junior is probably the worst of them all, but the other reissues would still benefit from a recap, different speaker, speaker jack, tightening of loose hardware, tone adjustments, and better input jacks.
How sad these popular amps seem doomed by design to fail. Really, Fender should have recalled them and sorted the overheating power tubes at the very least.
These amps are not cheap... in the UK they retail well over £600 and I’m sure the repair work you have done is equivalent to a minimum 1/3rd of the cost of the amp. Throw in a speaker change and you are into 50% of new cost easily.
I’d love to hear amp techs recommendations for affordable small tube combos that have been designed and built properly. I bet it would be a short list !
Fender should have. It's absolutely cynical- they figured out since they are and will continue moving the world's most popular amps there is no need to show any respect to the customer by improving their product.
Good video but please stop saying a capacitor's value is some yooeff. That letter is micro not u. Microfarad. Not Yooeff.
@@ross3818It's a small thing, but also rubs me the wrong way when people say that.
problem is that speaker is the worst of all,you really need to get a decent one to hear the real sound of the amp circuit,no shortcut here
Sept.-1-2023, ✝️
I never had any Fender gear that did NOT needed extra pimping. That is why I don't buy anything of this brand anymore. The damage on the board is something I am aware of. The first series - made in USA - hums like sh.t when you turn the reverb on. What I find interesting is that people spend a lot of money for US equipment and have to modify it afterwards - in a way it should be already when you buy the product. And no one seems to find this awkward. Only US made weapons seem to do their job properly. I swapped my Blues de Luxe Reissue and my above mentioned 1995 bought BJ with Japanese stuff - great sound and reliability under ALL circumstances since then. Fender to me is at the very most "The brand that creates urban legends." All the hue and cry about Fender - and especially Gibson - is just hilarious.
Couldn't I use a chopstick like that? Too push on things, tap on tubes, and all that?
Sounds worse after all that messing !!
Just looking at those PCB's , I see that Fender is outright RIPPING-OFF thier buyers. Wake up people!
They all do. Every amp company tries to get away with as much as possible to save a few bucks. Long gone are the days of companies over engineering products for the customers sake.
"Wake up people!" 🤣
I was considering purchasing a Fender Blues Junior 3 or 4 but looking at the electronics build quality is absolutely shockingly shit. Cheap components and circuit board. Mass produced rubbish.
It's a disposable amp. Just throw it out and get a new one
Nope never.
Well worth spending the money on repairing it you can't do it yourself.
one of the worst amps on earth only a vintage mullard at v1 can save the tone