Fender sets the bias too hot at the factory, a major design error. Fender uses cheap plastic jacks which break too easily. Thanks for installing new USA Switchcraft jacks ! You set a good example.
Great Stuff and much appreciated. I have a 1999 USA Blues Jr (green board 1995 Rev B P/N 049305) purchased new by me in ’99 which is different from all the cream board Jr’s all over YT. Even with limited use as a bedroom amp the hot bias has has resulted in a few power tube socket pins to loosen from the tube board, thus the desire to cool the bias and continue using the amp. As I understand this board revision schematic, R37 and R31 make the voltage divider circuit and a parallel resistor across R37 would cool off the bias. Values per the schematic are R37-33k and R31-22k. What would the proper ohm rating of the resistor to accomplish this? I hope I have described all this properly. Thank you…
I am in the same boat. Am I correct in that tacking a 68K ohm resistor across R37 on the old green boards is accomplishing the same as this procedure on R51 in the later cream and clear boards?
They come with handles for a REASON people! Little tip for machine (or any) screw re-insertion. Hold screw with fingers (or driver) and very slowly turn COUNTER clockwise while maintaining slight inward pressure. The male thread lead will seat itself in the female with a very slight and sudden drop. You need to pay very close attention though...if you're not sure, keep slowly turning and you'll definitely notice the sudden change in motion. If/when using a driver in a quiet environment, this will be even more noticeable, especially in hard materials. I've been using this method flawlessly for years. Cross-threading be gone! Great fix again Lyle, that thing sounds sweet.
Appreciate the info. I said I would not do another Blues Junior, but I was talked into another. This is after I just finished a Hot Rod Deluxe that was sitting in the back of a pickup truck that visits concrete contractor job sites for 3 weeks. Thanks again.
Fascinating video. I've just obtained a Blues Junior (not sure of the vintage, but it is a tweed and has the leather handle) and would like to have these same secure upgrades. Do you have a recommendation of a skilled tech on Long Island, NY, whom you would trust to do right by the amp? Also, is there a particular speaker (or series of speakers) you would suggest to replace the stock speaker? Much appreciate any guidance.
I detail cars as a side hustle and I’ve found that the best thing to clean my amp tolex is Meguiar’s all purpose cleaner diluted 10:1 and any water based dressing such as chemical guys tire kicker or vrp.
Sounds good. I have a dozen of these in various states of disrepair. They price point makes it hard for owners to justify getting them fixed and they want to cut their losses. Fixing them isn’t how I make my living, I just enjoy it. Another great video, thanks.
Did you somehow instantly switch from a green board, to a cream board? And then never show the jack insulation used? Or do they BOTH need it? I guess, this entirely depends on someone centering the jack in the chassis hole when tightening it down? If so, it would have been nice to see a pic of it....& maybe a reference to what & where of the insulation?
A friend brought his hotrod deluxe in with a missing dogbone handle. He had a makeshift replacement (scarf) and insisted that it was stable. I picked it up and down the amp went. I replaced it with the appropriate handle. Very inexpensive and easy to replace. Luckily, the amp still works. Now I can focus on the real issues with this amp.
You talked about the rg-174 shielded cable that you're using can you recommend a good two wire shielded cable of the same gage of wire? Thank you - I thoroughly enjoy watching repairs done correctly and professionally.
Hi there, thanks for this video! Really great, a lot easier than doing the trimpot! I have an old Blues Jr. as well which I want to cool down a bit, but it's the green board version. I do the resistors will have a different number on the board, but would the same procedure with the 68K resistor apply? Also a bit of a dumb question maybe... but how do 33K and 68K add up/subtract to become 24K? EDIT: Sorry I see there's a formula for that :) 1/Req = 1/R1 + 1/R2 ... So that makes the 68K and 33K resistors add up to about 22K. In your other video you're using an 81K, which seems even nicer, as it adds up to 23.45K. Cheers!
Hi again! I asked the wrong question earlier. What value resistor did you use for the grid stopper before the connection to V1 Pin 2? Thanks again for all the great videos!!
@@PsionicAudio Thanks that sounds about right. Really appreciate the response! I noticed you clipped R2 and R4 since they are no longer needed after this mod. I've been watching all your fender amp related videos. Really do appreciate the work you do. Keep Rockin'!
Just had a guitar in for service and the case had a broken handle... How the hell do you carry that to a gig? Same thing... $8. Blues Jr. sounds good man!
I'm learning a lot from these Blues Junior videos - thanks! I just recently picked up a nice used one (in lacquered tweed), so I might try the bias mod and the reverb mod from your other video. Dumb question: I noticed the labeling of the controls on my amp is upside-down compared to this one (if I stand facing the front of the amp and look down on the controls, the lettering is upside-down). The labels are also white-on-chrome, which is hard to read from most angles. I don't know the history of the Blues Junior - is this something Fender changed at some point?
Yeah, they reversed the print at some point. Insides are the same. I strongly recommend the bias mod as the amp is much less likely to catch on fire afterwards. That's not hyperbole.
What's the temperature of your soldering iron set to for the bios correction mod.? I have a Blues Jr. IV coming tomorrow. I didn't want to spend $1500 on a Deluxe Reverb reissue, so after a lot of research, decided on the Blues Jr. Seems like a good amp. for the price. Honestly, I'd grab a clean Peavey ValveKing II if I could find one--they have some nice features, IMO. I also ordered the amp. cover for the Blues Jr to keep all the dust and cat hair off when not in use. I don't dust often enough around here, lol.
That's how it works on the Princeton Reverb reissue. Not sure how the schematic is different on this amp and if it would work, but I'm guessing 'probably.' I don't like how the Princeton grounds to chassis because if the nut isn't super tight I get static, etc. Seems like a wire may make a better connection. I'm trying to find if I can replace the Princeton with a Switchcraft Jack like thus
At 11:32 you say to take a 68k resistor but in another video of yours you say to use an 82k ohm 1/2 W resistor. A 33k + 82k gives you 24k. Which is correct? Using an 82k you get and equivalent resistance of 23.5k and with a 68k it is 22.2k. Either is correct, I guess, but is it better at 22.2k? Thanks
I just scored a USA made Jr with the green board. Opened the back and all looks really good, no heat spots, original GT power tubes and a new set of JJ preamp tubes. Have read that the circuits are different between the green and brown boards, would the bias cooling mod be beneficial for my amp also? Great vids thanks
For the 1 meg resistor on the jack.... Is it 1/2 watt metal film resistor? Does that matter? Needing to replace a blues junior jack and can't find a clear answer Is that only needed if you're wiring outside of the PCB? Someone help. I'm working with a blues Jr IV black board with cathode biasing
Nobody "decided" they were going to butcher that board when they replaced the jack. Come on man. "yea, let me just go ahead and fk this input jack pad up.... And one more... Great! Perfect! Good and fked! Exactly like I decided I wanted to do!" 🤣🤣🤣🤣🤣 It actually just sounds pretentious. "somebosy decided they were going to screw this board up" you know good & well they didn't purposely do that. They just had crappy tools and/or a crappy repair procedure.
If you're looking for a less labour-intensive alternative for using a soft bristle toothbrush to clean tolex, get a soft bristle vegetable brush to clean the larger areas. (I stole this trick from @GranvilleGuitars.)
@@PsionicAudio Actually, LPS-1 is a better control cleaner. Deoxit G 100 is the best and has no solvents. Fader Lube is substandard, and won't last long enough. Use D-100 or G-100 or LPS-1 and it will work better.
Frankly, if I was building amps to sell, I'd probably use some kind of security screw to lessen the chance of tampering by wanna-be techs, or alert an actual technician from the look of the chewed-up screwheads that somebody with poor mechanical skills and the wrong tools had messed with the amp. Perhaps Torx screws with the pin in the middle of the head so that only a Tork bit with a hole in the center would fit the screw ( though those are easier to find nowadays). How obscure a fastener would you have to use to keep people from getting inside the amp? Maybe those hourglass-shaped clutch-drive heads that you see in restroom toilet stalls? Or "snake-eye" screws? Those two are sometimes used in prisons (Ampeg used the clutch-drive screws on their amplifiers back in the 1960s). Years ago, when I was doing nightclub sound system installations, we used to use square drive Robertson head screws (unusual in the US at the time, but now used for installing outside decking) to fasten covers over the crossovers and equalizers to prevent the DJ's from messing with them, but unfortunately the DJ's figured out that a small flat blade screwdriver of the right width would fit the square drive Robertson screws kiddy-corner and allow them to remove the screws and security covers.... You can never make anything completely full proof because fools are so ingenious; and dance-club DJ's are one of the lowest life forms on the planet....
To all the sniffers that think Fender products are superior.these PCB boards are one of the worst boards to work on . traces become detached with the littlest ease . just a joke as any thing from the Asian Market is superior ..... Peavey ,Jet city ,Orange TT are rock solid
I agree about PC boards in a Fender.....I have a Princeton Reverb RI and will be taking the CB out and doing a p-p wiring job. I have a Fender Deluxe RI and that will be my next project for 2022 !
Fender sets the bias too hot at the factory, a major design error.
Fender uses cheap plastic jacks which break too easily. Thanks for installing new USA Switchcraft jacks ! You set a good example.
Hey man, thanks a lot! I did the bias mod and the reverb mod this afternoon on my Blues Junior III. Sounds great! Your videos have been so helpful.
I'm a fan of the Blues Jr. perfect giging amp for old guys not ready to hang it up.
Great Stuff and much appreciated. I have a 1999 USA Blues Jr (green board 1995 Rev B P/N 049305) purchased new by me in ’99 which is different from all the cream board Jr’s all over YT. Even with limited use as a bedroom amp the hot bias has has resulted in a few power tube socket pins to loosen from the tube board, thus the desire to cool the bias and continue using the amp. As I understand this board revision schematic, R37 and R31 make the voltage divider circuit and a parallel resistor across R37 would cool off the bias. Values per the schematic are R37-33k and R31-22k. What would the proper ohm rating of the resistor to accomplish this?
I hope I have described all this properly.
Thank you…
I am in the same boat. Am I correct in that tacking a 68K ohm resistor across R37 on the old green boards is accomplishing the same as this procedure on R51 in the later cream and clear boards?
They come with handles for a REASON people! Little tip for machine (or any) screw re-insertion. Hold screw with fingers (or driver) and very slowly turn COUNTER clockwise while maintaining slight inward pressure. The male thread lead will seat itself in the female with a very slight and sudden drop. You need to pay very close attention though...if you're not sure, keep slowly turning and you'll definitely notice the sudden change in motion. If/when using a driver in a quiet environment, this will be even more noticeable, especially in hard materials. I've been using this method flawlessly for years. Cross-threading be gone! Great fix again Lyle, that thing sounds sweet.
I was just posting the same 😂 especially enclosure screws I handle that way.
Appreciate the info. I said I would not do another Blues Junior, but I was talked into another. This is after I just finished a Hot Rod Deluxe that was sitting in the back of a pickup truck that visits concrete contractor job sites for 3 weeks. Thanks again.
Nice fix Lyle..Great sound as well. Good tips as usual..Thanks for sharing..Ed..uk..😀
Fascinating video. I've just obtained a Blues Junior (not sure of the vintage, but it is a tweed and has the leather handle) and would like to have these same secure upgrades. Do you have a recommendation of a skilled tech on Long Island, NY, whom you would trust to do right by the amp? Also, is there a particular speaker (or series of speakers) you would suggest to replace the stock speaker? Much appreciate any guidance.
I detail cars as a side hustle and I’ve found that the best thing to clean my amp tolex is Meguiar’s all purpose cleaner diluted 10:1 and any water based dressing such as chemical guys tire kicker or vrp.
Diluted Murphy's Oil Soap works great on Tolex-type coverings.
Spin the wheel of stupidity.. haha, quote of the week.
“You can’t fix stupid!”
Sounds good. I have a dozen of these in various states of disrepair. They price point makes it hard for owners to justify getting them fixed and they want to cut their losses. Fixing them isn’t how I make my living, I just enjoy it. Another great video, thanks.
Highly enjoyable video, very educational
Did you somehow instantly switch from a green board, to a cream board?
And then never show the jack insulation used? Or do they BOTH need it?
I guess, this entirely depends on someone centering the jack in the chassis hole when tightening it down?
If so, it would have been nice to see a pic of it....& maybe a reference to what & where of the insulation?
Just did 68k Resistor mod,love new sound,thanks great vid
A friend brought his hotrod deluxe in with a missing dogbone handle. He had a makeshift replacement (scarf) and insisted that it was stable. I picked it up and down the amp went. I replaced it with the appropriate handle. Very inexpensive and easy to replace. Luckily, the amp still works. Now I can focus on the real issues with this amp.
Thanks for all your great videos! Does the shielded cable go to V1 Pin 2?
You talked about the rg-174 shielded cable that you're using can you recommend a good two wire shielded cable of the same gage of wire? Thank you - I thoroughly enjoy watching repairs done correctly and professionally.
Hi there, thanks for this video! Really great, a lot easier than doing the trimpot!
I have an old Blues Jr. as well which I want to cool down a bit, but it's the green board version. I do the resistors will have a different number on the board, but would the same procedure with the 68K resistor apply?
Also a bit of a dumb question maybe... but how do 33K and 68K add up/subtract to become 24K?
EDIT: Sorry I see there's a formula for that :) 1/Req = 1/R1 + 1/R2 ... So that makes the 68K and 33K resistors add up to about 22K. In your other video you're using an 81K, which seems even nicer, as it adds up to 23.45K.
Cheers!
Hi Lyle, I'm curious where you source shoulder washers for the input jack? Kinda necessary for mounting the jack, and avoiding ground loops. Thanks 😊
Hi again! I asked the wrong question earlier. What value resistor did you use for the grid stopper before the connection to V1 Pin 2? Thanks again for all the great videos!!
I would think a 33K to emulate a Princeton, Deluxe, etc. But I don't remember.
@@PsionicAudio Thanks that sounds about right. Really appreciate the response! I noticed you clipped R2 and R4 since they are no longer needed after this mod. I've been watching all your fender amp related videos. Really do appreciate the work you do. Keep Rockin'!
That sounds killer. I really like the Blues Jr's
Just had a guitar in for service and the case had a broken handle... How the hell do you carry that to a gig? Same thing... $8. Blues Jr. sounds good man!
I'm learning a lot from these Blues Junior videos - thanks! I just recently picked up a nice used one (in lacquered tweed), so I might try the bias mod and the reverb mod from your other video.
Dumb question: I noticed the labeling of the controls on my amp is upside-down compared to this one (if I stand facing the front of the amp and look down on the controls, the lettering is upside-down). The labels are also white-on-chrome, which is hard to read from most angles. I don't know the history of the Blues Junior - is this something Fender changed at some point?
Yeah, they reversed the print at some point. Insides are the same. I strongly recommend the bias mod as the amp is much less likely to catch on fire afterwards.
That's not hyperbole.
Thanks so much for posting. Your mods to care of the problems I was having with my amp.
What's the temperature of your soldering iron set to for the bios correction mod.? I have a Blues Jr. IV coming tomorrow. I didn't want to spend $1500 on a Deluxe Reverb reissue, so after a lot of research, decided on the Blues Jr. Seems like a good amp. for the price. Honestly, I'd grab a clean Peavey ValveKing II if I could find one--they have some nice features, IMO. I also ordered the amp. cover for the Blues Jr to keep all the dust and cat hair off when not in use. I don't dust often enough around here, lol.
700F.
But don't do anything to it for a bit. Think long and hard while you still have a return period.
I used the Bill m jack; switch raft jack with Mogami shielded cable.
When replacing the jack, could we just not run a ground wire and purposely ground it to the chassis with the nut and lock washer?
That's how it works on the Princeton Reverb reissue. Not sure how the schematic is different on this amp and if it would work, but I'm guessing 'probably.' I don't like how the Princeton grounds to chassis because if the nut isn't super tight I get static, etc. Seems like a wire may make a better connection. I'm trying to find if I can replace the Princeton with a Switchcraft Jack like thus
I happen to have some 1/4 watt 68K metal film resistors. Are those ok?
Coffee? That was indiscriminate spooge 😜
Those ribbon cables are a nightmare. Look at them wrong and you’ll be chasing gremlins for hours.
At 11:32 you say to take a 68k resistor but in another video of yours you say to use an 82k ohm 1/2 W resistor. A 33k + 82k gives you 24k. Which is correct? Using an 82k you get and equivalent resistance of 23.5k and with a 68k it is 22.2k. Either is correct, I guess, but is it better at 22.2k? Thanks
Either is fine. I slightly prefer the 68K now but it’s a minor difference. Both are vast improvements over the stock bias level.
Thanks for replying. Another video guy put in a 150K which brought the bios down to 22.2. Is that too cool?
It appears you redid the resisters on the board for r-1, r-2, and r-4. What where those changes?
Are those handle screws machine or wood?
I thought it was the other way around? Less power to the tubes should make them brake up earlier because of less headroom? I could be wrong :)
LMFAO.......a 'sterile' amp !...............nice informative video this Sat AM with a cup of java !
It’s sad that one cannot perform a repair on a piece of gear , or anything, without justifying every decision made. Nice job.
when has this not been the case?
I just scored a USA made Jr with the green board. Opened the back and all looks really good, no heat spots, original GT power tubes and a new set of JJ preamp tubes. Have read that the circuits are different between the green and brown boards, would the bias cooling mod be beneficial for my amp also? Great vids thanks
I am wondering the same. I have a Mexico cream board.
Hello do you do repairs on fender deluxe reverb If i ship you the chassis from north carolina here
Was this the IV version? I thought Fender had addressed the bias issue in the latest version.
No, the IV has bad bias too.
Where do you get your shielded cable? I need to buy some more, but the stuff I got last time was bulky compared to the stuff you use
I get this from Apex Jr. Terrible website but a good company.
@@PsionicAudio I'm just now seeing your replies. Thank you for all your help and knowledge
I use Tuff Stuff upholstery cleaner, and it works GREAT!
Armorall was banned from my property back in the 20th century. Armorall can screw up radial tires, so.....
Psionic amp coffee coasters... Sell the amp business and become a billionaire in amp coaster sales. So what's a good re-issue Fender amp to buy?
Is it time for a deposit on my new amp?
"who's we,sucker?"..."me, Smith and Wesson"
How high does the plate voltage get when you lower the bias? Thank you
I don't remember but I've measured it and it doesn't stress the 84s.
I have a 2000 pro Jr. I have done the same. I'll never use armerall again!
I can picture some player going, "screwdrivers have *numbers*?" 🤔
Holmes on Amps saves yet another tortured, stained and neglected tone orphan. "Please sir...may I have some tone...?" "MORE?!?!?" ;-)
Where did you get the shielded cable from?
apexjr.com
Are all blues jrs biased that way
V1-3 yes. V4 they improved it a little but it's still way too hot.
For the 1 meg resistor on the jack.... Is it 1/2 watt metal film resistor? Does that matter? Needing to replace a blues junior jack and can't find a clear answer
Is that only needed if you're wiring outside of the PCB? Someone help.
I'm working with a blues Jr IV black board with cathode biasing
1/2W MF, CF, or CC in an original ‘60s Fender. MF or CF in a Blues Jr.
@@PsionicAudio
Thanks a lot man. Your videos are very helpful
Simple Green works well.
I would dilute that heavily with a lot of water.
Nobody "decided" they were going to butcher that board when they replaced the jack. Come on man.
"yea, let me just go ahead and fk this input jack pad up.... And one more... Great! Perfect! Good and fked! Exactly like I decided I wanted to do!"
🤣🤣🤣🤣🤣
It actually just sounds pretentious. "somebosy decided they were going to screw this board up" you know good & well they didn't purposely do that. They just had crappy tools and/or a crappy repair procedure.
If you're looking for a less labour-intensive alternative for using a soft bristle toothbrush to clean tolex, get a soft bristle vegetable brush to clean the larger areas. (I stole this trick from @GranvilleGuitars.)
Hello how can you be reached for tech work?
info@psionicaudio.com
@@PsionicAudio yes I’ve sent there and no response
@@PsionicAudio not sure if you’re getting my emails? Any other way to contact? Facebook?
Spray9 ... is the best cleaner ....
Use some DeoxIT on those pots!
I've got that and fader lube and a few dozen other specialized products. But first, see if it can go away without solvents etc.
@@PsionicAudio Actually, LPS-1 is a better control cleaner. Deoxit G 100 is the best and has no solvents. Fader Lube is substandard, and won't last long enough. Use D-100 or G-100 or LPS-1 and it will work better.
@@michaelstevenfriedlander4583 Also, armour all, does f-all to PVC.
The correct value is 82k of piggy resistor.
Thank you.
Now - if we could just do something about the cheap flimsy plastic shaft volume pots...
Coffee stains.....does that make it a Marshall-adjacent "Kitchen" amp? 🤣
Frankly, if I was building amps to sell, I'd probably use some kind of security screw to lessen the chance of tampering by wanna-be techs, or alert an actual technician from the look of the chewed-up screwheads that somebody with poor mechanical skills and the wrong tools had messed with the amp. Perhaps Torx screws with the pin in the middle of the head so that only a Tork bit with a hole in the center would fit the screw ( though those are easier to find nowadays). How obscure a fastener would you have to use to keep people from getting inside the amp? Maybe those hourglass-shaped clutch-drive heads that you see in restroom toilet stalls? Or "snake-eye" screws? Those two are sometimes used in prisons (Ampeg used the clutch-drive screws on their amplifiers back in the 1960s). Years ago, when I was doing nightclub sound system installations, we used to use square drive Robertson head screws (unusual in the US at the time, but now used for installing outside decking) to fasten covers over the crossovers and equalizers to prevent the DJ's from messing with them, but unfortunately the DJ's figured out that a small flat blade screwdriver of the right width would fit the square drive Robertson screws kiddy-corner and allow them to remove the screws and security covers.... You can never make anything completely full proof because fools are so ingenious; and dance-club DJ's are one of the lowest life forms on the planet....
To all the sniffers that think Fender products are superior.these PCB boards are one of the worst boards to work on . traces become detached with the littlest ease . just a joke as any thing from the Asian Market is superior ..... Peavey ,Jet city ,Orange TT are rock solid
I agree about PC boards in a Fender.....I have a Princeton Reverb RI and will be taking the CB out and doing a p-p wiring job. I have a Fender Deluxe RI and that will be my next project for 2022 !
Its like a mechanic who has to work on a disgusting car.