Hi, Stuart. Just wanted to say how good your videos are! I've been working on a few amps over the last couple of months, and your videos are priceless. Thank you
Well done, Stuart. That death cap was waiting to send this amp's owner to the land of wind and ghosts. Safety of the customer clearly outweighs his request in leaving an amp with little, to no modification(s). Another vintage Fender tweed class lives on! Cheers!
Nice little amp to be working on. These do have a good clean sound, but not very loud. I played one back in the 70's and loved it. It's fun to watch you diagnosing issues and repairing them. I wish you had explained better the use of two caps to replace one for the novices like me. As always this was fun and educational. Keep it up Stuart.
I don't play guitar or own amps but I have a ridiculous amount of synths, drum machines, effects and eurorack modules.. I really appreciate and enjoy your videos while learning.. thank you Professor from Upstate, New York..
What a little beauty Stuart..! Nice job on that relic..Lovely to see such a nice piece of history..Great service and info on repair..More learned.Thanks for sharing your expertise once again..Ed..uk.😀
At 6:20, Stuart spins the tube shield expecting it to come off, but it's not the usual bayonet type of shield and socket. This socket has a sprungy, flanged base and the shield snaps down on to it, it's not bayonet mount. We see these pretty commonly here in the States on certain brands of amplifier such as Danelectro/Silvertone guitar amps and various radios and hifi gear.
Two issues: 1) Clipping out the "death cap" is only half of the job; as wired, the neutral is connected to and through the fuse holder, and the hot wire to/through the power switch; very bad wiring practice that doesn't meet modern electrical codes but was unfortunately common practice during the 50s and 60s. The neutral wire should be connected directly to one leg of the power transformer's primary winding, and the hot should pass through both the fuse holder and the switch before routing to the transformer primary. And 2) note the light greenish corrosion on the RCA jack used for the speaker connection: THIS IS A CRITICAL GROUND & CIRCUIT CONNECTION POINT. The plating of the female RCA connector (bolted to the chassis for a mechanical ground) is particularly prone to developing a powdery film of greenish-white corrosion which, if it causes intermittent connection to the male RCA plug and the speaker therefore cuts out as the amp is playing and vibrating can cause a blown output transformer! Note that the chassis mounted jack and the chassis is the ONLY negative connection for both the audio to the speaker *AND* the negative feedback circuit; a poor connection between the female jack and the chassis can cause a resistive chassis ground or loss of ground, which again can cause the speaker to cut out while the amp is being played, which could blow the output transformer! Even if the audio to the speaker doesn't cut out , a resistive connection here can cause reduction or loss of negative feedback, and hence more distortion. The speaker jack should always be unbolted from the chassis, both connectors cleaned and polished, and the chassis and bolts cleaned before reinstalling the jack. Spraying it with DeOxit won't fix it; you need to manually clean the parts with a a small wire brush, a pencil eraser, a fiberglass "scratch brush".... even a scrubbing with toothbrush and alcohol is better than leaving it as found, but you really need to unbolt that jack from the chassis and clean all those points. This is not a place where you can skimp in order to save 10 minutes time and save the customer a few dollars or pounds! Tweed Champs in good working order sound much much better than this; Billy Gibbons of ZZ top, and other famous guitarists, used to make records with a tweed Champ! At the very least, you could have measured the resistors (there are so few of them, it'd only take a couple minutes) to see if they're still in spec, including the feedback resistor; and a dried out, leaky or high ESR cathode-bypass cap for the preamp or output tube can throw off the bias of that stage and cause blocking distortion. The mains B+ filter caps do more than merely filter out hum, they also decouple successive gain stages and prevent unpleasant sonic interaction. PS, you misspoke slightly ---- those are Astron couplng caps, not Ariston ---- Ariston was a British high-end turntable (record deck) manufacturer. I've owned a few Ariston turntables myself, here in the States, having once worked for a hifi store that sold a lot of British gear (LInn, Naim, Rega, ProAc, Wharefedale etc,), though I eventually settled on a Linn Sondek. I believe there was once a lawsuit between Linn and Ariston because Ariston claimed that Linn had stolen their spindle-bearing design. For what it's worth, this phone drives me nuts when I type or speak some of these names, because it wants to translate Linn as "Lynn" and Ariston as "Aniston" (apparently the phone thinks I'm conversing about Jennifer Aniston).!
@@normdurkin6425 , Even in his wildest dreams Leo Fender never thought that people would still be using and playing through these amps 60+ years after they were built. As a former radio repair man he did build them to be fairly easily reparable but they were also built to a price point and Fender wasn't going to put too much effort into the cheaper entry level amps when what they really wanted to do was upsell you a larger, more powerful, better performing and more expensive amplifier. Because of this they sometimes cut corners specifically so as not to make the ascending models have similar enough performance that people couldn't justify spending more money on the more expensive amp. Note that the tweed champ and Princeton had just a single wire for the heater circuit of each tube and the chassis was used as the return for the heaters of all those tubes, which is a very noisy way to do things but it saves on labor. The more expensive amplifiers had twisted pairs of wire to heat the tubes and a proper center tap ground reference to balance the heater winding circuit. Anytime you're working on a 40 to 70year old amp, oxidation and corrosion of electromechanical connections is the rule and not the exception, and Invariably you can lower noise significantly and improve performance by cleaning and tightening all mechanical ground and electrical connections. The input jacks and the pots are making an audio ground connection where they're bolted to the chasse and so if you unbolt the jacks and clean the metal and bolt the parts back in place snugly, adding star washers behind them if they don't have them already, can make a big difference in lowering noise. The ground-switching leaf switch contacts built into the input jacks should also be very carefully cleaned ( Bend them just a hair too far and you will misalign them to where they won't work at all ---- been there, done that 😖) and again, just spraying them with DeOxit is not really a cure. Ditto for the output jack which, even on the larger amps may get its negative ground from the chassis and not through a dedicated wire , Giving rise to the possibility of losing audio to the speaker and perhaps blowing up the output transformer, and if the amp has negative feedback, the feedback circuit wont work without that ground reference either. And whenever I encount an amplifier that has the chasse used as the return for the heaters of the tubes I always rewire it with twisted pairs and add a pair of resistors as a balancing center tap, which not only lowers noise but it can save the power transformer for emergency from destruction if a tube shorts out ( A pair of half Watt carbon film resistors used as the artificial center tap will function as fuses and burn up in order to save the transformer). Under no circumstances would I ever leave filter caps this ancient inside an amplifier that is gonna be played through. When a cap shorts out it will likely do more than just cause hum, it could well take out the transformer. If the customer insists on it and you can't talk him or her out of it, then add a fuse inside the chassis for the B plus between the rectifier tube and the first filter cap.
7:30 Nice bit of asbestos on that rear panel. I'd say be careful, but the job is likely out the door by now. Just have an extra lung dart, she'll be right mate!
Stuart, I leave the death cap in the amp just disconnect the hot end. Vintage amps like that champ only. Enjoy your vids, hope you found a 12ax pin straightener somewhere.
Another great tutorial, Question, whilst I understand the 'death cap' issue, and it needs to be removed, but surely the chassis is earthed? especially here in the UK , so the worst that could happen is a blown fuse or the RCD will trip.
Hi Gary. YEs you're right about the RCD but if you didn't have one of those the chassis could go quite live before it drew enough current to blow a mains fuse (I've seen MANY guitar amps with 13A fuses in the plugtops!). And in any case even if there is protection you don't really want to leave something in which could cause this fault when it's so easy to remove. What I have never found out (Haven't really looked tbh) is why these caps were fitted in the first place. Someone will know!!
great video Sewart, i have a 1957 stock original fender champ amp with the same death cap, my question is can i also clip it out. like you did and leave the 2 prong power chord? does just clipping out the death cap make the amp safe to play? looking forward to your reply.
Hi Gary Thanks. The purpose of the 'death cap' is to provide a path to ground for very high frequency noise which may be on the AC line. I'm thiinking taxi cab radios and suchlike. Because the cap is a fairly small value, it doesn;t have any effect on the very low (50/60Hz) line frequency. However, if this cap ever failed (short circuit, not open circuit), then mains AC voltage would find its way onto the chasis - not good. There are no negative safety implications to removing it. If it was me, I'd also replace your current 2-pin mains chord with a 3-pin, taking earth to the chassis via a solder tag etc. The problem with unearthed equipment is that if a live wire 'falls off' inside and touches the chassis, the chassis goes live. Next time you touch the chassis (i.e. via the ground of your guitar lead) you receive the full benefit of that voltage. If the chassis is earthed, if that live wire touches the chassis, it is immediately grounded, blowing a fuse and thus protecting you. All the best
@@stuartukguitarampguy5830 thanks for the quick response and comments on the ground safety Stewart. Just another quick question for you, After i remove the original 2 plug do i re solder the white and black wires of the 3 prong to the same spots as the original and as you pointed out solder the green earth wire to the chassis? sorry to be a pest on this i just want to do it right so if the amp ever left me it would be proper for the next owner(s)
Hi Gary yes. White and black go to exactly where they did on the two prong. Green goes to chassis (assuming your cable is green for earth, can;t recall for the USA cable.) Cut out the deatn cap completely and chuck it away. @@gomannpro
Hi Stuart, I was hoping for some advice! I have a Fender Blues Junior IV that has barely been played but makes a HORRENDOUS sound when it's switched on. I also noticed one of the power tubes is glowing purple. I have a video of the noise it makes on my channel. Do I need to replace the tubes or is it something else? I'm a novice with this stuff! Thanks for any help you can give! Have a great day!
A soft purple glow that hugs the inside of the glass bottle doesn't necessarily indicate a bad tube (it's caused by stray electrons striking the glass). If the purple glow is inside of the metal structures, however, it means the tube is most definitely bad (contaminated vacuum) and will draw excess current with a strong possibility of damaging the amp (it could blow the output transformer).
@@stuartukguitarampguy5830 Have you ever thought about restringing the Epiphone before checking the tone on the amp . It sounds like your strings were cast by Brunel 😃
Ha ha! I really only use the guitar as a signal source and a basic check to see the amp is working ok. I rarely/never 'check the tone' on an amp. It's eaither faulty or it's working. If it's working, it has the tone god gave it and I don't mess with it! But... you're right I do need a new set of strings.
The speakers in the Champs and Vibro Champs were never very good to begin with. From the looks of it, my '79 Vibro Champ has the same 8" Oxford Alnico speaker. I play mine through a 2 x 10" cabinet, and I get a loud and clean sound out of it.
A 1979 Vibrochamp would absolutely not have a factory-installed alnico speaker. At that late date, it would be a ceramic-magnet speaker. Fender started switching over to ceramic magnet speakers in the early to mid 1960's.
@@goodun2974 I am the original owner of the '79 Vibro Champ. Bought it new in Tulsa Oklahoma in 1979. I have seen videos of 79's with the Oxford ceramic magnet speaker, but mine definitely has an alnico. I would post a photo of it on thefenderforum or tdpri forum if interested. Edit: I have posted photos of the speaker on the tdpri forum under the title "Is this an Alnico speaker?" I know it's unusual to see an alnico this late in a VC, but maybe someone at Fender did some house cleaning and found a stock of alnicos that they then decided to use up.
Hi, Stuart. Just wanted to say how good your videos are! I've been working on a few amps over the last couple of months, and your videos are priceless. Thank you
Thanks. I also learn a lot from other people's videos. All the best
Well done, Stuart. That death cap was waiting to send this amp's owner to the land of wind and ghosts. Safety of the customer clearly outweighs his request in leaving an amp with little, to no modification(s). Another vintage Fender tweed class lives on! Cheers!
Thanks Alex. Yes I'd always do safety stuff regardless of instructions.
I wish newer amps were this simplistic! Another great repair Stuart! Thanks!
Thanks!
Nice little amp to be working on. These do have a good clean sound, but not very loud. I played one back in the 70's and loved it.
It's fun to watch you diagnosing issues and repairing them. I wish you had explained better the use of two caps to replace one for the novices like me.
As always this was fun and educational.
Keep it up Stuart.
I don't play guitar or own amps but I have a ridiculous amount of synths, drum machines, effects and eurorack modules.. I really appreciate and enjoy your videos while learning.. thank you Professor from Upstate, New York..
Thanks Norm!
What a little beauty Stuart..! Nice job on that relic..Lovely to see such a nice piece of history..Great service and info on repair..More learned.Thanks for sharing your expertise once again..Ed..uk.😀
Thanks Edward yes nice little amp and in good condition..
At 6:20, Stuart spins the tube shield expecting it to come off, but it's not the usual bayonet type of shield and socket. This socket has a sprungy, flanged base and the shield snaps down on to it, it's not bayonet mount. We see these pretty commonly here in the States on certain brands of amplifier such as Danelectro/Silvertone guitar amps and various radios and hifi gear.
Yes took me a while to work out why the thing wouldn;t come off!
Great video Stuart! Keep them coming
Thanks!
Hello Stuart. That's in great condition. Another good video. Take care.
Yes it was in amazing condition.
Good one Stuart. Much fun thanks
Thanks Monty
Two issues: 1) Clipping out the "death cap" is only half of the job; as wired, the neutral is connected to and through the fuse holder, and the hot wire to/through the power switch; very bad wiring practice that doesn't meet modern electrical codes but was unfortunately common practice during the 50s and 60s. The neutral wire should be connected directly to one leg of the power transformer's primary winding, and the hot should pass through both the fuse holder and the switch before routing to the transformer primary. And 2) note the light greenish corrosion on the RCA jack used for the speaker connection: THIS IS A CRITICAL GROUND & CIRCUIT CONNECTION POINT. The plating of the female RCA connector (bolted to the chassis for a mechanical ground) is particularly prone to developing a powdery film of greenish-white corrosion which, if it causes intermittent connection to the male RCA plug and the speaker therefore cuts out as the amp is playing and vibrating can cause a blown output transformer! Note that the chassis mounted jack and the chassis is the ONLY negative connection for both the audio to the speaker *AND* the negative feedback circuit; a poor connection between the female jack and the chassis can cause a resistive chassis ground or loss of ground, which again can cause the speaker to cut out while the amp is being played, which could blow the output transformer! Even if the audio to the speaker doesn't cut out , a resistive connection here can cause reduction or loss of negative feedback, and hence more distortion. The speaker jack should always be unbolted from the chassis, both connectors cleaned and polished, and the chassis and bolts cleaned before reinstalling the jack. Spraying it with DeOxit won't fix it; you need to manually clean the parts with a a small wire brush, a pencil eraser, a fiberglass "scratch brush".... even a scrubbing with toothbrush and alcohol is better than leaving it as found, but you really need to unbolt that jack from the chassis and clean all those points. This is not a place where you can skimp in order to save 10 minutes time and save the customer a few dollars or pounds!
Tweed Champs in good working order sound much much better than this; Billy Gibbons of ZZ top, and other famous guitarists, used to make records with a tweed Champ! At the very least, you could have measured the resistors (there are so few of them, it'd only take a couple minutes) to see if they're still in spec, including the feedback resistor; and a dried out, leaky or high ESR cathode-bypass cap for the preamp or output tube can throw off the bias of that stage and cause blocking distortion. The mains B+ filter caps do more than merely filter out hum, they also decouple successive gain stages and prevent unpleasant sonic interaction.
PS, you misspoke slightly ---- those are Astron couplng caps, not Ariston ---- Ariston was a British high-end turntable (record deck) manufacturer. I've owned a few Ariston turntables myself, here in the States, having once worked for a hifi store that sold a lot of British gear (LInn, Naim, Rega, ProAc, Wharefedale etc,), though I eventually settled on a Linn Sondek. I believe there was once a lawsuit between Linn and Ariston because Ariston claimed that Linn had stolen their spindle-bearing design. For what it's worth, this phone drives me nuts when I type or speak some of these names, because it wants to translate Linn as "Lynn" and Ariston as "Aniston" (apparently the phone thinks I'm conversing about Jennifer Aniston).!
..very interesting..
@@normdurkin6425 , Even in his wildest dreams Leo Fender never thought that people would still be using and playing through these amps 60+ years after they were built. As a former radio repair man he did build them to be fairly easily reparable but they were also built to a price point and Fender wasn't going to put too much effort into the cheaper entry level amps when what they really wanted to do was upsell you a larger, more powerful, better performing and more expensive amplifier. Because of this they sometimes cut corners specifically so as not to make the ascending models have similar enough performance that people couldn't justify spending more money on the more expensive amp. Note that the tweed champ and Princeton had just a single wire for the heater circuit of each tube and the chassis was used as the return for the heaters of all those tubes, which is a very noisy way to do things but it saves on labor. The more expensive amplifiers had twisted pairs of wire to heat the tubes and a proper center tap ground reference to balance the heater winding circuit.
Anytime you're working on a 40 to 70year old amp, oxidation and corrosion of electromechanical connections is the rule and not the exception, and Invariably you can lower noise significantly and improve performance by cleaning and tightening all mechanical ground and electrical connections. The input jacks and the pots are making an audio ground connection where they're bolted to the chasse and so if you unbolt the jacks and clean the metal and bolt the parts back in place snugly, adding star washers behind them if they don't have them already, can make a big difference in lowering noise. The ground-switching leaf switch contacts built into the input jacks should also be very carefully cleaned ( Bend them just a hair too far and you will misalign them to where they won't work at all ---- been there, done that 😖) and again, just spraying them with DeOxit is not really a cure. Ditto for the output jack which, even on the larger amps may get its negative ground from the chassis and not through a dedicated wire , Giving rise to the possibility of losing audio to the speaker and perhaps blowing up the output transformer, and if the amp has negative feedback, the feedback circuit wont work without that ground reference either. And whenever I encount an amplifier that has the chasse used as the return for the heaters of the tubes I always rewire it with twisted pairs and add a pair of resistors as a balancing center tap, which not only lowers noise but it can save the power transformer for emergency from destruction if a tube shorts out ( A pair of half Watt carbon film resistors used as the artificial center tap will function as fuses and burn up in order to save the transformer).
Under no circumstances would I ever leave filter caps this ancient inside an amplifier that is gonna be played through. When a cap shorts out it will likely do more than just cause hum, it could well take out the transformer. If the customer insists on it and you can't talk him or her out of it, then add a fuse inside the chassis for the B plus between the rectifier tube and the first filter cap.
Stuart is one of the best on here don't you think..? His casual manner and fun, and of course expertise is just fab..Glad you check him out..😀
@@edwardhannigan6324 ..I absolutely agree and learning new things..
@@normdurkin6425yeah, he's cool eh..😀
7:30 Nice bit of asbestos on that rear panel.
I'd say be careful, but the job is likely out the door by now.
Just have an extra lung dart, she'll be right mate!
Ah I didn't notice that!
Stuart, I leave the death cap in the amp just disconnect the hot end. Vintage amps like that champ only. Enjoy your vids, hope you found a 12ax pin straightener somewhere.
Ah yes, that's a good idea. Yes I managed to get a 12AX7 pin straightener. Quite expensive though!
Hello Stuart, interesting video again. What is de max resistance (after charging) you accept with this megger test on these capacitors?
Hi William. Pretty much infinite really. There shouldn;t be any leakage. But if I had to pout a figure on it, greater than 50M
Another great tutorial, Question, whilst I understand the 'death cap' issue, and it needs to be removed, but surely the chassis is earthed? especially here in the UK , so the worst that could happen is a blown fuse or the RCD will trip.
Hi Gary. YEs you're right about the RCD but if you didn't have one of those the chassis could go quite live before it drew enough current to blow a mains fuse (I've seen MANY guitar amps with 13A fuses in the plugtops!). And in any case even if there is protection you don't really want to leave something in which could cause this fault when it's so easy to remove.
What I have never found out (Haven't really looked tbh) is why these caps were fitted in the first place. Someone will know!!
great video Sewart, i have a 1957 stock original fender champ amp with the same death cap, my question is can i also clip it out. like you did and leave the 2 prong power chord? does just clipping out the death cap make the amp safe to play? looking forward to your reply.
Hi Gary Thanks. The purpose of the 'death cap' is to provide a path to ground for very high frequency noise which may be on the AC line. I'm thiinking taxi cab radios and suchlike.
Because the cap is a fairly small value, it doesn;t have any effect on the very low (50/60Hz) line frequency. However, if this cap ever failed (short circuit, not open circuit), then mains AC voltage would find its way onto the chasis - not good. There are no negative safety implications to removing it. If it was me, I'd also replace your current 2-pin mains chord with a 3-pin, taking earth to the chassis via a solder tag etc. The problem with unearthed equipment is that if a live wire 'falls off' inside and touches the chassis, the chassis goes live. Next time you touch the chassis (i.e. via the ground of your guitar lead) you receive the full benefit of that voltage. If the chassis is earthed, if that live wire touches the chassis, it is immediately grounded, blowing a fuse and thus protecting you. All the best
@@stuartukguitarampguy5830 thanks for the quick response and comments on the ground safety Stewart. Just another quick question for you, After i remove the original 2 plug do i re solder the white and black wires of the 3 prong to the same spots as the original and as you pointed out solder the green earth wire to the chassis? sorry to be a pest on this i just want to do it right so if the amp ever left me it would be proper for the next owner(s)
Hi Gary yes. White and black go to exactly where they did on the two prong. Green goes to chassis (assuming your cable is green for earth, can;t recall for the USA cable.)
Cut out the deatn cap completely and chuck it away.
@@gomannpro
@@stuartukguitarampguy5830 👌👍🙏🙏
Sounded like a Bavarian brass band in the beginning 😂🎺🎷
Ha ha!
Hi Stuart, I was hoping for some advice! I have a Fender Blues Junior IV that has barely been played but makes a HORRENDOUS sound when it's switched on. I also noticed one of the power tubes is glowing purple. I have a video of the noise it makes on my channel. Do I need to replace the tubes or is it something else? I'm a novice with this stuff! Thanks for any help you can give! Have a great day!
Try replacing the tube first. I'm fairly sure that will sort it.
@@stuartukguitarampguy5830 really appreciate your help! I'll give that a go
A soft purple glow that hugs the inside of the glass bottle doesn't necessarily indicate a bad tube (it's caused by stray electrons striking the glass). If the purple glow is inside of the metal structures, however, it means the tube is most definitely bad (contaminated vacuum) and will draw excess current with a strong possibility of damaging the amp (it could blow the output transformer).
Nice one 😊
Thanks!
@@stuartukguitarampguy5830 Have you ever thought about restringing the Epiphone before checking the tone on the amp . It sounds like your strings were cast by Brunel
😃
Ha ha! I really only use the guitar as a signal source and a basic check to see the amp is working ok. I rarely/never 'check the tone' on an
amp. It's eaither faulty or it's working. If it's working, it has the tone god gave it and I don't mess with it! But... you're right I do need a new set of strings.
The speakers in the Champs and Vibro Champs were never very good to begin with. From the looks of it, my '79 Vibro Champ has the same 8" Oxford Alnico speaker. I play mine through a 2 x 10" cabinet, and I get a loud and clean sound out of it.
Interesting thanks for your input Michael.
A 1979 Vibrochamp would absolutely not have a factory-installed alnico speaker. At that late date, it would be a ceramic-magnet speaker. Fender started switching over to ceramic magnet speakers in the early to mid 1960's.
@@goodun2974 I am the original owner of the '79 Vibro Champ. Bought it new in Tulsa Oklahoma in 1979. I have seen videos of 79's with the Oxford ceramic magnet speaker, but mine definitely has an alnico. I would post a photo of it on thefenderforum or tdpri forum if interested.
Edit: I have posted photos of the speaker on the tdpri forum under the title "Is this an Alnico speaker?" I know it's unusual to see an alnico this late in a VC, but maybe someone at Fender did some house cleaning and found a stock of alnicos that they then decided to use up.
THAT'S A TOUGH ONE ---- what should be done VS what the customer wants... I went broke doing the former!
Yep agreed. Also none of this is in the least bit critical. The amp isn;t even gigged.
@@stuartukguitarampguy5830Long story short, the customer is always right. Unless you're at the bank, then the bank is always right!
your strings are grounded didn't you realise?
Yes, grounded through me!!!