My mains transformet melted in my Princeton. To hot to touch for almost half an hour :) Less then a year old so I exchanged it under warrenty. Seems to be a common problem in the Princeton Reissue. I had no cracle or other warnings, it just quit while playing. Don’t know why it blew since I got a brand new replacement. Really like these video’s, always something to learn. Thanks!
I bought a set of probes for my meter that have needle tips. What a lifesaver those are! I can get into some very small areas to measure voltages or to inject a signal. Money well spent!
@@stuartukguitarampguy5830 don't feel bad, it took me 35 years of frustration before I finally bought the needle tips. Wish I had done it 34 years ago 😪
Funny, the 2 meters I bought came with needle tips. I had to purchase a set of clip on probes. Luckily I found a set of 4 online at a reasonable price.
At 20:10, here in the States those nuts with the built-in star washer are called Keps nuts; presumably because they "keps" the nuts from vibrating loose! 🙂
I've been catching up on your excellent videos on various topics on amp repair..! Must say, they are so interesting and informative..Learning loads..Excellent stuff..Ed..Herts..uk..😀
Stuart, I am a newbie at amplifier repair/maintenance. Thank you so much for your invaluable videos, and your wealth of knowledge. One quick question: is there a reason that you didn’t twist the 2 red wires to the rectifier together?
Hi Marko. It's great that you are learing! There are some very good vids like Uncle Doug and The Guitarlogist. There is no particular benefit to twoisting the wires together. It's just a neatness thing if you want to do it.
I would love to see the underside of that board. I noticed the topside jumpers. THESE are common on single sided P.C.B.'s But I'd still like to see the traces.
The white striped black wire sitting on the wire holder is for 240V wiring, so you just change the white wire with the white/black striped to go from 230V to 240V on the mains.
Is there a thermal fuse pinned between the wraps/windings of the power transformer primary? Most 1980's Japanese hifi gear with open-frame transformers (no end bells) will have thermal fusing. I've repaired a few no-longer-available transformers by bypassing/ replacing the dead thermal fuse ---- ideally, sometimes you can pull the old thermal fuse out from inbetween the windings with pliers and slip a new one in its place with a dab of heatsink grease (better and safer to install a new thermal fuse up against the windings than to merely bypass it). It may be instructive to pull the end bells off the old transformer and have a look. By the way, I once worked on a fancy direct drive turntable ( a Denon, I think?) that was "dead"; it had power, and the tranny was good, but the motor wouldn't spin. It had a blown thermal fuse on the direct-drive motor windings, under the shrink wrap. I replaced the thermal fuse and got the motor to spin ---- at about 150 RPM! Apparently, one of the driver transistors was shorted, which made it spin at high speed until the motor coil overheated and blew the thermal fuse. Replacing the shorted driver transistor got the platter down to the correct speed.
So Stuart, what was the problem with the rectifier tube and why did it’s failure result in the PT being burnt up? How does one protect against the loss of the PT?
Am I correct in assuming there is no way to check for a failing rectifier tube? They either produce the correct HT voltage or they don't? I've seen amps with each of the power tubes individually fused. Would it be possible to fuse the rectifier tube to protect the power transformer? Or should the mains fuse have blown in this case?
Hi Michael. In my experience rectifier tubes rarely fail. I don;t knowof a way of checking one. The mains fuse or possibly HT fuse should blow if the rectifier tube fails.
Hi Matthew, no I try to avoid these. They are hard to work on (not designed to be fixed), no schematics and you can often buy something similar on eBay for not much money.
Hi Mr Stuart, I got confused on how your wired the primary connections of the transformer. is it ok also to connect the white and brown wires and make the blue and black as the primary wires? ty
If you need a 230V primary *UK) you need to connect the two primary windings in series. SO from memory it was brown to black then the primary across blue and white - whatever I did in the video is correct. Obviously this would be different if you want to run it on USA voltage.
Hello, i just got a Princeton i believe is 2019 or 2020 as the inspection stickers say inside, i got it used and it looks brand new all of it looks perfect, a few days after buying it, i did made a really loud crackle that stopped when i tapped around the volume knowb area, only happened once. 2 days later im playing it cranked and all of a sudden i notice a huge volume drop, before the amp just died light went off and it wont turn on.. fuse is ok, i bought more and swapped it and still nothing. I checked the power switch also good but i got confused on how you tested the power transformer. Any help would be appreciated!
Hi Pedro. Hmm that doesn't sound good. It's the correct voltage model for your area, right? Assuming you know what you're doing (high voltages etc). Do the valves light up? If not AND the mains fuse is ok, I would suspect the tramsformer. To test the mains transformer you're going to need to disconnect all the secondaries, power it up, then use a meter to see if the correct secondary AC voltages are present. Good luck..
@@stuartukguitarampguy5830 Hey, thanks for repliying to me. At the moment nothing turns on at all, So, voltage should be fine, most i know about electricity is from this video 😇, and I followed most of yor stes, i noticed that when im messuring from the hot to the fuse. All is good, just like in your video, also are the black cables that go to the power switch, also show continuity, the white ones on the other hand, dont’t. Same thing when i unokug those 2 cables that are right by the mains transformer. Just like yours reads nothing, i never smelled anything weird, i did noticed it getting fairly hot around the tranform, rectifier tube are.
@@peterdaze1 Hi Pedro. Ok, well there's not a lot more I can do really as it's hard to diagnose/fix things by message. Best thing is to find a tech near you who cn look at it. Good kuck!
Hi - have you had any ‘68 Princeton Custom Reverb reissues in? Mine has a rattle/fizz/ring sort of sound on certain notes on the low E string. Does that ring any bells with you? Cheers
There is a common cause for that problem and it may be what you are experiencing. It's almost always a mechanical problem - the sound waves rattling a component such as a valve, resistor or capacitor. Use a towel to firmly grab hold of each valve in turn and see if that stops the issue. If so, then it's a valve and changing it will cure it. If that doesn;t stop it, it may be a component with a slight dry joint. You'll need a tech to investigate.
Why? You even said during the repair process that something was most likely causing the transformer to fail. You mentioned that 2 or 3 times. I watched the whole video. Did I miss the part where you figured you had that solved? My jaw hit the floor at the end after reading the final outcome.
Not as far as my jaw fell when it came back! My theory was that the mains transformer had arced internally - that does happen. So I replaced it and tested it and all was well. Job Done! Unfortunately it was the rectifier tube which only broke down under certain conditions which, alas, didn't happen on the bench.
Stuart, my amp is doing this exact same thing! When the crackling noise happens, the 6V6 next to the rectifier, the same position as the burnt-out tube on this amp, is red plating, all orange. Luckily, I have not fried the transformer yet and would like to prevent that from happening. What do you recommend? Replace just the rectifier or rectifier and 6V6s?
I was able to catch it happening, which was difficult. You can hear the noise with master volume down and then look at the tube overheating. ua-cam.com/video/lVUjuCXGavk/v-deo.html
Hi Steve sorry for the delay you may have got it sorted by now so this is for others. You have one tube clearly red plating (drawing too much current). It's nothing to do with the rectifier. It MAY be the tube but I doubt it. Do try that first. If still red plating it's almost certainly lost negative bias on pin 5 of that valve. Check with a meter. It should be negative 35 to 45 volts (not sure of exact on this amp) If no negative voltage, that's your issue.
@@stuartukguitarampguy5830 Thanks Stuart! After I few more days it stopped working completely. I ended up getting it repaired under warranty by Fender. It took 2 months, but it was free. In the end, the shop said "There was a cold solder joint that wasn’t making a good enough/consistent connection.".
You know; I don't really have a prejudice against these modern PC Board clone-of-old model amps. (Well, maybe the crappy tube sockets, and those can certainly cause problems) We all know that even a simple Princeton Rev requires significant man or woman hours to wire up at the factory. But....did 5 year old Princeton Reverbs fail in 1968? 1972? I guess....by the time they were offered for sale as used amps any early-on failures got fixed. Over 100 pounds = hellaciously pricey for that part!
![Repairing a VINTAGE Silverface Fender Princeton Reverb [Full Service+DEMO]](http://i.ytimg.com/vi/Is8QwMcZzr0/mqdefault.jpg)
![Repairing a VINTAGE Silverface Fender Princeton Reverb [Full Service+DEMO]](/img/tr.png)
My mains transformet melted in my Princeton. To hot to touch for almost half an hour :) Less then a year old so I exchanged it under warrenty. Seems to be a common problem in the Princeton Reissue. I had no cracle or other warnings, it just quit while playing. Don’t know why it blew since I got a brand new replacement. Really like these video’s, always something to learn. Thanks!
Thanks! I learn something new evey time I repair an amp.
What an amazing customer service Stuart. Loving this channel!
Thanks Jan!
I bought a set of probes for my meter that have needle tips. What a lifesaver those are! I can get into some very small areas to measure voltages or to inject a signal. Money well spent!
Yes I should get some of those! My current probes drive me crazy - almost as though designed NOT to be able to probe onto something!
@@stuartukguitarampguy5830 don't feel bad, it took me 35 years of frustration before I finally bought the needle tips. Wish I had done it 34 years ago 😪
Just ordered some on eBay!
@@stuartukguitarampguy5830 I think you're going to love them!
Funny, the 2 meters I bought came with needle tips. I had to purchase a set of clip on probes. Luckily I found a set of 4 online at a reasonable price.
At 20:10, here in the States those nuts with the built-in star washer are called Keps nuts; presumably because they "keps" the nuts from vibrating loose! 🙂
I've been catching up on your excellent videos on various topics on amp repair..! Must say, they are so interesting and informative..Learning loads..Excellent stuff..Ed..Herts..uk..😀
Brilliant I'm pleased you are enjoying them!
Stuart, a good choice for a power transformer. The folks at Hammond Mfg over design their product. I have never had an issue with them. Cheers 😀
Stuart, I am a newbie at amplifier repair/maintenance. Thank you so much for your invaluable videos, and your wealth of knowledge. One quick question: is there a reason that you didn’t twist the 2 red wires to the rectifier together?
Hi Marko. It's great that you are learing! There are some very good vids like Uncle Doug and The Guitarlogist. There is no particular benefit to twoisting the wires together. It's just a neatness thing if you want to do it.
I would love to see the underside of that board. I noticed the topside jumpers. THESE are common on single sided P.C.B.'s But I'd still like to see the traces.
The white striped black wire sitting on the wire holder is for 240V wiring, so you just change the white wire with the white/black striped to go from 230V to 240V on the mains.
Ah, ok thanks Thomas.
I enjoy your end of vids wrap up.
Is there a thermal fuse pinned between the wraps/windings of the power transformer primary? Most 1980's Japanese hifi gear with open-frame transformers (no end bells) will have thermal fusing. I've repaired a few no-longer-available transformers by bypassing/ replacing the dead thermal fuse ---- ideally, sometimes you can pull the old thermal fuse out from inbetween the windings with pliers and slip a new one in its place with a dab of heatsink grease (better and safer to install a new thermal fuse up against the windings than to merely bypass it). It may be instructive to pull the end bells off the old transformer and have a look.
By the way, I once worked on a fancy direct drive turntable ( a Denon, I think?) that was "dead"; it had power, and the tranny was good, but the motor wouldn't spin. It had a blown thermal fuse on the direct-drive motor windings, under the shrink wrap. I replaced the thermal fuse and got the motor to spin ---- at about 150 RPM! Apparently, one of the driver transistors was shorted, which made it spin at high speed until the motor coil overheated and blew the thermal fuse. Replacing the shorted driver transistor got the platter down to the correct speed.
So Stuart, what was the problem with the rectifier tube and why did it’s failure result in the PT being burnt up? How does one protect against the loss of the PT?
Hi Reggie tbh I can;t remember!
Am I correct in assuming there is no way to check for a failing rectifier tube? They either produce the correct HT voltage or they don't? I've seen amps with each of the power tubes individually fused. Would it be possible to fuse the rectifier tube to protect the power transformer? Or should the mains fuse have blown in this case?
Hi Michael. In my experience rectifier tubes rarely fail. I don;t knowof a way of checking one. The mains fuse or possibly HT fuse should blow if the rectifier tube fails.
Stuart do you ever repair any other kinds of amps like hi-fi stereo amps, surround receievers etc?
Hi Matthew, no I try to avoid these. They are hard to work on (not designed to be fixed), no schematics and you can often buy something similar on eBay for not much money.
STEINEL - good old german engineering 😬
You're not wrong there Markus, I've had it simnce 1986!
Hi Mr Stuart, I got confused on how your wired the primary connections of the transformer. is it ok also to connect the white and brown wires and make the blue and black as the primary wires? ty
If you need a 230V primary *UK) you need to connect the two primary windings in series. SO from memory it was brown to black then the primary across blue
and white - whatever I did in the video is correct. Obviously this would be different if you want to run it on USA voltage.
@@stuartukguitarampguy5830 Thanks!
Hello, i just got a Princeton i believe is 2019 or 2020 as the inspection stickers say inside, i got it used and it looks brand new all of it looks perfect, a few days after buying it, i did made a really loud crackle that stopped when i tapped around the volume knowb area, only happened once. 2 days later im playing it cranked and all of a sudden i notice a huge volume drop, before the amp just died light went off and it wont turn on.. fuse is ok, i bought more and swapped it and still nothing. I checked the power switch also good but i got confused on how you tested the power transformer. Any help would be appreciated!
Hi Pedro. Hmm that doesn't sound good. It's the correct voltage model for your area, right? Assuming you know what you're doing (high voltages etc). Do the valves light up? If not AND the mains fuse is ok, I would suspect the tramsformer. To test the mains transformer you're going to need to disconnect all the secondaries, power it up, then use a meter to see if the correct secondary AC voltages are present. Good luck..
Also you should be able to test for an open circuit primary using an ohm meter.
@@stuartukguitarampguy5830 Hey, thanks for repliying to me. At the moment nothing turns on at all, So, voltage should be fine, most i know about electricity is from this video 😇, and I followed most of yor stes, i noticed that when im messuring from the hot to the fuse. All is good, just like in your video, also are the black cables that go to the power switch, also show continuity, the white ones on the other hand, dont’t. Same thing when i unokug those 2 cables that are right by the mains transformer. Just like yours reads nothing, i never smelled anything weird, i did noticed it getting fairly hot around the tranform, rectifier tube are.
@@peterdaze1 Hi Pedro. Ok, well there's not a lot more I can do really as it's hard to diagnose/fix things by message. Best thing is to find a tech near you who cn look at it. Good kuck!
What brand was the bad rectifier tube?
I think it was a Groove Rube - Fender's own brand.
"Wire em up randomly"... Hilarious
Hi - have you had any ‘68 Princeton Custom Reverb reissues in? Mine has a rattle/fizz/ring sort of sound on certain notes on the low E string. Does that ring any bells with you? Cheers
There is a common cause for that problem and it may be what you are experiencing. It's almost always a mechanical problem - the sound waves rattling a component such as a valve, resistor or capacitor. Use a towel to firmly grab hold of each valve in turn and see if that stops the issue. If so, then it's a valve and changing it will cure it. If that doesn;t stop it, it may be a component with a slight dry joint. You'll need a tech to investigate.
@@stuartukguitarampguy5830 Thanks Stuart, I’ll check that out.
Why? You even said during the repair process that something was most likely causing the transformer to fail. You mentioned that 2 or 3 times.
I watched the whole video. Did I miss the part where you figured you had that solved?
My jaw hit the floor at the end after reading the final outcome.
Not as far as my jaw fell when it came back! My theory was that the mains transformer had arced internally - that does happen. So I replaced it and tested it and all was well. Job Done! Unfortunately it was the rectifier tube which only broke down under certain conditions which, alas, didn't happen on the bench.
It could be true the 6v6 shorted which caused the power transformer to fail. Just possible.
@@kengevers8738 Yes possible. I did see the rectifier tube flash over though.
Stuart, my amp is doing this exact same thing! When the crackling noise happens, the 6V6 next to the rectifier, the same position as the burnt-out tube on this amp, is red plating, all orange. Luckily, I have not fried the transformer yet and would like to prevent that from happening. What do you recommend? Replace just the rectifier or rectifier and 6V6s?
I was able to catch it happening, which was difficult. You can hear the noise with master volume down and then look at the tube overheating. ua-cam.com/video/lVUjuCXGavk/v-deo.html
Hi Steve sorry for the delay you may have got it sorted by now so this is for others. You have one tube clearly red plating (drawing too much current). It's nothing to do with the rectifier. It MAY be the tube but I doubt it. Do try that first. If still red plating it's almost certainly lost negative bias on pin 5 of that valve. Check with a meter. It should be negative 35 to 45 volts (not sure of exact on this amp) If no negative voltage, that's your issue.
@@stuartukguitarampguy5830 Thanks Stuart! After I few more days it stopped working completely. I ended up getting it repaired under warranty by Fender. It took 2 months, but it was free. In the end, the shop said "There was a cold solder joint that wasn’t making a good enough/consistent connection.".
Ah okay glad you got it sorted!
Same thing happened to my Princeton recently, first the crackling, then me continuing to play it, then PFffffttzzz....Transformer went.
Not good!
good fix
You know; I don't really have a prejudice against these modern PC Board clone-of-old model amps. (Well, maybe the crappy tube sockets, and those can certainly cause problems) We all know that even a simple Princeton Rev requires significant man or woman hours to wire up at the factory. But....did 5 year old Princeton Reverbs fail in 1968? 1972? I guess....by the time they were offered for sale as used amps any early-on failures got fixed. Over 100 pounds = hellaciously pricey for that part!
No they didn't!
Great channel!
огромное спасибо