You totally saved my bacon! I have a gig tonight and my Fender Bassman was cracking up real bad. I thought it was a torn speaker. A little deoxit and I am back in business. Thanks!
You're not just an electronics guy. You are a curator of classic amplifiers. Not many guys wouldn't leave those Ajax caps in there and sell them on eBay for $50 each. I hate those guys. It's dirty to rip people off because they're ignorant of the inner workings of their electronics.
Great info on current draw via center tap of output transformer!So... I measured 60 ma, (at 460 volts plate )...split in two equals 30ma per tube. What is the range from cold to hot bias in ma?Thanks for your help and informative videos!Jeff
Hey Ted! I love your videos, even if i don't actually mess with this stuff, it's interesting to kind of troubleshoot some issues and more or less get the repairs done faster when you tell your repair technician what you think the problem is. You should shoot a small video of the owners playing the amps if they want to so you can show a before and after and whatnot. Cheers! // Viggo
As a player, I would not want any of those filter caps -- nothing but ATOMS! Dude. You're doing all that in bare feet? You must REALLY know what you're doing!
Great vid... I had my '68 Vibrolux looked at by a local tech a couple of years ago and had some caps done as well as the bias. Sounded great! A friend brought over his BiasMaster unit today and I was a little surprised to see that the amp had between 44-46mA as the idle current! That seemed quite high according to documentation...how dangerous is it to leave it running that hot? It sounds great and I'm hesitant to drop it to 30-35ma! What do you think?? Thanks!!!!
great channel, very helpful for us noobs te get an idea of what might be wrong with our amps, you should make a tutorial on home basic maintenance.. cheers
btw i’ve got a Fender 65 Deluxe Reverb reissue (type: pr 239), got it new in 2010. works great but the vibrato died a year or two after i got it. i’ve replaced caps, resistors and other pcb components in other types of electronics, but i wonder if this possibly a DIY fix for me.
Great videos! Just curious as to when you tested the capacitors before removing are you not also testing the capacitance of the rest of the circuit in parallel? I would have assumed any component needs removing before it can be tested. Having said that I'm not much of a wine drinker so that could be where I'm going wrong...
Great overview of 66 Fender Vibrolux Reverb chassis you nailed it so even I could understand the issues. I have this same amp but zero electronics experience and would like you to service it, replacing any noisy transformers, preamp tubes, capacitors and etc. It’s a great amp I inherited from my best friend who died some time ago and would like to keep it in as good a shape when my friend played it. Are you game?
Great video! Nice job recording and commenting. I have a 66 Deluxe Amp (Not Reverb). It crackles pretty loud when warming up. I've been told it;s the output tubes, the pre-amp tubes, the rectifier. I'm sure you;ve come across this many times and wonder what you think it might be?
Very good repair video, good procedures. Isn't it so nice to see an unmolested vintage amp when it comes in for repair. It just breaks my heart and ears when I see them come in and another so called tech has removed all the "ajax" coupling caps and replaced them with orange drops (harsh and brittle sounding). You gotta have the "Blues in those old blackface Fenders" or they just don't sound right! And Thank Goodness you use an oscilloscope and an audio generator, it is a must have for amp repair! Pulling the OT CT is also my preferred method of bias adjustment, indiscreet and accurate. Then, if needed, the power tubes can be individually checked for match. Wine for the mind! You did a good job for that customer, I hope it was appreciated. 👣
I have a peavey stereo chorus 400 1987-D model amp..works awesome..however..i live i roanoke virginia . i wish i could get this amp to you to check out and see if anything needs to be updated or fixed..let me know where your at i might be able to ship it to you..thanks..what is your email address.
For the bias, you explain that you disconnected the center tap connect one ammeter probe but you didn't say what the other probe was attached to. Is that the output from the power tubes?
D'lab, Can you some day explain the reverb section how it works on an old fender vibrolux reverb, I got one and I can't find the problema in it, thank you.
Thank you so much for your videos, i have leaned a lot a great learning curve for me and everybody that is watching your very fine channel...blessings from the UK...Nice red wine :-)
I have noticed something weird on a tweed Bassman of mine. Plugged in the guitar volume pot makes noise when turned. The pot is good. I have measured 300mv on the guitar cable jack when plugged in the amp , first time I see this. Any idea ? greetings from France.
Dear D-lab, it is not the right topic for this video but I wanted to ask you if you encountered a tube becoming microphonic not due to the tube itself but to its chassis socket where it is plugged ? In other words can a socket induce microphonics into a tube ? Sounds strange I agree but all my several brand tubes (6SL7s) cannot be microphonic !! Thank you.
Hello, could i ask if you could check out my vibrolux hum video.. cant find anything like it on UA-cam. . Had no suggestions either. Have you come across this. Many thanks
Terry, I love your videos and have found them incredibly helpful! I always believed that you had to remove a capacitor from the circuit to test it properly. Is this just a myth?
Sure wish you could tell me why my original '63 Fender Reverb tank starts a hum after a few days of "ON" / playing through it, then "OFF" ... Changed out the caps, couple diff 6k6's, changed the cable leads to and from the tank ... I have spent a small fortune paying two repair "techs" to fix this thing and neither could. What sayest thou kind Sir? (I just tracked down your Email address and sent this message to it; so hopefully, you will receive it!). Thanks!
Is it Terry? Jonny Here... I really love your channel... what with all your COOL usage of test equipment... really old school pro. In what part of the country are you located? I'm in Los Angeles. Thanx for a great vid and... cheers
Last month I saw an old 60s tube Sunn bass amp at Guitar Center for 800$ w / 15" speaker. If I had the money, it would have been mine. It was in pretty good shape, but who knows what was inside? Don
Terry this is a great video! I love your Fender amp videos, especially. Speaking of that I have a Vibroverb I want to bring in to you to get a couple power tube ceramic sockets installed. Will be calling you soon!
hi... saw you vid..nice.. have a friends 83 fender concert on desk. rebuilt with adjustable bias to run the 5881 he had in the unit. C- too hi=15mv/ma at test point(1ohm between gnd and 1-pin8 on output tube). 475 B+ with the 5881s. after mod i have correct 36ma/mv at idle . now that the amp is *functional; i have very little vol on eith chan. tones work ..but each chan is distorted.. no clean. ?? swapped tubes out 1-2 at a time with know good. no change. swicthing ped/knobpulls do their job..i am stumped. bad OT?
7:58 LOL: "Liquid encouragement" I use Red Label the scottish one, from the highlands of the brave. I'm realy sorry but try the usa one's a Jack D, but i get more distracted... More better the Black Lable.... woooot my hears hear more highs.... * hic *
I just cannot understand why a tech would replace some but not all of those ancient electrolytics. BTW, I use chopsticks from Panda Express for the ancient Chinese chopstick test. lol
Ted, had the 6L6's not worked out to 33 mA each,.. for example if they were too high (>44 mA), what would have been your remedy? Bias them down with resistors?
I once read that DeOxit is not good to use on tube sockets as it coats them; but rather TV contact cleaner on the sockets. But this guy's a pro so he knows his stuff ...
I'm just getting 'round to viewing your videos. I have a question about this rebuild. When you removed the old Mallory caps, why did you replace them with the ceramic disc caps? All the other Fender amp rebuilds I've watched say to use the "can" style caps, because the discs tend to pick up RF
I followed this method, unmounted tha caps with different values, but when outside the circuit they gave me good values. After replacing them with new caps, inside the circuit these new caps gave me the same exact values measured on the old ones. So I was wondering how those values inside the circuit can tell if a condenser has to be replaced.
+Mia Cameretta Hello, The values can measure normal outside of the circuit. However, when in circuit, leakage can cause issues. Did you notice a difference in tone quality after changing them?
Do you prefer WD-40 over contact cleaner for the scratchy pots? I have been afraid of the WD thinking it has some oil residue in it! You do great work, where are you located.
Hello, I have used WD-40 on controls for over 35 years, no problems. In the past, I have had contact cleaner lock up pots. No fear using WD-40 my friend. I am located in Battle Creek, Mi
A safe, but slightly more complicated and accurate way to test the bias is measure the DC resistance of each primary winding to CT on the OT. The take the voltage drop over each one and use Ohm's law to find the current. You'll find that will yield the same results as the transformer shunt method without running deadly current through your meter as well as the bias of each half of the OT primary (instead of the entire primary and dividing by two). The only downside is if you have 4 output tubes, you'll have to take the average current for each pair.
That wasn't the transformer shunt method. That involves the meter being connected in parallel with each half of the OPT primary in turn, relying on the fact that almost all the plate current will flow through the lower resistance of the meter. Not as accurate as Terry's method, but the result will be in the ball park.
Love the video. Hope you make more videos just like this, very informative and too the point. I'd let you work on my amps in a heartbeat. GREAT amp tech here.
You said Ajax tubes, then said Ajax caps. Hmm. Measuring current to both finals and assuming that half of that current is what each tube is pulling equals the true bias to each tube. Double-hmm.
Thanks for the quick reply. I'm all the way in S. California, or I would of loved to have you service my Peavey 112 solo series. It's solid state but still a great garage/practice amp. I love the videos! Cheers :)
+D-lab Electronics sorry i would take itmto,you,if i lived in the USA, lol...imthink it just needs a service, the pots are a bit scratchy, affecting its EQ.
Nice amp. Good job on the repair!
This man is incredible.
Would beer work?
You totally saved my bacon! I have a gig tonight and my Fender Bassman was cracking up real bad. I thought it was a torn speaker. A little deoxit and I am back in business. Thanks!
You're not just an electronics guy. You are a curator of classic amplifiers. Not many guys wouldn't leave those Ajax caps in there and sell them on eBay for $50 each.
I hate those guys. It's dirty to rip people off because they're ignorant of the inner workings of their electronics.
If you still have that amp, I will be glad to send you my address! (But please clean it up, first!)
Great info on current draw via center tap of output transformer!So... I measured 60 ma, (at 460 volts plate )...split in two equals 30ma per tube. What is the range from cold to hot bias in ma?Thanks for your help and informative videos!Jeff
Somebody got in there and tweaked the CAAANtacts
Hey Ted! I love your videos, even if i don't actually mess with this stuff, it's interesting to kind of troubleshoot some issues and more or less get the repairs done faster when you tell your repair technician what you think the problem is. You should shoot a small video of the owners playing the amps if they want to so you can show a before and after and whatnot.
Cheers! // Viggo
As a player, I would not want any of those filter caps -- nothing but ATOMS! Dude. You're doing all that in bare feet? You must REALLY know what you're doing!
Great vid...
I had my '68 Vibrolux looked at by a local tech a couple of years ago and had some caps done as well as the bias. Sounded great!
A friend brought over his BiasMaster unit today and I was a little surprised to see that the amp had between 44-46mA as the idle current!
That seemed quite high according to documentation...how dangerous is it to leave it running that hot?
It sounds great and I'm hesitant to drop it to 30-35ma!
What do you think??
Thanks!!!!
great channel, very helpful for us noobs te get an idea of what might be wrong with our amps, you should make a tutorial on home basic maintenance.. cheers
btw i’ve got a Fender 65 Deluxe Reverb reissue (type: pr 239), got it new in 2010. works great but the vibrato died a year or two after i got it. i’ve replaced caps, resistors and other pcb components in other types of electronics, but i wonder if this possibly a DIY fix for me.
Great videos! Just curious as to when you tested the capacitors before removing are you not also testing the capacitance of the rest of the circuit in parallel? I would have assumed any component needs removing before it can be tested. Having said that I'm not much of a wine drinker so that could be where I'm going wrong...
I have the same question! Love your videos D-Lab :)
@@axedoc2010 I always check capacitors barefoot, with a glass of wine in my hand. Thats why my hair is curly , whats left of it that is
How do I get in touch with you ?
Great overview of 66 Fender Vibrolux Reverb chassis you nailed it so even I could understand the issues. I have this same amp but zero electronics experience and would like you to service it, replacing any noisy transformers, preamp tubes, capacitors and etc. It’s a great amp I inherited from my best friend who died some time ago and would like to keep it in as good a shape when my friend played it. Are you game?
SO sorry about your friend, Sir. But you have a real fine, sweet amp. Too pricey for me these days, but I hope you enjoy this one!
Great video! Nice job recording and commenting. I have a 66 Deluxe Amp (Not Reverb). It crackles pretty loud when warming up. I've been told it;s the output tubes, the pre-amp tubes, the rectifier. I'm sure you;ve come across this many times and wonder what you think it might be?
Very good repair video, good procedures. Isn't it so nice to see an unmolested vintage amp when it comes in for repair. It just breaks my heart and ears when I see them come in and another so called tech has removed all the "ajax" coupling caps and replaced them with orange drops (harsh and brittle sounding). You gotta have the "Blues in those old blackface Fenders" or they just don't sound right! And Thank Goodness you use an oscilloscope and an audio generator, it is a must have for amp repair!
Pulling the OT CT is also my preferred method of bias adjustment, indiscreet and accurate. Then, if needed, the power tubes can be individually checked for match. Wine for the mind! You did a good job for that customer, I hope it was appreciated. 👣
I have a peavey stereo chorus 400 1987-D model amp..works awesome..however..i live i roanoke virginia . i wish i could get this amp to you to check out and see if anything needs to be updated or fixed..let me know where your at i might be able to ship it to you..thanks..what is your email address.
Liquid encouragement,😂😂😂
I have a ‘62 blonde vibrolux head. Can you mod it get the high end sparkle of a B circuit ‘62-63 Bassman? Also the Bassman has more compression.
For the bias, you explain that you disconnected the center tap connect one ammeter probe but you didn't say what the other probe was attached to. Is that the output from the power tubes?
Ur D real back to D future guy hands down! my jr amp making noise on d 1st tube 12ax7 no Master vol noisy n it cuts out? thanks for any advice
D'lab, Can you some day explain the reverb section how it works on an old fender vibrolux reverb, I got one and I can't find the problema in it, thank you.
Thank you so much for your videos, i have leaned a lot a great learning curve for me and everybody that is watching your very fine channel...blessings from the UK...Nice red wine :-)
The old VAIIIII-a-BRAYto! You are fantastic, fella. Great video.
I truly miss my old blackface Vibrolux. One the worst decisions I ever made to trade that amp in the late ‘70s. Nice video!
Thank you so much!!! your video was quite helpful. Greetings from México
Bloomin' excellent channel, alcohol, whimsy and solder - respect from the U.K.
I have noticed something weird on a tweed Bassman of mine. Plugged in the guitar volume pot makes noise when turned. The pot is good. I have measured 300mv on the guitar cable jack when plugged in the amp , first time I see this. Any idea ? greetings from France.
Heck! Looks like the original DIRT!! From when God first made dirt!
Dear D-lab, it is not the right topic for this video but I wanted to ask you if you encountered a tube becoming microphonic not due to the tube itself but to its chassis socket where it is plugged ? In other words can a socket induce microphonics into a tube ? Sounds strange I agree but all my several brand tubes (6SL7s) cannot be microphonic !! Thank you.
I thought if the knobs had the setscrew was on 1 not 10, and the 8 was not the snowman 8, the amp was post CBS? did the owner replace the knobs?
Hello, could i ask if you could check out my vibrolux hum video.. cant find anything like it on UA-cam. . Had no suggestions either. Have you come across this. Many thanks
I haven't watched the whole video yet.... Please don't replace the Ajax blue turds unless they are leaking high voltage.
Nice work! I’m looking for someone to work on my 68 twin in New York, any recommendations?
Terry, I love your videos and have found them incredibly helpful! I always believed that you had to remove a capacitor from the circuit to test it properly. Is this just a myth?
Yes, I'd like to know that too please.
You’re the guy to ask ... do hand wired amps really sound better than PCB amps?
Good video. I would like to see you add the guitarist though putting it through its paces......Russell D.
How to bias an old trayner, point to point. I looked at the schematic and I can find a bias pot. Help!
Why would you clean the pins right over the socket? Just saying.
S Biggs yeah I was kinda thinking the sae
Aaawww! The liquid courage, used it many times!
really appreciate the new camera the closeups are unequaled on youtube. thanks!
Sure wish you could tell me why my original '63 Fender Reverb tank starts a hum after a few days of "ON" / playing through it, then "OFF" ... Changed out the caps, couple diff 6k6's, changed the cable leads to and from the tank ... I have spent a small fortune paying two repair "techs" to fix this thing and neither could. What sayest thou kind Sir? (I just tracked down your Email address and sent this message to it; so hopefully, you will receive it!). Thanks!
E-mail sent
I love all your videos and i have learned a lot from them. Thank you sir and thank you for your service. I like the juice idea,lol
Is it Terry?
Jonny Here...
I really love your channel... what with all your COOL usage of test equipment... really old school pro.
In what part of the country are you located?
I'm in Los Angeles.
Thanx for a great vid and...
cheers
Hello Jonny. I am located in Battle Creek, MI (Kelloggs)
Super informative! Now ive got a project for the weekend haha
Love your work D., thanks for posting.
SCOPE-eramus! LOVE IT! And then you totally outdid yourself with "Speakeramuses"! I want to live in D-Lab Land!
You can add "ramus" to any word!
great video! I learned alot! Thank You!
Certainly enjoyed it. Thx!
Rad. I have the same amp. I need to change the caps and I want to add a ppimv.
hey, if you ever needed an apprentice, id like to apply
Last month I saw an old 60s tube Sunn bass amp at Guitar Center for 800$ w / 15" speaker. If I had the money, it would have been mine. It was in pretty good shape, but who knows what was inside? Don
***** Roger that man, I have a nice Marshall Plexi and quad speaker here for sale. Any interest?
Don't usually comment but D-lab I love your vids. Please keep them coming. Entertaining and I'm learning a lot so thank you!
Thanks man, I'll keep it fun
Terry this is a great video! I love your Fender amp videos, especially. Speaking of that I have a Vibroverb I want to bring in to you to get a couple power tube ceramic sockets installed. Will be calling you soon!
Roger-o my friend
hi... saw you vid..nice.. have a friends 83 fender concert on desk. rebuilt with adjustable bias to run the 5881 he had in the unit. C- too hi=15mv/ma at test point(1ohm between gnd and 1-pin8 on output tube). 475 B+ with the 5881s. after mod i have correct 36ma/mv at idle . now that the amp is *functional; i have very little vol on eith chan. tones work ..but each chan is distorted.. no clean. ?? swapped tubes out 1-2 at a time with know good. no change. swicthing ped/knobpulls do their job..i am stumped. bad OT?
7:58 LOL: "Liquid encouragement" I use Red Label the scottish one, from the highlands of the brave. I'm realy sorry but try the usa one's a Jack D, but i get more distracted... More better the Black Lable.... woooot my hears hear more highs.... * hic *
Very nice! Please more guitar amp repair videos. I totally dig 'em.
John Simms Will do John, I have several more in the shop. Just need some spare time.
I just cannot understand why a tech would replace some but not all of those ancient electrolytics. BTW, I use chopsticks from Panda Express for the ancient Chinese chopstick test. lol
+Robert Hurless Yep, I agree. Chopsticks would be perfect for the test tap tool.
Nice work Terry, nice amp i gota say too.
nice work! loving these videos
Wish you were in Houston
Ted, had the 6L6's not worked out to 33 mA each,.. for example if they were too high (>44 mA), what would have been your remedy? Bias them down with resistors?
I once read that DeOxit is not good to use on tube sockets as it coats them; but rather TV contact cleaner on the sockets. But this guy's a pro so he knows his stuff ...
There are several kinds of deoxit. The D5 should leave no residue.
I'm just getting 'round to viewing your videos. I have a question about this rebuild. When you removed the old Mallory caps, why did you replace them with the ceramic disc caps? All the other Fender amp rebuilds I've watched say to use the "can" style caps, because the discs tend to pick up RF
Cool I’m fans from Thailand
Good man, Good video!
He works on them drinking wine. I watch them drinking Jack and coke.
Don Stewart :
High voltages and alcohol ...
not a good mix.
Does this bias test work with dry white wine also ?
Yes, but it has a tendency to give me a headache
I'm trying to take off faceplate from my 1968 silver face twin having trouble around the pilot light area any tips?
Good work. Good tube test techniques! Thanks for sharing!
Is it ok to put tube shields on el84 tubes?
Nice job , Terry have a great day
would love an AT1000 .....
Howdy, Terry. That's a nifty little tester you use for your tubes - what kind is it, and where might a feller be able to get one? Thanks!
Haha i just poured a glass of Mondavi.
Me too!
outstanding
Great Stuff!!
Detail repair carried out as it should be done, thumbs up Mister Terry. More 🍷
Where are you located? I'm in Texas.
Tube amps sound great but if you look at them the wrong way 💣
Any idea on what's wrong with an amp if it's not getting the amount of volume you need? Like it just lost volume mid song.
What kind of amp is it?
It's a Fender supersonic 60 watt head
Red plating output tubes possibly.
When you tap on the tubes how do you have the volumes and knobs set?
I like how you left the blue Ajax in there. Great video.
Did you ever have any liquid encouragement from Mr. Mogen and Mr. David? ha-ha-ha Aka mad dog 20/20.
+Robert Hurless My brothers used to drink that stuff + Thunderbird!
D-Lab always gets a thumbs up from me.
I followed this method, unmounted tha caps with different values, but when outside the circuit they gave me good values. After replacing them with new caps, inside the circuit these new caps gave me the same exact values measured on the old ones. So I was wondering how those values inside the circuit can tell if a condenser has to be replaced.
+Mia Cameretta Hello, The values can measure normal outside of the circuit. However, when in circuit, leakage can cause issues. Did you notice a difference in tone quality after changing them?
Do you prefer WD-40 over contact cleaner for the scratchy pots? I have been afraid of the WD thinking it has some oil residue in it! You do great work, where are you located.
Hello, I have used WD-40 on controls for over 35 years, no problems. In the past, I have had contact cleaner lock up pots. No fear using WD-40 my friend. I am located in Battle Creek, Mi
New favorite channel!
Cool deal man, Stick with me
A safe, but slightly more complicated and accurate way to test the bias is measure the DC resistance of each primary winding to CT on the OT. The take the voltage drop over each one and use Ohm's law to find the current. You'll find that will yield the same results as the transformer shunt method without running deadly current through your meter as well as the bias of each half of the OT primary (instead of the entire primary and dividing by two). The only downside is if you have 4 output tubes, you'll have to take the average current for each pair.
That wasn't the transformer shunt method. That involves the meter being connected in parallel with each half of the OPT primary in turn, relying on the fact that almost all the plate current will flow through the lower resistance of the meter. Not as accurate as Terry's method, but the result will be in the ball park.
What is the model number of your crusty old heathkit audio generator?
+David Powell Its a EUW-27 They called them Heath Built
+D-lab Electronics Thanks, found one, on it's way :)
Nice tips to clean those tube pins Terry, cheers 🥂
Love the video. Hope you make more videos just like this, very informative and too the point. I'd let you work on my amps in a heartbeat. GREAT amp tech here.
***** Will do man, Thanks
ah yesss! "liquid encouragement"
Very cool amp...
bmwm3cs Yep, it's fun having the vintage ones roll in the shop
great videos...just take care with that glass of wine and the bare feet!
+MrAletube Oops, didn't know I showed my feet! What a great videographer huh?
You said Ajax tubes, then said Ajax caps.
Hmm.
Measuring current to both finals and assuming that half of that current is what each tube is pulling equals the true bias to each tube. Double-hmm.
Where's your shop at Terry?
Battle Creek, MI
Thanks for the quick reply. I'm all the way in S. California, or I would of loved to have you service my Peavey 112 solo series. It's solid state but still a great garage/practice amp. I love the videos! Cheers :)
Mate, yr a legend, can you fix my Vox AC125 Climax?
Yes, can do. What is the problem with the amp?
+D-lab Electronics sorry i would take itmto,you,if i lived in the USA, lol...imthink it just needs a service, the pots are a bit scratchy, affecting its EQ.
Roger that man, WD40 works well for cleaning pots