Fender DeVille Amplifier, Repair and Bias Set Procedure

This is a video explaining some common repair issues with guitar amplifiers. You will see some troubleshooting procedures, an LED mod, how to set the amplifier bias, and jack repair.

[@karlfell3768]

Nice to see someone taking the time to repair at a component level rather than just swapping out the parts for new ones. Keep up the good work. Karl

[@MrCarlsonsLab]

Thanks Karl!

[@Geopholus]

I hate those jacks,... they fail so often... Would be nice if someone made sturdier ones that fit in the same space.

[@russellesimonetta3835]

@@Geopholus hey this is sop from fender since leo owned the company. It,s called pinching pennies.

[@OpSic66]

I'm 50/50 on this. It really can depend on how much time, and how simple it is to test the path. Rather than just replace a very common known failure point. I've replaced dozens of these jacks. If it's not the switch that fails, it's the plastic barrel going through the face plate. These jacks really are a terrible item.

[@denniswalsh8476]

@@Geopholus they do... Switch craft and Neutrix.

[@jameslucas6589]

As before, you are brilliantly explaining the basic needs for repair that so many people need; and you make it fun and interesting. Some bloggers are an instant cure for insomnia, but you keep us glued to every word. Great Job. Thank you.

[@MrCarlsonsLab]

Thanks for the nice comment James!

[@BavarianM]

Mr Carlson's Lab i cant sleep because of your awsome videos

[@MrCarlsonsLab]

Vader Starligth Thanks! Glad your enjoying them.

[@waynewayne3709]

Us old techs had to learn to understand how a circuits worked and trouble shoot them to aid in solving many problems.. Not just pop new parts in.. Thumbs up for taking the time to talk about many different amplifiers etc.. Wayne.

[@206ltd2]

channel select switch not working is one of the most common problems i find with used amps. personally, i don't use them, but it's taken into account for resale often. thank you for illuminating me on likely culprits for this and explaining the schematic. videos like this are rare and you do a wonderful job of explaining and informing. i encourage you to make more videos like this!

[@MrCarlsonsLab]

Thanks 206 Ltd! Many more videos coming. Stop by anytime!

[@grandtechnology]

Yes that is seems like that.

[@jdcdnet]

I just got the same assignment...buddy wants his Hot Rod Deluxe 410 repaired and I have the very same OS-8C/U that i'm going to use in place of the digital scope for kicks! Thanks Paul for documenting this. I think this was one of the videos I first viewed that got me interested in your channel and ultimately why I became a Patreon member of Mr. Carlson's Lab! Cheers, JD

[@MrCarlsonsLab]

Glad you enjoyed JD! Using older test equipment is where the fun is :^)

[@orion681]

You are the man, sir. You have shown me several videos directly in my wheelhouse. I have one of these amps actually. And I'm a total CB and ham nerd. You're becoming my favorite channel

[@Deebz270]

Excellent. Guitar valve amps are my thing and as always, a nice, concise and precise tutorial.

[@Callmenobody174]

If you ever get tired of doing electronics, you could always do voice-over work for Jim Carrey. You're a dead-ringer for him, voice-wise. I'm no electronics expert, but I really enjoy your videos. Keep up the good work!

[@jwl9286]

Another Great job! I would have suspected a bad tube myself. Your testing methods to prove your suspicion and inner tube working explanations are beyond anything I've ever heard. I can't believe how exciting these video's are. Thanks!

[@MrCarlsonsLab]

+jwl9286 Thanks for the kind words! Working on the next video right now.

[@jbyeats]

You have a great way with communicating & expressing yourself. Making sense of what can be quite a difficult subject at times. Please keep it up. Really enjoy your professional approach to working out these problems. Good luck to you.

[@MrCarlsonsLab]

jbyeats Thanks for the nice comment!

[@Impractical_Engineer]

Here I am 7 years after this video is posted and I am highly enjoying this master class in electronics, logic and good old fashion learning fun.

[@thomascowan1825]

Really enjoyed your repair. This helped me to understand more so proper procedure in testing and troubleshooting. Thank you.

[@MrCarlsonsLab]

Your Welcome Thomas!

[@hyperluminalreality1]

Here is a tip for you all. If a tube amp makes noise, turn it off, pull the input tube and turn the amp on. If the noise is still there with the first tube out, turn the amp off and put it back in. Do the same thing with the second tube. When you get to the tube that makes the noise stop, you know which gain stage is making the noise. Then when you pull the chassis you already know exactly where to go to look for the problem. I have been repairing and custom building tube amps since 1995. I really like your vacuum tube test equipment cove. Oh yeah, biggest jolt so far was 650Vdc@500mA in the right hand while my left hand completed the circuit to the chassis. Have not slipped in years, and if I am in a live amp I wear Nitrile 7 mil(blue) or 9 mil(black) gloves as an insulator.

[@barneycarparts]

great tip thanks. I have a Blues Deluxe RI with opamps in the preamp section. It has intermittent crackle like bacon frying. I haven't scoped it yet but I imagine, it may be one of those disc caps with the dip too far down the leg causing a dry solder joint in a plated through hole.

[@dougtaylor7724]

Have not heard that before. Great pointer! Thank you for the info.

[@bobc7968]

I had to take quantum mechanics to get my graduate degree and you blew me away with your sophisticated knowledge of the practical,, but you might want to consider dumbing it down in certain sections where you make assumptions of the viewers knowledge, you have a gift, the rest of us don't. However, you are the messenger of hope. I have a Fender Deville 410 that I bought busted up from a pawn shop for $200 and have pieced together. Same design as in the video as in the rest of the hybrids of the era. I now find the overdrive channel doesn't activate at the hand switch, haven't tried the foot switch as in the video. Bottom line is you gave me hope and direction to address the problem. You're doing a great service for the few of us that have it within to take off the cover and not only look inside, but to make it right, just like a surgeon. Keep the good work up. Looking forward to more postings. BTW, how about a video on a Line 6 Boger Spider Valve, another problem child?

[@michaelrelaz4808]

Glad I found your page! I’m planning on modifying my Hot Rod Deluxe and changing out the speaker in the future and I grabbed a few great tips like re-soldering pots and such.

[@jimadams2473]

Watched this video again. Loved it even more the second time. Great job on these instructional videos!!

[@MrCarlsonsLab]

Thanks Jim!

[@raynunez4366]

The best info I've seen, thank you so much for taking the time.

[@johnnyrood]

Very well done and in depth video! You are truly a master of your craft. Kepp up the good work!

[@MrCarlsonsLab]

Glad you enjoyed!

[@chrismosley409]

really good info. I like how you repair switches instead of just replacing them. the tube diagnosis was especially helpful.

[@MrCarlsonsLab]

+Chris Mosley Glad you enjoyed Chris!

[@budandbean1]

Really enjoyed learning about using the scope to assist in the testing of this amp. It's great information to know because so many tube amps are built just like this, well, a lot of them are not this complex. Like using a valve (tube) in the power supply. I really love these old amps, thank you so much for your time and expertise, you are really great to watch and learn from. B.

[@MrCarlsonsLab]

Glad you enjoyed Buddy!

[@Geopholus]

Paul . Love Your channel. Your repair video's and great ideas for circuit tracing and component checking projects are the best!

[@MrCarlsonsLab]

Many thanks!

[@johncunningham5435]

Nicely demonstrated; just goes to show when simple techniques are deployed, troubleshooting becomes much easier.

[@knifeswitch5973]

Just bought the 60W 4x10 version of this amp. You sir, hit the spot!

[@MrMuppetbaby]

Absolutely electrifying! Thank you today's Mr. Wizard, Mr. Carlson. You have a great TV persona. So entertaining.

[@MrCarlsonsLab]

Thanks, more to come!

[@MrMuppetbaby]

I have a Heathkit SB-220. Would love to see your take on the old war horse. Parasitic oscillations mod, etc. if you can.

[@peterbigblock]

Awesome video! Man, I learned so much from this one presentation. Paul is an excellent teacher. Thank you!

[@MrCarlsonsLab]

Glad it was helpful Pete!

[@robertgephart5954]

I loved your speal, you stand up for what you know and I appreciate that.

[@francmgomez8124]

Thanks for the In depth tutorial , I will definitely check out your other video tutorials

[@martinreid1740]

glad you put an end to the myth of nos valves. I really respect your vast knowledge and wish I could find someone like you to give my amp a service.

[@MrCarlsonsLab]

Thanks Martin!

[@mrdayvidjon]

Wow simply brilliant very well said maybe one day you will see his own amplifiers or wonder box on the market

[@magreger]

You are so very good at what you do.

[@TMoody]

I feel like I just went to school and church at the same time and for that I say "thank you". Great video!

[@28_gauge]

Mr Carelson knows his stuff. Thanks for the video.

[@phillipyannone3195]

Great trouble shooting video, I'm learning a lot watching your Chanel. Thanks!

[@tedzomplin4810]

Excellent video. Well done and very much appreciated. You are also an excellent communicator as well as a very meticulous and thorough technician . I have been working on amps for many years myself and I very much approve and recommend your skilled workmanship and knowledge. Some real good professional skills demonstrated here. Good advice as well. A1+ bro!

[@MrCarlsonsLab]

***** Thanks for the nice comment Ted!

[@percypenamora7121]

Great video! Lots of useful tips and advice. Thanks!

[@whynotme5926]

You make this look so easy.-I am just getting into this at age, 64. Wish I had done this when I was younger. When I was in school I thought I hated learning, now I can't seem to learn enough, funny how that works with some of us.I am trying to learn 30 years of knowledge in one year. I am going to build my first amp before long. I just have to keep telling myself to be careful, even though I wired all the houses I built over the years. Thank you for your videos.The biggest problem I have is-When you look at the blue prints of a house, the items are exactly in the same place on the print as they are in the house and in a schematic they are not and this just blows my mind!!!!!!!I am thinking about going point to point instead of using a board.

[@erikdenhouter]

Please remember, Mr Carlson makes it seem so easy because he has compressed a lot (a LOT) of work in a few minutes video. I bet you, some of his videos are days per hour. For you, after so many years wiring houses, your mind is set for blueprints where all the parts you need to install have a physical place in each room, determined by the architect. But for most electronics of this kind the physical place is almost of no importance, as long as the wire connections are placed as the schematics demand. This just needs another mind set, but it comes with more freedom. Please try to look trough that, and see it as an opportunity. Maybe you can start with a project where there's also a drawing of the wiring. Specially older magazines have published these. www.americanradiohistory.com/ My only advice (and I also try to listen to myself), keep your workplace clean, and tidy up after each days work, no matter how short. This will surely help keep your mind tidy as well.

[@whiskeyify]

I've worked on quite a few tube tv's, you had to be careful not to touch the sockets. Even though I'm an old timer I've learned a lot from watching your videos. Thx for uploading them.

[@MrCarlsonsLab]

whiskeyify Thanks for your comment, glad your enjoying the video's!

[@telecomex]

Hi Paul. Hey, you are incredible! Your lab is incredible! WOW! Thank you so much for introducing these topics the way you do. You really are a great teacher! I have a lot to learn but really appreciate your instructions. A thousand thank yous from Canada.

[@MrCarlsonsLab]

+Sunny Skies Thanks for the very kind words!

[@probono9341]

Excellent job in diagnosing and explaining the issues.

[@MrCarlsonsLab]

Thanks Bill!

[@PeterCCamilleri]

This brings back a lot of memories. In ancient times, I used to fix my friends guitar amps. It was fun and it discouraged them from giving me a hard time. I was taught and required to keep one hand in a pocket at all times. I also plugged those ancient amps into an isolation transformer since many had a hot chassis. The repairs where typically replacing bad tubes and bad electrolytic caps.

[@MrCarlsonsLab]

Peter Camilleri Glad this stirred some old memories Peter. Thanks for the comment!

[@wtangodelta1715]

I love you videos and this dovetails nicely with what I'm Learning from Uncle Doug! Best wishes and power to you bruddah!

[@MrCarlsonsLab]

Thank You!

[@mikesamra9126]

I work on and rebuild mostly all vintage tube audio gear these days. 120hz hum problems are pretty straight forward but 60hz problems get a little more challenging it seems.Your videos are so superb and they are a great teaching tool.

[@MrCarlsonsLab]

Mike Samra Thanks Mike, glad your enjoying the video's!

[@mikesamra9126]

Mr Carlson's Lab Paul,do you have an email where I can send you a service manual for a Sencore Lc-102 capacitor/inductor analyzer?.Everything works well on it as far as testing capacitors and inductors and values of both but I can get the HV B+ to charge the caps I want to test over 46vdc.Logic circuitry is all ok but one of the FETS are not turning on and the one that does heats up in a hurry. You may have the service manual as they are on line but I could post it maybe? Mike

[@MrCarlsonsLab]

I'm not quite sure of the question. Did you want me to take a look and see if I can spot, (take a guess) at the problem?

[@mikesamra9126]

Mr Carlson's Lab Yes if you would..I think I'm on the right spot but I want to double check with you.

[@joelaughlin5532]

Excellent reassembly advice!

[@georgekoerner6591]

Another excellent presentation

[@djfrank59]

The DeVilles are known to have problems with the foot switch jacks. I get many of them in with the same problem. One of the other common issues beside cold solder joints are the ribbon leads. I've encountered many of them broken. What I usually do is, I replace them with conventional hookup wire which is more durable. The H2C shorts in the 12AX7's are nothing unusual. It happens with NOS tubes as well. Good video for the advanced tech. Keep up the good work! Frank Ferraro--Audio Craft Electronics. :).

[@MrCarlsonsLab]

Thanks for the comment Frank!

[@wakkowarner7391]

Haha, "It shakes the crap out of 'em". I love that line. Great videos with excellent explainations, I always enjoy your videos Paul. Thanks for making them!

[@MrCarlsonsLab]

Glad you're enjoying!

[@mopar3502001]

Excellent video, thank you! I had one of these amps come through my shop a while back. It presented with the same mode of failure (intermittent loud hum). My customer said that he bought the amp used, and he had owned it for about 5 years. He said he uses it every weekend playing gigs. The seller told him that he was the original owner, and that he never had to change the tubes. Tube fatigue can also cause plenty of other problems as well (especially in output stages). I would suggest even if the amp is working fine, to replace the tubes in every regularly used amplifier at least every couple of years. An ounce of prevention is worth a pound of cure.

[@CryptoTonight9393]

I've been trying to find out how often to change tubes since I'm now taking care of 3 amps at the venue I FOH engineer for. I've had just as many people tell me to change them regularly every other year as I have people telling me to only change them when a problem occurs and their tubes have lasted for 10years with regular use 🤷‍♂️.

[@mopar3502001]

@@CryptoTonight9393 Tubes are funny in terms of how long they can last; and there are plenty of reasons a tube can fail. But as a rule of thumb, you shouldn't change tubes unless they need to be changed. A tube tester is a must have if you are regularly diagnosing tube driven amplifiers. One sign of a tube failing is when a tube becomes microphonic, meaning it picks up sound from outside sources and propagates that into the signal path. Just throwing tubes at an amp without checking out the decoupling cap(s) and screen resistors and when applicable, the bias, can be a bad thing also. If you're not sure what any of this means I high suggest you take it to someone who does. The B+ side of these circuits can be lethal.

[@denniswalsh8476]

My cousin has two different Mesa amps that use the same tubeset. He buys one set a year and alternately changes out one amp each year. Works for him and very few other problems and these are both far from new.

[@Geopholus]

@@mopar3502001 Great reply, Yes tubes can last for 10 years or more even with lots of use. I would't replace tubes unless they start causing problems, like sounding thin, red plating , or microphonic. Pays to find a good amp tech, who can help You troubleshoot.

[@lfiof]

Great tutorial explained very well!

[@MrCarlsonsLab]

Thanks for the comment!

[@mrclubike]

The description of your O scope cracked me up LOL

[@arthurchapin778]

Nice to see an OS-8 scope! they were on Navy ships during the 1960's but not used very much

[@bailamosmundolatino]

That's a great tutorial, you explain all things very clear; it's clear that you have a very deep knowledge of the theoretical part as well as practice. Best regards. Ben

[@MrCarlsonsLab]

bailamosmundolatino Thanks for the nice comment Ben!

[@johnrees44..G4EIJ]

Compulsive watching...many thanks for a crystal clear explanation...JR..UK

[@bluesbubba7429]

Thanks for the help. Mine was at 34 milli-volts. I adjusted it to 60, and it sounds a lot better.

[@omarcusihuaman4261]

im learning good stuff with your vids. im a process ingenieer but electronics and music are my passion, your vids teach me and also inspire me. suscribed already.

[@MrCarlsonsLab]

Great Omar! I'm privileged to be that inspiration.

[@stupidjubei]

Your videos are beyond informative. WOW! Just one thing, you forgot to plug in at the end and jam out. hahaha. Thank you for your good work.

[@MrCarlsonsLab]

Thanks Michael!

[@raymondheath7668]

Good video, makes me want to break out my old Sylvania, GE and RCA tube books!

[@robertturner2000]

Thank You for covering Chinese Tubes - I've been leary about buying them even though they look great. Ordering some now...

[@JohnnyMacTahoe]

Thank you for your videos! As you were bending that input switch piece back in line I was yelling "replace that pos!" Those jacks are notorious for failure. I hate to tell ya, but you'll be back inside that one again... swapping all those plastic input jacks with Switchcraft jacks and leads to the board.

[@dave-d]

Ha! Love it. The lab is full of way out gear and the little pre-historic single trace, (probably tube driven), scope is all that gets used. Love it. I fix audio gear for my local music store and always like to see how others approach things. I keep a few known good valves on the bench and just swap out 1st gain stage to do a quick check in this case. Nice to see the correct test demonstrated though. Bang on mate. Maybe an explanation of what bias is would be nice. Good work. Subscribed. Thanks. Play safe.

[@MrCarlsonsLab]

Dave D Thanks Dave!

[@flockoglock]

Outstanding video as usual. I've had six of these amps in for repair in the past five months, with problems ranging from bad tubes, failed solder joints, bad filter caps and one user that tried to modify his amp, but doesn't have adequate soldering skills. Many of the amps have worked for twenty years, with no problems, which says a lot about the design of these amps. I'm do this mostly as a hobby and could really use some instruction in safe and proper Oscilloscope use in troubleshooting tube guitar amps, especially oscillation in reverb circuits and diagnosing other problems. Any chance of you doing a video like this? Thank you so much for everything you do.

[@mdshack6371]

I had a similar problem. I first "did the twist" on all potentiometers. Aggressively tapping on the knobs and literally moving them. Then tightening the pots to ground. Found/heard a cold solder in the midrange pot. (No testing equipment. at all). cold solder on the cap. The problem was intermittent as well. I prefer to use the use a bigger hammer method before bulling out the scope. GREAT video for those of us who worship the sound of this amp. Do not be fooled about the III model, distortion beak up and reduced volume with guitar volume pot is no where near as good as the older versions.

[@lesjohnson9740]

Magic videos yet again.

[@MrCarlsonsLab]

+Les Johnson LOL, Thanks!

[@robertcalkjr.8325]

Thanks for the video, keep'em coming. I didn't even know that Tektronix made DMM's.

[@MrCarlsonsLab]

Thanks Robert! That Tek TX-3 Is a very nice DMM. It's very fast, even in dual display mode.

[@Wi66pro]

Really informative and clearly explained. I have the Hot Rod Deluxe which has a similar layout. A friend gave me an old Brimar 12AT7 to try in the V1 slot. As soon as I put it in I had an horrendous hum. Now I know what caused it I can give it back with a very smug explanation as to why his tube is crap. :-)

[@MrCarlsonsLab]

Fender56 Thanks for the comment, glad you enjoyed the video!

[@jjiacobucci]

Thank you for sharing your knowledge. Also, your advice on Chinese tubes is greatly appreciated. NOS tubes are getting harder to find and very expensive

[@GingerBeker]

Mr Carlson..yesterday i bought the same ikea desk lamp you have. i think it's the only common stuff becouse i'm completely distaster in electronic. ^_^ i love every video you made....

[@Geopholus]

I've been working on HiFi and Guitar amps for over 50 years. My first experience with a DeVille was a disaster. perhaps 12 years ago. It had about 5 issues! First one it would go into low frequency oscillation like a continuous belch, because the input jack being very flimsy and mounted to the large resonant chassis directly opposite the speaker, would act like a car horn, a vibration from the speaker would cause the contact from the input to discontinue, which would pop and then it would reclose (acoustic feedback from the speaker), and this cycle once started wouldn't stop , unless you pressed on the jack, or turned down the vol. Replaced the Jack with a switchcraft traditional jack and had to cut off part of the circuit board. Then there was excessive hum, apparently due to all the ribbon connectors, and poor ground geometry. As soon as I removed the board from the chassis, which includes pulling all the knobs and pulling a bunch of connectors to the back board , and hard to reach screws, the ribbon connectors broke because they are too stiff. (the board must have gone in and out ten times because there were more and more issues). Bad plate resistors, conductive chemicals, not cleaned off the board during manufacture, and really cheap caps etc, etc. I ended up having to replace all the ribbon cables almost with skinny shielded wires. The kicker at the end, was that one of the speakers had been replaced with an Alnico speaker that was perhaps 8 inches from front to back, and the end bell had to be taken off just to get it in the Box. This had been done previously by the owner? The large Alnico magnet was directly nuzzled up against the Filter choke. and depending on where one hit the power cycle in terms of the residual hysteresis on the choke laminations, at turn on, it would hum slightly , or not. This was especially annoying as I had been working on the amp on my bench, off and on for several weeks without it being in the box (so I hadn't realized this would be a problem! ) Luckily the next two that I worked on briefly were much better in quality. But I won't work on them anymore. Yuck! Poorly executed design.

[@SteveHacker]

There's my old U.S. Navy Hickock scope from the 1950s! LLLOVE IT! I want mine restored so bad! Awesome! 😊😊😊

[@alb.7763]

Good T&T & understanding Carl.

[@MrCarlsonsLab]

Glad this helped!

[@bobsykes]

I was waiting for you to plug in and play it at the end so we'd here how the thing sounds!

Some of the problems and solutions Paul gives here for the Hot Rod DeVille also apply to the HotRod Deluxe I and II and 40 watt Blues versions.I cannot speak for the HRD iii because they are modified (Blackface) The explanations here about heater to cathode and heater to grid shorts was intriguing because I never considered the mica insulator to oversize from vibration, and whether psychoacoustics is involved or not in Tube amplifiers, and the tubes country or manufacturer of origin meant diddly if the tube was actually a good performing tube. I would think that to reduce warranty costs and customer satisfaction,and yet make a nice profit- that many different makes of tubes at various cost/performance attributes would be lab tested.What do we have here is possibly a one year Factory warranty

[@MrShobar]

Nice job, as usual. Many thanks.

[@MrCarlsonsLab]

+MrShobar Your welcome!

[@bluesideup007]

Another great video! Thanks. To differentiate the sound quality differences of a Chinese vs US made vacuum tube you will need a hard to find piece of test equipment: a Psycoscilloscope. ;-) (sometimes can be found at CIA garage sales)

[@silasfatchett5693]

I could sell you one for $45,000. It looks just like an old fashioned oscilloscope.

[@tonyz4292]

Would love to see a video regarding the topic of psychoacoustics!!!!

[@strangersound]

Agreed. I would love to hear his thoughts. My head would probably explode from over stimulation. ;)

[@Amp497]

I have met customers with chronic psychoacoustic disorder.

[@scubaman2546]

2 year old post; however, I agree with it. An episode on psychoacoutics from an electrical engineer's POV would be fascinating!

[@gingercat777]

If you're aware of the frequency difference between 120Hz and 60Hz hum, it's easy to determine if it's tubes (60Hz) or filter capacitor/ground issue (120Hz) is the source of the prob.

[@MrCarlsonsLab]

+Squizzy Bollocks Thanks for your comment!

[@frankgeeraerts6243]

50/60 Hz HUMMMMMMMMMMMMMM 100/120 Hz BUZZZZZZZZZZZZZZZZZZZZZZ

[@terryeaster1]

Your work is amazing

[@jeffb6161]

very good video, love the scope, I have a Hitachi v-212 that i use, works just fine

[@MrCarlsonsLab]

+jeff b Thanks Jeff!

[@kimhansen6384]

Around 1980 I bought one of those scopes and I actually troubleshooted a homebuild 6502 CPU and I/O board with it. The boards were laid out on Eurocards for thruplating, which I didn´t have, so I needed to solder the chips on both sides ... good old days :-) I gave up on the floppy controller though, and sold it.

[@absurdengineering]

Kim Hansen I did a design in the 90s that had 9 Intel CTC chips attached to a Z80 - for a device that was essentially a precursor of Vive lighthouses (there were two light sheets instead of four, because the lighthouses were on a common metal frame). I etched it myself and then drilled it and had to solder both sides. This was a Swiss laminate with photo resist that doubled as oxidation protector and flux. It wasn’t hard to do the double side soldering, but there were just so many pins! From what I recall, I managed zero bodge wires. Must have been a real simple design, as that feat has never happened again I think on a first prototype for me.

[@robertc7682]

Nice clean work !

[@user-gz5yf1xy3s]

I sweat when I work on mine you're in there like nothing hat's off to you sir

[@PeterDad60]

My guess is you are/were a Navy man. But I say very seriously you are the best trained/educated tech I have every seen! I have the Hot Rod Deville 410 III a 60W 4 x 10" speaker combo amplifier. Mine has a Preamp Tube stabilizer -a vibration absorbing stabilizer installed around the preamp tubes to minimize tube microphonics. I did a tube re-bias and I set it a little cool for longevity. I have my notes somewhere. I think I set it downwards from 60% to 57% (divided by 2) I'm not positive about that without my notes in fron of me. I do not do re-biasing frequently so my memory is sketchy. The amp is still very loud and no problems so far with the tubes. I know most people want to have the bias set hooter than 68% to have it distort earlier. I may rethink what I did because I just can't get the power tubes driven into distortion without the volume completely overwhelming my ears. I don't even try. Rather I use the preamp tubes to get my distortion. I can get distortion at low volumes using that technique. However to my ears it's not as pleasant as overdriven power tubes. It is my understanding that the reason why so many musicians prefer tube amps is because of the tone. From what I have learned the tone is different because tubes have more inherent distortion than transistors. I do not think many musicians are even aware of this fact. They think tubes are warmer., and so they are. I grew up during the '50's and '60's and has a tube amplified AM Radio on my night table to help keep me warm! Yes I suppose people can and do design a transistor S.S. amp to emulate tube distortion. I was always interested in electronics and had a few good tech books. Somewhere somehow my American Ham Radio Handbook went missing. It had a lot of information about amplifiers and tubes. I'm kind of helpless without it. In fact all my books on electronics are missing. Me thinks I need to purchase another Handbook. Now back to you pleasingly executed and educational video... P.S. I know that your Father is proud of you. I have a son a little younger than you and I know what it means to be proud of a Son. ASNF.

[@PeterDad60]

+PeterDad60 Ha! I knew I meant to write 60 Millivolts not 60% and re-biased down to 57/58 mv not 57%. I'm very rusty on my terminology these days because I am so inactive (retired).

[@MrCarlsonsLab]

+PeterDad60 Thanks for taking the time to write, and the kind words too!

[@johnboleyjr.1698]

As a former "M" Brancher in the Navy I am completely jealous of your gear there. One day I'll have my workshop, and I'm hoping to get some nice older pieces from a DRMO auction. I personally own one of these amplifiers, Fender Hot Rod Deville 212, and I am planning on performing some mods to her. One in particular, employs the use of a switch to select between "Triode and Pentode" operation of the Output tubes. The solution requires a separate DPDT switch be mounted on the chassis (the original modification is represented on page 111 in the book "Inside Tube Amps" by Dan Torres), however if possible, I would like to change the "Standby" switch out with a DP3T switch (I'm thinking) instead of adding another switch somewhere on the chassis. This way I would have a "Triode-Standby-Pentode" switch. I'm just having an issue of figuring out how the switch would be wired to accommodate this desired outcome. Do you have any suggestions for a solution, or where I might find an example of this wiring? I haven't been able to find information on the original amp modification anywhere except the book, much less the modification I'm trying to perform.

[@killerguitars52]

I took my marshal tube amp out of storage and ran an overdrive pedal through it for 10 mins and BOOM no more sound. Have yet to take it in to be fixed, who the hell knows what broke. Anyways love all your vids Mr. Carlson!

[@davidportch8837]

Great job Paul. I had one of the Fender Tweed Blues Deluxe amps (pretty similar but one speaker). Original USA make and not the more recent Asian ones. Terrific sounding amp but having the valves (tubes) in the "box" plus the hybrid design meant that with regular use, it did require some repairs... and I never did understand why you would mount a valve upside down so that all the heat went back into the valve! So I am back with a separate tranny amp and separate speakers, which are more reliable... keep up the good work...

[@MrCarlsonsLab]

Thanks for taking the time to write David!

[@gabriel62892]

Hi, nice video. I have a blues deville reissue from 2007. 60 watts, 4x10 blue alnico emminence speakers, Made in Mexico. And it was biased at 51.8mv with a kind of glue from factory, in the bias pot.. I rebias it at 60mv. It sounds better but realized increases chasis temperature too. I hope not burning the circuit tracks, as many hot rod I've seen, next to the bias pot

[@Micotech1]

That looks like a receiving tube manual, i got mine in 1975.still the best book

[@pepecohetes492]

Great tutorial, thank you very much!

[@MrCarlsonsLab]

Glad you enjoyed!

[@rhinkashi]

its very nice all your video. I learn a lot because. Im a technician for tube audio amplifier in her in the Philippines. i have no oscilloscope, the only i have is a multimeter analog.. i want to know more complicated. I see and watch your many video and thats great i like it. I already 10 moths experience for repairing tube. because my last job is repairing cellphone and laptop, say its transistors amplifier. I subscribe to your channel and keep it up for more video tuturial and tips. happy electronics life.

[@MrCarlsonsLab]

+Mark Anthony Estrada Glad your enjoying the video's Mark! Glad to read your working on the older devices as well. Thanks for your kind comment!

[@Jjosh1358]

I just watched AvE do a Clive video. Now lets watch Mr. Carlson do a Guitologist video. I love it! Its crossover city! All jokes aside, in all seriousness, previously mentioned youtubers are easily my favorites.

[@themagnetc]

I had a friend ground my input jack like you do in the video, the hum went away but my amp nearly overheated (turned it off just in time). Now it's running fine but still has its original high noise floor.

[@gustavcida2987]

Recently I got the same model with a failed plate resistor in the phase inverter circuit. The owner never had the amp serviced at a proper service, he just took advice from a local music store, btw he purchased a new device, so he left me the amp for scrap. As he've ordered some spares, I ended up with the amp, a brand new set off tubes and a ....spare O.T. Greetings from Austria

[@MrCarlsonsLab]

+Gustav Cida Thanks for your comment Gustav!

[@Willam_J]

I had an amp that hummed...... It didn't know the words. Bah-dum-tish!

[@MrCarlsonsLab]

:/ .... LOL

[@budandbean1]

Before retiring, I was the Fire Safety Inspector for a school board and during our annual inspections we came across so many different items that hum and ultimately, me or one of the fellas that usually went around with me asked the question, "you know why it's humming?"... "Duh, no... why?", "Because it doesn't know the words"... Bah, ha, everyone laughs. Well we did it every year, same stupid question and let me tell you, we got the same guys for ten years or more asking why it hums. We had a great school system and the job, after I got there, well after the first few years, got so boring that this was the best running joke. It's the little things in life. :-)

[@W1RMD]

Thanks! :)

[@badfender223]

Great videos - thanks.

[@Blueslicks321]

LOTS OF INFO GREAT VID THANKS ...

[@MrCarlsonsLab]

+Paul Calugaru Your welcome Paul!

[@jeffbeck6501]

Wow. I just joined you channel from the giant transmitter video for no apparent reason, and then I see this video which is more relevant to me. I once had one of these amps before a "friend" stole it. But it came to me with a tube that had been replaced to hot rod the hot rod amp. I think, and am basically sure, they had taken out a 12AX7 and put in a 12TA7, and man alive. The amp just came alive. Way way more clear. Only problem was that it rattled on an Ab note. It was like a mid-range rattle hum. So it was not perfect. But with the regular 12AX7 the amp sounded just dead. Not alive. Lifeless. Boring. Not a great sound, but probably okay for some Stevie Ray raking style. But with the 12AT7 is was so clear and so warm and so full sounding. I had to replace the 12AT7 when I had received the amp, but after doing so, it just sounded so good, my ex "friend" stole it. Look for some documentation on this modification. It sounded great for me. ...as long as I did not hit an Ab bass or mid-ranged note. Then it was almost like a feedback oscillation problem. If that could be fixed somehow, maybe by adjusting the bias or other mods, that would be nice.

[@fredyearian4968]

I made a comment on another of your videos about heater cathode leakage I found, but in my case the leakage killed proper dc bias rather than injecting hum.

[@smbrob]

I really like the way you work true the problem, it makes it easy to understand and follow. For me these video's are a way to keep in touch with my old hobby , and even make my fingers itch to start again :-) So thanks for the great vids keep it up. Just to let you know , it looks a bit like you look past the camera to the left for us. I don't know what the reason is, do you ??

[@MrCarlsonsLab]

smbrob Thanks for the nice comments! I think the reason was the lighting. More to the right and it may have glared in the lens. OK "EDIT" I remember now...... I hadn't bought the wide angle lens for the old camera at this point, and I needed to get that little scope in the shot and make it plainly visible. So that made for a tight shot.

[@StevePietras]

Hate those 1/4 plastic jacks. Used to have to replace them in some live truck abused Rane mixers. Thought maybe you would treat us to a six string solo of some April Wine Paul! Fun video, 73's Steve

[@MrCarlsonsLab]

LOL, I'll stick to electronics :^)

[@jimirox1928]

Set the bias until it sounds the way you like THEN check to make sure the bias is in spec.

[@MrBoriswart]

Very Informative.