D-lab series Basic Training Tube Guitar amp repair Fender Champ Low power is the transformer bad?

Another cool problem dished out by Fred & Fink. This time a Fender Vibro Champ having a low power output issue. I performed my routine cap change assuming that was all the amp needed. To my surprise, the low power symptom remained. After some research & inspection, the culprit surfaced. A unique problem, almost fooled me. Always exhaust your resources before condemning components, especially when it could be a pricy transformer! Basic training fun from D-Lab electronics. Remember these original type filter capacitors can be purchased from Amplifiedparts.com. Maintain the original performance & look of your classic amp!

[@daveanderson5680]

Yay D-Lab fixes another vintage Fender amp!

[@jonpardue]

I bet you are right, this unit came wired that way and has never played at full volume. Great fix Terry!

[@blues61]

Sweet! Nice troubleshooting Terry.

[@edwardhannigan6324]

Wow, what a fix..! Great how you found that out and funny how it was always configured that way. It looked like a bad transformer at first. So much to look out for eh Terry, and those tips are great...Loving the tech, and Basic Training series. More, more..! Ed..uk..😀

[@greggaieck4808]

D_lAB ELECTRONICS the owners tube guitar amplifier is cool my hobbys are painting pictures and lisining to shortwave and ssb iam thinking about getting my ham license I have 4 shortwave receivers me and my cousin are going to a Swap meet June 5th 2022 Sunday morning at 8 am in Milwaukee my

[@greggaieck4808]

My other hobby is lisn to music records and CDs and fmstreo on my Yamaha reciver

[@jimbeaux4988]

Wow. That guy is in for a surprise when he gets it back.

[@josephmagedanz4070]

I guess I didn't know that heat shrink tubing was that old...live and learn!

[@jimgiordano8218]

I got the problem as soon as you started the voltage checks. The owner is going to be beside himself with the volume improvement. Great job.

[@CRUNCHCOLE]

Love your videos. I learn a lot from them. If I could only remember what I learn at 68. lol

[@bkbinj6320]

Very cool sleuthing to get this amp up to full power.

[@bsicotte]

Who would have thought? Good catch on this one.

[@meesterprofe007]

As usual, you have another excellent video and confident delivery! A surprising situation in this little amp. Your expertise is wonderful and I always am interested in your projects and restorations. Thank you Sir Terrance for your great contribution to KZbin education.....I am always impressed with your knowledge and style.😊

[@pickholder6189]

`I was looking at that transformer thinking nothing was wrong. Of course I am in the UK so used to seeing theses wired this way......

[@preiter20]

Great troubleshooting video Terry. Very comprehensive. It didn't occur to me that the transformer was wired for 230 until you pointed it out.

[@danielsaturnino5715]

D-lab delivers again!

[@daveogarf]

Fascinating! I'd never have imagined that a factory wiring 'error' would've been the culprit.

[@OIE82]

The shrink tube and power cord, seems to me, to mean that someone recently (as in not from the factory) wired it that way maybe. But I will not be overlooking transformer wiring on the initial inspection anymore. Being in the weights and measures industry, we get calls from time to time, saying "my weights are off by about half. I need a service call." The first thing I tell them to do is push the "units" key to switch it from kg back to lbs. That usually corrects the issue.😊 Same kinda thing with with that transformer. Thanks Terry

[@greengrayradio1394]

You found it right away! Actually, when you reported the PT AC voltages, I thought the same- an amp wired for European power voltage!

[@gingercat777]

Good job the volts/situation weren't the opposite.

[@sting1111]

I like this series and am bookmarking when I have time to go thru it. Thanks

[@sboy1955]

Enjoy your videos immensely. Subscribed

[@jdmccorful]

Good catch! Enjoyed watching. Thanks.

[@kevinmiller4486]

My uncle was a tv repairman and had two or more tube caddies to do house calls. If he couldn’t fix it he would bring the chassis back to the shop.

[@whatsstefon]

As soon as you showed all the voltages were half I though “I bet this is an export transformer.” Being in Australia, I see that all the time. But for me that’s good news.

[@colinsvid]

Thoroughly enjoying the videos, I’m learning more all the time, thanks terry

[@MarkGutierrez]

Great investigation. Love these vids.

[@ericdee6802]

Great save!🎸🎶🔉

[@haroldsparkman6008]

Wow that's crazy. Never would have dreamed that. That's why we leave the repairs to you Terry 😂

[@YeatzeeGuitar]

Fascinating, really neat!

[@weschilton]

Wow, great detective work! I am amazed that the owner even kept the amp sounding as bad as it did. He is in for a real treat now!

[@markolson9778]

Excellent lesson.

[@juliochingaling5824]

Wow, big difference. Great job and excellent video. God bless

[@jeffreyadams4952]

My fender supersonic 60 is doing exactly what you are describing. I'm very glad I watched this now I'll at least have something to suggest to the tech I'm taking it to for repair .... Great

[@miguelrichartmellado2834]

allwais the raigth schematic. In coutries with 230v, people looking for this problem, one autotransformer. This conection , kill the problem. Big Terry !!!

[@PhoenixGuitars]

Great lesson today. Some background from the owner may have helped but sometimes you get what you get. Thanks for the content!

[@Xpyburnt_ndz]

Gr8 job and vid Terry! Likin these vids!!!

[@Scooter110]

I noticed that the transformer pigtail had heat shrink on it. It looked a lot less than 30 years old.

[@srtamplification]

There's Fred again.

[@Paul-ow6of]

Now that was a good one!

[@jenniferwhitewolf3784]

Very odd that it was factory mis-wired. Good catch... and a good reason to check B+ voltage and the filament voltage right away.

[@dhpbear2]

5:54 - My guess: the transformer is wired for 220-volt operation.

[@CC-te5zf]

Incredible Terry! And some techs would’ve just charged for a new tranny and kept the vintage one.

[@rciancia]

Wow Terry, that was a really good one !!!!! Most people would start shot gunning that problem but you thought it out and solved it.. Well done D-Lab awesome as usual .

[@oimate4201]

That was really great. Thanks for taking us through the basic troubleshooting steps. Not an average problem, but it’s one that was found with above average understanding of fundamentals. Good job and thanks for sharing!

[@alewis6451]

Very interesting and presentation thanks for sharing as I love electrical trouble shooting. I was given a fender blues junior that has no sound and making it a challenge to fix it.

[@electrolytics]

D-Lab great insight into electronics and always a conceptual innovator.

[@TheTrueVoiceOfReason]

When you reported ALL voltages low by half, my first thought was this was a European amp that just had a North American plug slapped on the end. Sure enough...

[@thedevilinthecircuit1414]

Somebody's been in there before you. They incorrectly hooked up a new three-wire AC mains cable and ran the neutral line to the fuse. This means if there's a failure in the amp (AC to ground) and the fuse pops, the chassis can still be live at mains voltage. Always run the black/hot wire to the fuse, then the switch, then to one PT primary. The white/neutral goes directly to the other PT primary.

[@cheycasters]

Great stuff Terry as always

[@ericedelman]

Love seeing the silver face repairs. I grew up in the silver face era, so I've always identified with them vs the black face amps. I love the super clean/glassy tones. Great video Terry!

[@mikemix1361]

Terry, thank you for great content.

[@pda49184]

Brilliant Terry.. I would never have looked at the TX hookup as it's been owned for 30 years living in a 120 volt country. Who'd have thought it.. Not me ! USA made amps here in the UK,, Oh yes, I'd check the TX wiring, but then that's a given when the amp originated from a country with different mains AC volts. I wouldn't be checking a 'made in England' Marshall.. But from now on , I will !

[@fabdofasol8990]

Great, I’ve used this 010020 Schumacher PT facility to plug a silverface non reverb Princeton in Europe a few years ago!

[@mikesmuseum]

Should have named that amplifier the Euro-Champ, lol.

[@VictorJenks]

Good job D-Lab . I’m a technician Ham and am enjoying your workmanship as I am also a Singer Songwriter in the market for a Tube Amp . I have lots of effects that I use though for the time through a 100 watt Champ Solid State . I miss Tubes so much though .

[@whynotmaple6014]

Great video and series! Thank you, and Keep it up!

[@miguelrichartmellado2834]

Thanks you Terry. Very good video.

[@stevencraig]

That was nicely unexpected

[@volesrock]

I just bought, recapped, and sold a bone stock 78 Vibrochamp this year and it indeed had those extra red/yellow and black/yellow leads soldered off to a terminal strip where the death cap lived. I checked my pics of it. Had NO idea what the hell they were.

[@reggiewallace260]

Although I'm a subscriber, I don't normally leave comments. This time though, I found this video so interesting I just had to say, well done! Always look forward to your next video. Thank you Terry

[@manfredbaer3297]

Great video, Terry! I bet too, that this amp was wired for 230 volts ever since.

[@tigertownmusiclab]

Great stuff!!

[@jcmcclain57]

Great lesson, thank you!

[@jagtone]

Hey, Terry, I did the opposite operation on my Vibro Champ when I moved abroad--rewired it for 234 volt operation. What a relief it was to find that I didn't need a transformerectomy or to lug a stepdown tranny around with me. (Mine is still sounding anemic though, so I still have some trouble shooting to do.) I did the same thing on a Laney acoustic amp I have, too. I wish more amp PTs had dual primaries like that.

[@nickk9202]

If it had been wired correctly the magic smoke would probably have escaped from the power transformer when the filter caps died .

[@shakeypeet]

Thank You my man .

[@johnmac8084]

Well spotted Terry. I think you're right, it was wired for Europe. That guys going to have a new amp!

[@richardbarrios8132]

My 1965 vibro champ has the same problem. Need to have someone check the wiring!

[@gaylen8467]

Nice One

[@joepeezy4sheezy]

Too cool! I wonder how many people would have just changed out the tranny. Amazing.

[@zbaby82]

That amp was probably wired for Great Britain.

[@nikkisimpson1835]

Very interesting repair! Did not see that coming. I'll trust your judgment though I can't help but wonder if some unqualified diy'er rewired the primary to drop the B+...but didn't know enough to think and or check the filament windings. I say this because it looks like quite a lot of work has been done, coupling caps, bat toggle switch in place of the slide switch...

[@adrianshingler9783]

Or very simply it was wired for use in the UK 😎👍

[@pauldow1648]

Question. A 120 plug is quite different from a 220 plug.. So if it had European 220 plug someone uninformed made a big bobo long ago.

[@Starcrunch72]

That's quite a wild find! I imagine the plug end of the power cord had the standard hardware store replacement plug on it, because those always twisted and frayed. Was there further indication on the back of the chassis that it was wired for 230V?

[@Zelleram55]

Did that cabinet tube chart label or anything say “For Export Only” ? That might be something for others to look out for in the future. On one of my amps it has printed on the tube chart label “for export only” then from the factory they ran a black sharpie over that to block it out unless you look close.

[@dprice1077]

Terry, did anyone look at the back of the amp to see if it was labeled for 230? I have a Fender frontman15 power light came on no sound. I noticed it was labeled for 230.

[@stevem.1853]

I wonder if the original power cord was replaced... might have originally had European style 240v plug? Also the power switch is not the cheap slider switch that you always see on the champ. Maybe that switch was not compliant with European electrical code, or did the original fail and was replaced with a higher quality toggle...

[@d-labelectronics]

Funny you would bring that up. Yes, I replaced the cord & power switch. The cord had previously been replaced, but was in poor condition. The power switch was odd looking, black plastic flipper, had 4 terminals, but had the new power cord connected. May have been the euro type? Good thought

[@stevem.1853]

@@d-labelectronics I've always thought that the stock power switch on the black/silver face champs looked cheap, but I've never seen a video of a champ with a bad power switch. Either way, that new switch is better quality than stock. Fender was definitely cutting corners on their entry-level amp, but adjusted for inflation, you were still getting a good amp for the money.

[@thedevilinthecircuit1414]

@@d-labelectronics The power cord is improperly installed. Neutral to the fuse like that means if there's an AC mains short to ground and the fuse pops, the chassis can still be live at mains voltage.

[@jimcastillo8950]

Hello, my question is do fender amps need the brass plate where the pots are located? I just grounded to the chassis and have no issue..... thanks

[@MrChopin2323]

A lesser man/woman would have just replaced the transformer. Good deal, Fred, as always.

[@exciter2506]

Never seen this one before on a vintage amp. The owner is going to think you hot-rodded his amp.

[@jeffalessi]

Terry, What is the part number for the solder cartridge you use with your heavy duty Unger soldering iron? Have a most awesome evening!

[@d-labelectronics]

4033, 50 watt

[@jeffalessi]

@@d-labelectronics Thank you very much and have a most awesome afternoon!

[@rumproast2000]

The amp looks to have a replacement power cord installed. I'd bet that someone read the schematic wrong and wired it for 230V. Whomever wired the new cord in should have also corrected the fuse wiring - it's inline with the neutral.

[@JohnvL]

Lol we have 230v (-10/+6%) volts line EU. You lucky, if i have 2 parallel 115 volts it smokes...for short time and its gone forever

[@trbr1799]

First, great work and sleuthing! Thanks for the great content, as always. Second, I am experiencing the same lower output on my champ. History, the stock volume pot seemed damaged as the shaft was loose and its the loudest champ I've ever heard. It also seemed to have a linear taper. Replaced the volume pot with same value and audio, but it's now the most quiet champ I've heard! Anyone have ideas?

[@natb9121]

Why didn't you correct the white/black wires on the primary (black to fuse)?

[@d-labelectronics]

Wired per the Fender print

[@thedevilinthecircuit1414]

@@d-labelectronics Whoa. Scary!

[@nigeldurrant7868]

if it was configured for European sales, it would not have a U.S. power plug on the cord, a factory wiring 'error'