How to repair Vintage Sunn 2000s 100 watt 6550 tube guitar amp D-lab

[@bbking82]

I have an extremely short attention span due to ADD, yet your videos are really easy to watch.Love watching these videos.

[@jeffreycollins7297]

Friggin amps are so heavy it was most likely dropped (instead of placed) onto whatever speaker cabinet it was on each time it was moved. Cool to see one being worked on. Those things have gotten expensive since the group came around.

[@Yoda8945]

It is great seeing that amp on the bench. I was a dealer for those amps in the 60's and 70's. They were reliable and LOUD! The 2000S was the bass head and Sunn claimed 120 Watts. The way they were set up from the factory, the plates would glow red. I think that was due to wrong bias.

[@Buhhhhhh-xi4ju]

You wouldnt happen to know how to repair the trem on the old 1200s heads would you?

[@djfrank59]

Hi Terry! Have to admire a thorough check out and repair. Taking the time to carefully go over all connections assures that the amp won't come back for future failures. I had a few Sunn 2000S's come in over the past 2 years with similar issues. However, one customer wasn't so lucky. 2 shorted 6550's not only took out the plate/screen resistors, but killed the PT...mainly due to the customer replacing the 5 amp Slo-Blo fuse with a 30 amp SFE-30 car fuse. After discovering the wrong fuse installed, I actually made the amp kid proof--I installed a second pigtail fuse of proper size inside the amp. PT's for the Sunn amps don't come cheap. Bad ground connections aren't anything new with those amps (as well as many others). Another great video as always...Keep 'em comin' I'm a watchin' :)

[@riccardocriscenti6076]

love this video i wanna learn more about electronics there's not enough people repairing these days

[@robhaskell4043]

Your knowledge and explanations are excellent, Sir! What an interesting video. No loud background music, clear articulation of issues and correction activities. You do a fantastic job on these videos. Keep em coming. Cheers from Canada....

[@erichrichter1877]

this is a very informative video I appreciate the way you take the precautions before firing up a tube amp. I have a Sunn amp similar to this one but has the same issues so this video is very helpful. thank for sharing your knowledge.

[@petedazer2556]

Back in my playing days, Sunn was an amp I stayed far far away from. Nice job!

[@deuteronimus750]

Leslie West used a 200 watt Sunn PA head live.

[@bucyruserie1211]

Another FANTASTIC D-Lab Production and Repair... Not to discredit your outstanding tech work Terry, but I think your missing out on your true calling in life....... Film Producer.. Satire, Drama, Comedy, you can do it all Terry! Great Video

[@contrabandjoe7974]

I'm 52 and in the late 70's and early 80's while in high school I worked afternoons at a music shop. We were a Sunn dealer, some of those Sunn's were really good.. What I always wondered was why Music manufacturers made such humongous large amps back then? I've seen Fenders, Peavey, Sunn, Ampeg etc that required you to be an Eastern European weightlifter to move. I understand that in the 60's prior to the availability of efficient PA systems a larger amp was needed, but these companies continued to make heavy and large amps up to the 90's. look at the console portion of this Sunn Amp, it looks like a mission control panel for NASA... Musicians back in those days must have been stronger than today's player... LOL

[@billdyke9745]

If they didn't weigh much you wouldn't need a roadie. And without a roadie you have no-one to blame if you play a crap gig...

[@billdyke9745]

If they didn't weigh much you wouldn't need a roadie. And without a roadie you have no-one to blame if you play a crap gig...

[@stephenquail3168]

She got you out in the hobby shop all the time .I know how it feels.great job.

[@d-labelectronics]

By rule of the rolling pin! At times, I do need the push

[@charlesshaw9090]

Great attention to details Terry. Another cool bit of work.

[@robertedwards3147]

your videos are well done so well that I watch them to the end I have been restoring radios and test equipment Most have been run on 240/250v and not 110v so that is fun for me

[@BurtonBoyz715]

I"M A GEEK for this stuff....this was an outstanding run-thru...very well explained and nicely videoed....I'm in...SUBSCRIBED. Thumbs up....one of the best Tech Tutorials I've seen. Really. Perfect. Thanks.

[@luthravin4774]

Very professionally repaired!! You do great work on these gems of old!! I couldn’t help my enjoyment when I saw that Beaver Cap.. Black and Orange.. being the amp was built Oregon the name fits.. can’t remember the exact city...Taultain, Oregon... just outside Portland.. late 60’s-70’s.. huge power in 2000s... thanks again

[@henkkman]

Holy moly! Look at the size of those transformers! 😳

[@TheRadioShop]

Another great repair, you deserve your glass of wine on that one. Also loved the opening and ending.

[@jonpardue]

Thanks for taking time to show the terminal strip details.

[@ross3818]

Thanks for not playing that Ghoul recording. And thanks for sharing your skill and knowledge!

[@bcarr3116]

Hey Uncle Doug another great Vid. So why did you not use your Current Limiter Lamp on this repair? I built one after watching your vid. on building the Current Limiter Lamp. It works great. Thanks Again B

[@bartmeijer1059]

And again a interesting video, Terry! There where a lot of problems to repair, and again you fixed it! Well done!

[@hotwirehenry]

Awesome. Didn’t even know Sunn made tube amps.

[@joecarpenter5602]

I have one now in my shop that was built with a 1000s faceplate, its missing the reverb circuit that how I figured out it was a 2000S. Looks bastardized like they hobbled parts together, even has the 12AU7 socket installed with no pins. Took me a little time to figure out what they were doing, looking at old schematics to find a match. Thanks for your video.

[@GhostWorkersComp]

Ok Marcia, I need the rolling pin attention to a Hallicrafter there in the shop. :). Never knew you were such the driver!!! Great video! The DLab Master is responsible for the rising of the sun!

[@GTOJeffman]

Thanks! This will be helpful if I experience problems with my Sunn 2000S amp. 👍🏻

[@geoffbarber2860]

Hi D-lab, Do you have any knowledge of what type of reverb tank was fitted into the Birch-Stolec 1970 model, please? It looks like the amp has never been fitted with a reverb tank but is wired for one. It must be a high impedance reverb as its driven direct from the anode of an ECC83 via a 2n2 cap. Any information you may have will be greatly appreciated. Regards Geoff

[@audiotechlabs4650]

Fantastic Terry! I have aJCM800 with 6550s and I will take your recommendation on the Tung-sols. Thankz

[@kayciecarryl3366]

I would have replaced the 2 prong AC cord with a 3 prong cord. Other than that, it was wonderful to see the inside of that 2000s. I've owned or seen the entire '60s amp line. Not only did they sound great, they also looked SO. TOTALLY. COOL!!! 👀!

[@wojciech_migda]

I really envy your knowledge :-)..... I wonder how much work, time, blood and sweat went into getting to that level of expertise. Always a pleasure to watch!

[@martinreid1740]

Thanks Terry for another great video. You are sir,are a great amp technician. All the best for a Happy Christmas and a good New Year from Scotland.

[@d-labelectronics]

Thank you, my friend, I appreciate it.

[@chungaleta1234]

Cor blimey, your intros and outros always crack me up! LOL.. Great vid mate!

[@d-labelectronics]

Thanks man, I try my best

[@viniciusandrea3251]

Nice video, Terry! You're awesome! Thanks for sharing your tremendous knowledge.

[@d-labelectronics]

Thank you my friend

[@simonspeaker]

I like you D-Lab youre the best amp tech I ever seen! you always know what youre talking about and you are very meticulous and funny with your joke and your wine its a pleasure to see you! keep doing videos ! youre the best 😎 Simon from Canada Montreal in province of Quebec

[@timbalint]

Great video. What adapter are you using on your audio generator to go to banana jacks to 1/4”?

[@paulkielt9301]

When you replaced those two resistors on one of the power tubes, why didn't you replace the other two on the other tube? Maybe it's not an issue, but everything you swap on power tubes has to be well matched, because it affects the sound. Even if it's subtle, there will be a difference.

[@boulder89984]

Do you ever clear out the old paper cap and install the new ones inside the paper body. Takes time but retains original look

[@chokkan7]

Who was that crazy woman who interrupted your reveries? Never mind... Helluva job, Terry...I remember my older brother had one of these for his organ when I was a kid...LOUD!

[@ThomasACarlos]

Hi Terry: What is the value of the resistor that you are using during your power up testing? Thanks!

[@MikeGervasi]

"Solder isn't glue". Important lesson I learned.

[@christianboddum8783]

Man you're crazy. It's official. DO NOT CHANGE OK? Love your vids.

[@Chuck-dh5qn]

Awesome repair job. Easy to follow and clear explanations. I always enjoy your videos! I have a 1969 Sunn 1000S guitar amp that I've been asked to restore and I'm in desperate need of help!. I cannot find the service manual for it and I'm lost without it!. If you know where I can find one, please let me know... . Keep up the good work!!!

[@materialsguy2002]

Great video Terry, thanks.

[@Jah_Rastafari_ORIG]

Hey Terry; I remember you used to have a large Fender-ish speaker cabinet in your lab, but it seems to have disappeared (or perhaps it's just invisible...?)...

[@MrBillsmith60]

Terry, that's was a good one, thanks

[@d-labelectronics]

Glad you liked my friend

[@mackfisher4487]

Terry does the XYL send you to the Lab to keep working, but on the bright side she does bring you wine!

[@HazmatB]

When you talk about monitoring the negative bias, you're talking about the voltage drop from cathode to ground (i.e. across the cathode bias)?

[@robhaskell4043]

What I find very cool and interesting is that you are confident the amps work without actually playing an instrument through them, or do you before you return it to the customer? Does your scope tell you everything you need to know?

[@danielgoodson703]

Just revived a 1969 SUNN Sonaro. Loved your video. Thanks for posting such an informative and useful presentation. Curious your thoughts on removing the "death cap" and disabling the polarity switch. Found new power switches on ebay. Works great now. Thanks for your help!

[@ferraridinoman]

Nice one Young Tel!!

[@MrMac5150]

Nice work Sir.

[@rhykko77]

Amazing work ! If this is a hobby ........what do you do for a day job ?

[@d-labelectronics]

Thanks man, I work at corporate america as an industrial controls/electronics guy

[@shiner555]

Terry! I've done a ton of work on these old Sunn's. I have a 2000's myself. You right on with all of the rivet ground issue. I normally have to go and solder all of them down in each amp. These amps are also really prone to ground loops. Question though...why not re-cap the whole thing? Normally amps of this vintage I do that, esp the can cap.

[@d-labelectronics]

Hello, You are correct Sir. Initially the owner just wanted me to re-tube and make sure it played OK. After reviewing the video, he contacted me and requested that I go ahead, change the main filter cap. That is on order. Should have it installed by weeks end. Thanks for your observation + kind comment. TD

[@shiner555]

One other thing to watch out for if you ever see more of these is standby switch arcing! I had a tough time tracking down a final issue in my 2000s and it had to do with the standby switch internally arcing. As you can imagine, you can't source that switch anymore. Luckily the polarity switch is the same as the standby, so I just swapped it. BTW, keep up the great work and videos! I enjoy them a ton!!

[@silasfatchett5693]

There are many problems caused by standby switches. In this amp it is between the rectifiers and the first filter cap so that the rectifiers see almost a dead short when the amp is switched out of standby, which is an excellent way to shorten their useful life. If this were my amp I would forget the standby switch and turn down the volume during breaks. However, if you want to carry on using your switch and prolong its life, connect the cathode of a diode (1N4007 or similar) to the rectifier side of the switch and its anode to the choke side of the switch. Connect the cathode of another diode to the choke side of the switch with its anode to ground. This will kill back-e.m.f. spikes from the chokes when switching into standby and help to prevent arcing in the switch.

[@skycarl]

Good stuff Terry.

[@d-labelectronics]

Thank you Sir. I appreciate the kind support. I will continue to produce hi quality vids

[@thefilthygringo9228]

What does a repair like this cost?

[@petercornell2002]

Nice vid, thanks Terry!

[@creoquesoyunrobot]

Wooowww very nice and clean job!! Cheers mate! Thanks from mexicoo!

[@michaeljones19731]

Great job. Big thumbs up.

[@TheHorn123456]

Hi, what is your background? How did you get into working on tube amps? I'd like to get into tube amps and I want to build an education about it.

[@d-labelectronics]

Hey man, I stated at 12yrs old building Heathkits. 2 years electronics in HS. 2 Yrs Vocational training. Dad was a Ham radio op, running tube gear. 12 yrs USAF, Moonlighted in TV/video shops. 30 yrs Industrial controls. Hobby with it. Just have lived it all my life. Man, Im getting old!

[@kornami8678]

You may have two bad GZ34s, but you have now two brand new GZ34 maracas.

[@PaulaXism]

Good stuff.. nice sounding amps these, but does this one actually make it's rated 100 watts? .. most don't

[@d-labelectronics]

Hello, may be so. I did not put the amp to full power or check with wattmeters. Plenty loud

[@florencesyllunaclaytonmart4675]

The Noel Redding amp!

[@Kmuggle]

Nice roomy chassis!

[@Kalkaekie]

Enjoyed the video !

[@ZenturaAudio]

Good Video!! good tips on what to check for.😀 thank You for making!

[@nicoll420]

you ever try the new Mullard preamp, or output tubes ?

[@d-labelectronics]

Yes, excellent quality

[@nicoll420]

Thanks!

[@MrDonc78]

great video! I'm getting a sunn 2000s today that is having problems after its turned passed 5 on the volume knob(flabby, boatmotor sounds)... any ideas before I grab it? thanks!

[@d-labelectronics]

That sounds like bad filter caps. Change them if they are original.

[@MrDonc78]

thanks man! that was quick! I'll let you know more after I grab it. wish you were in memphis!

[@MrDonc78]

D-lab Electronics ok I got it in (1200s ss rectified) and replaced the leaky filter caps. I'm still getting the low end oscillations and the first power tube (v3) motorboats when I turn the bass knob to ten. there was a cap on v1 that had broken it's solder joint that i resoldered. Not sure where to go from here...

[@charlesmcmahan3718]

what brand is your oscilliscope?

[@d-labelectronics]

That one is an Iwatsu 5702. I have 3 other scopes. The Iwatsu is a great scope from back in the day made in Japan.

[@drplasmodius]

great intro!

[@ijamsum]

6550 tubes are 50 watts each maximum power and voltage but 4 6550 tubes in class A/B push pull designs put out nearly 200 watts not 100 watts ! If cathode bias its less power !

[@jimmycake7143]

Some flux would be good on that chassis soldering job.

[@jimcatanzaro7808]

That amp is huge

[@logicalconclusion3180]

Well done

[@vintagesynthlab4425]

Drilling out the rivet is a better way to go. The solder will not be a sufficient long term connection, both physically and electrically.

[@vintagesynthlab4425]

...that is to say: you really should drill the river out, and then install a screw and locking nut, and/or star washer.

[@DeadKoby]

Sunn.... the legacy of Louie Louie. Look it up if you don't believe me.

[@RobertKohut]

Nice!!

[@deuteronimus750]

You didn't call the 100 watt Unger iron by it's proper names "The Shnozz" aka "Shnozzola".

[@hazysativa3045]

Could you not run a wire to the chassis for the ground? The solder will just crack again, it has no adhesive strength at all.

[@CrowemagModelWorks]

You should make a Variac called the Terriac

[@messmer777]

Interesting thing about some of these older Sunns, they were based off, and in some cases...repurposed Dynaco audio amps with ultralinear design. Not ideal for guitar paying from today's perspective, but at that time many amp designers hadnt gotten the memo about how guitar players like certain types of distorted signal.

[@psychorock83]

only 100w??? i ve know from information directly with conrad sundholm (SUNN) with rectifier tubes 120/130w rms the solid state rectifier 150 w rms

[@dan_perry]

With enough plate voltage, capable OT and a SS rectifier, a single pair "could" get you around 100wrms.

[@LestonDr]

Dayton Shirt, Tenma test equipment. Are you in Ohio?

[@d-labelectronics]

Nope Battle Creek, but on of my crazy life influences lives in Ohio, The Ghoul!

[@69mercurycyclone44]

All done? Tell that to your wife! Bet you aren't done! LOL

[@umajunkcollector]

oh how I wish that sanny clozz would bring one of them thar Sunn toys? I've been pretty good this year, but must admit to some potty mouth in my vids, mama had to wash my mouth out with some Lifeboy, I got soap poisoning - caused me to go blind. Whom ever owns this Sunn is one happy camper now. And it's all because of the big bad soldering IRON. Don

[@TheWarped45]

7:08 so sad GE Mullard GZ34s

[@jonathanstrand2474]

Hmmm I can see why a Sunn does not play like a Marshall. Amazing, just 1preamp, 1 phase inverter!

[@MichaelLloyd]

If I was a musician you would get all of my amp work... and I know how to work on them...

[@d-labelectronics]

Cool deal man. Thank you for your support + friendship

[@pushpendrakhaira9337]

Nice RCA tubes = sacrificial tubes ???? Dungsols = new??? Make sure Filament voltage is not more than 6.3volts. 6.0 is even better. Almost all tube transformers are designed for 117volts input and cook tubes at 125v inputs . solder for grounds ? - better to have a backup wire to ground point escpecially for the power supply and output tubes

[@robertedwards3147]

I see good behaviour does get you out sooner

[@davidsigglekow1349]

Ball and Chain sir?LOL

[@robinsattahip2376]

There's the chain, this must be a victim of marriage.

[@aman-mn5kc]

Skicklig lirare!

[@whynotme5926]

Thanks for the info. I guess beings you do this for a hobby, my amp you build me will be free labor. HA!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[@d-labelectronics]

My rates are very low. What kind of amp are you thinking?

[@jaycee30865]

What a terrible amp. Look at all that wasted space. Now look at the area WITHOUT the components. Somebody clearly dropped out of manufacturing engineering school (and/or kindergarten) and went straight to building amplifiers.