D-Lab Basic Training Tube guitar amp sound fades Visual inspection reveals cause of the malfunction

Fred & Fink present, D-Lab's Basic training. This time we troubleshoot a hand built boutique guitar amp. Reported fault: After a varying period of time, the sound fades out. Sometimes 10 minutes, or maybe a few hours, but the fault has existed since purchase. After a thorough visual inspection under lighted magnifying glass, bad connections appeared on the turret terminals. The turret terminals has a dark appearance, maybe some type of tarnish. To get the solder to adhere, I have to scrape, then use rosin plus Kester solder. The process is very time consuming. If I had my guess, I'd say these terminals are low quality overseas type. Save yourself time/expense and reputation, use the best quality components at the starting line. Redo is always more time consuming. NOTE: The Dino-Lite footage was by hand, so yes, its not perfect, some shaking, but shows the detail of the connections. Remember, I'm no spring chicken.

[@MrJrsmith3]

The corrosion on the turrets and leads is caused by oxidation. Possibly the results of overheating or arc faults. It’s what happens to soldering iron tips if they are left on long at high temps without being tinned. It makes it very difficult to near impossible to tin them later. When connections oxidize like that all you can do is scrape the oxidation away or replace the connections.

[@pd9458]

My first thought was cheap Chinese alloy used for the turrets (who knows what the mix is). Then I wondered if the person who built the amp used a slightly active flux and didn't 'wash' the excess away, leaving it to corrode both the turret and the solder joint. As always, an excellent video Terry and quite a thought provoking one.

[@patprop74]

After all, only the Chinese can make stainless steel that rusts lmaooo

[@jameswooldridge8757]

There is no one better!! Would almost kill to study with this genius!

[@d-labelectronics]

Thank you my friend, YT has opened a great world for me

[@mysteryjesus]

You and me both, I wish I had someone nearby to teach me how to fix my electronics.

[@rayhogan785]

Bad solder flow on turrets: good catch! Perhaps a friendly warning to our kit builders: before installing board, lightly clean turrets with a very fine scotch-brite (gray). Once cleaned, rinse off with alcohol. I also use the Kester solder (.031) and a very small drop of GC Liquid Solder-Flux (p/n: 10-4202). I've seen a lot of these kit builders having the same issues with turret connections. IPC or Mil-Std acceptable soldering connections would be a great reference for anyone building or repairing amps. Sorry, I don't have available at this time pictures of correct/acceptable connections. Perhaps someone has some they share.

[@bluesbondsman]

I got a cheap turret board off of Ebay to build a 5E3 and it was murder to get a decent soldier joint. I tossed the board and went with a good eyelet board. Lesson learned!

[@DeathCapAmplification]

I have experienced this issue with turrets before. I’ve found one solution when this happens that seems to work pretty good. First use a small metal file to scrap up at least the tops of the turrets which will give the solder something extra to stick to. Second, clean the turrets after filing with 99% Alcohol. And most importantly, apply more heat than most soldering irons can put out for a quick flash time and also added rosin paste. I have a good desoldering gun that actually gets really nice and hot. Touching the desoldering gun tip to the turret for about 4-5 seconds is usually enough. Then clean all the flux after with Alcohol. This methods seems to work extremely well if you have pain in the butt turrets. But most important step I think is applying higher heat for shorter time so you don’t damage any components. That seems to work. Turrets have a pretty large surface area and they really need to get hot all the way through.

[@ibanezleftyclub]

Yep, someone didn’t pre-clean the turrets first, I wipe them with alcohol and hit each one up with a little sandpaper before using. It probably had some sort of oil or something on them from the factory, or it’s just cheap metal. Guarantee you the person was fighting those turrets the entire build which should have been a huge red flag.

[@d-labelectronics]

Roger that Sir

[@HarpinJScott]

This is the main reason I don't use turrets in my builds. Eyelets all the way for me.

[@d-labelectronics]

I'm all about eyelets too!

[@LitesLAB]

Excellent Information Terry! Thank you :)

[@MidnightVisions]

I believe the chrome coating on the turrets is causing the issue. I've had several projects that solder refused to adhere to chrome because the wrong type was used. Chrome is too polished resists solder and needs to be etched in acid if this happens to get rid of the polished coating.

[@ross3818]

That visual inspection was a horror movie.

[@tomk1tl39]

NIce job Terry........I had similar issues with a turret board with same problem with soldering trying to adhere to them.....was a royal PITA.......BUT finally got all the connections soldered properly......

[@d-labelectronics]

I have a stash of 1970's military turret boards,. Use them for bias boards in amps. The Turrets solder like a dream. I am convinced that these terminals came from a (low or no) quality supplier.

[@im247frogs]

It's amazing how many genius-level solderer's have commented on this video.

[@itsonlyme9938]

PL259 plugs are also very bad to solder too

[@brentnearhood8874]

Thanks! Fink

[@edwardhannigan6324]

Cool video Terry..Probably as you've said, inferior product and bad solder and skills..Lessons learned for sure..!.. Ed..UK..😀

[@Robert-Smith]

Love the videos Terry I have learned a lot from you thank you. I have a question about a 5f1 clone I built, when I test the capacitor voltage I get all good readings but when I shut it off and unplug the amp the voltage seems to drain itself to around 2V is this a sign of a problem? thank you.

[@tomp538]

Looked good before zooming in. Zoomed in soldering looked like something done for the first time. But if the turrets are bogus that more than explains the sub amateurish solder job. You know soldering used to be taught in 7th grade basic electric shop.

[@rustyrobinson8027]

Thanks

[@user-ft6zf9hr5u]

I believe that he used lead-free solder and a bit lower temperature for soldering.

[@keithnorris6348]

That was a good video very interesting in content and form. You sound exactly like JP Sears. He , JP Sears is one of the funnyest KZbin presentations, I recomend you check him out just for the voice let alone the content.

[@d-labelectronics]

Roger that Sir, I will take a peek at his channel. Appreciate the tip

[@jaijimenez8089]

sir can you be answered ,why my 15 watts guitar amp,,sound weak and become loud and sometimes no sound..thank you😊

[@d.dickson8243]

Nice job as always Terry. I was wondering what model of Dino-Light are you using? Thks Terry.

[@d-labelectronics]

AM4013T series Premier

[@infectionsman]

A stereo potentiometer that I had to use that was like this, it just would not take solder. Nothing improved it: cleaning with acetone, scratching the metal with exacto and sand paper, flux, heat, lead solder. I got a wire on there but I dont trust it to stick around for long. I might just make a mechanical connection with a metal ring around the shaft instead.

[@michaeltobin643]

If this is a newer build, perhaps it was assembled with lead-free solder? This could at least be part of the issue.

[@chrischwaz7788]

Great video thanks for showing us. So did the bad joints solve this amps problem? I have a amp that does the similar so I’m going to take a closer look at the joints. So I just wipe some rosin on the bad joint and heat it up and apply more solider ? What heat range is good for doing this I have the variable welder brand soldiering station? Thanks again Terry

[@d-labelectronics]

Yes, clean/scrape the terminal, apply rosin paste, My iron was set at 730 deg F. Clean the rosin with alcohol afterwards

[@michealalynn5318]

Hilarious hat on Fink!

[@jeddak]

Yikes - what kind of solder did the builder use? Plumbing solder?

[@tronics666]

Maybe acid core solder was used? Please be advised that acid core solder is NOT recommended for electrical or electronic soldering applications due to the corrosive nature of the residue.

[@SB-kw6oo]

I have a question, I have a Marshall Valvestate and I've seen multiple videos on how to discharge tube amps before inspection. Is there any different method for discharging a solid state amp before inspection? Thanks in advance :)

[@sw6188]

Solid state amps rarely have the kinds of high voltages present that tube amps do. Some really high power PA amps can run several hundred volts rail to rail but because they tend to be reasonably modern, the caps usually have discharge resistors or will discharge into the circuitry if left powered down for a while. When working on them I always check the main filter caps just in case, to be sure there's nothing ugly lurking there to bite me.

[@SB-kw6oo]

@@sw6188 thank you 🙏

[@waynegram8907]

D LABS, What is the max current rating for those Turret terminals? or what type of plating if on those turret terminals? I think fender use to spray some type of coating on there turret terminals to prevent oxidation what do you know the name of the spray that marshall and fender used to coat their turret terminals?

[@d-labelectronics]

I have no idea of the Turret specs. I did not build this amp

[@waynegram8907]

@@d-labelectronics I mean for fender, vox, Marshalls ext they used so type of spray and type of plating used for better soldering?

[@ross3818]

@@waynegram8907 Terry didn't build those amps either.

[@neccron9956]

Would it be better to completely rebuild the board from scratch?

[@d-labelectronics]

Yes, we discussed pulling the turret board & installing an eyelet type

[@James-dt7ky]

Turrets made from chinesium.

[@robnamowicz8073]

Certainly not unobtainium,,,,

[@hestheMaster]

Poor choice of connection point terminals. Takes too much heat and solder to try and make it right. Eyelets all the way.

[@roberthurless4615]

THe bigger the glob, the better the job. lol Btw, I use aim Glowcore 63/37 0.050. I works just fine for me.

[@electrolytics]

A boutique amp you say? The kind that cost 2-3 grand a pop?

[@CC-te5zf]

This will give me bad dreams tonight. I hope the didn't pay too much for this amp.

[@d-labelectronics]

Yes, it was an expensive amp

[@CC-te5zf]

@@d-labelectronics Wow - yikes!

[@cirenosnor5768]

Everyone wants a hand wired amp…but whoever builds the amp has to know basic soldering and use good turrets, etc 🤷🏽‍♂️

[@d-labelectronics]

Yes, there are many out there being built. I was happy to see Belton sockets in this one. If not for the turret situation, I would have rated this a nice build.

[@DanielSmith-rw9ms]

That was scarey, i could hardly watch, may have nightmare

[@dannyfreitas2120]

every thing omg.

[@danerickson1632]

China turrets 😆 I use the nickel plated brass turrets from antique electronic supply.

[@MrJrsmith3]

What a mess! The guy that built this amp needs to go learn how to solder and how connections are made. Solder is not glue. Learn how to connect wire and component leads to a turret. Pre-tin your wire leads. Wrap the loads around the turret 270 degrees or more, enough for the lead to stay on the turret without solder. Free movement of the lead at this point will cause a cold solder joint. I learned the hard way. Working for military contractors.

[@d-labelectronics]

Yep, me too, I went to Boeings high reliability soldering class for Nuke maintenance

[@sw6188]

There are a lot of people out there who don't know how to solder properly. They've never learned, or there's been no one around with the skills to teach them. I just smh when I see people dabbing solder on the iron, then dabbing it onto the joint and smearing it around like they are painting a picture.

[@michaelhager4270]

solder isn't glue

[@d-labelectronics]

I believe that would be a great title for another basic training video! Fusing is a type of adhesion.

[@moodyga40]

solder is Horrendous bigger the glob better the job the builder thought not enough head poor quality solder

[@patprop74]

Sounds like china made perhaps even some aluminum terminals.

[@zbaby82]

Probably a cheap knockoff turret board from who knows where.

[@jimcatanzaro7808]

Cheap china turret board

[@noelgraham4607]

Those are some ugly soldering joints

[@moodyga40]

flux condenser🤣 is bad

[@yomommaahotoo264]

Maybe that original solder was a plumbers type.

[@leiferickson3183]

This is what I suspect also. I've never seen acid flux solder results when used on turrets, but maybe this is what we have here.

[@tiki_trash]

I've read on forums that people were having issues with some batches of turrets they were buying. They were resorting to using alcohol or Deoxit and having to sand or scrape them in order to get solder to stick.