Can this amp be fixed?

[RockinJay]

Thanks for playing, guys.

Both you guys are right, Jazz and Dawg.

I gather we all can claim a HIGH LEVEL of experience with electronics troubleshooting.

But the SoundGuru has STILL got the major point. These single-sided circuit boards used in MOST audio equipment, have been notorious for faulty connections that work in the beginning but fail after hours of use, am I right or am I right? <- 2 choices there.

Yes, other things can and will go wrong, but, guys, cut the crap, we all know that the "COLD SOLDER JOINT" is responsible for, as the SoundGuruGuy puts it: 99% of the failures in AUDIO equipment.

Jazz, of course there are double sided and even multi layer boards in electronic equipment, but NOT in audio.. I fix synthesizers and stereo amps, tuners, etc. and the board reproducing the audio will always be single sided*, and it's probably, as you say, due to the lack of preheat, thus the solder glazes over at times and really doesn't flow like it needs to.

Resolder everything IS the only way an armature with a soldering iron can handle it. But looking closely usually reveals the problem joint, and in my case, the 2 power transistors, may have gotten so hot during operation, that the solder melted and didn't re-flow. Therefore I didn't need to waste my roll of solder trying to reflow each joint.

*Now that I thinkaboutit, I fixed a Mackie Mixer recently and I think the main board was double-sided.

[Chuck H]

FWIW...

I never saw many sturdy PCB's in audio for many years once manufacturing went east. This is the specific fault of bean counters choosing cheap parts. More QC seems to be creeping into the market and now I see even cheap amps often have double sided, through hole, heavier traces, properly mounted hot components, etc. Eventually even the bean counters get hip to the expense of poorly designed products. There is still plenty of crap out there, but a lot less than there use to be. Interestingly, and worthy of note is that many US made PCB products are still being done on the cheap boards. The lower cost of using the eastern manufacturing machine often allows for those products to be made from higher quality parts! Not always the case, but worth mentioning.

[km6xz]

ATE usually has cameras that can detect board problems that are in the visual domain, like unsoldered joints and flag the board for a human operator to check it. Even cheap gear is more reliable out of the box than 30 years ago. Surface mount greatly increased ruggedness and reliability of soldering in inexpensive audio gear.
If a tech applied for a job and he repeats things that SGM spouted he 100% would not be hired. The claim that 99% of failures are fixed by resoldering a board is pure, unadulterated bullshit and no real bench tech would make that claim. Look through your database of the last 1,000 repairs, how many were based on bad soldering? Some but the majority are electronic or mechanical defects that arose after the unit was in the field for some time.
Just re-soldering a board has more chance of inducing harder to find defects with solder bridges, burned pad adhesive, etc. Shot gunning of any type is amateur and should not be done on paying customers units. You are paid to diagnosis a problem's cause. Do it by isolating the cause, not by shotgunning because without definitive isolation of the fault and determining the fault mechanism it is just a guess whether it was really fixed. If flaky joints are found, remove the old solder and use a good quality flux and re-solder it, after you have identified the original problem and resolved it.
There are multiple reasons SGM is no longer on the forum, his BS got so thick more experienced techs and engineers went away. He was banned.

[Enzo]

Hi Rockinjay, welcome to the forum. I agree with Stan.

SGM may have a valid point now and then, much in the way a stopped clock is right twice a day, but he also just made stuff up all the time. SO how is a novice to know when he is telling the truth and when not? I for one found him dangerous for that reason.

As a tech with over 60 years of electronics, the last 29 years of it as a pro audio service tech and business owner, I have to say 99% of failures are NOT cold solder joints. They occur, but the majority of units never have the issue.

[Chuck H]

I don't KNOW that SGM was banned. I never read anything to confirm that. I thought we just sort of ran him out of town. Tarred and feathered under torch light.

As to funky solder joints. I really can't argue with you. Your level is experience in the repair biz is eminently more considerable than my tinker time. But you know I'm going to talk about my experience on the matter anyway

Admittedly, most of what I've fixed was made in that era you mention between twenty and forty years ago. I've seen plenty of cold solder joints. And I've also seen them in recent amps. The new lead free solders were mentioned. I think the problems may have been short lived as working with the stuff improved though. New amps all look to have nicely flowed and shiny joints. Not like the grainy dull joints some seven or eight years ago. And I mentioned that construction seems to be getting sturdier too. That's going to help a lot because I've fixed cold joints that only showed up after some time after an amp was assembled and some stress on the thin, single sided board eventually reveals it. I saw this on jacks and pots mostly. Placed where the stress on the joint would have been greater because the pots or jacks are mounted first to the board and then to the chassis.

I'm actually defending myself because I'm the guy that said earlier to touch up the solder joints. Maybe bad modern advice, and I'm glad to have more experienced people around to keep accuracy over lore. But I will say this... If I were having trouble with a board mounted speaker jack and I didn't have reason to think the jack was bad, I'd certainly touchup the joints there and see how it worked out before replacing the jack on any assumption that the rarity of cold solder joints makes it foolish to consider.

[olddawg]

Wow... I didn't know SGM was banned. I thought he just ran out of bs and moved on. Some of it was even entertaining. But I can see him annoying the real engineers and being downright dangerous for a novice. Lol.

[The Dude]

Wow... I didn't know SGM was banned. I thought he just ran out of bs and moved on. Some of it was even entertaining. But I can see him annoying the real engineers and being downright dangerous for a novice. Lol.

I've no proof he was banned. However, he didn't strike me as the type to just tuck his tail between his legs and run off.

[DrGonz78]

Yes, other things can and will go wrong, but, guys, cut the crap, we all know that the "COLD SOLDER JOINT" is responsible for, as the SoundGuruGuy puts it: 99% of the failures in AUDIO equipment.

I think when we say something like "99% of the failures" in audio equipment are caused by cold solder joints, is too much of a blanket statement. I just don't think that statement is something to live by for an amp tech or a newbie. Not disagreeing with the fact that it is a very common failure, but so is dirt and oxidation build up anywhere in an amp. Also, I think we can lump "Cracked and Cold" solder joints all into one failure group. I always felt short changed when I would simple re-flow everything and fix the intermittent problem. As I got better at troubleshooting I could eventually sniff out the exact cold or cracked solder joints and know 100% what I fixed.

On an aside, any time that SGM(Soundguruman) is mentioned I tend to cringe. For example, I could have a Crate brand amp that had a bad solder joint as it's only failure. I would come to this website as a newbie and ask for advice to troubleshoot this amps failure. 99% of the time SGM would have suggested to throw the thing in the garbage as it is not worth the price to fix it and it will only fail later on down the road. So 99% of the time he should have just said "check for cold solder joints", but the members of this forum know that was not true. Okay sorry my RANT is over now.

Jazz, of course there are double sided and even multi layer boards in electronic equipment, but NOT in audio.. I fix synthesizers and stereo amps, tuners, etc. and the board reproducing the audio will always be single sided*, and it's probably, as you say, due to the lack of preheat, thus the solder glazes over at times and really doesn't flow like it needs to.
*Now that I thinkaboutit, I fixed a Mackie Mixer recently and I think the main board was double-sided.

More and more we find double sided boards in audio equipment. Horrible to trace out the circuit and it slows me down every time. Oldest piece of equipment that was double sided that I have worked on was from the 70's. It was the Conn Multivider effects unit.

[The Dude]

More and more we find double sided boards in audio equipment. Horrible to trace out the circuit and it slows me down every time. Oldest piece of equipment that was double sided that I have worked on was from the 70's. It was the Conn Multivider effects unit.

And more and more SMD.

[J M Fahey]

Soundguruman last recorded activity:

diyAudio
Last Activity: 12th February 2014 11:49 PM

Harmony Central
Last Activity: 08-26-2014, 07:49 AM

forum.ampage.org:
5/24/2014 3:03 AM

thegearpage.net:
soundguruman was last seen: Sep 12, 2011

music-electronics-forum.com:
Last Activity 03-28-2015 10:14 PM <---- SURPRISE !!!!!!!
he stopped posting here way earlier

forum.grailtone.com (the Boogie Board):
Joined: Tue Jan 07, 2014 10:54 pm Posts: 69
joined there about same time when he left here, obviously he couldn't stand us any more, he's using "there" the Royal "we", argues with OP about what they posted, asks silly questions such as transformer buzzing, then mentions posts on other forums as witnesses, then claims "I've been authorized MB service center for years, have repaired thousands"... oh well.
So he's alive and in good health.

Believe it or not, I'm happy about that, I had been considering a stroke, heart attack or worse as an explanation, and knew he was not banned here.
Why? : RG or Enzo's word is more than enough for me

scitechdaily.com: June 25, 2015 at 10:30 am (2 days ago)

So I stop here, he's alive and well and exactly the same guy.

Let others enjoy him

[Leo_Gnardo]

Soundguruman last recorded activity:

< snip >

So he's alive and in good health.

Believe it or not, I'm happy about that, I had been considering a stroke, heart attack or worse as an explanation, and knew he was not banned here.
Why? : RG or Enzo's word is more than enough for me

scitechdaily.com: June 25, 2015 at 10:30 am (2 days ago)

So I stop here, he's alive and well and exactly the same guy.

Did I read here a couple months back that he's involved in remastering old hit records or am I having a hullaballution? I figured either that's a helluva career change or perhaps his self generated BS field running at its usual 199% saturation. Whatever, I used to be (disgusted then I was) amused at his accounts of "arching" between components and circuit boards in Mesa amps. All the Mesa-Boogies I've seen, scarcely ever seen arches whether St. Louis or McD's twin golden variety.

Let others enjoy him

D'accord, as they say in France. If "enjoy" is the appropriate verb.

[km6xz]

One of the problems is the broad use of the term "cold solder joint" is being confused with mechanical failure with a stressed joint such as a pot or jack that physically breaks the connection mechanically versus a "cold joint" where the solder is crystallized. Broken board, heavier part interface is an intermittent problem and is the easiest to troubleshoot and does not require 3 hours of removing solder and resoldering a board. The problem is obvious and not a mystery at all even for a beginner. A cold joint is harder to find but also reveals itself with proper troubleshooting, as the THE problem.
I have a database here from my old shop where it lists 60,000 repairs and broken connections are common on heavy parts without positive support as is physical damage to jacks and pots but those are not haphazard shotgunning exercises, it has a symptom and the evidence supports a diagnosis that would be very specific with taking only a few data point. I had one yesterday, an Ampeg SVT 5 pro where heavy current would be pulled when levels reached a certain level. They are monsters to get fully apart and can't be run while apart, my focus was on punch through on one of the silpads or a broken lead on one of the pre-drivers since they are free standing with a clip on heat sink. Sure enough the extra weight of the heatsink broke 2 of the 3 TO-220 leads but were touching just fine most of the time. But it was a 2 hour job to disassemble and reassemble. If I had re-soldered everything in a shot jun approach it would have been the 2 hours plus 3 hours blindly soldering when that was not even the problem. Plus I would be risking adding a solder bridge.
The next on the bench was a Little Mark bass amp. Never seen a bad solder joint on one. They are mostly SMD but also some high mass parts pc mounted but all supported. A SMD zener was the problem with the power supply (SMPS) shutting down with load. Re-soldering that board would have been a nightmare. But actual trouble shooting based on collected evidence made shotgunning unnecessary. I can't even remember the last time a board needed to be resoldered randomly to solve a problem. Maybe 10 years ago.
Enzo, you got me beat, my first independent shop was when I was 13 which I ran until graduating HS when I moved to San Francisco in 1967, and before I got me BSEE. A life time of design, recording and repair(all at the same time) gives a bit of perspective that is at odds with most of the internet rumors and speculation. It was not just my bench experience but my last big shop was the largest pro audio repair shop in the country at the time with 23 techs and high volume. If cold solder was a problem in a high number of units I surely would have seen in in the 50-125 units that came or were shipped in daily. I kept statistics on frequency of defects and with enough samples it can be very helpful.

[Jazz P Bass]

My bitch on double sided boards is the fact that if not done properly, the solder does not wick up onto the top board.
Meniscus.

To me, Behringer is the worst.

Newer Samson equipment comes in a close second.

Whether or not the cause is too short of a preaheat time or too small of a component hole, I can only surmise.

[Mick Bailey]

Jazz, of course there are double sided and even multi layer boards in electronic equipment, but NOT in audio

I've just ran through my 20 most recent audio jobs and most are double-sided, including the Orange Rockerverb I'm currently working on and the Mackie HD1501 powered Sub I finished on Friday. I also have a Dunlop Slash signature wah that went out last week (SMD/DS), a Mackie SRM450, Blackstar Soloist 60 and a Blackstar HT-40, amongst others.

Only one had a solder joint problem - a Marshall MG50DFX - but that wasn't the primary failure, the speaker was OC.

[Chuck H]

One of the problems is the broad use of the term "cold solder joint" is being confused with mechanical failure with a stressed joint such as a pot or jack that physically breaks the connection mechanically versus a "cold joint" where the solder is crystallized.

Agreed, and conceded. But I've rarely seen a physical failure with this sort of condition other than the component lead being loose. Rarely a torn pad or cracked trace. Sans either of those things, a hit with flux and solder will fix it (measures to unstress the area as well of course). That led me to conclude it was a cold joint revealing itself. My other assumption being that there may be other such conditions in unstressed areas that simply never manifest.