Diagnoses

[Enzo]

I was reading a thread a moment ago. Someone wrote in with some issue with his amp, and a member here suggested several things to look at. This member is someone whom I respect, someone I think knows what he is doing. But I realized, the suggestions made were totally not what I would have suggested at that point. But I had to consider that there was absolutely nothing wrong with these other suggestions, they just aren't the ones I'd start with.

Point being, there are as many approaches to service as there are servicers, and while there are idiots with soldering irons, most approaches are legitimate if they work. It saddens me a lot when some folks - mainly the less experienced - think there is only the "right" way, and then everything else. And the corollary to that, they tend to think there exists a list, telling us for each amp that when THIS happens, it will be THUS that is wrong.

Somebody likes to check tubes first, while I might like to check jacks first. Or whatever. Neither thing precludes the other. Most of the time, the ten things that come to the top of the list can be quickly performed in whatever order you like. So we ought to encourage the novice to spend less time worrying about which suggestion was the better, and just start working.

Gee, this thought was a lot more articulate in my head than it is now in print.

[Leo_Gnardo]

Gee, this thought was a lot more articulate in my head than it is now in print.

Our friends in the legal profession have a word for it: "probitive." What leads directly to a solution, so we're not beating around the bush wasting time in court. "Probitive" works well on the electronics repair bench, good concept.

Good thoughts all Enzo, there are multiple paths to a solution. Tightening up grounds to start, at typical ground points as well as input & output jacks, sometimes that fixes things fast and it has for me just within the past week, also needs no test equipment just a couple simple tools. And "when you hear hoofbeats think horses not zebras", some lucky folks hear that one in medical school or during their internship/residency, also fully applies to electronic repairs. You gotta start somewhere, start with the simple stuff, often the solution is to be found there.

These days half the people that call me with malfunctioning tube amps say "I think it's a transformer", I guess those Mercury Magnetics ads must have them convinced, and it's almost never the case. Seen some unfortunate cases where someone has bolted in $400-500 of Mercury iron and their problems persist. I wind 'em up a little: "My car won't start, must need a new engine, right? No? . . . must need a new transmission then." Then they begin to see the light. Sometimes.

[Enzo]

You cannot sit through a training seminar with me and not hear the zebra line, I use it all the time. In science it is called Occam's Razor.


I recall quite a few years ago now on this board, someone had a Fender and the external speaker jack wasn't working. The person had decided the only possible reason must be that the added external speaker was too low impedance for the amp. Some discussion ensued. Since the internal worked and the jacks are in parallel, I suggested the external jack. This bought me an earful of scolding, but that is another story.

[potatofarmer]

I usually wind up playing 20 questions so the guitarist doesn't wind up trying a bunch of fixes that don't work. Is the humming louder than a breadbox?

It's not the greatest approach and I'm guessing it's frustrating to the guitarist, at least partially because I could really use a "technical person"-to-guitarist translator... But then my free advice is worth just as much as the guy yelling that every problem can be fixed by pouring a gallon of deoxit into the chassis.

I imagine experience plays well into this too. I don't tech or do any sort of paid amp work, so I'm generally looking for, well, general solutions that could apply to any malfunctioning amp. Someone who's run a shop for the past however many years and repaired this particular amp however many times would ask if R382 is coming loose from the board because they've seen failed solder joints there a couple dozen times.

I wonder if Caig has a viral marketing team where they pay people to recommend Deoxit on Facebook. I wonder if they're hiring.

[Enzo]

And one needs to be aware of the poster's understanding level. Sometimes we suggest removing a part to check something, and they assume we mean that will fix it, when all we want is an unencumbered voltage reading. "I pulled the rectifier tube like you said, and now the amp doesn;t work."

[J M Fahey]

What always gets me is the all too often heard question "what is the typical/average/common cause for such and such"?
Which might make sense if it were very specific, such as "no voltage on V2 plate" which usually might be "open plate resistor/no +V from PSU/shorted tube" although there are other possibilities too, including "operator error" such as : measuring the wrong pin / misplaced "black probe" / bad multimeter or its cables or probes / probe not pushed hard enough /; etc.

All that for just *one* junction in an amp, yet many post such wide ranging questions as "my XYZ amp does not work/hums/farts ... I can use a multimeter and solder .... what part must I replace"?

If it only were that easy, even for us.

Oh well.

BIG problem is on most Forums the poor OP gets some 10 or 20 contradicting suggestions, all yell at the same time, and a sensible suggestion or two gets lost in the background noise.

Oh well [2]

[Leo_Gnardo]

I've noticed a good trend lately, here and on TAG, to ask the person presenting the problem what tech abilities they may have, and what test equipment and tools.

When I see "I read somewhere that . . . " or "somebody told me . . ." usually it's rubbish.

[g1]

I've noticed a good trend lately, here and on TAG, to ask the person presenting the problem what tech abilities they may have, and what test equipment and tools.

Tom Phillips put it very concisely the other day "To help us help you please put your location in your profile and let us know your experience/capabilities to work on this type of equipment".
It would be nice to see that question asked when new members sign up, then have the info added into their profile.

[52 Bill]

The hardest thing for me in long distance diagnosis is not being able to see, hear, feel and even smell for myself what is going on with thing that we are trying to fix. Written descriptions like "hums", "distorts", "sounds weird", etc. only help so much.

I will bet Enzo's lunch money that a lot of you guys can recognize the sound when half the output signal waveform is missing and most of you will know immediately where to start looking.

But I will also bet that none of us can figure out that problem from a written description of "it sounds funny" or "it doesn't sound right". We all end up having to get the owner or tech to read voltages or scope the waveform or do some sort of long involved procedure to figure it out. And because it could be caused by any number of things any number of different approaches could all be correct.

I think that we are all influenced by our past experiences and when we see those hoof prints some of us may normally think horses, but I suppose that someone in Africa may normally think zebras.

[Alex R]

e

I think that we are all influenced by our past experiences and when we see those hoof prints some of us may normally think horses, but I suppose that someone in Africa may normally think zebras.

For a fully global approach shall we settle on "assume it's angry rhinos and work down"? Come to think of it that's the only approach that works for me with a smoked SMPS

[lowell]

All I have to say, which isn't necessarily relevant, is that over the last 10 years I have gone from a new poster asking questions, to actually being able to help some folks fix things. And for that I have everyone on here to thank. This is the GREATEST forum, and that is saying a lot being that it's occupied by techies and guitarist alike. Every time I find myself browsing some other forum for something I don't see the kind of humanitarianism I see on Ampage.org. Thanks to Enzo, JM Fahey, RG, Steve Connor, Chuck H, 52Bill, MarkusBass especially, and to anyone whom I'm failing to mention for your selfless expertise!

[Chuck H]

I don't have a photographic memory. Photogenic perhaps, I've never removed it for a snapshot so I can't be sure on this. But I do have a little Asperger's/OCD thing where I repeat, ad nauseam, tests and recreate mistakes to look for correlations, etc. Being able to cross reference peripheral circumstances and commonly related issues is what keeps me from thinking "Zebra's!" And these experiences have come in handy when trying to get clues from posters. But I'm not a tech. My experience is VERY limited when compared to many here that have three repairs on their bench in a week, or in a day. This is probably why I'm somewhat inconsistent with "good" advice. But I hit often enough now to be proud and when I throw wide the members here are typically graceful about it. Sometimes I'll ask a poster to try something and they get kicked sideways by another suggestion. Often times it's another responder with a straight opinion on the problem and they suggest a course of action for a repair. The OP will almost always gravitate towards this in an attempt to skip any troubleshooting or diagnostic testing. I really hate this because it's usually doesn't work. A green OP is already frustrated by the time they post and the allure of a solution is too tempting. In the end it results in more frustration more often than not. So...

Wise observation Enzo. There's more than one way to skin an OP (and I'd like to skin some ) For the purposes of tech support via forum the problem partly becomes navigating personalities. Some of us are better at this than others. I don't think I'm very good at this and I truly appreciate all the tolerance I get here. From everyone!

Most OP's are looking for the quick fix. A concise answer with the lowest number of steps. And one that gets them to a solution rather than a test result. This is really the problem we're solving for. We sometimes step on each others feet in the initial scramble and forget the OP probably isn't even aware that this is play time for us. In other words, it's not just electronics problems that we deal with when trying to get to the solution. It gets a little clumsy sometimes. A bad OP doesn't help matters. One that doesn't run tests of give results in the manner suggested. Some members here just straight up bail at the first sign of this. I try not to. Remembering that it's not always just electronics problems we deal with here.

[lowell]

Well said Chuck. I agree in regards to someone chiming in on a suggestion that distracts the OP from the first suggestion. I always try to say "Do what they said, and then maybe this." It may even be better if we were to wait for the OP to report back on one response first. Maybe an unwritten rule. But then again, it's a team effort a lot of the time so someone MIGHT have a better suggestion anyways. Hard to say. When it really boils down to it I guess we all just go with the flow and have to remind the OP to "try the suggestion from post #x"

[Chuck H]

Well said Chuck. I agree in regards to someone chiming in on a suggestion that distracts the OP from the first suggestion. I always try to say "Do what they said, and then maybe this." It may even be better if we were to wait for the OP to report back on one response first. Maybe an unwritten rule. But then again, it's a team effort a lot of the time so someone MIGHT have a better suggestion anyways. Hard to say. When it really boils down to it I guess we all just go with the flow and have to remind the OP to "try the suggestion from post #x"

Duly noted (and edited )

[lowell]

Posters such as yourself and others I have lots of respect for can chime in on my response ANYTIME. It's only a bother if it's someone who may or may not have a good suggestion or who ignores what has already been said.