Manufacturer Gaffs

[Jazz P Bass]

Often times individuals believe that a component has failed if there piece of equipment does not function properly.

As has been shown here on MEF, repeated times, that is not necessarily so.

My favorite pet peeve is when component leads are bent over at assembly, into the next copper trace.
There is a layer on a PCB that is labeled the 'mask'.
It is a non conductive layer that when applied to the PCB, does not cover component pads & vias.
That way the wavesolder will only be applied where it is needed.
So far, so good.

What happens, over time, when the 'bent over into the next trace' decides to puncture the mask layer.
Why it conducts into that trace.
Depending on the 'shorted across' circuit & the applied voltages, this can cause some real problems.

I happened to come up with a name for this gaff: TTB.
Ticking Time Bombs.

Feel free to add any other manufacturerer boo boo's as you may see fit.

[nashvillebill]

I had a Technics stereo amp (one of their higher-end models) that would suddenly develop an intermittent hum, of varying intensity. I reflowed the power supply filter caps, nothing changed--still had intermittent hum. Finally did the Chopstick Test going component by component, and there it was: a leg to one of the components had folded over on insertion. Viewed from underneath, the solder joint looked fine, but of course the leg wasn't extending down into the solder joint, the leg was in the hole just enough to occasionally contact the underlying solder/pad and work OK. Easy fix once I found it.

[The Dude]

Electrolytic capacitors sitting up against heat sinks, hot resistors, or hot running SS devices. One of my peeves. We all know heat is the enemy of electrolytics, with the exception of design engineers it seems. When I have something apart and if cap leads are long enough, I always try to steer the caps away from the heat. If I replace a cap next to something that runs hot, I leave the leads long enough to tip the cap away from the heat source.

[Mick Bailey]

All-time favourite;

EVERY SINGLE Fender Hotrod and Deville-family amp sold here in the UK is wired for 230v. We're on 240v. The transformers have 240v taps. The amps are labelled "230V UK Mains".

I don't get it.

Neither does Fender.

[Tom Phillips]

Electrolytic capacitors sitting up against...hot resistors...

Like the attached example found inside an expensive amp from a long time commercial boutique operation. This one also includes one of my peeves of bad soldering.

[nickb]

Like the attached example found inside an expensive amp from a long time commercial boutique operation. This one also includes one of my peeves of bad soldering.

...and it has an electrolytic on top of hot resistor. Yay! We have a winner?

Hold on, how about all the amps with power tubes mounted upside down on PCBs where the sockets solder joints fail because of the heat.

[J M Fahey]

Like the attached example found inside an expensive amp from a long time commercial boutique operation. This one also includes one of my peeves of bad soldering.

You-must-be-joking

Although "Boutique" in my mind *often* means "nonsense" and no, Iīm not kidding.

At least it means something thatīs sold based on some esoteric or not-related-to-quality factor.

As in: "its cabinet is CNC carved from a 25 pound solid block of aircraft grade aluminum"
Hexateq / Products / Reference Series
"the caps are dipped in 5000 y.o. wax found inside of Ramses' pyramid" or
"the speaker cone is made out of Stradivarius violin grade wood".

No, Iīm not making this out, just read all about it in:
Wood Cone Speakers

Where they explain everything, including how the head designer got the solution after eating one too many squids soaked in sake.

As the modern philosopher Homer Simpson often says:

[Dave H]

All-time favourite;

EVERY SINGLE Fender Hotrod and Deville-family amp sold here in the UK is wired for 230v. We're on 240v. The transformers have 240v taps. The amps are labelled "230V UK Mains".

I don't get it.

Neither does Fender.

Perhaps Fender is thinking that 230V OK because it is the ‘Harmonised’ EU mains voltage and should therefore be correct for the whole of Europe. I mean who would think that the EU would be stupid enough to ‘harmonise’ to 230V by fiddling the numbers without any country actually changing its voltage. The voltage where I am (mid Cheshire) consistently measures about 247V.

[Chuck H]

Like the attached example found inside an expensive amp from a long time commercial boutique operation. This one also includes one of my peeves of bad soldering.

That amp, which apparently shall remain nameless, wasn't designed or built by a knowledgeable tech.

[Chuck H]

Although "Boutique" in my mind *often* means "nonsense" and no, Iīm not kidding.

At least it means something thatīs sold based on some esoteric or not-related-to-quality factor.

As in: "its cabinet is CNC carved from a 25 pound solid block of aircraft grade aluminum"...

"the caps are dipped in 5000 y.o. wax found inside of Ramses' pyramid" or
"the speaker cone is made out of Stradivarius violin grade wood"...

Where they explain everything, including how the head designer got the solution after eating one too many squids soaked in sake.

I make hand built amplifiers. I have been reduced to using the term "boutique" at times. It's always troubling to me when I see something like that cap/resistor circuit or when some builders are selling mostly snake oil. one of the worst offenders I've seen was on a thread here where the builder used a solder tab connection power transformer with all the soldered joints above the chassis and exposed! Holy crap! Not even a little sharpie note that say's "You really don't want to touch this". This sort of thing just brings a whole cottage industry into question. Some of us are well meaning amp builders selling products that are well considered and won't electrocute customers or burn them to death in a fire.

[gui_tarzan]

Um...

Like the attached example found inside an expensive amp from a long time commercial boutique operation. This one also includes one of my peeves of bad soldering.

I was shocked by the lack of QC in some of the newer amps I've repaired. Bad solder joints, a circuit board screw wedged under another part (with no screws missing from the board), a wood mounting rail that made the chassis bend when it was tightened down, not to mention the horrific soldering "techniques" of other techs I've seen.

[J M Fahey]

I make hand built amplifiers. I have been reduced to using the term "boutique" at times...... Some of us are well meaning amp builders selling products that are well considered and won't electrocute customers or burn them to death in a fire.

You bet
And thatīs why I used the word "often" but not the word "always".
I myself make custom builds, all the time, obviously because customers canīt find a commercial product which doesexactly what they want.
But we all know the horror stories

[Mick Bailey]

The voltage where I am (mid Cheshire) consistently measures about 247V.

I'm in N.Staffs and the voltage is about the same. It varies a bit, but I've never seen it lower than 240v. In some parts of the country they get 250v. That's a big multiplier on the B+ through a PT strapped for 230v.

[Mick Bailey]

Her'es another;

The Two Rock Classic head uses relay switching. The relay supply is taken off a small 6v (nominal output) transformer, bridge and filter cap. With no load the cap charges to 9.7v. When the factory footswitch is used, the voltage is bled off via resistors to power a couple of status LEDs in the pedal, so the voltage the relays see is lower depending on whether one or both relays are operated.

But,

If only the panel switches are used and no footswitch connected, the first relay operated gets the 9.7v hit off the charged cap, and then drops to about 8v under load. The second relay pulls this down to around the 7v mark.

The flaw in all this?

Both relays have 5v coils.

[JHow]

Like the attached example found inside an expensive amp from a long time commercial boutique operation. This one also includes one of my peeves of bad soldering.

Is that hot-melt glue holding the resistor to the chassis? And what's with the silicone on the wires?