PCB design and high voltages

[booj]

Or do repairs....

[guitronics]

PCB Madness and Litigation

First:
Back in the 60's and before,people innovated without a "Big Brother" fear.There was a very common AM radio circuit called the "All American 5"...

5 tubes,filaments wired in series,no power supply transformer.The radio's had every knob,screw,etc. insulated or made out of insulated material. I'm positive some folks died as the result of stupidity (washing the radio when it was on)...but for the most part,they were good products,and inexpensive.That's why some tubes had 50 volt filaments (50L6 comes to mind)....

I think MOST companies went to task to make products as good and dependable as they could, balanced with safety concerns.There were, however, professional service technicians who fried their test equipment working on those "Hot Chassis" products.I remember the isolation transformers coming onto the market....

Secondly:

PCB's and tube amps don't mix well. I've had Guitar amps that had to be "RE-Wired" with real wire, not traces, because the heat,mechanical strain,and voltages were a bit much for circuit boards.

Look at the classic Tube amps...Fenders,Marshalls, Vox,among many.

Now look at "Modern" Tube amps with PCB's....chinese - built junk.

Not worth much money,even when new. Who wants them? Maybe as the basis of a "Modded" amp....putting in all the non-pcb stuff,to make them more reliable.

New circuits:I'm working on my brother's Line 6 floorboard....no luck getting out of the manufacturer what the parts in ANYTHING are.In fact - They actually told him "We don't make the products; we design them".

So:Unless you are a "Factory authorized service center", you can't find out what the IC's are (house marked).There will be precious little modding of their products! Do you think that equipment will increase in value over time?

And unless you have a few Million $ to spend on design and marketing,you won't come close to any of the Emulator's.

The "Throw away society". People actually bought products in the past that were meant to be fixed.

Vintage amps and modern high - value amps use point - to -point wiring,period. They will always hold their value.

>>>> End of Rant <<<<

[loudthud]

I designed PCB's back in the days before PC computer drafting. Bishop Graphics published a book that had design rules for clearance vs voltage and line width vs current. (Naturally, copper thickness and plating was taken into account.) The line width specs told you what the trace could take but often the voltage drop was more than you would like. To get the voltage drop you had to go to a physics book and calculate the resistance of the copper trace to control voltage drop. UL also had specs that called for additional clearance around traces that connected to the incoming power line and clearance to ground. There was also a UL spec having to do with line width next to the edge of a PCB because there was a tendency for those to start a fire. I'll see if I can find some of those specs.

[GainFreak]

PCB's and tube amps don't mix well.

Unfortunately with amps becoming more and more complex you can't get away without PCBs unless you want to enter a real nightmare.

I recently ordered out of curiousity some RoHS compliant PCBs from the local PCB shop and tried some RoHS solder along. To tell you the truth it's a BIG pain in the ass to solder these. The solder melts at higher temperature and it takes longer for it to spread over the pads.

Below is an online calculator I found concerning traces, current, resistance etc.:

http://circuitcalculator.com/wordpre...th-calculator/

[guitronics]

PCB's

Wow,Loudthud...

What a headache! I imagine PCB design is still a pain...inductance between traces,timing circuits going haywire because of stray capacitance,etc.

I know Large scale Integration and PCB's are the only economical way for Manufacturers to recoup their investment, in almost all Consumer Electronics.

The very idea of "Mega-Scaling" is a necessary evil.

I'm just glad for the things that aren't "Proprietary" and can be hacked and modified.

Like Guitar amps that are point-to point.