Eliminating the switchable polarity power option on old amp?

[TomCarlos]

Friends...

Just curious... When you work on old amps that have the two position power switch (which I take swaps the hot and neutral leads going to the primary sides of the Power Transformer), do you leave as-is or suggest removing it and hardwiring the neutral to the PT, leaving the ground wire in place (tied to the chassis), and using the Hot as the switch?

From time to time, I come across old amps, let's say an old Peavey, where it has the two position toggle for the power, along with the old (death) caps. And I wonder, what if those caps go bad? So I am wondering if going forward, I should remove the caps, get rid of the reversing polarity, and try to conform to the newer standard.

Thanks for comments.

Tom

[DrGonz78]

Well many Peavey amps have that x shaped connection that flips the poles on the power switch. So it's (On-Off-On) and yes I cut off the death cap. I clip the x crisscross configuration off of the switch so it just becomes a normal switch again without the flip flopping. I have wired these where it now becomes (On-Off-Off) which is easy enough. However In retrospect I think the switch might be able to wired where it is still On-Off-On. I would have to check the continuity of how the switch functions once you cut that x flip flop connection. I just made it On-Off-Off for simplicity sake. That's what I do with Peavey amps or old Roland's. If it is a separate polarity switch I tend to just remove its connections from the circuit.

[Leo_Gnardo]

What DrGonz says^^^ is best. Sometimes I leave the death cap & switch alone, either because of laziness/forgetfulness or the owner wants everything "stock from the factory." A scary side note: on some occasions I have found criss-cross wired toggleswitches failed spectacularly, with their insides charred and a hole blown thru the side of the housing. I can only guess sticky contacts failed to break when asked to, and that means a short across the AC line inside the switch. In those cases I replace the toggle with a simple SPST and get on with life.

[TomCarlos]

Thank you....

I appreciate the replies and suggestions- just wanted to make sure I was on the right track before making these changes.

And another reminder to the hobbyists (like me) who come across the thread - check to make sure the main fuse is the correct amperage rating and check the chord by giving it the wiggle test at the plug end. I was recently working on an old amp that kept cutting out (the power that is). The power cord "looked" ok but when I gave it a slight tug/wiggle, I found the problem.

Tom

[DrGonz78]

Yup good advice on the intermittent power cable. I had a friend bring me an old Peavey amp to look over and clean up. Found that someone had soldered the neutral wire to ground and had the ground wire in the neutral position. Flabbergasted!!

[drewl]

Yikes.

Sometimes the plug end becomes intermittent from people yanking it out repeatedly.

[DrGonz78]

A scary side note: on some occasions I have found criss-cross wired toggleswitches failed spectacularly, with their insides charred and a hole blown thru the side of the housing. I can only guess sticky contacts failed to break when asked to, and that means a short across the AC line inside the switch.

Yup I had a Vox Night Train amp come through the shop years ago. Big blown out hole in the on/off switch. Luckily parts is parts had the replacement in stock.