[Granny Gremlin]

So I fixed up someone's (new to them) TS-50b (turned on, no sound; the only issue was someone replaced the original 3 prong with a 2 prong plug so there was no ground - just had to buy a 3 prong end and install it on the original 3 wire cord).

So then this person brought me their old TS-50, which they now realised had been modified with 2 extra switches on the back. Turns out one of them is a ground lift. The second is not connected to anything at all (looks like never was), just taking up space.

But why a ground lift? Like if the first TS-50 wouldn't even work without the ground connected, why would someone try this? Like an ill-advised attempt at reducing hum (thinking it was like a 2 prong tube amp with the switch moving ground between prongs, and then the second switch for a standby)? Is there something I am missing here? There's a sticker in there from a guitar store/repair shop that appears to have closed in 2016 (in QC, looks like Gatineau region). Did they just not finish this since the second switch is doing nothing, but they bothered to put it in? Like the work is reasonably well done I just can't figure out why they bothered.

I don't even wanna test this thing with the switch flipped to lift. Trying to decide if I just bypass the switch in place (use the new ground location, moving the wire off the switch - easy), or put the ground connection back in the original location (the wire may be too short to eliminate the extension completely or that would be the obvious choice - like it'll reach but not with enough slack).

The green line is the original ground.

Here's the switch:

 

[aC2rs]

Put it back to stock.

 

[Granny Gremlin]

With or without some extension though?

 

[Mark Brown]

I can't understand the thought process here. The common from the main and the ground have the same reference, what the hell is the point of removing it?

What am I missing

 

[tomee2]

Put it back to stock.

No idea what the point was but this is good advice. Take the switches out.

 

[Granny Gremlin]

Def taking the switches out, just not sure if it is preferable to put back stock and have the ground wire to grommet not have the recomended slack (longer than hot and neutral for safety). Or whether better to have the slack via a soldered extension. Like what is preferable standards/best practices wise.

.... or whether I should loosen the grommet, pull more wire through to get the length I need for the ground, and trim hot and neutral shorter. I guess that would be the ideal.

 

[tomee2]

Def taking the switches out, just not sure if it is preferable to put back stock and have the ground wire to grommet not have the recomended slack (longer than hot and neutral for safety). Or whether better to have the slack via a soldered extension. Like what is preferable standards/best practices wise.

.... or whether I should loosen the grommet, pull more wire through to get the length I need for the ground, and trim hot and neutral shorter. I guess that would be the ideal.

I’m not a tech, but I did convert an amp to 3 prong, and I followed the modern standards. I think taking the grommet out and getting more fresh power wire to work with and getting the ground lead longer is not hard but is important.

 

[nonreverb]

If I were to guess, perhaps it was to keep one common ground with whatever the customer was planning on plugging into this thing to prevent a loop.

 

[Rski]

Modern two prong plugs come with one wider prong for proper line and nuetral polarity, seen some older amps, with polarity reversal, thats what that second switch could of configured for, reverse the power transformer polarity, might reduce some odd humm .. perhaps lifting the ground was a simular intention, not wise, what so ever.

 

[nonreverb]

Lifting the ground on a solid state amp is not that problematic although it's far more sensible to have it there. Home stereo amps used unkeyed 2 prong for decades.
The shitty circuit breaker however, is another story....

 

[Granny Gremlin]

Lifting the ground on a solid state amp is not that problematic although it's far more sensible to have it there. Home stereo amps used unkeyed 2 prong for decades.
The shitty circuit breaker however, is another story....

That was stock on most models of the TS series (I'd say all but not 100% on that). On the TS-50b at least (I assume in other larger models, I should check my 75; don't recall seeing it in the 15s or 25s I have worked on but its easy to miss) there is also a thermistor in line after it (the breaker) hanging off the power switch, which I expect is supposed to be a secondary fuse.

 

[bolero]

Do those have a line out? Maybe they tried the lift to get quieter DI?

 

[Granny Gremlin]

Nope, no line out. my 75 has a DI out on XLR - a ground lift there would make sense; but not the mains ground.

Anyway, finished her up. Ground back to stock (drilled a new hole - there's plenty in there what's one more) bc the original (I think) hole was too big, so a smaller hole will make better contact. the solder tab is a lock washer but threw a lock washer under the screw head on the outside for good measure (and then locktite). Good thing I checked out the hot and neutral leads - neutral to the TX was hanging by a thread and about to break. Shortenned that so the ground has most slack - soldered and crimped back in the (original? think I've seen those in other TSes) connector thinger.

Gain pot was super scratchy and the rest stiff (about to get scratchy) so cleaned all those out, now they turn quiet and easy.

Lastly the replacement wall plug looked no good so redid that proper. As it was it wasn't making use of the built in strain relief.

Fixed up the piping that was hanging loose when I put it back in the headshell.

Note the thermistor hangin off the power switch on the left.

This is the wall plug as it came in:

Shortenned the leads so it's sitting tight and the wires stay looped through the strain relief there.