Grounding Yamaha g100 212

[PrematurelyAirConditioned_Love]

Howdy y'all,

I recently acquired an old solid state Yamaha G100 212 mark ii and I had a few questions about the grounding of the amp that I wasn't able to fully discover online. The amp itself has a classic two-way polarity on switch, and the power cable which came hard connected to the amp itself is only two prong. The problem lies in the plug also having a hole for the ground pin, but no ground pin. In doing some forum digging across multiple sites, other users have claimed that the amp is grounded despite the polarity switch. What I am trying to find out is whether or not the plug needs to be replaced, or an entire operation to install a new grounded cable. If anyone has ever owned one, and could verify if the third hole is the result of a plug that was intentionally broken, that would be very helpful. The manuals I have come across do not seem to mention the grounding, and the previous owner claims it always had two prongs. I am mostly wondering if this could be dangerous to keep using/ what I would need to fix. I attached some photos below for reference. Best and Thanks.

[The Dude]

It looks to me like the ground pin has been torn out of the plug. I would cut the end off. Then, if you have 3 wires and one of them shows continuity to chassis ground, just replace the end. If there are only 2 wires, you should replace the cable anyway with a grounded cable, so you haven't lost anything.

[PrematurelyAirConditioned_Love]

Thank you, Dude. I am new to these types of repairs and am wondering if this can be dangerous to do? Are there any precautions I should take beforehand? My girlfriend is scared I am going to be killed attempting this.

[g1]

Make sure the unit is unplugged when you cut the plug off. Then there is no hazard.
Check if there are 3 different color wires in the AC cord, or just 2.
If it has 3 wires and you just need to replace the plug, if you are not comfortable doing it any electrician or appliance repair shop should be able to do the job for a minimum cost.

[sugeda]

,,

https://mega.nz/folder/XNxjib4S#9AR-F6K5-ndfMYKWsU9cNA

[PrematurelyAirConditioned_Love]

Thank you, all!

[The Dude]

Dangerous is NOT having a grounded plug on the amp. A short to chassis could make the chassis hot and kill you. If you can replace an AC connector, it shouldn't be a problem. If you need assistance, post pics and we can help, or ask someone more qualified to do the repair. It shouldn't cost much. It's just replacing a connector.

[The Dude]

Make sure the unit is unplugged when you cut the plug off......

I know it was likely not intended to be humorous, but this cracks me up.

[g1]

I know it was likely not intended to be humorous, but this cracks me up.

If someone who hasn't posted here before asks if something might be dangerous, I figure I'd better consider the worst case scenario.

[Greg Robinson]

The amp also features a "death cap" - C2 in the schematic shared by Sugeda. This should also be removed as it predates modern Class Y capacitors. The power switch is a 3 position ON-OFF-ON, so serves double-duty as power and "polarity" switch. With a properly earthed plug RCD/GFI/GFCI circuits should protect you if this cap fails, but you should never rely on that.
So there is other work to be done in addition to replacing the vandalised power cord plug in order to make the amp safe.

[The Dude]

I was going to mention the death cap earlier on in the thread, but figured it wasn't something for the op to do since even a power connector rewire is leading to questions. No offense is intended. While I agree the death cap should be removed, this might be something he needs to have a tech do.