Ampeg SVT 350H chassis ground question

[jlinger]

Hi all,

Hope this question is in the right place. Recently picked up a cheap Ampeg SVT 350H as a backup for my Peavey Mark III. I've given it a going over and, aside from a couple of small issues I had to fix, it works well and sounds good enough.

But looking at the back panel, there looks to be a hole which on investigation was for grounding the chassis. It looks like a screw went in there and, looking at the power socket board, there seems to be a U shaped piece of metal that touches the chassis (presumably grounding it?).

So, my question is; does that screw simply pull that part of the board to the chassis or is there some sort of other connection (a wire etc) that's missing that needs to be there to achieve ground? A photo would be great, or just some info to confirm.

Sorry for the long, rambling post. Hope it makes sense. And thanks for having me!

 

[anderbass]

Here's a SVT 350H pic I found at this link: SOLD - AMPEG SVT-350 Bass Amp Head U.S.A. made

Does this pic show the location your referring to?

 

[jlinger]

Here's a SVT 350H pic I found at this link: SOLD - AMPEG SVT-350 Bass Amp Head U.S.A. made

Does this pic show the location your referring to?

View attachment 4933592

Hi,

Yes, just to the right of the power input. You can see there's a screw there, where mine had been removed. I just need to know what's that screw is doing on the other side of the chassis!

Also, to add to this; this is an export (UK) model. Does that make any difference? I don't recall mine having the earth/ground symbol next to it.

 

[jlinger]

Just checked; mine doesn't have the grounding symbol. Does that point require to be ground if the mains is UK/3 prong?

 

[agedhorse]

Yes.

The screw could be either metric or imperial, you will need to determine the correct one.

It was probably lost from a previous service by an unqualified person, it’s is important part since it’s related to safety and/or EMC compliance.

 

[jlinger]

Thanks for that. I'll still need to see what it attached to on the other side of the chassis, just so I can make sure there's nothing missing on the board that holds the power socket

 

[BasturdBlaster]

best pic I could find, though it's a B2 (same amp)

 

[jlinger]

best pic I could find, though it's a B2 (same amp)View attachment 4933772

Thanks, that is indeed what mine looks like from the inside. Looks like the screw just goes through that U shaped metal bracket, doesn't it?

 

[BasturdBlaster]

That is exactly what I see as well

 

[agedhorse]

Yes, that’s an essential bonding screw.

 

[jlinger]

Yes, that’s an essential bonding screw.

Is there a specific material (metal) a replacement should be made of?

 

[agedhorse]

Is there a specific material (metal) a replacement should be made of?

Yes, steel and generally a lock washer is used under the screw head.