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help repairing cavalli cth


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Hello,

I have a Cavalli CTH amp that I built about 8-9 years ago. During that time I tinkered with it and had to rebuild parts of it once or twice, and then again rewired it and installed a new volume pot. Long story short, I burned out the input ground (IG) connection on the board. I was able to get it to connect to some degree, or so I though, but recently when trying to bring it back to life it came off again. I wanted to ask advice on how I might go about repairing this. The IG seems isolated from rest of the board, so am wondering if I can just install a isolated nylon spacer on the chassis and put a metal screw on it, run IG wire to that. IG currently is connected to ground connection on the volume pot, loose on other end. 

I don't have a schematic for the amp, those were posted on Cavalli's site which is not up anymore. Was able to find some images of board and wiring diagrams of the later revision of the amp I have, but I think as far as the IG connection goes, it is the same. 

Images uploaded here - https://imgur.com/a/05Lhb

I also posted this on head-fi, but the DIY community here seems more ..alive. Thanks for the help!!

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As you may have already discerned, this board doesn't have many fans of Cavalli.

That said, at least from what appears to be the Eagle board file you posted in your link, IG connects to a rather large ground plane on the top of the board (there is a 2nd ground plane for OG?). The common junction between R1L and R1R appears to also connect to IG, right by the IG pad. If you have a DVM, you could verify this. There is probably shit all over the board that is connected to this ground plane and could be used to connect IG from the pot to.

And no on your screw idea... IG has to connect to the board as reference for the input section.

oHZLtM4.jpg

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Thanks very much for the quick reply @Pars, measuring resistance between R1L, R1R, and what remained of IG it would seem they are indeed on the same plane. I will try to wire it all up shortly. 

Personally have nothing but good things to say about Alex, met him at RMAF once, good dude. Also this little amp is good fun, when you don't go breaking it. Compatible with lots of tubes, sound ain't too bad for what it is. 

Thanks again, will let you know how it works out.

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Got a reply on head-fi along the same lines as yours, but also that star ground was same as input ground. Tested that, worked fine, went with it as it would be least messy option in this case. Thanks again for your reply, you guys have some cool weird shit going on here. Have been looking for a new headamp project to start that won't be all too intimidating, this has been a good place to look.

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