Hi All
I recently saw a video on youtube on making a guitar amplifier from an old record player but it was not real clear on wiring.
I would just like to know if anyone has done this and how.

I thought I better ask before I fry myself.
Your post isn't very specific.

I would imagine that the easiest (not necessarily best) way to do it would be to replace the cartridge with a 1/4" phone jack. The output of a phono cartridge is not the same as a guitar pickup so you'll probably overdrive the circuit. This may or may not sound good (probably not).

A better way to do it would be to insert the guitar signal later in the circuit, rather than at the beginning, so that it won't clip as much or at all. This would involve tracing the circuit or having a schematic. You might as well just build or buy a cheap amp.

The best way to do it, in my humble opinion, is to not even bother. Besides the fact that this is a waste of what is likely a perfectly good or repairable phono, these things are meant for hi-fi sound reproduction, not guitars. Hi-fi amps and guitar amps are very different in tonal response. Ever plug a guitar into a hi-fi amp? Sounds like shit.