Plexi, is it safe to power up?

[Manalito]

I've just taken delivery of a 40 year old Marshall JPM50 Plexi, which has lay in someone's attic for twenty years unused. Every thing looks ok, when I turn the power switch on with an ohmmeter across the power cord I get a resistance measurement of 12.5 Ohms.

I would be grateful for comments on the following:-

With that resitance reading will it be safe to connect to a power supply and switch on.

Any tips on how I should approach power up as this thing has been idle for so long.
Regards and Thanks
Manilito

[stokes]

It is best to power it up thru a variac or a current limiter first,to "re-form" the caps.IME an amp that has sat that long without being powered up needs to be re-capped anyway,so you may want to skip the "safe" power up and go right to a re-cap.

[deluxe reverb92]

i second that.....re cap it, then bring it up with a variac, slowly, so you have a chance to see if anything has gone wrong before you reach the danger zone! :-)