Mr D - There is no way I would answer your question over the internet. You haven't told us whether the broken power unit is ac or dc, whether it is regulated or unregulated, if the latter what the max oc voltage is, and whether it contains any filtering to avoid interference with ADSL or modem (router?). And you have not told us how you 'know' the fault is in the supply, not the router. As both items are specialist matching units and I guess owned by your isp, I would advise hands off don't touch.
