Solid State Guitar Amp Forum | DIY Guitar Amplifiers

A friend gave me a Fender Frontman 15G to tackle.  Found the TDA2050 is toast.. pulls down the rails to about +/- 2 volts (at least the fuse didn't blow..)  IN any case I've been reading up on using a LM1875 as a replacement as the TDA2050 is no longer made..  Any advice on this as a replacement??  From what I can tell so far it should be a direct replacement..  I don't know the impedance of the speaker as I don't have it, but 1875 datasheet says it can drive down to a 4 ohm load with +/-25 volt rails..  with the old part out the rails measure something like +/-23.8V.     Also, as for heat sinking..  there is a little rubber like insulator on the back of the old part. Would it be wise to try to reuse this on a new part?  Would it need thermal grease?  When searching on Digikey, I can find all sorts of mica and alum/Oxide insulators for TO220 packages, but nothing for TO220-5 which I believe this package is.  Any advice or words of caution??  Thanks.. 

TO220-5 simply means TO220 with five legs.  The insulator doesn;t care how many legs it has.  The 5 leg is the same width as the 3 leg.

The LM1875 is a drop in for the TDA2050.

The flexible rubbery insulators do not use thermal grease, just the rigid mica insulators use it.
If the insulator is not torn or damaged I would just re-use it.

Thanks for the info!!  Much appreciated!