Magnavox 8804 amp

[jberlin2153]

I've examined the underside of my amp and read most of the posts on the magnavox 88XX amps and pardon my ignorance. Are the .0047 and the .047 capacitors polarized? I see the red stripe on all the sprague capacitors and thought that they were the neg side. I,ve also observed that the caps that are installed to relace the ones in the can cap seem to be. Any help would be appriciated

 

[Tom Bavis]

The electrolytic capacitors are polarized - they'll fail rapidly if reversed. The coupling capacitors are marked with a line for "outside foil", which can serve a a shield under some conditions - the idea was that the side with the line would connect to ground or the lower impedance side of the circuit - input for a coupling cap. But it seldom makes a difference, and modern caps generally aren't marked.

 

[gadget73]

What he said. If you have a scope or want to build a test rig that ties the cap to an audio amp you can figure out which is the outside foil, but frankly it just doesn't matter all that much in audio applications and probably doesn't matter a whole lot in most other spots either.

 

[Pio1980]

My standard procedure is that the outside foil (if known) is outward in the input end of a stage, and outward on the output end. I think if it matters at all the input end treatment may be more critical re noise and stability-wise. Just another thing along with layout and grounding to watch if problems arise.