All resistors come with a tolerance rating. 1% up to 5% Depends on which ones you buy. Most resistors in the Marantz gear is 5% tolerance. If you measure and it is farther than that. then maybe it needs replacing. Carbon resistors change value with just age. Heat speeds up the value change. Others will chime in with their thoughts.Is that why it measures less then it's counterpart? At 100 ohms how close to the actual value should they be? How much of a drop would be considered " normal " and not heat damage. Just trying to learn as I go.
When in doubt ...throw it out..or at least keep the old component just in case you want to put it back in.So having said that, at 5% for instance, the reading could be as low as 95 ohms and regardless of the burn mark on the resistor still be within tolerance and realistically could be left in place??? Hmmmm.... I understand that under my circumstances ( and the minimum cost of replacements) knowing that there was a wisp of smoke it's just preventive medicine regardless of the tolerance percentage. Is this an accurate statement?
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Don't use a carbon. As Randy said, they drift. ...
https://www.manualslib.com/manual/906440/Marantz-2270.html?page=2#manual
Its not a list, but it has some schematics.
Don't use a carbon. As Randy said, they drift. MO is very good choice.
Before you install any substitute transistor, Make darn sure the EBC legs are in the same location
Did you try digital docs for a parts list in the manual there? There should be a list towards the back.
As far as transistors go, its good if you can stick to the closest hfe and match the set you put in.
As far as changing all the transistors, Don't do it. Just change the bad one and its mate with a hfe matched pair. You could end up with a bias issue or unbalance in the amp if you put a bunch of subs in.
Original new parts are OK, But substitutes can make you pull your hair out if your amp will not adjust afterwards.
Heres a good post to read.
http://www.audiokarma.org/forums/index.php?threads/marantz-2270-bias-wont-go-below-15mv.322206/
Tried the search feature on here but had no luck finding a BOM list for Mouser for a 2270.