On Wednesday, December 27, 2017 at 2:43:04 AM UTC-5, Phil Allison wrote:
David Farber wrote:

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I'm servicing a Behringer EUROPOWER PMH2000. The + and - 15 volt regulators
need replacing because the leads have failed. The transistor is mounted to
the chassis at a 90 degree angle and then soldered to the pc board. The
problem is that pc board fits very tightly into the chassis. The leads on
the regulators keep getting flexed with each pc board removal. Anyway, I
want to replace them because a couple of the leads have broken off. They are
packaged in a TO-220 case. The center tab is nonmetallic so it is insulated
from the chassis.


** The *mounting tab* is definitely metal, just coated in epoxy to insulate it.
Huh, we buy either spendy teflon shoulder washers, or cheaper nylon.
(with 4-40 screw.)

George H.


Though the schematic says terminal 2 is grounded in the
7815A anyway, I was wondering if it made any difference whether or not I
purchased ones with metallic backing or ones with a plastic backing.

I just looked at the LM7915 spec sheet and it says that terminal 1 is ground
and terminal 2 is the input which is reversed from the positive regulator.
It also doesn't mention whether or not it has a metal tab, which if it did,
would have to be insulated from the chassis. Do any of you have any
experience replacing these regulators in a chassis mount situation?


** If the originals are held on with a clamp, you need to buy the same again.

If held with 3mm bolts, you can use the ones you have.

BUT you MUST add insulating bushes and mica pads to BOTH - plus a smear of white thermal grease.

Bolting the positive one straight to the chassis is likely to result in ground loop hum.


... Phil