[alantf]

[attachment=0:qdnentp9]img080.jpg[/attachment:qdnentp9]The only way to test a rectifier is to check the forward resistance of each plate, but I don't know what the resistance should be, and I don't think you're up to it. A rectifier is only (each plate) a gadget for allowing current to flow one way, and not in the reverse direction, so that the forward/reverse flow of alternating current is converted into the forward only flow of direct current.

Here's a simplified drawing of a little bridge rectifier that I made (using blocking diodes) so that I could fit a 12v dc buzzer to our 12v ac door entry system. If you follow the path, each way, from the ac to the dc, you'll see that in each case, current must flow from left to right across the dc terminals in each case. The diodes simply let the current flow in the forward direction, but not the reverse. You can see from this that if any diode went faulty, then we wouldn't get true dc across the dc terminals. That's why I said that your rectifier can't possibly be faulty, or the mechanic wouldn't have got dc at the battery terminals. there's really no need to test - you're either getting dc or not.

By the way........sounds like the mechanic's trying to baffle you with bullshit.