Beware of bridge rectifiers

[ppppenguin]

In post #61 of this thread http://golbornevintageradio.co.uk/forum/...p?tid=6396&pid=71402#pid71402  I mentioned replacing a bridge rectifier. Many bridges are in a 4 in line package. These packages have a chamfer on one upper corner to indicate polarity. Do not assume that the indication is consistent.

I replaced a Phlips part, BY164, with an International Rectifier part, 2KBB10R. The former has the chamfer above the plus terminal, the latter above the minus.

In case you're wondering, I didn't find out the hard way

[alanworland]

That's standardisation for you!

Alan

[Murphyv310]

I take it that's a new thing Alan.
I give up now with so many things that should conform to standardisation that don't.
Recently I found some AC128 transistors admittedly 40 years old that were made the opposite way, collector emitter junctions were swapped.

[Refugee]

Wait until you get a humped back bridge rectifier wired plus_AC_minus_AC.
It is a pain when you are fitting them into a PCB.

[ppppenguin]

Recently I found some AC128 transistors admittedly 40 years old that were made the opposite way, collector emitter junctions were swapped.

That's a subtle one. Most transistors will work after a fashion with collector and emitter swapped. For small signal applications this normally gives very low gain but also lower than normal saturation voltage. A very few transistors, notably the OC140, are symmetrical. Almost impossible to replace if the circuit needs that special property. The BBC analogue 625>405 converter uses lots of them as symmetrical switches.

[Murphyv310]

It is subtle Jeffrey and if it wasn't in an output stage I'd have been head scratching for a while.
It was low output and very distorted, only on test with my peak tester was it properly confirmed.

[Craig]

It is even worse than a +/- swap. From the chamfer

BY164: + AC AC -
2KBB10R: -AC + AC

Madness!

Craig

[ppppenguin]

Now you're trying to scare me. The 2KBB10R in my drawer are marked - AC AC +. But the data sheet here is - AC + AC : http://www.farnell.com/datasheets/2049156.pdf

Mine are NOS International Rectifier parts. Presumably IR got taken over by Vishay.

[Murphyv310]

TBH I have come across reversed connections on Bridges perhaps a couple of times at most.
They actually were a fairly regular replacement in TV servicing when Power supplies blew up, the bridge would be taken out too.
One incorrectly marked bridge that was fitted just blew the 3.15 amp fuse, took a bit of faultfinding and that's the reason I remember the issue. It is though very rare.