Vishay/ BC PR01?

[Structo]

I got a Mouser order today and I had ordered a bunch of these Vishay 1 watt metal film resistors.
The PR01 Power Metal Film series

I think we discussed this once before.

These friggin things are the size of a 1/8 watt resistor.

WTF?

Seriously? These are 1 watt resistors?

http://www.mouser.com/catalog/specsheets/pr010203.pdf

I guess I should have looked more carefully at the data sheet where it says the OD is only 2.5 mm.
I got a bunch of these suckers too....
DANG IT!

I just had to vent.

Back to the drawing board.

BUYER BEWARE>

[ampdork]

Why buyer beware?

[ToneMerc]

My lastest build I used the PR02 on the precision bleeders and the PR03 at the nodes. The wattages are fine, but the tiny size doesn't do much for build symmetry. Yeah, always read the datasheets.

TM

[Bob-I]

I wouldn't worry, they're fine. I've used them for power tube cathode, 1R 1W. They're tiny but they really are 1 watters.

[FYL]

Seriously? These are 1 watt resistors?

They are. Just adjust your boards accordingly...

[FYL]

My lastest build I used the PR02 on the precision bleeders and the PR03 at the nodes.

Be careful with PR02 and PR03 resistors: they exist in two versions.

The FeCu-leaded version should be suitably derated to 1.3 W for the PR02 and 2.5 W for the PR03. The superior Cu-leaded version is the one spec'ed at 2 W for the PR02 and 3 W for the PR03.

[David Root]

I got stung with a few of these too. Andy Fuchs and John Suhr got screwed by these tiny resistors, they open up in plate load duty.

Other than that they are fine apparently. I won't use them as they look silly against the regular size stuff.

I do use 1/8W 220K as a failsafe across a bias pot, entry to wiper, which are smaller than these new 1W types, but not I think the same formulation.

[VacuumVoodoo]

So now size matters? These were Phoenix until Vishay bought the company and ramped up QC. Still, I would be checking manufacturing date codes and if made during the carnival I'd return them. You know, carnival in Rio...

[FYL]

Andy Fuchs and John Suhr got screwed by these tiny resistors, they open up in plate load duty.

I've been using PR series resistors for quite a long time and haven't seen any failure. Zero, nada, zilch.

I asked Andy to supply details about the supplier, exact model, lot number, etc. but got no answer. Traceability is a must.

Even if the resistors were OK when delivered, manufacturing could induce failures : leads could be bended too close to the body (poor thermal dissipation, mechanical failure at the end caps), soldering could have been too long or too hot (spec is 2s max. at 235° C), wrong fluxes could have been used (the PR series aren't qualified for aggressive fluxes), etc.

Andy also posted a few years ago on TGP about his problems with Koa-Speer 2W carbon films failing with only a 400 mW load, so he must really be unlucky when it comes to resistors...

[FYL]

So now size matters?

Ask Gojira...

These were Phoenix until Vishay bought the company and ramped up QC.

They have been for quite a long time under the Beyschlag (Vishay BCcomponents) umbrella. Made in India. No more samba.

[VacuumVoodoo]

So now size matters?

Ask Gojira...

These were Phoenix until Vishay bought the company and ramped up QC.

They have been for quite a long time under the Beyschlag (Vishay BCcomponents) umbrella. Made in India. No more samba.

Great, now I'll have to check manufacturing dates against all the festivals and carnivals they have in India.

[FYL]

Great, now I'll have to check manufacturing dates against all the festivals and carnivals they have in India.

Don't forget the incense when you receive the bandoliers...

[VacuumVoodoo]

I'm switching to russian made components. At least I know they are permanently drunk at work so quality level is constant.

Well, this is the least of my worries. I'm taking a big leap during the weekend, upgrading from my old trusty Windows 2000 to W7.

[glasman]

The only place I have used these is for creating the artificial ground for filaments. The 1W are only rated for 250V, so having them open in a plate circuit is not too surprising.

[FYL]

The 1W are only rated for 250V, so having them open in a plate circuit is not too surprising.

The PR01s are rated at 350 V RMS or DC. This rating applies to voltages *across* the resistor. A stage with 100 K from 300 V B+ to plate and 2 mA current drops 200 V across the resistor, well into the SOA.