Be careful when buying parts

[bsco]

This happened to me just the other day so I thought I would post this....I went down to the local electronics shop...(we only have one here)....and bought a dozen 33 ohm, 5W resistors...while I was at the counter I spot checked a couple and they looked fine....When I got home, I checked all of them with my meter....(I do that with everything)....good thing I did...there were three resistors measuring .33 ohms....the rest were fine....I called the store to let them know of the mistake and suggested they check all the resistors in the container....I went in the next day to get the resistors exchanged and the guys said that they checked the resistors and they all measured the same....38 ohms......I told them that there was something wrong with the meter that they were using...of course they didn't believe me...so they opened up a brand new meter from the display case and tried it....sure enough the 38 ohm resistor now measured 33ohms and the .33 ohm resistors measured correct as well.....33R and R33 are two different values...but the person who looked after the inventory just assumed that they were the same....Good thing I checked as these were to be used as screen resistors in a tube amp....so if there is somebody who is getting started in repairs watch out when you buy parts.....you could end up with an incorrect part and all sorts of trouble which would probably drive you nuts.....or cause all kinds of damage.....so DOUBLE CHECK all parts that you buy and I mean everything....fuses, pots, capacitors, resistors.....transistors, everything...
Cheers,
Bernie

[Mick Bailey]

Even the big supply companies get it wrong, especially with resistors. It's not so easy to spot with small metal-film types and some of the SMD caps I get have no markings at all.

My nearest 'electronics' store (Maplin, which used to be superb but now sells mainly crap and toys) is a 25 mile round trip. Emergency purchases only, these days. So imagine the pleasure of getting back with a bag of the wrong resistors after the guy pulled them from the parts bin one-level down.

[bsco]

Yeah...I know Mick...I had ordered pots from Fender and the package stated the value but the pots were a different value...and that happened three times in a row until we got the right ones.....luckily for me the parts store isn't all that far away but it still is a pain when that stuff happens.....

[Justin Thomas]

I was okay with resistors when the tolerance bands were gold or silver, and there were no more than four bands on the part. I recently found one I had put in an amp that was a five-bander, and the tolerance was red or some other color. It was a half-watter, so there's not a lot of room for the space difference between value/tolerance. And if I can make that mistake pulling parts, I'm sure so can someone in the warehouse.

Miniaturization and precision have their pitfalls too, I guess...

Justin

[Jazz P Bass]

38 ohm screen resistors?

[bsco]

No.....they are 33 ohms but the meter that they had used showed 38 ohms....so there was something wrong with their meter...

[g1]

38 ohm screen resistors?

33 ohm, I think for the Traynor YBA300 he is working on: traynoramps.com/downloads/servman/smyba300.pdf