Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dude on January 17, 2021, 03:51:36 pm
-
I blew my BK meter biasing an amp, had a miswire. The fuse was blown but replacing didn't fix. I suspect the large R in this pic. The big resistor in shows the bands clearly but according to my charts I can't figure a value. Seems to be Black, gold, silver, blue, blue. Usually the gold is 5% and silver is 10% but these colors seem out of order. I know black is 0, but gold after...? blue is 6..?
The resistor has continuity but has reads 1 or 2 ohms, which would also read shorted..? I pretty sure the R is blown but can't find a schematic for this meter, BK2704B
Any help in identifying the value would be appreciated.
al
-
That's an inductor. It's good. Search Google for "inductor color code".
-
Ha, thanks. Another component l know nothing about, not found in amps. I checked the inductor band values but the gold and silver in that position don’t show on inductor values? Anyway, you say it’s most likely good. I had the meter on Mv to read bias but the miswire applied way too much voltage and the meter blew, fuse too but replacing didn’t fix. I’d toss the meter but this older one has pico f slots that give accurate reading, most other meters don’t read pico f that well. Nothing seems burnt, guess time to toss
-
There are two fuses in that meter. Did you check both?
https://www.testequipmentdepot.com/bk-precision/pdf/2704c.pdf
https://www.testequipmentdepot.com/bk-precision/pdf/2704c_manual.pdf
-
It’s an older BK, 2704 “B” not the newer “C”. Had the meter completely apart, one fuse. But thanks for taking the time to look it up.
Pico f in the 10p to 1000p range on most meters don’t measure that low. I have a Klein meter, try to measure a 500p and seem to always get a high reading, 650p for a 500p, consistently over reads. Seems to get power but only continuity works, dial always says 0.00. Something blew, no signs and components are micro small.
The old BK, had holes you could push a cap in, always was close to what was stamped on cap. They just don’t make meters that l can find that measure pico f accurately