8 ohm 100watt resistor?

[sejose]

Ok I went to Radio Shack and Fry's, largest wattage resistor I could find was 25w. I am preparing to make the middle point potential adjustment on my Sanyo P55 amp. The manual shows a resistor 8 ohm 100watt across the test leads which go to the speaker out terminals.

Question, is this resistor a line balance and if I dont include it will I get a false reading when I make the adjustment?

I can order from Mouser the resistor I need, but I rather get this done today.

See the attached doc file for what I am referring to.

Thanks

Scott

[spkrman57]

I don't see the need for 100 watt resistor to be used when millivolts are to be read.

Maybe they are just being extremely overly carefull.

25 watt would work as far as I can see for adjusting the bias/DC offset or balance controls.

Let's see if someone more knowledgable than I can chime in here on this!

Regards, Ron

[toxcrusadr]

Sounds like a dummy load if it is across the outputs. I don't know much about what you are adjusting, but if the test requires high volume operation, you have to be able to dissipate that much power. If it's at low to moderate volume, you don't need that much wattage capacity.

Most people routinely doing max power output testing will use enormous open wirewounds that look like heaters.

[Paul C]

I believe the large 8 ohm resistors that Radio Shack carried were 20 watt.

Wire four of those in series-parallel, and that will give you the equivilent of an 8 ohm 80 watt resistor.

http://audiokarma.org/forums/attachment.php?attachmentid=53949&d=1183999965

[spkrman57]

The attached doc said to "short the input of the amp" which would only leave the residual DC offset.

So why do we need a high power resistor unless there was a problem with the amp????

So go with whatever resistor you have on hand. A 5 watter would be more than enough for this test at least.

Ron

[Tube_Dude]

I don't see the need for 100 watt resistor to be used when millivolts are to be read.

Me too!

Maybe the constructor want that everybody bring the amp to a authorized service center... ;)

Or maybe I have a suspicious mind... :scratch2:

[sejose]

LOL OK I got it done. I used the Radio Shack 20w, the resistor didnt even get warm. So I was able to tune out the no load right channel annoying noise. Then I had a bad interconnect, which gave me fits, my mind being on the amp. Always take a deep breath and step back and start from square one. I know to do that but I dont always.

Thanks guys, always nice to have someone watch my back when I open the hood on these things.

Scott

[majoco]

can be made from electric heater and toaster elements from your local junk shop. Ones with screw connectors are best 'cos you can't solder the wire. Measure the resistance with your digital multimeter and adjust as required. Although why you need 100watt resistor to set a DC offset of millivolts is beyond me. Perhaps the manufacturer has shares in the resistor factory!

[totem]

perhaps a typo?

[grateful]

A high power resistor is unnecessary. I suspect they are showing a standard shop set-up

[sejose]

I will tell you there are plenty of typos in the service manual for this amp, not the least of which is 'parts rist'