Normal temp of a 2 watt resistor? - Page 2

cliffforrest · 28th May 2008, 07:07 PM

Get two 510R (or close) 5W wirewounds.

Stand them up vertically, one in each pcb hole, and solder the tops together.

One 10W resistor for 20 cents, last for ever, temperature < 50C

That is a crappy design, as is.

Burnedfingers · 28th May 2008, 08:24 PM

Post #4 looks like a Sonance 260 amplifier. Is there a R number by the resistor?

turbo_slug · 29th May 2008, 02:32 AM

Quote:

Originally posted by burnedfingers
Post #4 looks like a Sonance 260 amplifier. Is there a R number by the resistor?

Very good guess...it's actually a sonamp 2120 though. are you able to provide me the value of R021?

Mayank · 29th May 2008, 03:27 AM

turbo-slug:

Very recently I went through a similar experience.

Had a Carver TFM-15cb on the bench with dead VU meters. Found two 2W resistors on the power supply to the VU meter IC, getting *very* hot. They looked very much like your R021. The design called for the voltage to be brought down from 52V to 8.5V These were actually 2.2k (yes, the red bands had become brown with heat). Poor design. I replaced them with 5W ceramic wire wounds. The VU meters work and the resistors get warm, but not as *hot*.

Good Luck
Mayank

Mooly · 29th May 2008, 06:57 AM

Hi
Post's 11 and 12 answered question

. If you want to stick with just replacing the resistor, leave the leads "long" under the PCB and bend and solder them along the track. This will significantly reduce the "spot" temperature at each leg.
By the way, back to TV's again, it's not uncommon to see small heatsinks fitted to resistor legs (crimped on).

Burnedfingers · 29th May 2008, 10:58 AM

Quote:

are you able to provide me the value of R021?

I looked thru my files and all I have on those amps are schematics of the turn on circuits in which I signed a non disclosure agreement. If I can obtain the value I will pass it on to you thru email.

turbo_slug · 29th May 2008, 04:40 PM

Quote:

Originally posted by burnedfingers

I looked thru my files and all I have on those amps are schematics of the turn on circuits in which I signed a non disclosure agreement. If I can obtain the value I will pass it on to you thru email.

Thanks for the help.

Is R021 in your schematics of the turn on circuit? I belive it's used in the circuit that switches the relay on/off.

wakibaki · 30th May 2008, 11:08 PM

120 degrees C is undoubtedly very hot, but evidently since a 2W part is fitted, some considerable dissipation was expected.

If it ain't broke, don't fix it...

Seriously.

w

Mr Teal · 30th May 2008, 11:25 PM

Get a resistor like this one.

Dale RHB

You might be able to mount it horizontally and drape leads through the hole. If not, grind down the solder lug until it's round and fits through the hole, and mount it vertically. It'll dissipate better that way anyway.

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28th May 2008, 07:07 PM	#11
cliffforrest diyAudio Member Join Date: Sep 2004 Location: South Coast, UK	Get two 510R (or close) 5W wirewounds. Stand them up vertically, one in each pcb hole, and solder the tops together. One 10W resistor for 20 cents, last for ever, temperature < 50C That is a crappy design, as is.

28th May 2008, 08:24 PM	#12
Burnedfingers diyAudio Member Join Date: Nov 2002 Location: Iowa	Post #4 looks like a Sonance 260 amplifier. Is there a R number by the resistor?

29th May 2008, 03:27 AM	#14
Mayank diyAudio Member Join Date: Oct 2004 Location: Falls Church, VA	turbo-slug: Very recently I went through a similar experience. Had a Carver TFM-15cb on the bench with dead VU meters. Found two 2W resistors on the power supply to the VU meter IC, getting very hot. They looked very much like your R021. The design called for the voltage to be brought down from 52V to 8.5V These were actually 2.2k (yes, the red bands had become brown with heat). Poor design. I replaced them with 5W ceramic wire wounds. The VU meters work and the resistors get warm, but not as hot. Good Luck Mayank

29th May 2008, 06:57 AM	#15
Mooly diyAudio Moderator Join Date: Sep 2007	Hi Post's 11 and 12 answered question . If you want to stick with just replacing the resistor, leave the leads "long" under the PCB and bend and solder them along the track. This will significantly reduce the "spot" temperature at each leg. By the way, back to TV's again, it's not uncommon to see small heatsinks fitted to resistor legs (crimped on).

30th May 2008, 11:08 PM	#18
wakibaki Banned Join Date: Jan 2008	120 degrees C is undoubtedly very hot, but evidently since a 2W part is fitted, some considerable dissipation was expected. If it ain't broke, don't fix it... Seriously. w

30th May 2008, 11:25 PM	#19
Mr Teal diyAudio Member Join Date: Nov 2003 Location: Saskatoon	Get a resistor like this one. Dale RHB You might be able to mount it horizontally and drape leads through the hole. If not, grind down the solder lug until it's round and fits through the hole, and mount it vertically. It'll dissipate better that way anyway.