Resistor needed

Captain Jack

Captain Jack

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I am trying to a source a new resistor which failed/scorched as a result of a failed voltage regulator in my computer speaker amp. The resistor is 340 ohms (O-Y-Br-Br) and 15mm long. Does anyone know what wattage this is? From reading around, it's 2W but need confirmation.

Also, where can I get one? Most are 250mW, which is nowhere near what I need... Preferably 1 piece - I don't need 50 of them!
 
Captain Jack said:
I am trying to a source a new resistor which failed/scorched as a result of a failed voltage regulator in my computer speaker amp. The resistor is 340 ohms (O-Y-Br-Br) and 15mm long. Does anyone know what wattage this is? From reading around, it's 2W but need confirmation.

Also, where can I get one? Most are 250mW, which is nowhere near what I need... Preferably 1 piece - I don't need 50 of them!
Click to expand...
A photo of the component might help Alex ..
Preferably in situe so it's physical size can be referenced to surrounding devices..

The material is also important ..
ie Carbon ..metal film..wirewound etc etc
 
Was hoping you'd reply, Evan. Here it is - circled. I believe Q3 failed causing the resistor to heat up and scorch the surrounding area. The symptom was that even at minimum volume setting, the actual volume was near maximum...

2017-03-06 11.52.14.webp
 
Captain Jack said:
I am trying to a source a new resistor which failed/scorched as a result of a failed voltage regulator in my computer speaker amp. The resistor is 340 ohms (O-Y-Br-Br) and 15mm long. Does anyone know what wattage this is? From reading around, it's 2W but need confirmation.

Also, where can I get one? Most are 250mW, which is nowhere near what I need... Preferably 1 piece - I don't need 50 of them!
Click to expand...
Would these do ?
They can supply a small quantity relatively inexpensive ..
closest is 330 ohm ..
close enough for most purposes ..
1 and 2w metal film ..
100ohm-1M ohm Various Value Resistors In 1W-2W Power 5% (Pack of 5) | eBay
 
Yep ..that does look like Carbon 2W ..
Personally I'd use metal film and go up a size wattage wise ..
3W isn't overkill ..
3W Metal Oxide Film Resistors 5% Tolerance | eBay
After scraping away the scorched surface of the pcb ..Id re-fit the new one stood off the board a few mm ...so air can circulate under and between..
 
390 ohm.webp
Captain Jack said:
Thanks VS, will get these on order.
Click to expand...
Before you do order buddy ..
are you certain ...that is yellow ??
It looks white to me which would make it 390 ohms ..
and are a much more common value than 340
???
 
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Humm... maybe. It's measuring 380 ohms across, which I thought was down to the scorching or effect from other components. But scorching might have turned it yellow!

And you say your eyesight is failing....
 
added a picture above..
..and yep my eyesight IS failing ....but years of practice etc ..
lol
 
Captain Jack said:
I am trying to a source a new resistor which failed/scorched as a result of a failed voltage regulator in my computer speaker amp. The resistor is 340 ohms (O-Y-Br-Br) and 15mm long. Does anyone know what wattage this is? From reading around, it's 2W but need confirmation.

Also, where can I get one? Most are 250mW, which is nowhere near what I need... Preferably 1 piece - I don't need 50 of them!
Click to expand...


Knowing the make model of the amp and then checking the schematic for R48 value will nail it down. The rest of the components look standard issue.
 
That brown third ring might be black, considering the component size.
 
CPC Farnell can be a good source as well - see here for 390 Ohm Resistors. Only issue is that you have to spend £5 exc VAT to get free P&P, but I am sure there are some other things you would want to bring the cost up to that level!
 
Another trick we used on single sided pcb for severe scorching ..
Check if there are ANY tracks on the other side between the 2 resistor connections ..
?
If none then drill a hole between and file out the paper/paxolin board in the scorched area between those points as much as is practical to retain rigidity ..
allowing air to circulate ...and prevent future overheating..
The board itself when scorched has resistance..
so ..basically nullifying the poor pcb design..
 
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Channel Hopper said:
Knowing the make model of the amp and then checking the schematic for R48 value will nail it down. The rest of the components look standard issue.
Click to expand...
It's not a stand-alone amp but one built into 'active subwoofer'. It's a 12 year old TEAC 2.1 system - lovely sound and don't want to change it if I don't have to.
 
Channel Hopper said:
Knowing the make model of the amp and then checking the schematic for R48 value will nail it down. The rest of the components look standard issue.
Click to expand...
Lol ..if you can get your hands on the schematic ..
Post 2000 ...it became ridiculously difficult if at all possible to get hold of schematics ..and service info.
The manufacturers ...just stopped providing it.
a) to save pennies ..
b) to discourage repair & encourage consumers to bin and buy new..
cest la vie
 
I have my sources (as you do)

TSW100 ?
 
Channel Hopper said:
I have my sources (as you do)

TSW100 ?
Click to expand...
I'll keep that in mind CH..
Are you a member of Euras perhaps ?
I'm not on account of their ridiculous yearly membership fees ..
Grrrr
 
Never subscribed to anything.
 
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