What kind of RESISTOR is this??? - diyAudio
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Old 1st January 2004, 01:25 AM   #1
slownlo is offline slownlo  United States
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Question What kind of RESISTOR is this???

Can someone help me identify this type of resistor? It looks like a ceramic power resistor...value is 180 Ohms / 2 watts (2WJ). I am trying to repair and old Mitsubishi receiver. Upon inspection of the PCB, I found 2 of these resistors on the board in the power amplifier section that appeared to be burned out so I removed them, but I want to replace them with the proper type/value ....Thanks in advance!

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Old 1st January 2004, 07:14 AM   #2
MWP is offline MWP  Australia
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Youve measured thier values or just noticed the brown color?
If you havnt measured the value, do so, becuase they still might be ok... resistors going brown from heat isnt a problem.

If you still want to replace them, try using 5W resistors instead, they will be easier to find.
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Old 1st January 2004, 07:23 AM   #3
slownlo is offline slownlo  United States
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<<< You've measured thier values or just noticed the brown color?
If you havnt measured the value, do so, becuase they still might be ok... resistors going brown from heat isnt a problem.>>>


Thanks for the reply,

No I haven't measured them (can't find my dang multi-meter) but the fact that the inside top of the receiver cover just above them is black from the smoke emmitted from them is a good assumption that they may be burned out. You are right, discolouration from heat is normal...

Again, everything else on the board seems fine except these 2 resistors.

Can you tell me what type (cerramic, metal film, carbon, etc...) they are?
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Old 1st January 2004, 09:37 AM   #4
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Quote:
Can you tell me what type (cerramic, metal film, carbon, etc...) they are?
But why would you care? Trying to preserve the aural flavour of a seventies jap receiver? I sincerely doubt it will be possible to distinguish them. Get a cheap metal film replacement but only after finding the 'dang multi-meter'. You'll be very lucky if those resistors are the only problem.
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Old 1st January 2004, 09:51 AM   #5
dhaen is offline dhaen  Europe
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Default It got pushed, rather than jumped...

What model is it? And what's the problem?
I probably worked for this [crap?] company during the period this was produced...
The long leads mean that this resistor was meant to get hot. It should have been spaced away from the PCB, probably using fibreglass sleeving.
The fact that there are black marks on the lid above these, does not necessarily indicate smoke. Hot components cause air convection. This convected air contains dust and grease particles that are deposited.
I expect this kit has worked reliably for 20+ years. Plenty of time for air flow..
The resistor is a metal film 180 ohms 2w 5%, but I agree it is probably not faulty.
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Old 1st January 2004, 10:21 AM   #6
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I have some of those resistors and IIRC they're low inductance types but I can be wrong.
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Old 1st January 2004, 10:48 AM   #7
slownlo is offline slownlo  United States
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Default Re: It got pushed, rather than jumped...

Quote:
Originally posted by dhaen
What model is it? And what's the problem?
The long leads mean that this resistor was meant to get hot. It should have been spaced away from the PCB, probably using fibreglass sleeving.
The fact that there are black marks on the lid above these, does not necessarily indicate smoke. Hot components cause air convection. This convected air contains dust and grease particles that are deposited.
Yes, they were spaced away from the PCB, but lacked the fiberglass sleeving...Thanks for the tip on the air convection, now that I look, the space above the power transformer is a little dark too, but it does not appear damaged (I'll have to check it). Its a Mitsubishi receiver model # DA-U109 100WPC (yeah right) that only produces sound from the left channel. Just tinkering to see if I can fix it. I have to check the preamp section as well to see if the issue isn't with it. Once I find my multi-meter I can verify the integrity of these parts. I hope it IS the resistors so it'll be an easy fix...

Thanks again dhaen!
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Old 1st January 2004, 10:55 AM   #8
slownlo is offline slownlo  United States
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Quote:
Originally posted by analog_sa


But why would you care? Trying to preserve the aural flavour of a seventies jap receiver? I sincerely doubt it will be possible to distinguish them. Get a cheap metal film replacement

You're probably right. )
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Old 1st January 2004, 11:29 AM   #9
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If the resistors have gone, then its a near certain bet that something else much more serious has happened to cause them to go. Resistors are the most passive component and very rugged (as compared to transistors which will go at the slightest provocation.)

Shoog
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Old 1st January 2004, 12:25 PM   #10
dhaen is offline dhaen  Europe
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Default DA-U109

I didn't see that model in Europe, but the DA-U's were not high quality units (performance wise), though the build was good.
Shoog is certainly right. probably a semiconductor device in the output stage failed, and will have taken others with it Around this time was the changeover from discrete component output stages to hybrid IC (usually Sanken). I suspect yours has the former.
The bottom line is: You'll need an expert to fix it, and it probably doesn't merit the labour cost....sorry.
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