Need help indentifying a component.

Thread Starter

Banthors

Joined May 19, 2022
31
This component is in line on the speaker amp output circut. Seems to output from both sides. I can attach a schematic if it helps
 

Thread Starter

Banthors

Joined May 19, 2022
31
Two 0.27Ω 5W non-inductive resistors (center common).
Mind if i ask how you determined that? Im trying to learn as well. The main problem i am having is something in this circut is shorted which keeps causing it to go up in smoke. This specific piece on all the other outputs will output to both end legs but this one it does not. The person i am repairing this for spilt a small amount of coffee in the reciever as you can see from the small stain on it. Also found 2 bad mosfet drivers shorted to themselves.
 

MrChips

Joined Oct 2, 2009
26,088
Check the resistance between the legs of that component. It is unlikely to be blown.

R takes the place of the decimal point. For example, 2R7 would be 2.7Ω.

If things are going up in smoke it is more likely one or both of the output transistors are blown shorted. Remove both transistors and test on a DMM on the diode range. Chances are you will find two legs are shorted.
 

abrsvc

Joined Jun 16, 2018
117
These are very common in receiver amp circuits and usually fail along with the output transistors. What is the make and model of the unit here? If you can, post the entire schematic (or at least the amp section).
 

Ian0

Joined Aug 7, 2020
5,097
Is there a preset off the page to the left where it says 47nF?
If not, what is off the page to the left where it says 47nF?
If there is a preset, then the coffee might have got between the wiper and the track. It would be better if he drinks black coffee without sugar.
 

Thread Starter

Banthors

Joined May 19, 2022
31
I can post the full schematic. Yes after i replaced 2 obviously shorted transistors and replaced all the resistors that started on fire it happened again after i put power to it so there is for sure more shorts. I ordered all 4 transistor replacements for that track and also this component in question does not have continutiy between any legs. Open line so this piece is dead.
 

abrsvc

Joined Jun 16, 2018
117
The part you show is a 0.27ohm dual emitter resistor as stated before. From the parts list, this is R244xx for example. Can you post here which one is failing? There should be an "R" number on the PC board. Knowing which specific one is failing will help to provide you with the likely shorted transistor that is causing this failure. If it is R2444, are both sides open? Check Q213-Q216 for shorts. Also check to see if either R229 or R230 are open.
 

Thread Starter

Banthors

Joined May 19, 2022
31
The part you show is a 0.27ohm dual emitter resistor as stated before. From the parts list, this is R244xx for example. Can you post here which one is failing? There should be an "R" number on the PC board. Knowing which specific one is failing will help to provide you with the likely shorted transistor that is causing this failure. If it is R2444, are both sides open? Check Q213-Q216 for shorts. Also check to see if either R229 or R230 are open.
On the schematic it is R244FL. Fl stands for front left channel. I didnt find any direct shorts but i checked ohm readings from the base to the collector and got 000 on one of them so dead transistor and the other one i pulled had different readings then all the other ones on the same board so i pulled that one off as well. All resistors are showing correct values. I have just finished pulling all burnt components off the board i can post a screenshot of where im at now. The plan right now is to replace all transistors in line and replace the burned resistors and replace the dual resistor.
You also asked about q213 and q 214 those should be on a seperate channel. Those shouldnt affect my issue with fl chamnel right? Do you know where i can order that part?
 

Thread Starter

Banthors

Joined May 19, 2022
31
Check the resistance between the legs of that component. It is unlikely to be blown.

R takes the place of the decimal point. For example, 2R7 would be 2.7Ω.

If things are going up in smoke it is more likely one or both of the output transistors are blown shorted. Remove both transistors and test on a DMM on the diode range. Chances are you will find two legs are shorted.
Thank you. On this component it is testing open line across all legs. I tested the same component next to it and am getting .2 from center to each leg. So this piece is fried. Forgive me as i am still learning what is DMM. The only way i have seen to test transistors is to test resistance from base to collector or emitter. Im sure this is wrong i have all4 transistors pulled out of circut right now so i can test them. Thank you for your help.
 

Thread Starter

Banthors

Joined May 19, 2022
31
Sorry Mrchips i just realized DMM is digital multimeter. I dont think i have a diode mode. I have ohms and conductivity mode
 
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