Rodek r2180a and protect

[mladenke]

tip41c on positive and tip42c on negative channel. sorry, you min on that resistor. Its mps 160 tipe. on resistor r154. On resistor r255 i can read what is on transtor becouse its noting there. To mutch heat or something. And one like that on postive channel next to tip41c. :S

 

[Perry Babin]

Q254 and Q152

 

[mladenke]

mps 160.

 

[Perry Babin]

That doesn't seem right.

 

[mladenke]

r155-q151-r167-q158 trace +channel. With no r155 only strange sound from speaker, but no protection.
r256-q254-r268-q259 - channel. without r256 got protection.
r254-q264-r285-q258 - channel without r254 got protection
r156-q154-r185-q159 + chanel. without r154 no protection

 

[Perry Babin]

Post a photo of the faces of the transistors listed in #22.

 

[mladenke]

here

 

[Perry Babin]

MPSA56. The resistor that you need to pull is on leg 3.

 

[mladenke]

than definitly i pullout wrong resistor.

 

[mladenke]

so, i am cofused right now. leg 3 on mpsa56 will be on right side of picture. Do you whant me to pullout transistor between q254 and q259, or do you whant me to pullout r256 on the left side of mpsa56, Leg 3 will be on the right side. :S

 

[mladenke]

okej with removed r256 on q254 i have protection.
with removed r155 on q152 i dont have protection.

with removed r268 (right transistor to be removed ) i got red light and blue light still lighting.
removed r167 dont giving red light
For today is done. Time to sleep and tomorow on work. Tnx Perry

 

[mladenke]

correction. whithout r167 i got red light with blue light.
without r268 no red light.

 

[Perry Babin]

Need clarification.

Are you sure that the resistors and transistors you're working with correspond to the Qx62 transistor in the diagram I posted? If so, the transistor would be an MPSA06 (which is the same polarity as the 2n4401).

 

[mladenke]

thats the only 2 mpsa transistor who have resistors on 2 leg and resistor on 3 leg, like in 680a diagram. But the trace are different from 680a. In 680a diagram that trace have diode. On my board that trace have cap.

and on resistor r167 i have transistor mpsa56, on resistor r268 mpsa60

 

[mladenke]

are this on first pictures zener diodes? z1 and z3? I get a ressistance from both side of diode. Same with diodes on second pictures. Are they for reversed polarity?

 

[Perry Babin]

Are either of the two amps below any closer to what you have? Bear in mind that the pin configuration for the 2SA and 2SC transistors is different.

Yes, Z prefix likely means Zener.

The two large diodes are for reverse protection if they are connected across B+ and ground.

 

[mladenke]

no, 680a is closer than this two amp. Can you tell me what we looking for, and what we whant to do, than i think it will be easyer to find trace that you whant. Now i looking, but i dont know what am looking.

 

[mladenke]

If you whant to cut off channel by channel i think i have one trace i can try. Same with the other side. I think that transistor are mpsa56, but i need to recheck when i get home. Look at picture in attachment.

 

[Perry Babin]

The base and emitter of the protection circuit transistor are connected across the large emitter resistors.

What you do first is find the channel that's causing the amp to go into protection. After that, you can swap the protection circuit transistor from the good channel into the bad channel. If the amp no longer goes into protect on the bad channel, suspect the original transistor in that channel.

If it still goes into protect, suspect a bad solder connection on one of the emitter resistors of possibly an emitter resistor out of tolerance.

If the fixative on the emitter resistors has degraded and become conductive, that can also cause problems and will have to be removed from any resistors other than the emitter resistors.

 

[mladenke]

Ok. I pullout r280 and no protection. Pullout r180 on otherside, same. So, i need to take of r280 again, and put amp in car on 14v and test if it go to protect. If amp dont go in protect, a need to put back r280 and take of r180 and to same test again. If i get protect mode, than channel od r280 is defective. Right?

On the bench testing amp dont go to protect without resistors. That make me angry.