HELP!!!!!!!!!! MY alpine MRV 1507 damage. any 1 can help me?? pls.

[jasyip5052]

i hv a very big prob about my amp. many time i repair it already, but it still damage easily. At this time,i cannot find the prob.


Situation:

1. im using the amp, but suddenly it stop funtioning. the protection LED and power LED always blinking. after i checking. i change all the power mosfet and audio mosfet. it become the more big problems. im using a 12V 20A power supply to test it when repairing. when im power up the amp (just the power supply input). power LED is blinking with RED, audio LED ON with green, and don't have the any effect for the protection LED (OFF straightly). At the same time. the right channel power mosfet and audio mosfet getting hot. \
2. then i try to use the supply from the car battery. the protection LED and power LED blinking with RED. audio LED Always ON. Not for 2-3 second, the power mosfet (right channel) getting smoky and fire.
3. i change all the power mosfet for right channel. When i try to power up it. got no any effect for the LED (all OFF). at the same time and a very quickly. my power cable become very hot and melting.

HAVE ANY BODY CAN HELP ME ??? PLEASE!!!!

 

[Perry Babin]

Please read the basic amp repair page (link below in the sig line).

 

[jasyip5052]

thanks Perry.

im following the instuction to remove all the mosfet to check. i found that got 3 gettinh short.

and wanna ask :
1. i try to power up jst the power board without all the mosfet. jst the the power LED ON with solid RED. the other no effect. is that normal??

2. i hv try to check with the ohm meter for the battery and groung point. it show the 0 ohm and dorp slowly to high ohm. is it normal??

 

[jasyip5052]

I change the rectifier and the damage mosfet d. i try to power up the power unit, it get functioning, the power LED and the protection LED is blinking. then i jst left it for around 10 minute. the mosfet still cool, the output voltage also get around 49V.

but,with the power OFF, i connect it to the audio board. it get big spaking of the 6-pin connector. i power up again, the power LED become OFF, protection LED is blinking.

is it any thing wrong to the audio board?? i hv check the mosfet and also replace with the good 1 already.

 

[Perry Babin]

You need to check the output transistors to see if any are shorted.

 

[jasyip5052]

which 1 u mean???
is it 9540N and the 540N??

 

[Perry Babin]

Both of those are outputs. Check all of the ones in the amp with those numbers.

 

[jasyip5052]

i check n replace already, but it still the same.

is it got other thing can getting short??

 

[Perry Babin]

Were any of the original outputs defective? If so, which one (exact circuit board designation needed)?

 

[jasyip5052]

i don't know that.
i do not have the exact circuit board designation.



For this amp. it always damage when i try to run brige. at that time im doing the wrong setting (mono, 1+2, ST).



i try to remove all the 9540n and 540n.

after that i try to connect it to the power board again wtihout power up. it still get sparking on the 6-pin connection. is my action correct or not?

thanks for ur help.

 

[Perry Babin]

If you plug in the audio board with all of the 540s and 9540s removed, does the amp draw excessive current?

 

[jasyip5052]

i hv change the 540s and 9540s. it still cannot. then i chane the A1220A transistorfor audio part.

then i power up the amp.the power LED is solid green, sound input is solid green, just the protection LED is blinking.
at the same time, i hv connect the audio input from my PC. but the condition is still the same. the voltage from the power board at 49V.

then i try to connect a speaker to it. my speaker getting "BOB" then the power LED become RED blinking, and protection LED become solid RED. the voltage from power board become 3-4 volt.

is it still hv any problem to my amp??

 

[jasyip5052]

i have try to install my amp back to my car. it still the same condition. power and audio get solid green. protection get flashing with RED.

And i found that the transistor Q619 and Q620 getting hot. is it normal??

Perry, i have look back an old forum of u.

Black probe on RCA shield ground, red probe on the tab of EVERY semiconductor with a metal tab. Does any read near 0 ohms? If so which one.

Black probe on chassis ground, red probe on the tab of EVERY semiconductor with a metal tab. Does any read near 0 ohms? If so which one.

Black probe on the aluminum riser plates (each one individually if they're not screwed tightly to the heatsink), red probe on the tab of EVERY semiconductor with a metal tab. Does any read near 0 ohms? If so which one.

i have set my multimeter with 20k.

540s FET all get 1.
it all happen for 9540s FET.

for test 1- i get the reading increasing none stop for Right Channel.
- and also get the reading decreasing none stop for Left Channel.

test 2 - i get the reading increasing none stop for both Channel.

test 3 - i get the reading increasing none stop for both Channel.

what its mean? is it got problem?? any place?

Sorry for disturbing. but i really need help. PLS!!!!

 

[Perry Babin]

Are the bias potentiometers at the fully counter-clockwise position?

It's normal for those transistors to get hot (too hot to hold your finger on) if they're not clamped tightly to the heatsink. Otherwise, they'll only get warm.

 

[jasyip5052]

ok, im fully counter-clockwise all the potentiometer at the audio part now.

but the ohm result still remain with before.

 

[Perry Babin]

Does the amp still go into protect mode?

 

[jasyip5052]

YES

And i hv try to check all the leg of mosfet 540Ns and 9540Ns. for the S, G get 49V. and get around 35V for the D legs.

 

[Perry Babin]

What is the DC voltage measured directly across the speaker terminals for each channel?

 

[jasyip5052]

45V for each

 

[Perry Babin]

What's the DC voltage on the center leg of Q504?

What's the DC voltage on the center leg of Q511?