Blown Alpine MRD-M605 amp - Page 2

paulieb81 · 4th January 2010, 09:20 PM

ok with the tester set on the buzzer function, the 3205's all switch as they should. When the tester leads are placed on a leg, it will beep and then stop, meaning it switched, and switch legs, and again will beep then stop until i switch legs again, back and forth. So all (4) 3205's are switching ok.

The 540's if i touch leg 2 + 3 they will switch, much faster than the 3205's, its a very small fast blip on the buzzer. But all seem to switch consistently although two of them seem to be not as responsive as the rest, but do switch.

The single RF2001T2D switches just fine.

The single FRH20A15 switches just fine.

Here is a shot of the board, I have highlighted where the different banks of transistors are.

The red are the 540's
The yellow are the 3205's
The blue are as follows:
1: 2SC3421
2: 2SA1358
3: 2SC3421
4: RF2001T2D
5: FRH20A15

paulieb81 · 5th January 2010, 10:27 PM

OK, I removed the once broken transistor and powered it up and I am sad to report, still a no go, same blank blinking display. Please let me know what I should check next.

Perry Babin · 5th January 2010, 11:48 PM

Have you tried to locate (or buy) a schematic diagram for the amp?

If there are no obviously defective components, this amp is going to be difficult (for me) to troubleshoot without a schematic diagram.

paulieb81 · 6th January 2010, 06:13 AM

no i sure haven't. Where could I find one?

Perry Babin · 6th January 2010, 06:18 AM

Consumer Electronic Parts and Accessories at PacParts, Inc.

68ECD2005

jol50 · 10th January 2010, 07:09 PM

I've had two of these line of alpines with issues in the small traces, one was in the bias circuit after I had replaced outputs and drivers and it didn't work. The issues they had were pretty mysterious until I found that. Anyway, I'd take a close look at the SMD side/areas and look for a blown trace its worth a try. The one was right at a thru hole I forget the other, and they were not obvious my magnifying desk lamp was very helpful. You might be good replacing what is blown, but just something to keep in mind and something you don't need a schematic for.

paulieb81 · 11th January 2010, 10:58 PM

I am still not able to find out what is blown on this amp. I honestly wish I could find someone local to my area who wouldn't charge me an arm and a leg to repair it as I am at a lose and rather upset that I took it out of the box and it worked fine for two days until it blew. Only problem is I bought it two years ago and just never had the chance to use it as I was deployed during the time so I can't return it.

brandes.cm · 02:59 AM

I just recieved a MRD-M300, the smaller version of what you have. I attached a picture of what I see for voltages. Yours will differ, but it should give us an idea of what you are missing.

The rectifiers should be 4 and 5 on your pic. Mine have a voltage of 22Vdc on them.

The power supply fets are at the bottom of my pic, yours are the 3205's.

cory

You cant see what I wrote for voltages. The four bottom components have

Pin 3 0Vdc
Pin 2 15.5Vdc
Pin 1 120mV

Rectifiers next two up
Pin 1 0Vdc
Pin 2 22Vdc
Pin 3 0Vdc

paulieb81 · 14th January 2010, 05:24 AM

thank you for the reply, I looked the board over very carefully but don't notice anything appearing to be blown. I will test the fets again on the Vdc and see what I get.

jol50 · 15th January 2010, 02:58 PM

Here is a photo of a bad trace:

5th January 2010, 11:48 PM	#13
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Have you tried to locate (or buy) a schematic diagram for the amp? If there are no obviously defective components, this amp is going to be difficult (for me) to troubleshoot without a schematic diagram. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

6th January 2010, 06:18 AM	#15
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Consumer Electronic Parts and Accessories at PacParts, Inc. 68ECD2005 __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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4th January 2010, 09:20 PM	#11
paulieb81 diyAudio Member Join Date: Dec 2009 Location: South Florida	ok with the tester set on the buzzer function, the 3205's all switch as they should. When the tester leads are placed on a leg, it will beep and then stop, meaning it switched, and switch legs, and again will beep then stop until i switch legs again, back and forth. So all (4) 3205's are switching ok. The 540's if i touch leg 2 + 3 they will switch, much faster than the 3205's, its a very small fast blip on the buzzer. But all seem to switch consistently although two of them seem to be not as responsive as the rest, but do switch. The single RF2001T2D switches just fine. The single FRH20A15 switches just fine. Here is a shot of the board, I have highlighted where the different banks of transistors are. The red are the 540's The yellow are the 3205's The blue are as follows: 1: 2SC3421 2: 2SA1358 3: 2SC3421 4: RF2001T2D 5: FRH20A15

5th January 2010, 10:27 PM	#12
paulieb81 diyAudio Member Join Date: Dec 2009 Location: South Florida	OK, I removed the once broken transistor and powered it up and I am sad to report, still a no go, same blank blinking display. Please let me know what I should check next.

6th January 2010, 06:13 AM	#14
paulieb81 diyAudio Member Join Date: Dec 2009 Location: South Florida	no i sure haven't. Where could I find one?

10th January 2010, 07:09 PM	#16
jol50 diyAudio Member Join Date: Nov 2007	I've had two of these line of alpines with issues in the small traces, one was in the bias circuit after I had replaced outputs and drivers and it didn't work. The issues they had were pretty mysterious until I found that. Anyway, I'd take a close look at the SMD side/areas and look for a blown trace its worth a try. The one was right at a thru hole I forget the other, and they were not obvious my magnifying desk lamp was very helpful. You might be good replacing what is blown, but just something to keep in mind and something you don't need a schematic for.

11th January 2010, 10:58 PM	#17
paulieb81 diyAudio Member Join Date: Dec 2009 Location: South Florida	I am still not able to find out what is blown on this amp. I honestly wish I could find someone local to my area who wouldn't charge me an arm and a leg to repair it as I am at a lose and rather upset that I took it out of the box and it worked fine for two days until it blew. Only problem is I bought it two years ago and just never had the chance to use it as I was deployed during the time so I can't return it.

14th January 2010, 05:24 AM	#19
paulieb81 diyAudio Member Join Date: Dec 2009 Location: South Florida	thank you for the reply, I looked the board over very carefully but don't notice anything appearing to be blown. I will test the fets again on the Vdc and see what I get.

15th January 2010, 02:58 PM	#20
jol50 diyAudio Member Join Date: Nov 2007	Here is a photo of a bad trace:

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