Mackie CR4 (probably Zenner diodes burned.

Thread Starter

gallardoedgar

Joined Jul 4, 2020
5
Hello Everyone this is my first post... I have the Mackie CR4 audio monitors, and I see the PCB is kind of burned (images attached).

I do believe the Z3 and Z4 zenners were overheated but I'm not really sure.

I don't know the part numbers for those or if I'm missing something, I would appreciate any help on this. I can't seem to find an schematic that includes the Z3 and Z4 part for the Mackie's CR4.

Thanks everyoneIMG_20200704_172317.jpg
IMG_20200704_172331.jpg
 

Thread Starter

gallardoedgar

Joined Jul 4, 2020
5
You would have to turn the board around to see which traces have overheated. That will give you a clue.
After some research it seems it's a "common problem" with these models.

I proceeded as stated in the following video:

Explained in an image here... cut.png

Seriously... After I did this... everything is working perfectly fine now.

Thanks for your support guys
 

dkrn9000

Joined Oct 6, 2020
1
I'm so happy I found this thread. I had the exact same problem. The PCB looked burned just like in your images and I was also trying to replace the zener diodes, but this youtube tutorial worked like a charm!
 

nickalla

Joined Nov 20, 2020
1
Hi guys, have a similar problem in my CR4. The C80 capacitor completely blew its top shedding electrolyte everywhere. Anypne have any ide on a likely value? I Iam thinking 100uF but grateful if anyone can confirm. Also what value zener diodes? I am also thinking 3.3v eg 1N4728 or similar. They seem to use Z prefix on PCB lettering to mean 1N4148 small switching type diode as well as zener. Can anyone confirm please? Thanks in anticipation
 

slogo

Joined Feb 3, 2021
1
Hi guys, have a similar problem in my CR4. The C80 capacitor completely blew its top shedding electrolyte everywhere. Anypne have any ide on a likely value? I Iam thinking 100uF but grateful if anyone can confirm. Also what value zener diodes? I am also thinking 3.3v eg 1N4728 or similar. They seem to use Z prefix on PCB lettering to mean 1N4148 small switching type diode as well as zener. Can anyone confirm please? Thanks in anticipation
YOu are right the capacitor C80 is 16V and 100uF. On mine the C81 blown up, I believe it's same as the C80 but i wonder if anyone confirm
 
YOu are right the capacitor C80 is 16V and 100uF. On mine the C81 blown up, I believe it's same as the C80 but i wonder if anyone confirm
I'm so happy I found this thread. I had the exact same problem. The PCB looked burned just like in your images and I was also trying to replace the zener diodes, but this youtube tutorial worked like a charm!
Just to mention, desoldering pin 5 and bridging to pin 9 gets rid of all annoying noise that appears when just pin 5 is released. Working like a charm with that solution. Just leave pin 9 in place, desolder pin 5 and pull upwards, then bridge it to pin 9.
 
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DavidLvNv

Joined Oct 26, 2009
1
A friend of mine has a Pair of the CR4BT. And they had no power. Noticed an area that was almost burnt. So I checked to see if Z3 or Z4 shorted. Yep Z3 shorted, no +12 volts. Also found C80 had a slight dis-color and top was not mushroomed up but it looked different. Replaced both C80 & C81. I could not find schematics for the CR4BT version even contacted Mackie and they don't have the schematics for the version I'm trying to fix. The CR3 schematic is kind of close but R1 & R2 say 220 ohms. But on the CR4 they are 100 ohms 2 watt resistors. Found pictures of the board I have on the FCC web site. They didn't have schematics but they did have pictures of the board and it was an exact match. And R1 & R2 are 100 ohm 2 watt resistors. The FCC ID I looked is 2AD4XCR4BTCR5BT. First 5 characters are the company ID and the rest is device. So for anyone looking up info on any electronic device check here: https://apps.fcc.gov/oetcf/eas/reports/GenericSearch.cfm . Hope this helps anyone else!! Speakers sound great!
 
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