MACKIE PPM608 repair

[budm]

This unit is dead, no power indicator, all the fuses checked out good. I power it up and I can hear the power supply is ticking. I was able to download the service manual from MACKIE which is really nice of them. Check the DC output at the Cathode of the +5V, +15V and I can see the meter's bar graph is going up and down in sync with the ticking, then I check Anode of the -15V section and it does not show anything on the meter so that narrow down to something in the -15V section, sure enough, the rectifier is shorted and that is why I do not see the DC voltage going up and down. Easy fix.
The funny thing is that the power consumption is 160W, but it claims to have 500W out x 2! What a joke.

[Agent24]

Re: MACKIE PPM608 repair

The funny thing is that the power consumption is 160W, but it claims to have 500W out x 2! What a joke.

It will likely be measured in some obscure audiophool way.

[japlytic]

Re: MACKIE PPM608 repair

It appears that there are some bulging electrolytics under the largest heatsink.

[budm]

Re: MACKIE PPM608 repair

It appears that there are some bulging electrolytics under the largest heatsink.

Those are the caps in the Class D power amp section and it was a pain in the butt to get them out. Replacing the bad diode was easy.

[momaka]

Re: MACKIE PPM608 repair

Power supply appears to be built by the same company that makes Behringer. Or at least my EPQ-1200 has the same logo and "Ater" mark on its main transformer.

Yes, that rating is probably some exaggerated peak level. I, too, find it funny when I see amplifiers with some sky-high output ratings and a stated power consumption to be only a fraction of that. Maybe all these free energy videos on YouTube are real after all?

[cblanchette07]

Re: MACKIE PPM608 repair

I have the same issue just having a hard time location the part you said was clicking do you know the number on the board it is or where about is it in your 8th pic I believe that is where the tick is coming from

[Khron]

Re: MACKIE PPM608 repair

The faulty part is not the one that's ticking, it only causes the PWM controler to go into protection mode, and then it tries to re-start.

[cblanchette07]

Re: MACKIE PPM608 repair

Then what part on the board is faulty and needs to be replaced if you have it's number on the board or where it is in what photo that would be great.

[Khron]

Re: MACKIE PPM608 repair

Ehrm... Right...

Do you have any test equipment at hand? And, optimally, also a bit of knowledge about using it?

[cblanchette07]

Re: MACKIE PPM608 repair

I do and have fixed power supplies before however the issue was obvious plus my meters screen is messed up. What id like to do is narrow down what part on the board to test, what does it look like, I belive the rectifier is the black square pieces attached to the heatsink. I couldnt find any electrical schematics on the board but it sounds like what went on yours could be the same

[budm]

Re: MACKIE PPM608 repair

@cblan:
service manual:
http://elektrotanya.com/mackie_ppm60.../download.html

[cblanchette07]

Re: MACKIE PPM608 repair

Great thanks i took a quick look, great resource. Its been awhile since i read a diagram like that. Any hints on to where to start, i'd love to just check what you replaced if you remember where that was on the board, if not thanks for the help and i'll start to trace down the issue. Sorry for the all the questions i'm trying to fix this for a nonprofit that doesn't have the money to get a new one or pay for someone to get it fixed so i'm trying my hand at fixing it.
Thanks

[budm]

Re: MACKIE PPM608 repair

Read post and you will see what was bad, and then look at the diagram.

[cblanchette07]

Re: MACKIE PPM608 repair

Last post before you get mad lol you said " rectifier is shorted and that is why I do not see the DC voltage going up and down. Easy fix." I'm starting to think it's at BR1 which is in your 8th picture against the heat-sink just wondering if that was what you replaced or if it was a different one if so what one. If its a different one i'll just replace that one also see if it works.

[budm]

Re: MACKIE PPM608 repair

" then I check Anode of the -15V section and it does not show anything on the meter so that narrow down to something in the -15V section, sure enough, the rectifier is shorted and that is why I do not see the DC voltage going up and down."
The rectifier diode for the -15V power supply is shorted.

[cblanchette07]

Re: MACKIE PPM608 repair

I get what your saying in a way i'm just having a hard time location that rectifier. I've test all and the only that i get a reading that i'm not sure of is at U11 i didn't mean to put BR1 in the last post. It is sown in the picture circled in yellow. I'm hopping you can just give me a location to look as this is the first time for me testing rectifiers and i'm unsure if my reading are showing an issue or are normal. But i think D24 may be what you are talking about circled in red.

[budm]

Re: MACKIE PPM608 repair

D24 is the rectifier for the -15V power supply, that is the one I replaced. You might as well check the the other 3 as well since they are all the same so the failure in your may not be due to the -15, it can be the other 3 diodes (D23, 25, 26)

[meycom]

Re: MACKIE PPM608 repair

I have a PPM608 with exactly the same symptoms. After I looked at the power supply section it appears as if D25 may have fallen off somewhere. My friend who dropped it off to me said he had opened it to check the fuse, but the spot where I found the other diodes the spot for D25 has just the two solder pads.

[budm]

Re: MACKIE PPM608 repair

I have a PPM608 with exactly the same symptoms. After I looked at the power supply section it appears as if D25 may have fallen off somewhere. My friend who dropped it off to me said he had opened it to check the fuse, but the spot where I found the other diodes the spot for D25 has just the two solder pads.

Pictures of YOUR board? D25 is for +12V power supply.
Casp C62, C63 , C64, and inductor L9 are installed?

[mxslick]

Re: MACKIE PPM608 repair

.......
The funny thing is that the power consumption is 160W, but it claims to have 500W out x 2! What a joke.

Not so fast.

Depending on the DC voltage rails to the amplifier section, it is very possible that it is well capable of 500 watts.

Conversion from the 120vac line down to the DC voltages can be pretty efficient with SMPS, and since the rating is probably for a 4ohm load, it is quite possible to be a valid spec.

That said, Mackie is one of the more reputable companies. They aren't prone to exaggerating the power out.

BUT, P.A. gear is usually rated to peak output, not RMS (as hi-fi gear is) so it is also possible that is the peak power rating...

Yep, it is peak output rating:

From the spec sheet, RMS rating at 4 ohms is 250w @ 1% THD, 300w @ 3% THD and 8 ohms 160w @ 1% THD and 180w @ 3% THD

Here's the link to the specs:

http://mackie.com/sites/default/file.../PPM608_SS.pdf

So the 160w AC input consumption is within the range of possibility.

The digital cinema amp line I use for screening rooms is also very efficient and for the AC input, pounds out a lot of power per AC input watt.