Meter Trouble

[Eboy87]

I just uncased my Onyx 1620 today, and noticed that the main meters had both of the -30 LEDs lit continuously. When I solo a channel, the right -30 LED stays lit, while the left one goes out. A solid whack to the side does nothing to help (big surprise there). I tried this while plugging into a known good outlet, no inputs into the board, all knobs zeroed out, and all faders down. No outputs connected either. Does anyone have any ideas of where the problem might lie? Board is around four years old, lived in a case and my room for most of it's life, and has had a pretty easy one at that. My first thought was ribbon cables.

It's not a huge deal, but I thought that figuring this out would help in my repair skills later down the road. Oh yes, please refrain from replying if you simply are going to say "It's broke 'cause it's Mackie." I don't need to hear that.

Thanks in advance guys.

 

[avkid]

Ooohh...I'm not crazy.
Our 10 year old SR 32-4 Vlz Pro does this too.
-
It can happen for a week straight and then not happen again for months.
-
The older of the two 1604's does it constantly, but up a few levels.(why I won't use it)

 

[mixmaster]

Have you listened to the phones while the meter was acting strangely? I had a console once that had a similar problem. Turned out the meter was actually working, there was a small amount of electronic noise being generated in the master section that the meter was picking up on. I had to listen close, but I could hear it in the phones. Seems like I remember the repair tech traced the noise back to a diode in the power supply going out....
Just a thought.

 

[Eboy87]

Yes I have listened to the cans while it's lit. No noise. I might open it up later and take a looksey. Today it just creeped up to the -20 LEDs.

 

[howlingwolf487]

Today it just creeped up to the -20 LEDs.

Sounds like the tide's coming in - maybe you should wait until the full moon goes away...

 

[mbenonis]

You might give Mackie a call and just see if they have any thoughts on the issue. If you just bought it should be under warranty too - see if they'll send you a replacement to try out (BEFORE sending yours in!)

 

[avkid]

You might give Mackie a call and just see if they have any thoughts on the issue. If you just bought it should be under warranty too - see if they'll send you a replacement to try out (BEFORE sending yours in!)

If they play games with you, tell me.
It will be taken care of.

 

[FMEng]

This is just an educated guess, but I'd bet there is an electrolytic capacitor in the power supply section that is dying. Chances are there is a power supply rail that does nothing but power LEDs and maybe some switching logic, such as for the PFL and meter selection. The audio rails are probably +/-15V, the phantom supply is +48V (!), and the LED and logic rail is likely +5V. Look for the bad capacitor around hot stuff, like heatsinks, in the power supply section. If you are lucky, you might find one a little swollen on top or oozing. Electrolytics are polarity sensitive, so note which way the old one was installed to avoid small explosions.

Electrolytics don't like heat, and fail often when exposed to warm temperatures for long periods of time. I have repaired many pieces of equipment just by wholesale replacement of electrolytics located in hot spots, especially in power supplies.

This is also why equipment that is kept cool lasts a long time. Leave air space above and below your rack mounted gear when possible.

CAUTION: There are hazardous voltages inside that console! Make sure the cord has been unplugged for several minutes before opening it up.