Mackie Power Amp Problem - Need Quick Help

[Ed Dixon]

We have two Mackie 1400i power amps at church. One quit tonight and we have a service tomorrow with 300 people.

The power light does not come on when connected. The fuze inside looks blown and one of the 4 large capacitors in the center also looks funny (compared to the other three).

Any ideas? Have little time to come up with something.

Ed

[battleminnow]

What type of fuse? Is it a fuse you can replace? If the fuse blew, the amp should be fine. But, that doesn't mean there isn't another problem. I would change the fuse and then see what happens.

[Ed Dixon]

It looks replaceable. Fits in a fuze holder.

However something had to go wrong for the fuze to blow. The amps are bridged (input) and each set to the same power level (about -20 db) and each feeds a similar set of speakers in the ceiling area.

Nothing has been loud for the last few days that I know about.

Ed

[battleminnow]

My experience is sometimes strange things happen. However, I am incluined to agree with you that something might be "wrong." How long has the system been in place? Are the ohm's balanced from speakers to amp? How many speakers are being powered per side?

I have had electronics fault due to a power surge or spike, or a ground problem or if the amp was shut off or unplugged improperly. Sometimes they are fine and sometimes they are not.

[boingoman]

Rent or borrow to get you through your show.

Try replacing the fuse, maybe you'll get lucky. Sometimes they just go. But I bet that cap is bad, if it's puffed out on the ends, and that could blow fuses for sure.

[Ed Dixon]

Borrowed a Peavey 2000 for the short term. Will replace fuze tomorrow and see what occurs.

The amps are about 2 years old. Generally left on all the time. Speakers are not known (mounted before I got here), but look like 15" 2-way systems. One amp drives one, and the other 2 (3 total).

Ed

[Hard2Hear]

I have a set of 1400i's that I have abused for about 8 years now. I've used them outdoors in 100+ temps and tossed them around in a van. I never had one mess up on me, though. But they were always load balanced correctly when used and I always run a limiter before the amp. I actually use one of them now for my studio monitors cause they give such clean power.

From my many years working with church PA's I'd say it has something with the "that I know of" part. I saw the drivers for 4 Community speakers literally melt one time at a church. Very funny, but not for the people buying the speakers.

H2H

[boingoman]

I've never had a problem with any Mackie product I have owned. After two years of use and no problems, it sounds like a random component failure.

They did have a problem early on, but fixed it after the first year or so. A batch of crappy ribbon cables and connectors, of which I must have replaced 10 under warranty out of over 100 of those amps we sold.

[wilkee]

It sounds like one of your power supply caps could have gone short circuit. This is a very common problem on power amps and it is getting more common as cheap Asian parts are used.

One of mine died the same way two weeks ago but it was accompanied with loads of black smoke (one of my mates reckoned if I collected all the smoke and put it back in the capacitor casing all would work fine,,, twat).

Get it checked to make sure no other parts have become damaged which could cause problems later on.

Tony

[xstatic]

If the amps have really been left on for 2 years, I would not be surprised that there has finally been a failure. Especially in the smaller 1400. Those poor little caps have been exposed to a lot of heat and volatage if the amp has really been on that much. Granted idling doesn't add that much, but idling for 2 years is asking for some sort of trouble.

[Ed Dixon]

The left on portion would only have been for a month or two due to recent electrical changes.

We had a lot of breaker problems some months ago, and things have been left on in the 2 months since. We turn off the board and other input sources, but the amps have been on for 2+ months.

Ed

[boingoman]

I don't think leaving it on was the problem. People leave equipment on for way longer than that. Parts fail sometimes. I did maintenance last summer on a music/paging system that has been on 24/7 for the better part of five years. No problems except dust. One of the clubs I do sound in has had the same PA amps for almost twenty years. When they aren't doing PA, they do bar music.

[Ed Dixon]

Picked up some replacement fuses today. Put one in and powered it up. Initially it made a funny sound and took down 2 PCs on the same circuit, but the fuse did not blow. Rebooted all and tried again a few times, and then nothing unusual occured and amp came on.

Will try again tonight at church. My guess is that the amp has some problem and may be the source of our previous mentioned breaker problems.

Ed

[xstatic]

Leaving it on may not be the problem, but it is certainly a very possible source for problems. Not good for the speakers either if the FOH gear has been truned off and the amps still on. Paging systems are quite different as they often are 70v systems which are designed to be that way. Leaving things on can be especially bad depending on ventilation and dirt and dust issues. Once an amp starts to get clogged, it works much harder, which can often create even more clog. Nice little catch 22.

[Ed Dixon]

I replaced the fuse and retested tonight. One of the 4 large capacitors inside had stuff oozing out the top. The amp now badly distorts.

We had used the amp in bridged mode. I changed it to stereo and found that channel 1 distorts, but channel 2 sounds OK. I wired the speakers to channel 2 for the service tomorrow. Mackie is goiong to repair it for us.

Thanks for all the suggestions.

Ed