Mackie HD1531 amp issues

Evan Kirkendall

Evan Kirkendall

Senior
Jan 10, 2011
903
4
18
Abingdon, MD
www.harfordsound.com
Hi guys,
Trying to see if anything can help me troubleshoot a problem. I've got a Mackie HD1531 that is having some issues with the HF. It randomly cuts in and out at low to mid SPL. But, when you crank it up, it's fine. I can bang on the box and make it go in and out too. I pulled the amp out, and the actual driver, and all seems fine. All connections are tight. I didn't have time to inspect the circuit board, but I wanted to ask here before I really ripped into it. It's been sitting for the past month, so I don't know if that's played into anything...



Evan
 
Re: Mackie HD1531 amp issues

With unit open and turned on, tap around with a pencil eraser. If there is an intermittent solder joint it can be found.

Don't touch anything high voltage.

JR
 
Re: Mackie HD1531 amp issues

Just an update...

I pulled the cab apart, reseated every connector, and tapped around on the board looking for anything bad. While I had everything apart, I hooked up a horn and played some music for about a half hour. No issues at all, even when banging on the amp. I couldn't find any bad looking solder joints. So, I put the amp back in the cab with 2 screws. Fired it up again and all seemed well. Put all the screws back in, and sure enough, it was cutting in and out again... Lightly tapping on the shell of the amp with the end of a screw driver was enough to make it cut in and out. However, crank it up, and it's solid. Still only issues at low to mid SPL.

I'm stumped...



Evan
 
Re: Mackie HD1531 amp issues

Evan Kirkendall said:
Just an update...

I pulled the cab apart, reseated every connector, and tapped around on the board looking for anything bad. While I had everything apart, I hooked up a horn and played some music for about a half hour. No issues at all, even when banging on the amp. I couldn't find any bad looking solder joints. So, I put the amp back in the cab with 2 screws. Fired it up again and all seemed well. Put all the screws back in, and sure enough, it was cutting in and out again... Lightly tapping on the shell of the amp with the end of a screw driver was enough to make it cut in and out. However, crank it up, and it's solid. Still only issues at low to mid SPL.

I'm stumped...



Evan
Click to expand...

Sounds like the stress from the screws is causing a bad connection somewhere, possibly a cracked solder joint or PCB.
 
Re: Mackie HD1531 amp issues

Evan Kirkendall said:
I thought the same thing. But, the boards are all flawless(as far as I can tell). Also, loosening the screws did nothing! Even turning the screws would cause the HF to cut in and out.
Click to expand...

Those symptoms are exactly that of a bad connection somewhere. Broken solder connections can be nearly invisible to the naked eye. Go ahead and resolder connections all over the board and you'll probably fix your problem. However, it could also be a bad trace on the board itself. These are more difficult to find.
 
Re: Mackie HD1531 amp issues

I once had an intermittent DI - everything looked fine. I finally found the bad joint by tugging on the wire. The joint looked fine, but it wasn't - the solder on the terminal had not blended with the solder on the wire. I re-soldered it and all has been well. Get out the magnifying glass and a non-conductive pusher/puller.
 
Re: Mackie HD1531 amp issues

is there one particuar screw that makes it worse? if so the the fault is nearer that screw mount if not then it's probably nearer the centre of the board or one larger component which is being stressed by the scew tension across the board, if you can't see anything with a magnifing glass then it's time for someone with a signal generator and a schematic I'm afraid. The joys of lead free solder. G
 
Last edited:
Re: Mackie HD1531 amp issues

Evan Kirkendall said:
Hi guys,
Trying to see if anything can help me troubleshoot a problem. I've got a Mackie HD1531 that is having some issues with the HF. It randomly cuts in and out at low to mid SPL. But, when you crank it up, it's fine. I can bang on the box and make it go in and out too. I pulled the amp out, and the actual driver, and all seems fine. All connections are tight. I didn't have time to inspect the circuit board, but I wanted to ask here before I really ripped into it. It's been sitting for the past month, so I don't know if that's played into anything...



Evan
Click to expand...

I don't have an answer for your problem unfortunately but its worth mentioning we had absolutely nothing but problems in a club with the HD series(1521's). Mackie is local and swapped boxes for us several times before they pretty much told us were on our own.

Problems included: Distortion on one or both boxes after a band runs for more than a few minutes. This occurred while not being pushed very hard at all. Other problems range from one box being totally intermittent, as if going into protect but again, not being pushed very hard. Or a couple times it they would up and decide not to power on at all.

Once we switched back to the old passive JBL mpro boxes the mackies replaced, no more issues. (Amp ran from same power source as the Mackies). And we never had any issues with the 450's on monitors. (Aside from lackluster sound:roll:)

This led me to the conclusion that the Mackie HD series, while they have perfectly acceptable sound for the price, have serious reliability issues as we went through several of these boxes straight from Mackie and they all had problems. Maybe they were throwin' refurbs at us but regardless its unacceptable if you ask me.

It sounds like up until recently those boxes have been working great for you so hopefully you don't end up down the dark path of failures of that series that we went through.
 
Re: Mackie HD1531 amp issues

If you just loosen but don't remove the screws does the fault go away? The board could be put under stress and that is opening the connection.

This would be hard to fix though... touch up all solder joints, especially look at mechanical parts (jacks, pots, switches).

JR
 
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