Hartke HA3500 Transient Attack Bass head making 'woofing pops' while playing

[sleesaw]

I have a Hartke HA3500 Transient Attack bass head that is malfunctioning..
I turn it on and it powers up fine, and there is no crackling nor is the signal cutting in and out. I start playing and after a minute or so there are loud 'woofing' noises coming from the amp. Kind of a woofing pop. I'm wondering if there's some sort of grounding issue.. or some soldering broke free, etc..
PLEASE HELP!!
Like I said, no crackling or signal interruptions (the bass continues to play just fine under the massive woofing popping sound). But I'm wondering why it takes a minute to start doing it.
Any suggestions/questions PLEASE let me know!
Thanks!

[mozwell]

Measure all hte power supplies as a first step, are these all good ? Do any have large AC ripple volts?
When the speaker is making the "woofing" sound, does it push all the way in or out ?
If you disable the compressor, does this help

[Enzo]

Ball up your fist and whack the top of the amp while it plays. Does that have ANY effect on the amp or sound?

[sleesaw]

@ Enzo: I thought about hitting it several times... But I'm not sure if it will help the problem.. hahah.

@mozwell: I need to go buy a new volt meter today. Haven't used mine in awhile and it's failing to work.. Thanks for the Specs sheet though! Disabling the compressor doesn't change the woofing sound. And the speaker doesn't move that much when it does 'woof/pop'.

[sleesaw]

I have wanted to hit it.. but not sure if that'd actually help... haha

[sleesaw]

Thanks for the specs sheet! I have to get a new volt meter today and I'll check everything tonight. The speaker doesn't move very much when making the sounds. And the 'woof/pop' doesn't change when I disable the compressor. If I remember correctly, it may have gotten worse when I turned the compressor up. I'll double check tonight.

[pontiacpete]

Have you hit it yet> Enzo, was serious about that

[sleesaw]

I haven't hit it yet... What could that possibly fix? lol

[pontiacpete]

It could tell you if the problem you are having is the result of a bad solder joint or some other connection.

[sleesaw]

hmm. Well I suppose I'll give that a shot!

[J M Fahey]

Enzo *is* serious.
That's a tried and true diagnostic method.
"Big" manufacturers have shaker/vibration tables to catch such problems.

[Jazz P Bass]

The tech approach.

[Enzo]

I was dead serious. If you want to be official about it, use a rubber mallet instead of your fist.

Hitting the amp is not intended to fix anything. If the amp reacts to being hit, that means there is a loose connection somewhere inside. The hitting is a diagnostic to reveal loose connections.

[Jazz P Bass]

Tech approach II.

[Enzo]

There you go, the definitive rubber mallet pose.