Dynacord Powermate 1000 Protect Error
Posted 29 December 2007 - 08:47 PM
My dads band had a bit of a disaster at a gig at the weekend. As they came to start the second spot, their Powermate 1000 suddenly completely died and would not power on at all. They had to cancel the gig and go home shamefaced (the first time my dad has had to completely cancel a gig in 30 years - they've always been able to at least cobble together some sort of temporary solution to a problem).
Anyway, as of the next morning, the desk powers up with the 'Protect' LED lit. I understand this indicates that the desk has muted itself and shut down the outputs to protect itself. I've checked the ventilation areas - they aren't blocked. I've also had a peek inside and checked that both the fans are running OK, which they are.
Has anyone any other ideas what could have caused this, or what can be done to diagnose or solve the problem further. it doesnt seem to be the most obvious fault (I.e. a fan problem) so were now sat with a desk thats in protect mode, and no idea how to troubleshoot it.
If it can't be solved then it's off to a specialist, but nothing can be done over the xmas/new year period, so I'd like to take a further look at it in the meantime if possible.
(N.B. Ironically, they went through the whole rig about 6 weeks ago discussing what they would do if each component were to fail on a gig. They worked out that they could work temporarily around most problems, bar the desk failing! With this in mind, they invested in a second hand Powermate 1600, to use for larger gigs and as a backup. Having carried it as a spare to the past few gigs, they decided not to bring it to this one as space in cars and vans was limited. The one gig they don't have the spare...the desk breaks down! Talk about sods law!)
Posted 29 December 2007 - 10:07 PM
Firstly, check the fuses on the power amplifier boards - there may be quite a few, as this amplifier probably has several different positive and negative voltage supply rails. If the fuses are OK (check visually and with a continuity tester) - then try and measure the DC power supply voltages to make sure that they are all present and correct.
If they are all present and correct - then measure any voltage present at the amplifier output BEFORE the muting relay, possibly the easiest place might be at either end of the output coil. Measure the voltage with respect to earth. Should be a few 10's of millivolts only.
It is quite likely to be many 10's of volts (thus triggering the protection) - meaning that you possibly have an output transistor failure. If this is the case - you need the schematic diagram and probably some existing experience faulting power amplifier circuitry.
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