Steve Cheese Posted June 19, 2004 Share Posted June 19, 2004 I foolishly lent my QSC PLX 1602 to some mates for a gig they were doing. They were driving 4 x JBL control 12's with it. No problem there as I have ran that set up many times before with great results. Now the problem. They told me that half way through the gig "the bass dropped out". Just no bass at all, just tinny top frequencies comming out. Now I asked all the questions like:- How hard were you driving the system - Not very hard. Any way, the speakers would blow wouldn't they, not the amp. I asked if they had knocked the filter dip switches - no, the amp was safely tucked under the table. They say that they have tried it with other speakers but it is still the same. Now they have promised to get it repaired even though they say it was not their fault, they said it would probably have happened anyway.Now, what could it be? Are there any internal 'fuses that could have blown? There is not one on the back. I've never taken an amp apart before.What do you recon ? Link to comment Share on other sites More sharing options...
Brian Posted June 19, 2004 Share Posted June 19, 2004 Do both channels of the amp behave the same? There is no fuse (well not that I can see in the service manual) on the amp outputs, either internal or external. The PLX ranges uses switching power supplies and an interesting rail switching technique to improve efficiency. If you've never worked on such a unit I wouldn't recommend trying to fix it yourself. Link to comment Share on other sites More sharing options...
Peter Russell Posted June 19, 2004 Share Posted June 19, 2004 Moderation, 19/6/04 14:07 - moved to Sound & AV Link to comment Share on other sites More sharing options...
Steve Cheese Posted June 19, 2004 Author Share Posted June 19, 2004 Don't know if it is both channels as I havn't got it back yet. They were driving two speakers per channel. The message I got is that 'the bass has dropped out of the amp' ! So I am assuming that it is both channels. Link to comment Share on other sites More sharing options...
Brian Posted June 19, 2004 Share Posted June 19, 2004 If it is both channels then there isn't much circuitry shared between them. There is a dual OTA chip used in the clip limiter which is has one section used on each channel. Other than that it's the power supply but I can't think of a fault there which would cause the LF to go. Best get it back and try it. Feel free to ask questions when you get it. Link to comment Share on other sites More sharing options...
Steve Cheese Posted June 20, 2004 Author Share Posted June 20, 2004 I'll do that, Cheers. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.