Help with Symasym

[jandr49]

Hi - I've built a 6 channel symasym for use with a ESP LR4 crossover - worked well and sounded very nice until I tried scoping the left channel outputs of the crossover, at which point for a reason that I do not understand I melted R2 (10 ohm signal ground to power ground) on all three left channel amps - have replaced the resistors and the amps now appears to work perfectly apart from the fact that I have just recieved a shock from the signal input ground and can measure 74v from power -ve and chassis ground and 37v from signal ground and chassis ground - these measurments are all zero on the right channel amps so I obviously have a problem but am now not sure where to look for it. Any help would be welcomed

Richard

[pinkmouse]

First things first, test each module in isolation, preferably on the bench with a separate PSU. Then you can work though and eliminate each component as the source of the problem. However, I suspect an earthing problem, something is not tied to ground properly so voltages are floating.

[jandr49]

Many thanks for the advise

[pinkmouse]

Oh, and make yourself a lightbulb tester.

[jandr49]

I've already got one but I'm not sure how I can use it to problem solve an earthing problem

[pinkmouse]

You can't directly, but using it is always good practice, just in case.

[formula 22]

Hi
In order to gain the 27dB reduction in quality amps that I should lose nothing?
thanks