Dimmer Buzzing...No Output

[DAE]

I bought a Peak Electronics Atlas SCR-Thyristor and Triac analyser and have found it accurate and a time saver when repairing dimmers. It does not test under load being hand held, but has not led me astray yet.

 

[gordonmcleod]

That looks like an interesting product and relatively inexpensive
here is a link to the manufactures web site for it
Peak Electronic Design Limited - Atlas SCR - Triac and Thyristor Analyser - Model SCR100
It is probable that the dimmer in question is fireing at the lowest angle which would explain the buzzing choke
The only way to deal with it is for a qualified technician to scope the gate and probably the ramp comparator
Also DILOR made there dimmers current limiting
Those old TTI dimmers were very robust to say the least
Also on SCR sizing one has actually a lot of excess protection with dual SCRs since each one is only conducting for 1/2 the wave form and has more time to disipatate the heat into the heat sinks
The normal guidline for discete rectifiers is that for a single phase full wave bridge the minimum diode size is 2/3 of the peak full wave rectified current
regretably TRIACS and SSR blocks being one device don't get that 1/2 cycle to pass off some of the heat to the heat sinks

 

[WillLik]

Thanks for the info here.
I am attempting to find a solution for a couple of Chauvet dmx-4 with shorted triacs.
I have now ordered the triacs and we will soon see...,