HD Dimmers and You
HD dimmers predated RD dimmers, and were manufactured by LMI in the early 80's.ETC still stocks several parts for this rack -- the connectors, the fuses, triacs, and the fuse holders.
ETC can also perform board level repairs on the clock cards and dimmers. As each of these touring racks and installation racks were custom built, there are no manuals. ETC has schematics and some drawings.
Looking from the top of the dimmer module down:
- Recessed output trim screw to set top-end level.
- A 10 segment LED that will move in correspondence with incoming signal level. Incoming signal was 0-10Vdc -- there are no other control options.
- Next is a three position switch, this switch will set the dimmers into one of three modes:
- Off: No output
- Dim: Will dim from an incoming signal
- Full On: Will stay on regardless of incoming signal (spring loaded bump)
- Load neon. This will illuminate when a load is attached. This can be a handy way to see when you have a blown lamp.
- Plug-in jack to meter dimmer output.
- Neon lamp that illuminates when the module has power.
- Circuit Breaker.
- FuseThe modules are not SCR based -- dimming is done with a triac.
If you remove a module, you will see a small toggle switch behind them. This switch is to determine whether the slot has a dual 1.2kW or a single 2.4kW module in it. The rack pictured is a 1.2kW. You should not change this, as it may damage the modules. It should be noted that the chokes for the dimmers are in the rack -- not on the dimmer module. On the rack assembly for each row of dimmers (each row is a phase) is a control section. This section has test points for the Neutral, Line voltage, Clock signal, and control common. There is also an LED that indicates power to the clock card. The fuse provides protection for the clock card behind the small screw panel. This clock card takes the 0-10Vdc control signal and modifies it to a pulse-width signal based on the voltage zero-crossing per phase.
On the back side of the Rack are breakers and output connectors; generally Socapex. These racks are pretty durable and are not prone to many failures.
- The connectors between the dimmer and the enclosure are prone to burning out. We have new connectors in stock.
- Breakers and fuses can go. These we also have in stock.\
- The clock card can be damaged by voltage surges, but can be repaired (at the factory).
J313 CON 10M TERM BLK SOC EV Male (module)
J312 CON 10P STRIP Female (rack)
1050A1002 ASSY;DIMMER MODULE, 1K
Q107 TRIAC; Q6025P 25A 600V
F101 FUSE 10 AMP SC-10
CB102 CIR.BREAK;SP, SLOW, 10A
X102 FUSEHOLDER; HPS-EE
1050A1001 ASSY;DIMMER MODULE, 2K
Q109 SCR; 63A PACK
F106 FUSE 20 AMP SC-20
X111 FUSEHOLDER; HPF-JJ