Strand Tempus 10A/15 Dimmer Pack Fault

[Floydey]

Does anyone have any knowledge on the following fault on the Strand Tempus 10A/15 dimmer pack?

 

Channels 1 and 2 will rise to 75% brightness on the slightest touch of the appropriate slider on the lighting desk. The rest of the slider travel (approximately 90% of the rest of the travel) brings the lantern up to 100% brightness.

 

Thank you in appreciation of your replies.

[tokm]

You using a analogue desk or a DMX desk & demux? Sounds like some sort of control fault to me. Have you tried the standard test it with another desk routine? Or if your running the pack via a demux, with just an analogue desk strait into the pack, just to check if it could be the demux thats nackered?

 

I've seen a similar thing happen before with older racks, the 0-10v analogue signal wasn't getting 'decoded' (for lack of a better word) properly.. In that case the channel had a bit more movement on it.. something like 60% upwards, but sounds like a similar problem.

 

Seeing as the channel still has some variation on it and its not just stuck at 100%, it doesn't sound like a fault with the triac/resistor..

 

HTH.

 

Tom

[Floydey]

I am using the original Strand Tempus 18 analogue desk. I have two other dimmer packs that work fine so I suspect that the fault is not the desk but somthing common to chanels 1 and 2 as they reside on the same PCB in the dimmer pack itself.

[bisk]

The power supply on the board is common to both channels, this affects both topsets.

First thing to look for would be a dry joint, common on Tempus modules.

 

The power supply on the board is fairly straight forward so fault finding it shouldn't be too difficult.

 

But be aware the heat sinks are LIVE all the time.

SO only remove the module if your confident in doing so.

[Neil Hampson]

Considering that it affects a channel pair, it sounds like an error on the the two pots that control the preset and the top set for each channel pair of dimmer (I think they are called V1 and V2 on the PCB). I had the same problem on a Permus, the trick is to adjust the 'topset' pot to give 100% at -10V, then change the preheat pot to give a glow on a lamp at -0.5V (I found it best to use a lamp rather than rely on a multimeter reading as a Fluke can't handle the chopped waveform from a dimmer very well), repeat and you find that the top set is now nowhere near right, as the setting on the two pots interact with each other. it does take a bit of time to get a reasonable result. Also bear in mind that this is a procedure that is normally done live as you need to measure the output or at least observe the lanterns output.

When first ajusting the pot, swipe the pot through it's full extents to clean the track of any dust or anything otherwise you may get inermittent results across the swipe.

 

From the Permus Manual:

2. Setting Up Instructions

All this equipment is correctly set-up at the time of manufacture and no on-site adjustments should be necessary. However, should it be necessary for any reason the basic procedure is as follows :-

2.1 Dimmer Modules

 

 

2.1.1 Lamp load of at least 500W glowing when both dimmer levers at zero - bottom potentiometer VR1 set too high.

2.1.2 Lamp load of at least 500W no glow when control channel set to lever position 2 - bottom potentiometer VR1 set too low.

 

2.1.3 Lamp load of at least 500W reaching full light before control channel set to lever position 10 (i.e.dead travel at top) - top potentiometer VR2 set too high.

 

2.1.4 Lamp load of at least 500W not reaching full intensity when control channel set to lever position 10 - top potentiometer VR2 set too low.

 

2.1.5 The two potentiometers VR1 and VR2 are mounted on the trigger card of each module. On Mini-2+ packs, access is by removing the rear cover; on Perma 12 racks the large front cover provides access.

 

2.1.6VR1 is for bottom adjustment, VR2 for top adjustment. Clockwise rotation causes an increase of output, anti-clockwise a decrease. For example, for 2.1.1 above, VR1 should be turned anti-clockwise.

 

2.1.7 For accurate setting up of any Thyristor dimmer on output voltage a true RMS voltmeter (dynamometer or moving iron) is required. An AC multimeter, such as an AVO CAN be used but only as a comparison with a correctly set dimmer. With load of not less than 500W plugged in and the voltmeter connected either in the free socket or in numbers 2 and 4 in the terminal block, proceed as follows:-

 

2.1.8 With relevant master fader at full, set channel lever to 1, and adjust VR1 for an output of approximately 10 volts. (A better setting can be obtained if the setting potentiometer is rotated backwards and forwards a few times to clean the track before setting). With channel lever at 5, adjust VR2 for an output of 150 volts. Repeat 1 and 2 as necessary to achieve both settings.

 

2.1.9 With channel lever at 10, check that the output is within approximately 5 volts of mains voltage

 

Edit: I may be mistaken, I was under the impression that the Permus and Tempus shared the same dimmer modules, however the Permus and the Mini II share the same module so the above may not be exactly the same.