Strand Act 3 5kW dimmer

[Tom Baldwin]

I've got a Strand Act 3 dimmer, with channel 3 dead.

I don't have much time to spend fixing it (it's down the list of priorities), but I wondered if anyone had any tips of the most common thing(s) that cause this, which could speed my troubleshooting.

 

Symptoms:

- no output from channel, regardless of input

- breaker can be operated normally, and does not resist being put in the on position; LED indicator for this breaker follows the breaker position correctly

- ch 1 and 2 work fine

- input voltage verified as far as the trailing Bleecon connector going in to the unit

- 3 phase operation

 

My best guess would be that the triac has died; I'm not aware of any catastrophic lamp failures having affected the unit since I've owned it.

 

Any other thoughts?

 

It seems implausible that Maplin will stock the right part for a 5kW dimmer, which means a repair this weekend isn't going to happen, I guess

 

Cheers,

 

Tom

[JMC]

It's generally unlikely that Maplin will stock anything useful, ever

[tokm]

How cynical of you JMC! :( I'll have you know I've found many 'a' useful thing on their website.. Not that I bought it from them though Found it cheaper at CPC!

 

I purchased two of the old 5k racks off ebay a while ago cheaply, reported to be faulty, with the same symptoms as yours Tom.. one or two channels dead. Have you checked the control guts? I know you said some channels still work, but so did one of the 3 on 1 of the ones I bought, turned out that only part of the board was dead..

 

Other thing is to do what you suggested.. replace the triacs on the faulty channel, if not all! If you can get replacement triacs for a nice price, why not replace them all. Their going to be pretty old if their the originals, why not give your dimmer a new lease of life..

 

HTH.

 

Tom

[Don Allen]

I am going to start the post by emphasising that electrical safety comes first. In Australia you need to have a restricted electrical license to work on Mains equipment and develop a safe working method when operating on live equipment.

 

With troubleshooting equipment, there are two methods I use, substitution and the half split rule.

 

With substitution you replace one of the items in a non working or faulty system with a known working item.

 

Substitution Example 1 would be in a dimmer situation where a lamp does not work.

Patch in a known working lamp to see if that is the problem, if lamp lights, then suspect lamp is faulty. Repair lamp.

If not, patch the suspect lamp into a known good dimmer channel to confirm the suspect lamp is OK. If good then dimmer channel is faulty.

You now have to determine which one of the desk/dimmer rack is faulty so substitute desk or dimmer rack.

In order to get the best results, try to only change one variable at a time.

 

Substitution example 2 would be working on a dimmer rack without removable modules. See if the leads from a know good triac can be swapped with a suspect triac. The result will tell you whether the triac or the trigger circuit it faulty.

 

The Strand archive (great asset) says the ACT6 has 10 amp triacs. Triacs should be overrated so see if you can buy 45 amp triacs as replacements to help survive lamp failures.

 

In summary with the half split rule, you look at the middle of a system to see what is happening, then go to the middle of one half, down to a quarter now, then split again, down to looking at one eight now. Saves doing a linear check of every component or items in a system starting at the input and going through to the output.