Vintage Lighting Skirpan SED-2c Parts / troubleshooting help

[ROpp]

Hello,
I have recently become the guardian of a school theatre space with an old 18 X 2k Skirpan Dimmers. One of the dimmer modules is blown open and I am looking to replace the relay but am having a heck of a time finding a replacement part. Another dimmer module had a burnt out fuse. Upon replacing the fuse I can only get the dimmer to go to about 25% adjusting the trim pot does not help. Can anyone give me any leads/advice? Thanks in advance.

 

[derekleffew]

Lite-Trol on the other side of the country. More locally, have you tried Holzmueller or Musson?
.

 

[ROpp]

I had not thanks for the tip.

 

[JD]

Wow, haven't heard that name in years. Were pretty good if I remember correctly. The older style used back-to-back SCRs and if one was open you would only get the dimmer up to about 50%. Give us a picture and I might be able to advise a bit.

 

[ROpp]

Here is a picture of the Module from the top and front.

Interesting about the back to back SCRs.

 

[JD]

Yes, the two devices you see mounted on the end (one on each heat sink) are SCRs in a back-to-back configuration. Beware, those heat sinks are live when the unit is connected. Both SCRs must work correctly. If either is shorted, the dimmer will always be on at 100%. If one of them is open, or if one is not getting any drive signal, the dimmer will only operate on one half of the waveform. The result is that the lamp will dim up to about 50%. This will tend to look a lot lower than 50% because lamps do not have a liner dimmer curve. If I remember correctly, the SCRs are rated between 40 and 60 amps, with a PIV of 400 to 600 volts.

Because there is such a shock hazard, and even a fire hazard if the repair is not done correctly, you want to get them professionally serviced.

Despite the antiquated look, there were very good dimmers in their day.

 

[ROpp]

Thanks John.

 

[STEVETERRY]

Hello,
I have recently become the guardian of a school theatre space with an old 18 X 2k Skirpan Dimmers. One of the dimmer modules is blown open and I am looking to replace the relay but am having a heck of a time finding a replacement part. Another dimmer module had a burnt out fuse. Upon replacing the fuse I can only get the dimmer to go to about 25% adjusting the trim pot does not help. Can anyone give me any leads/advice? Thanks in advance.

For the full story on Skirpan dimmers, contact Bob Goddard at Goddard Design. He knows all there is to know about that product.

Goddard Design Company - DMX512 Equipment - Theatrical Control equipment

ST

 

[Dustincoc]

Could it be that it was due to be calibrated in 1976. LOL

 

[DavidNorth]

Just trying to add to what JD has already posted....

That looks like a Heinemann breaker. If so, there's one more thing to look for when troubleshooting. Those breakers are known for failing in an unusual manner, specifically, they may not completely conduct from input to output thereby causing a voltage drop to the input of the dimmer. If the dimmer does not go to full but acts pretty normal otherwise, you may wish to do an unpowered continuity check across the breaker looking for excessive resistance [greater than about 0.2 ohms].

If you are careful, safe, and are comfortable working around live electricity, make a voltage reading on the output of the breaker while powered up [please do this only if educated in live electrical work]. If you see much lower voltage on output than input, you have a bad breaker. Sounds odd but I've replaced many like that.

Of course, if they are not Heinemann breakers, then ignore my irrelevant advice. Lite-Trol Service is a good resource for parts and repair.

David

 

[derekleffew]

I have recently become the guardian of a school theatre space with an old 18 X 2k Skirpan Dimmers. ...

Can you also post a picture of the control console? Still using the original, or something more modern with a protocol converter?
.

 

[ROpp]

We are using an old analog Leprecon. So no converter needed. I spoke with Steve over at LITE-Trol(after talking with Denis over at Holzmuller) and he said it sounded like a timer card or timer transformer issue that he could fix.