Dimmer packs - what's gone wrong?

[MrKitkat]

I suppose you've checked the obvious with these 'always on' channels and made sure that no 'test' button is on?

It's been a while since I've worked with betapack 1's so I can't remember if they have have them or not.

 

Yes, first thing we checked. Anyway, someone came intoday to have a look at it, but thanks for all the info guys!! :up:

[Andrew C]

Moderation: Five posts removed. Sorry not to PM individually, it is lunchtime and I'm hungry

[tom_the_LD]

(Snap question to the OP, why is it unlikely to be a Triac / Thyristor (ie the bit that actually does the dimming / switching) fault???)

Not wanting to go too far off topic - but I'd like to know the answer to this question!

 

Is it becuase if it was a triac you'd likely only be down by 1 channel?

[ianknight]

Is it becuase if it was a triac you'd likely only be down by 1 channel

 

Yeah - partly - but the main clue is Betapack Mk1 and Channels 3&4. The Sync for channels 3&4 plus 5&6 is derived from a resistor network and with age - the resistors fail causing those channels to fail hard on.

 

It's also pretty rare to blow a triac on a BetaPack as they rated over the likely failure current so that fuses pop before the triac.

 

The repair job is easy to do if you can find the correct spec resistors - about 30 minutes on the bench or 45 minutes on site - rumour has it that Keith @ Zero can do it even quicker than that! :huh:

[Stan Hope-Streeter]

Looking at your profile page, it appears that you are a 14-year-old pupil at the school which is having problem. You should not even consider attempting to replace these components! It needs to be done by someone with the appropriate qualifications, experience, authorisation and insurance! And that person would know where to source the components...

 

Gosh, I was repairing (and building) valve radio sets and amplifiers, with the usual 300V dc power supplies, when I was 14.

 

It's no wonder this country now has such a shortage of scientists and engineers.

 

 

 

 

(running for the shelter....)

[Andrew C]

Me too Stan, but unfortunately, we live in a different world today. I was connecting dimmers into the supply in the school kitchen at 16 (probably shouldn't have been doing that even then!)

[adam2]

Looking at your profile page, it appears that you are a 14-year-old pupil at the school which is having problem. You should not even consider attempting to replace these components! It needs to be done by someone with the appropriate qualifications, experience, authorisation and insurance! And that person would know where to source the components...

 

Gosh, I was repairing (and building) valve radio sets and amplifiers, with the usual 300V dc power supplies, when I was 14.

 

It's no wonder this country now has such a shortage of scientists and engineers.

 

 

 

 

(running for the shelter....)

 

I would allways advise that young or inexperienced persons should be very cautious when dealing with mains or otherwise dangerous voltages.

However we have all got to learn, and IMHO an intelligent 14 year old should be able to wire plugs, replace fuses, replace lamps, and possibly even repair dimmers.

Such work should of course be overseen by someone older who has suitable qaulification or experience.

 

In a school or similar enviroment, students should in my view, be allowed to replace plugs, renew flexes on lanterns etc. provided that such work is supervised.

[Brian]

In a school or similar enviroment, students should in my view, be allowed to replace plugs, renew flexes on lanterns etc. provided that such work is supervised.

Absolutely. Or we end up with the situation where one day they can't do anything and the next, when they turn 16/18, they are magically allowed to do anything.

[Jivemaster]

Rather OT but I was expected to walk to school and to walk home at the age of 8, nowadays outside the local comp school at 1445 -yes quarter to three! there are about a hundred cars for kids that can't walk home. More woryingly there are about a dozen police officers needed each day to get the kids out without fights to the death.

 

I started my stage interest when dimmers were rheostats! Nowadays school electricity is dangerous if there are two PP3s in the circuit! I've still got the old 4 pin valves I did formatve circuitry with!

[dmxtothemax]

The fact that these resistors are failing means they are not quite up to the job required.

As a qualified electrical and electronic repairer I would recomend using,

2w metal film resistors rather than the original 1w carbon film resistors,

Metal film resistors are more stable and reliable

You can get them from good electronic suppliers.

Try Farnel.

 

1) RS, CPC, Maplins, or if you have deep pockets Stage, AC, and others.

2) What Pritch wrote.

 

See the search box up the top of the page? Searching for "Betapack" returned the first hit on our Wiki with the info the OP needs.

 

Definately Betapack 1.

 

They take sort of kettle lead type plugs if that's any help (There's probably a posh name for them but I don't know it) They are pretty old though, as our light diagram is dated april 1991!

 

Having looked at the page that pritch suggested, just one more question. Where can you get some 100K ohm 1 watt resistors? Would your average electrical shop have them?

[matt c]

(snip...) IMHO an intelligent 14 year old should be able to wire plugs, replace fuses, replace lamps, and possibly even repair dimmers. Such work should of course be overseen by someone older who has suitable qaulification or experience. (end snip...)

 

Couldn't agree more.

 

When I was 14, I'd have been more than capable of replacing a few resistors on a dimmer PCB. I did do an IT & Electronics GCSE, though, with a heavy practical element.

 

I must confess, though, I was soldering at the age of 10. And I had a soldering iron in my bedroom too. :D

[Blaize110]

possibly even repair dimmers.

 

It wasnt to be used in school, but I built a dimmer when I was 16 :D - PICTURE

As you may have guessed, I completely agree with letting younger people do stuff under the correct supervision/checking.

[achanner]

Hi All

 

Sorry to drag up an old thread, but I just took delivery of 2 x Zero Betapacks and im looking for the definitive answer on these 1K Resistors.

 

Anyone recommend 1k or 2k as someone suggested, and perhaps point me in the direction of a suitable RS code as im ordering a few new fuseholders and fuses so thought I would bang some new resistors in while im at it.

 

Im looking at 683-5417 but there has been a lot of discussion around using 2k resistors instead and the plot has got a little muddy!

 

Thanks in advance.

 

Anthony

[adam2]

Hi All

 

Sorry to drag up an old thread, but I just took delivery of 2 x Zero Betapacks and im looking for the definitive answer on these 1K Resistors.

 

Anyone recommend 1k or 2k as someone suggested, and perhaps point me in the direction of a suitable RS code as im ordering a few new fuseholders and fuses so thought I would bang some new resistors in while im at it.

 

Im looking at 683-5417 but there has been a lot of discussion around using 2k resistors instead and the plot has got a little muddy!

 

Thanks in advance.

 

Anthony

 

A resistor should not be replaced with one a different value, in any ordinary circumstances. A 1K should allways be replaced with 1K ohm. (unless an expert advises that the original was incorrect)

Use of a replacement of a higher wattage can do no harm, and may well enhance reliability especialy if the original component was run near the limit..

 

Replace 1K 1W with 1K 2W certainly.

[achanner]

A resistor should not be replaced with one a different value, in any ordinary circumstances. A 1K should allways be replaced with 1K ohm. (unless an expert advises that the original was incorrect)

Use of a replacement of a higher wattage can do no harm, and may well enhance reliability especialy if the original component was run near the limit..

 

Replace 1K 1W with 1K 2W certainly.

 

Doh! Replace 1W with 2W is of course what I meant - Thanks Adam, I'm having one of those days!

 

Anyone done this successfully and can point me at an RS code?

 

Anthony