"Andrew Gabriel" wrote in message
...
In article ,
"Arfa Daily" writes:
Well, I've fixed the bloody thing now, and I have to say that it had me
fooled. The problem turned out to be a knackered lamp socket. Looking
closer
at the specs, it's actually 250 watts not 150 as I first thought, so even
with the forced air cooling it has, the lamp house runs pretty damned
hot,
and the lamp socket with it. Basically, the ballast is not a very good
design. It doesn't run at all with no load on it, and as the lampholder
was

That's by design, and it's because there's no active regulation,
so if the load is too small, the output voltage would be too high.
That's why a typical 20-60W electronic transformer has a minimum
load output. If you try it with a 10W lamp, it won't run as the
output voltage would be too high.



Yeah, I understand the reasons why. I guess that just condemning it as a
"not very good design", is setting aside the need for it to be cheap. I
suppose that I am 'spoiled' by usually working on properly designed clean
switchers that do have a tight control loop. I mean, at the end of the day,
it's not actually that hard or expensive to do, given that there are tons of
cheap 8 pin controller ICs out there. Thinking of some of the properly
regulated ones that I do work on regularly, they probably actually have less
components in them than this thing does ...

Still, done now, so it can go back on eBay when I have time !

Arfa


Andrew Gabriel
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