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uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions.

Somebody down my way...



 
 
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  #31  
Old November 13th 16, 06:55 PM posted to uk.tech.digital-tv
tony sayer
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Posts: 4,955
Default Somebody down my way...

220mW BC148 with a 300mA BC108.

At least the early marks had the same stacked pair of horizontal output
transistors as the Philips G8. Setting up the balancing inductor was lots
of
fun.

Unforgiving was the word I would have used.

And that over-volts limiter on the thyristor PSU


Anyone remember the 100 K resistor slow start mod?..



What balancing inductor used to work on them don't recall that?.

The BU 105's used to fallover quite regularly;(...


Probably because you didn't balance them.

They were in series, so you had to balance the base drive. Whichever
transistor turned off too soon got all the flyback pulse to itself.


Do you know i don't think anyone in the workshop did that!. Or even knew
you had to do that.

Is the manual around online anywhere, just out of curiosity;!

Mind you, a long time ago now...

--
Tony Sayer



  #32  
Old November 13th 16, 07:29 PM posted to uk.tech.digital-tv
Benderthe.evilrobot
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Posts: 147
Default Somebody down my way...


"tony sayer" wrote in message
...
220mW BC148 with a 300mA BC108.

At least the early marks had the same stacked pair of horizontal output
transistors as the Philips G8. Setting up the balancing inductor was
lots
of
fun.

Unforgiving was the word I would have used.

And that over-volts limiter on the thyristor PSU

Anyone remember the 100 K resistor slow start mod?..



What balancing inductor used to work on them don't recall that?.

The BU 105's used to fallover quite regularly;(...


Probably because you didn't balance them.

They were in series, so you had to balance the base drive. Whichever
transistor turned off too soon got all the flyback pulse to itself.


Do you know i don't think anyone in the workshop did that!. Or even knew
you had to do that.

Is the manual around online anywhere, just out of curiosity;!


Its bound to be in manuals for any pre-BU208 solid state chassis.

My introduction to the setup procedure was excessive width after replacing
the LOPT.

One of the flyback tuning capacitors had failed SC - the job turned into a
bit of a struggle, hence the RTFM session.

Finding the capacitor was easy enough, but what followed was a growing pile
of scrap parts on the bench.

I can't remember the procedure because it was so long ago and I rarely had
to do it, but it may have involved diode/capacitor peak detectors and at
least one test point.

It was certainly described in the G8 S/manual, and highly likely in the
A823.

Most other makes probably jumped straight from PL519 to BU208.

 




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