Trevor Wilson wrote:
"Sylvia Else" wrote in message
...
Whatever happened to circuits that just contained a couple of valves?


**There never were any "circuits that just contained a couple of valves".
When they first arrived, TV sets were mindbogglingly complex devices
compared to anything that preceded them (in domestic appliance-speak). They
were also fabulously unreliable. You could figure that the average TV set
would require several repair jobs every year. Your incredibly complex, LSI
controlled, TV set is likely to be vastly more reliable. You've probably
found the first fault it has ever had.

Well, OK, but the use of a programmable LSI chip makes it rather hard to
determine whether the chip outputs are what was intended, particular in
the absence of a schematic, and with the manufacture apparently out of
business.


BTW: If you post your request on aus.electronics, with the appropriate model
and chassis numbers, you may gain more of an insight. Even better, you could
join these guys:

Well, the model number is RK-32HDP81. Not sure where I'd look for the
chassis number - it doesn't really have a chassis. The serial number is
RK00000027, making me wonder how many of these were sold, though I
suppose the guy I bought it from could have been an early-adopter.

I've added aus.electronics, as per you suggestion, so to summarise the
situation as I perceive it now:

There is no picture, but sound works. The receiver side of the video
clearly works because it outputs to an AV output socket[*], and
plugging a suitable screen into that gives a picture.

The horizontal and vertical scanning outputs appear to be present. At
least, there are substantial signals there - whether they're the right
shape I couldn't say.

The most evident issue is that the EHT switching transistor, which
itself appears intact, has no base drive, and so far I haven't been able
to find a signal by backtracking.

The one good thing I have to say about the boards in this TV is that
they have component numbers on the soldered side of the board.

http://www.ceta.org.au/

Someone there has almost certainly serviced the same model and, perhaps, the
same fault.


I couldn't see any sort of public forum, and I wouldn't qualify for
membership.

Sylvia.
[*] The signal remains even when the TV is in standby mode. You can't
change channels in that mode, but the channel the TV was tuned to is
still available. Maybe this is common - I've never looked at other TV
outputs in standby mode, but it doesn't suggest the minimum possible
power consumption in that mode.