Rank Arena Widescreen CRT

[Sylvia Else]

I bought this on Ebay for $5.50 on the off chance that I could fix it.
It was described as having lost picture with a "pop", and with the
observation that a TV repairman said it sounded like it could be a power
supply issue.

I've determined that the sound works OK, as does the tuner and video
signal stage - it outputs the composite video on an AV out socket.

It's clear what produced the "pop" noise.

http://members.optusnet.com.au/sylviae/tv1.jpg

http://members.optusnet.com.au/sylviae/tv2.jpg

Presumably this diode shorted out. It's on a board close the EHT circuitry.

But what are the chances that that's all that's wrong with it? Just
getting the board out to gain access to the underside will be a fairly
major exercise.

Sylvia.

 

[Sylvia Else]

I bought this on Ebay for $5.50 on the off chance that I could fix it.
It was described as having lost picture with a "pop", and with the
observation that a TV repairman said it sounded like it could be a power
supply issue.

I've determined that the sound works OK, as does the tuner and video
signal stage - it outputs the composite video on an AV out socket.

It's clear what produced the "pop" noise.

http://members.optusnet.com.au/sylviae/tv1.jpg

http://members.optusnet.com.au/sylviae/tv2.jpg

Presumably this diode shorted out. It's on a board close the EHT circuitry.

But what are the chances that that's all that's wrong with it? Just
getting the board out to gain access to the underside will be a fairly
major exercise.

Sylvia.

Um, strike that. Once I started pulling it apart, it was apparent that
that's actually a diode with an inductive bead on its lead.

Sylvia.

 

[D Yuniskis]

I bought this on Ebay for $5.50 on the off chance that I could fix it.
It was described as having lost picture with a "pop", and with the
observation that a TV repairman said it sounded like it could be a power
supply issue.

I've determined that the sound works OK, as does the tuner and video
signal stage - it outputs the composite video on an AV out socket.

It's clear what produced the "pop" noise.

http://members.optusnet.com.au/sylviae/tv1.jpg

http://members.optusnet.com.au/sylviae/tv2.jpg

The diode *looks* OK. Though it seems like there
might be a wire or maybe some "glue fibers" draped
across it?

Presumably this diode shorted out. It's on a board close the EHT circuitry.

I'd look at the switching transistor (HOT) first.

But what are the chances that that's all that's wrong with it? Just
getting the board out to gain access to the underside will be a fairly
major exercise.

<grin> You should see what a nuisance some of the high end
Sony monitors are (were?) to service! :<

 

[Sylvia Else]

The diode *looks* OK. Though it seems like there
might be a wire or maybe some "glue fibers" draped
across it?


I'd look at the switching transistor (HOT) first.


<grin> You should see what a nuisance some of the high end
Sony monitors are (were?) to service! :<

As far as I can see, and despite the numerous headers, it's impossible
to remove the circuit board from this TV without desoldering some wires
from it. I rather think it was never intended to be repaired. However,
with some of the unpluggable wires unplugged, there is just enough slack
in the remainder to prop the circuit board up into a vertical position.

Based on the described "pop" symptom, I was looking for something
showing physical trauma, but if there's any visible, I'm missing it, and
I've spent a good while looking.

I've established that the HT (190V) is present at the powersupply.

The switching transistor seems OK

Sylvia.

 

[Sylvia Else]

The "pop" could have come through the speakers and not made by an
exploding cap.

Yes. I also have to confess to wondering whether I've been suckered in,
with the pop being just to give the impression that it might be easily
fixable. The guy wasn't even very interested in his $5.50, and said that
he really just wanted to get rid of of the TV which turned out to be so
heavy it requires two to lift.

There seems to be a lack of sync signals making me suspect that the
fault lies at a low power section where component failure is unlikely to
make a noise.

Turns out that "Rank Arena" is a brand name that is transferred between
companies. The one using the name at the time no longer exists.

I've heard a lot of pops, snaps, cracks, etc...over my lifetime in the
industry and as a rule pops are generated by older electrolytic caps
as they now have a safety valves built in and only hiss.

When I repaired my first CRT 51" TV it seemed a daunting task with
all the interconnecting boards and other things in the way of the
convergence amp board. But I was driven by necessity. In your case
the $5.50 you paid should be an incentive as long as you remain
curious.

I've determined that it will cost me a further $10 to take it to the
tip, if it comes to it. Ho hum.

Perhaps I should try to sell it on Ebay.

Sylvia.

 

[D Yuniskis]

This is A Good Sign.

As far as I can see, and despite the numerous headers, it's impossible
to remove the circuit board from this TV without desoldering some wires
from it. I rather think it was never intended to be repaired. However,

....like many *cars*! :-/

with some of the unpluggable wires unplugged, there is just enough slack
in the remainder to prop the circuit board up into a vertical position.

Based on the described "pop" symptom, I was looking for something
showing physical trauma, but if there's any visible, I'm missing it, and
I've spent a good while looking.

I've established that the HT (190V) is present at the powersupply.

That's *mains* voltage (rectified and filtered?). Are you
sure the flyback is working?

 

[Sylvia Else]

This is A Good Sign.


...like many *cars*! :-/


That's *mains* voltage (rectified and filtered?).

I'm in Australia, mains voltage 240V RMS.

Are you
sure the flyback is working?

At this stage, I'm reasonably sure that it's not, but due to a lack of
appropriate input signals.

I'm somewhat aghast at the sheer complexity of the board that's creating
the horizontal and vertical scanning outputs, and the anode voltage.

It has two LSI circuits, including one that contains a programmable
processor, and no less than six transformers (I don't think any are
chokes, but don't quote me), not including the EHT transformer.

OK, so it's implementing the functions of a multi-sync monitor (the set
has an XVGA input), but even so....

Whatever happened to circuits that just contained a couple of valves?

Sylvia.

 

[Sylvia Else]

**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.

 

[Sylvia Else]

I bought this on Ebay for $5.50 on the off chance that I could fix it.
It was described as having lost picture with a "pop", and with the
observation that a TV repairman said it sounded like it could be a power
supply issue.

I've determined that the sound works OK, as does the tuner and video
signal stage - it outputs the composite video on an AV out socket.

It's clear what produced the "pop" noise.

http://members.optusnet.com.au/sylviae/tv1.jpg

http://members.optusnet.com.au/sylviae/tv2.jpg

Presumably this diode shorted out. It's on a board close the EHT circuitry.

But what are the chances that that's all that's wrong with it? Just
getting the board out to gain access to the underside will be a fairly
major exercise.

Sylvia.

I've given up on this anyway. Having run out of other ideas, I pulled
apart the box mounted on the neck of the tube, to see whether the
reported "pop" might have come from there. Nothing of note inside,
except yet more large heat-sinks. Anyway, I decided that putting it back
together again was going to be more trouble than it's worth. So it's off
to the tip tomorrow.

Sylvia.

 

[Sylvia Else]

It sounds like they only sold crap in Australia, and that you've
never seen the very low parts count in a Muntz TV.

My parents had three service calls in 15 years. Two of those were
due to lightning taking out the front end in the VHF tuner. The third
was a bad electrolytic in a voltage doubler that took out a fusible
resistor. That isn't a couple times a year.

It must be thirty or thirty five years ago that my family in England got
one of the early fully transistorised Philips colour televisions, with
teletext. This was our upgrade from B/W. We rented it, rather than
bought it, which was just as well, because it frequently broke down.
Indeed, the first occasion was within days of its arrival, with an
intermittent fault that the service company never did track down [*].
Often repairs involved fixing dry joints.

So Trevor's comment does fit my own experience. Televisions have become
more reliable. But I wonder whether that's because of improved
construction and quality control, rather than because of the circuitry
now in use. If individual components are very reliable, and they're
fixed properly to the circuit board, then the result can be reliable.
That doesn't mean that the design doesn't use an excessively large
number of components.

[*] The fault had the dual effect of killing the sound, and making the
picture about twice as wide as it should be. Years later, I obtained the
schematics for the set, and it was quite obvious where the fault had to
lie. I can only assume that the technicians who came to fix it either
didn't understand the circuit, or just couldn't be bothered. After they
fiddled with the set a bit, the fault would go away. Later I found that
a good thump on the cabinet would work just as well as calling the
technician.

Sylvia.

 

[Trevor Wilson]

It sounds like they only sold crap in Australia, and that you've
never seen the very low parts count in a Muntz TV.

**Very possibly. Don't forget: We are talking about the mid-late 1950s.
Valve TV sets were not very reliable. Dunno about foriegn sets. I never saw
one.

My parents had three service calls in 15 years. Two of those were
due to lightning taking out the front end in the VHF tuner. The third
was a bad electrolytic in a voltage doubler that took out a fusible
resistor. That isn't a couple times a year.

**My parents first transistorised set was very reliable. It developed a
fault in 1967 (I was 14 years old). My dad took it to the service guy and
was horrified at being asked to pay $50.00 for a quote. He brought it back
home and asked me if I wanted to have a go at it. I diagnosed the fault at a
dead rectifier in the power supply. I caught the train into the city to buy
a rectifier diode, soldered it in and the thing has operated perfectly ever
since. My dad figured that buying that multimeter for my 13th birthday was
an excellent investment.

Valve sets, OTOH, were not very reliable. The first Aussie made colour sets
(all solid state) from Kriesler were basically a large box-full of dry
solder joints. Great picture, but crap reliability.

 

[Sylvia Else]

you shouldn't give up yet.
Any static on screen?
what happens if you raise the g2/screen pot on the line o/p
transformer?
have you got volts on the RGB o/p stage on the CRT neck pcb?
have you checked for open resistros in the frame circuit feed (very
common 'black screen' cause)? have you checked components in the line
driver cct?
these are all fundamental first steps - I think your troubleshooting
has not been very systematic if you haven't done 'em!
-B

The switching transistor for the EHT transformer has no base drive. I
traced backwards through a transformer, another bibolar transistor, a
pair of FETs, a pair of bipolar transistors and ultimately reached two
outputs from the programmable LSI circuit. So the reason there was no
EHT was that the outputs from the LSI were unchanging. I surmise that it
had probably detected some fault, and disabled the EHT for that reason,
but since it's programmable, I have no way of determining what it might
be objecting to. I couldn't find any dead transistors, or capacitors
that were evidently faulty, and the low resistance resistors that I
measured were all within tolerance. Nothing had obviously burnt out.

Anyway, it's in the car now. Given how heavy it is, there's no way it's
moving from there other than at the tip.

Sylvia.

 

[William Sommerwerck]

And crap solder has come full circle, with ROHS.

I'm bothered about buying expensive products with non-lead solder.

 

[Trevor Wilson]

Rank Arena were old UK names, the Rank/Bush/Murphy brands were all
used in the 60s and 70s. Likely bought out by some chinese/turkish
firm, as have other former respected names like Dual, wharfefdale, and
Sansui.

**Dual was purchased by Thorens. Thorens is still a European made product.

 

[Sylvia Else]

if you had checked the RGB and frame stages, I'm sure you would have
found something amiss causing the set to prevent the EHT starting.

Well, perhaps. But by the time I'd got the metal box partly apart, which
required desoldering, I'd already managed to cut myself on it, and I
wasn't feeling particularly goodwilled towards the set. There was also
the question of what I was going to do with it if I managed to fix it.
It was rather bigger than I envisaged when I bid for it, so it wasn't
really going to suit my living room. I wouldn't feel entirely
comfortable about selling a TV that I'd taken a soldering iron to the
insides of. So if I'd fixed it, it might have ended up on the tip anyway

Sylvia.

 

[Trevor Wilson]

Sorry, not true. In the last 4 years, have seen the Dual name,
including the logo, on chinese made DVD player and a Turkish vestel
TV.

**Dual was STILL purchased by Thorens. Thorens may have recently on-sold the
name. Or not. It is not beyond the realms of possibility that the Chinese
are illegally using the name.

 

[PeterD]

The originals were still in the transmitter, and it was built in
1952. Backing the bolts off allowed some change in length, so they were
backed off and then set to a minimum torque. The new tube was
installed, and the voltage measured. Then each was tightened to the
recommended filament voltage. A new tube would last a couple years, so
it didn't have to be done very often. What bugged me was 3 KW of
electricity was used to get 25 KW out of the tube.

Amazing, isn't it! <g> What was used to measure the filament voltage
with that accuracy?

 

[Baron]

They will laugh in your face if you aren't familiar with the new
Harris solid state transmitters.


BTW, I found four high power GE X Ray heads yesterday. They use
about 100 KV DC to power them. Heavy bastards, with cooling fans. I
wonder if the store has any idea what they are really work, or just
how dangerous?

If its just the heads they could be worth more for the lead in them !

 

[Baron]

What lead? This is the aluminum waveguide & tube part. The lead is
part of the moving arm and holds the X ray assembly. They still weigh
about 5o pounds each for the smaller pair. I didn't know it was legal
to dispose of these outside the medical electronics industry. I would
think they would be rebuilt, like all the other types.

Oh ! I'm thinking about the wrong bit. I've seen a couple in scrap
metal yards. Didn't have a tube in them though.