Murphy Acoustic Deluxe

[stuie319]

Good evening Ladies and Gents.

I had this week, the opportunity to acquire a Murphy TV.
What was known from the sparse details and blurry picture was that it was a white Acoustic Deluxe. What wasn't known was whether it was a colour A823, or a mono set. The set looked more like the 823 than the 640 mono, but happy with either a little sojourn to north of the border was undertaken today.

Well, - It's neither!

It's model V2427, and it's a 24" mono set sporting the A816C chassis. Not something that I'd heard or seen of before. It's completely solid state, although the massive dropper resistor would to me have hinted otherwise.

It was sold as 'working', so after a cursory look over I gave it some mains, and work it seems to. And reasonably well too. However - I dare not run it for more than a few moments. The 302R section of the dropper resistor is getting much hotter than I would have deemed fit, in fact it's giving forth the magic smoke. Obviously I don't want it to fail o/c. At first I thought it might be burning off dust, but, it's dropping 99 volts, a dissipation of over 32 watts if I'm right.

Cold checks with the meter don't reveal any obvious clues, but in the absence of the schematic I'm somewhat blind
Does anybody know what would be a reasonable load handling of that section of the dropper, and in fact any idea where a schematic could be purchased?

I did a forum search on this chassis and the general consensus seems to be that it's not the friendliest of things!

As ever, any pointers are very gratefully received

Best

Stu

[thermionic]

Excellent . Well done !



Can we see the innards, please......?😜

[stuie319]

Hi,

Here are a couple of pictures of the chassis.

Regards,

Stu

[neil29]

I've got a V2029 and a TV311 with this chassis in them. the V2029 did work well but now doesn't and the TV311 never actually did work when I bought it.




Cheers
Neil.

[Electrical]

Hello Stu
Please find attached a PDF copy of the service information for the Rank Bush Murphy A816 Chassis from Radio & Television Servicing 1974-75 volume. I hope the information is of some help. I have included the recent developments section of the manual showing some of the modifications to the chassis. Note this is not the A816C version so there may be some differences in the information.
Regards Stan.

[vinrads]

Oh the memories come flooding back , they were made in black /blue orange I think anyone remember more colours . Mick.

[FERNSEH]

Teak wood cabinet was another option. The Murphy V2427 sets I rented out were either white or teak. Various stands were fitted; clip on metal legs, the A772 swivel pedestal stand and the very posh S800 chromium stand.
The set was very popular and well liked by the customers.

DFWB.

[dseymo1]

I've always liked these - very clean understated styling in their day, and still attractive today.

[stuie319]

Hi Folks,

First of all thank you indeed to Valveman for providing the manual.

It looks as though I might just have been being over cautious.
The manual gives the current drawn on HT1, the rail supplied by my hot dropper as 345 mA, and in fact the set measures at 330 mA,
so obviously there isn't an over current situation after all.
It simply must have been dust burning off.
I don't see a heat shield of any description though, and it does sit alarmingly close to the CRT when the chassis is closed.

The focus looks a little soft. I will have a play with the different tappings once I've found my test card DVD

Thanks all again

Stu

[Welsh Anorak]

Hi
I must admit these sets worked extremely well, though they did cost quite a bit more - and were far more complex - than the average 1500. The circuit's a bit unusual with the HT unregulated (hence the dropper) - the regulation taking place 'south' of the line output transistor. Unfortunately most faults were due, in my experience, to the LOPT, though the symptoms didn't point that way.
However yours works so rejoice! I imagine the CRT will soon come up to strength after some use.
The colour Z718, which also appeared in the Acoustic cabinets, used a very similar regulation circuit.
I have the more common A640 in a similar cabinet.

[dazzlevision]

I'd also agree that, when working correctly, they are very good sets. They have the same high gain as the famed RBM A640 dual standard hybrid mono chassis, plus a user switchable 4.43MHz subcarrier trap and good black level stability.

I have the 20" Bush model TV309, which is let down by the "fake plastic veneer" used to finish the cabinet (as per the awful Pye CT205 colour TV's cabinet, with the equally awful 697 hybrid chassis).

Not of such importance now, but the Bush models had six channel selector pushbutton units fitted, whereas, the Murphys had four position types. Six was useful if you could receive more than one ITV region (in the days when regional ITV schedules weren't all virtually the same!).

[stuie319]

Hello Chaps,

Well, I let the set run a while, between work and other normality,
and I'm sure I could detect a slight, but perceptible improvement in the definition -
So I made the fatal mistake didn't I! I put the back on....
It looks as if it's a tuner / IF problem now. Well it'd be boring if it was easy
Hopefully the weekend will allow some further fettling. I'll report back

Cheers

Stu

[jayceebee]

I notice that your set unusually is fitted with a Mullard ELC1043 so is highly suspect. RBMs own varicap tuner was a lot narrower body and very reliable.

I have a soft spot for this chassis whereas a lot of people hated it. There was also a 20" Acoustic Deluxe model in this range, the V2029.

John.

[G8vsjDave]

Hi folks, nice to know there are still some A816 televisions out there and that some of you actually like them. I worked on the development of the A816 at Rank's Chiswick factory back in 1971(ish). The original 'design aim spec' called for a thyristor controlled, stabilised power supply and few very early lab prototypes were built for evaluation purposes. Unfortunately (for everyone), the bean counters said it was too expensive and the thyristor was replaced with that huge, wasteful dropper, much to the engineers annoyance. IIRC the PCB was laid out for several tuners, including the ELC1043.

Dave (G8VSJ)

[Welsh Anorak]

It would be interesting to know what the design brief was for the A816 as all other manufacturers were concentrating on colour. I would have thought Rank would just have let the A774 be the 'run out' set - and they might even have got a decent LOPT for it! Or were there a lot of die hards who just wanted the best mono picture?

[FERNSEH]

When I opened the shop in June 1972 there was still a good demand for monochrome TVs, my main suppliers then were GEC and Rank-Bush-Murphy along with the wholesaler brands Alba and Marconi.
So it followed there was still a good number of customers wanting a better quality black and white TV set and the Rank A816 in Murphy V2427 guise was just what they were looking for. It displayed far better pictures than the awful A774.
The A816 employed the Motorola MC1330 synchronous vision demodulator chip and due attention was paid to maintaining the video DC component.
Light action varicap tuner buttons and even a chroma patterning filter switch.

DFWB.

[G8vsjDave]

Hi Glyn, an interesting question which set me pondering all morning. My position at that time was very junior, so I was not fully aware of the company politics, but looking back on it, this is my best guess.

The A774 project was handed over to production some time in 1969/70, and at that time the marketing department believed that there was a market for a fully transistorised large screen monochrome television – the A816. I don’t think the unreliability of the A774 played any part in the decision to make the A816, as we were somewhat removed from the post production department, and would only become involved if there were any major problems. The A816 project rumbled on for about a year, without very much direction or progress, then quite suddenly, one Friday, the A816 Project leader… err ‘left the company’. The following week, the project was re-assessed, and about a year later, went to production. I don’t know how it performed in the field, but unlike the A774, there was no sign of future problems whilst in development.

So, the A816 was very late getting to production, and by that time the demand for colour sets was on the increase. I feel sure the A816 with a thyristor power supply and a year earlier would have been a television to rival the A640

Our next project was the Z718, which along with the Z179 was the last sets to be designed at Chiswick. Very few Chiswick engineers moved to Plymouth, several engineers retired, others (myself included,) went into industrial electronics, and one young lad moved to Thorn where, I believe, he designed the Cyclops power supply/line output system used in the Thorn 9000.
I wonder, did you chaps notice any significant changes in Rank televisions after this time, before it became Toshiba?

Reading some of the threads, I do wonder what the problem was with the monochrome LOPT’s. I know 640, 774, 816, and 718 LOPTs were all designed by the same man, but whether there was some problem with the design or if it was a production problem, I don’t know.

Good times they were.

Dave

[Welsh Anorak]

Now that's an interesting question.
One thing about Bush sets was that they seemed to follow an evolutionary process - the last dual standard chassis was not a million miles away from the first TV125 series. Then the A774 came and surprised us, as did the A816.
Colour sets were different - the A823 owed little to the CTV25 (luckily!) - the only nod to the dual standard was the SL901 IC also used in the CTV174D. However the Z718 (did the Z signify anything?) was quite a departure with its layout and circuitry that owed quite a lot to the A816. The T20/22 looked superficially like the Z718 but with a proper power supply. The excellent (apart from the tube and socketry) T26 was a logical development of this design.
The oddball was the Z179 with a chassis that looked like a big A816 and had the Sl901/918 refined from the A823. Not a common set, and one that would have appealed to the owners of A816s upgrading to colour with its large screen, touch tuning, slimline cabinet and good performance.

[neil29]

Its been interesting to hear from someone who worked for rank and who can hopefully reveal some more info regarding design testing production of the sets that at least I like anyway. and I wouldn't mind acquiring a Z179 set if one should appear for a good price...


Cheers
Neil.

[DangerMan]

I remember these sets quite well and always thought they displayed excellent pictures. I liked them.

I recall we did have a rash of blank raster failures, almost always one or other of the IC's in the i.f. strip, and one new set in particular that used to eat them on a weekly or even daily basis.
It was in a very nice house, so a dry environment, and all voltages, EHT etc. were correct leading to the conclusion was that the tube must have had a tendency to small flashovers.

So, having checked the crt wiring and spark trap wiring... all correct... as a last resort I swapped the crt for one taken from an identical stock set which eventually went out on rental.

Oddly enough both sets went on to have long and uneventful lives thereafter!


G8vsjDave, if you have any tales relating to those days back in the Rank factory I'm sure we'd all love to hear them!