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Murphy V310A
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August 15, 2017
9:34 pm
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PYE625
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Thanks Marion,

Some good advice there. I had initially briefly used a 12v supply and noticed the Aurora got quite warm. I’m using a 9v battery at the moment, but will get/make something a bit more elaborate soon.

Why I never got an Aurora sooner, I really can’t imagine to be honest.

Andrew.                                                                                   

                         

August 15, 2017
9:45 pm
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Lloyd
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That is a fantastic result from the Murphy! Those Aurora’s are damn good too, I wouldn’t be doing TV restorations if I’d never bought one, I couldn’t afford the Domino when it was available, and I nearly didn’t buy the Aurora either. A really handy little gadget.

Regards,

Lloyd

August 15, 2017
9:47 pm
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Katie_Bush
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Hi Andrew,

Your very welcome.thumb_gifI was just relating Daryl’s advice to me on the ‘old’ VRAT forum, with regard to operating voltages. I run my own from a regulated multi-voltage PSU set to 7.5V, though I have also used a 9V fixed voltage adapter for short demonstrations. I think Daryl said 12V is as high you’d want to go even though the absolute maximum is around 14V if memory serves me. Personally though, I’d never run an Aurora anywhere near that high.

The coax adapter was my own idea from about 5 or 6 years ago. It certainly helps to cool the unit, though touch wood, I’ve never yet tried tugging the plug out, accidentally or on purpose, but it must be a safer bet than the rigidly attached ‘F’ connector.

Marion

If at first you don't succeed, try a new fuse!

August 15, 2017
10:22 pm
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PYE625
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Interestingly, I found a switch-mode multi output psu (set to 7.5v) and it caused noise on screen. The 9v battery doesn’t, and neither does my bench psu set to anything between 7 and 9v.

I might build myself a linear regulated psu for it. It’s a pain really as I wish it came with one.

Andrew.                                                                                   

                         

August 15, 2017
10:33 pm
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ntscuser
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PYE625 said
I might build myself a linear regulated psu for it. It’s a pain really as I wish it came with one.  

Wouldn’t help as it would probably be 110v with a US style plug and you would need a second adapter to run it off. It would also push up carriage costs significantly.

August 15, 2017
10:36 pm
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PYE625
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ntscuser said

Wouldn’t help as it would probably be 110v with a US style plug and you would need a second adapter to run it off. It would also push up carriage costs significantly.  

True….I hadn’t considered that.

Andrew.                                                                                   

                         

August 15, 2017
10:42 pm
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Jayceebee
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Well, what excellent results you have there Andrew. Must admit I was holding my breath with that CRM172 but it looks absolutely fantastic.

John.

August 15, 2017
10:52 pm
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PYE625 said
Interestingly, I found a switch-mode multi output psu (set to 7.5v) and it caused noise on screen. The 9v battery doesn’t, and neither does my bench psu set to anything between 7 and 9v.

I might build myself a linear regulated psu for it. It’s a pain really as I wish it came with one.  

Ah, and therein lies one big difference, my PSU has a nice big lump of iron wrapped in copper wire!winkWeighs a ton and makes a nice hum if you put ear against it.smileOh, and is regulated.

If at first you don't succeed, try a new fuse!

August 16, 2017
9:15 am
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PYE625 said

True….I hadn’t considered that.  

Given the universal availability of 90 – 264V switchers with clip-on mains plugs for most of the Western world it wouldn’t be an issue to do so, but would add to costs.

I don’t know how much current an Aurora takes (I don’t own one) but something like an LM317 (adjustable) or 7808 (fixed 8V), or their 3A counterparts would be ideal as a linear regulator.

To know yet to think that one does not know is best; not to know yet to think that one knows will lead to difficulty. Lao Tzu
August 16, 2017
7:56 pm
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PYE625
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Cathovisor said

I don’t know how much current an Aurora takes (I don’t own one) but something like an LM317 (adjustable) or 7808 (fixed 8V), or their 3A counterparts would be ideal as a linear regulator.  

It’s only 250mA, so plenty of choice for linear regulators.  

Andrew.                                                                                   

                         

August 16, 2017
8:02 pm
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PYE625
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The vertical hold control is one ended on the Murphy, and as the set warms, hold drifts away. I will need to look at the circuit and check resistor values R156 and R162. I temporarily replaced V16 (6/30L2) but had no effect.

Andrew.                                                                                   

                         

August 16, 2017
8:14 pm
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nuvistor
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I suppose it’s to be expected that faults will show themselves after the set not being powered for many years. At least you know the set is capable of excellent performance.

Frank

August 16, 2017
9:12 pm
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PYE625
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nuvistor said
I suppose it’s to be expected that faults will show themselves after the set not being powered for many years. At least you know the set is capable of excellent performance.  

Quite right, and not forgetting it has the vast majority of wax and Hunt’s mouldseal capacitors still fitted.

I have replaced/re-stuffed ones as mentioned previously in the timebase section, and one or two elsewhere as a precautionary measure, but I want to see faults and correct them as and when they appear. This can be leaky caps or resistors going high in value, plus valves of course too.

For instance when first switched on, the frame output valve V17 (PL82/30P16) takes ages to reach full frame scan with severe cramping at the bottom, but substituting this for a new PL82 cures the problem. 

rsz_img_3150.jpgImage Enlarger

rsz_img_3151.jpgImage Enlarger

Andrew.                                                                                   

                         

August 16, 2017
10:27 pm
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PYE625
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PYE625 said
The vertical hold control is one ended on the Murphy, and as the set warms, hold drifts away. I will need to look at the circuit and check resistor values R156 and R162. I temporarily replaced V16 (6/30L2) but had no effect.  

Voltages were roughly correct around the frame stage, but it turned out to be R156, a 1.2Meg resistor that was reading 1.4Meg and more when warmed. Not very much out, but more than the 10% tolerance and just enough to push the vertical hold right to the limit of travel for the preset.

That resistor would be ok in a less critical circuit, so I’ll keep it for another use. I’m so tight lol  grin_gif

Andrew.                                                                                   

                         

August 17, 2017
9:55 am
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Till Eulenspiegel
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Cramping at the bottom of the picture is usually the cathode bypass capacitor of the frame output valve C112 (250mfd 50v ) and/or the ramp forming capacitor C119 (0.1mfd) Also check/replace C118 (0.05mfd) Note the direct coupling between the oscillator and frame output valve.  The consequence of this will result in the cathode volts of the frame output valve will be higher than normal, expect to measure something like 23volts instead of the more usual 9 volts. I’ve got plenty PL82 valves if you need one.   Service information for the Murphy V310A series can be found in the 1959/60 Radio and Television servicing book.

Till Eulenspiegel.MurphyV310A_FTB.jpgImage Enlarger

August 17, 2017
6:26 pm
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PYE625
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Hi Till,

After 3 or 4 mins the fault clears as the old valve warms, a new one is fine right at the start. The cathode bypass cap is fine and I have replaced/re-stuffed C116,8 and 9 in the frame stage. I now have correct voltages and good frame lock and decent linearity too.

Thanks for the offer of a PL82, but just gone and bought a Mazda type off ebay. (I had a Mullard type for testing with).

Th PL82 is mentioned here as having that type of fault as it ages…..

http://www.r-type.org/articles…..rt-012.htm

Andrew.                                                                                   

                         

August 18, 2017
6:17 pm
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PYE625
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Purely as a matter of interest, I see the frame circuitry of the V310 and V310A is more or less identical. The only apparent difference is that the V310A uses a 30P16, whereas the V310 uses a 30P12. I tried fitting a 30P12 and obtained perfect linearity and height, better in fact than using a new PL82 (30P16) in the set. Furthermore, both the linearity and height controls are in their approximate mid position for best results with plenty of range either way. 

The voltage conditions were little different and all seems well. There are of course slight differences in the valve types, but I could not see why Murphy changed from the original 30P12 to the 30P16.

Your thoughts on the subject would be most welcome.

Andrew.                                                                                   

                         

August 18, 2017
6:59 pm
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PYE625
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On a slightly different note, I re-checked the oil level in the LOPT can when it was warm (after an hour or so of use). I could not notice much difference in the level between cool and warm. The level is probably just above the top of the transformer within the can from what I can tell, but the big question I face is do I need to add more. My gut feeling is to leave alone.

Again, your opinions are most welcome.

Andrew.                                                                                   

                         

August 18, 2017
7:46 pm
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nuvistor
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The 30P16 spec indicates a much more robust valve, nearly double the Pout. The 30P12 was introduced in 1958 the PL82/30P16 in 1951.

http://www.r-type.org/exhib/aaa0195.htm

http://www.r-type.org/exhib/aaa1405.htm

Just why the change, perhaps a deal with Mazda.

As for the LOPTX, well Andrew you are into cars so how about a dipstick permanently installed so you can check it after some many miles, sorry hours. rolf_gif

If it covers the TX and does not change much with temp I would leave alone.

Frank

August 18, 2017
9:32 pm
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PYE625
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Thanks Frank, 

Your opinion is valued thumb_gif

I’ll check the oil every 405 hours  grin_gif

Andrew.                                                                                   

                         

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