HMV 2807 Restoration

[murphyv310]

Hi
This video shows the result on a radar tube
We need to possibly recap the tuner IF deck again as ceramics don't work too well on these chassis. The horizontal hold controls needs to be replaced some how or another.
I hope to get some time tomorrow if my arm is OK after my booster jab.

https://youtu.be/QnVmBNhvql4

[murphyv310]

Hi.
Today I decided to wire up the Aurora directly to the Video output grid and feed in baseband. The Tuner and IF will come at later date. I have fitted a couple of rotary controls for line and frame hold which is is a little underrated TBH. The frame linearity control is duff to but I've just put in a 47k as a temporary "fix". There is issues with the frame circuit with a false lock. Every single capacitor was faulty in the set and so many resistors are seriously off value, the set in a way is getting rebuilt.
Getting there but quite slowly.

https://youtu.be/uadFipK8sBg

[murphyv310]

Hi.
Great progress today. The fault with the false lock turned out to be a new yellow cap (thank goodness I don't re-stuff unless particularly asked. C41 in R&TV servicing books Volume 2 page 336 (Marconiphone) was the issue, It read OK in both value and didn't leak but it did break down in circuit.
Other than the use of the radar CRT the picture is very nice. The next job is to do the another re-cap of the Tuner and IF as it certainly doesn't like ceramic caps.

https://youtu.be/KGDmPLf8lQM

[peter_scott]

Great progress!

Peter

[murphyv310]

Thanks Peter.
I've since tidied up below the chassis and played a little normal program material to demonstrate the persistence effect of the tube. Mains tapping is now correct etc. HT voltage is a little high, which is odd but perhaps HMVs capacitors always leaked it's still using the original rectifier as well.
The jitter isn't a cap or valve it's the crimping of the resistance wire at one end of the height control.
Next week is to replace the caps in the tuner and IF section and collect the Emiscope CRT kindly donated by my good friend Peter and see if it will do anything after sitting since 1963, should we have a poll on its success?

Last video of the week here. https://youtu.be/SF1ryU30ECQ

[murphyv310]

Hi.
Incidentally there is an error on page 336 of the R&TV servicing book Volume 2 (Television Servicing). The error is R43, 10k earthy end return is incorrect. It should be returned to the lower line that goes to the bottom of the brightness control and back to the video amp valves cathode.
The attachment is from the page in the book showing the error.

[Heatercathodeshort]

I have replaced all the RF/I.F. decoupling capacitors with ceramics Trevor and never had any problems. They were the approved replacements for the miniature Hunts type originally fitted that went O/C.

EMI eventually supplied a large kit of caps as a cure all for low gain, motor boating and sound on vision, vision on sound and general instability. To avoid realignment they have to be fitted in the same physical position as the originals.
This is the type I use. They are NOS 3500pf and 1000pf. It's amazing how many are used particularly in the PYE D16T. The TC picture was taken a few moments ago. It has not been switched on for a long time but it's not 'bad'.
The picture was hardly visible when I brought the VC53DA back to life but Bertha did a Sussex special on the 3/16 and it appears to be holding up. The picture is actually a lot better than than the photo.
Regards, John.

[murphyv310]

Hi John.
Ah those mixed ceramics, fitted as replacements in the Murphy V310 to 510 series, one of my first Jobs in the trade for instability.
The senior engineer told me they were in fact not true ceramics as they are tubular construction and have a small amount of inductance. This proves the theory that the ceramics I fitted are no good in this chassis just like in the 310 etc. Unfortunately I don't have any mixed ceramics so it'll need to be Mullard Mustards or nothing right now.
Your picture now reminded me of what I was told..... Thanks John.

PS, the picture on yours looks good indeed, is it bright enough to see in a lit room?
I'll need to build a Bertha, some info would be good if available.

[FERNSEH]

Hi Trevor,
I can supply you with 1000pF and 1500pF mustards for your 1807 IF amplifier.
Being of rolled foil construction the capacitors will have a degree of inductance.
Many will recall the strange instability fault that often occurred in the Murphy V410 TV set. The fault was caused by failure of a decoupling capacitor in the sound IF amplifier. Murphy Radio supplied a specific type of capacitor as the replacement.

DFWB.

[akuram1]

Was that where the set howled on warm-up, I remember fitting loads of replacements as almost every set developed it?

[FERNSEH]

"Was that where the set howled on warm-up, I remember fitting loads of replacements as almost every set developed it?"

I believe it was. However, the Murphy V410 I have here was displaying strange patterning effects which was finally traced out to be a decoupling capacitor in the sound IF amplifier.
Evidently, a well known fault back in the day.

DFWB.

[murphyv310]

That's indeed the fault David, one I remember only too well as BRW were Murphy dealers with the V310/410/510 series still out as pensioner rentals in the early 70s and a surprising amount too. In fact my first TV I was given as newbie apprentice was a V310, hence why I'm "MurphyV310" on different forums.

[murphyv310]

Hi.
Virtually complete now. I've fitted a thermistor, and found 4 suitable capacitors for the tuner IF deck although David Boynes is sending me some mustards. The results are now pretty good with just a little more to do. This was indeed a very rough set and I didn't think it would live again, admittedly not the worst I've done with was a terrible Pye D16T. So to do now is possibly the frame blocking transformer, a few more mustards, realignment if needed, and then a CRT which will be the biggest challenge of all.
Latest video here: https://youtu.be/Wy-JR_7DU2I

[murphyv310]

Hi.
Well I picked up a CRT from Peter Scott this afternoon, it did look a little rough and has a scratch on the screen with a tiny bit of phosphor missing inside the screen, I actually thought it was down to air. I decided I'd just fit it anyway and see if there was any life in it.
Well I was rather taken aback with the result and its excellent, bright and with decent focus. I'm very surprised
I've still some small adjustments to do and replace the blocking osc transformer but overall very pleased indeed.
Keep an eye on my channel for part 10.

Here https://youtu.be/lJyuY2Fmb4E

[peter_scott]

I'm absolutely delighted that Trevor has been able to put that 3/16 to good use. I was given the HMV 1808 by a school friend when I was 13. It was the first television that I was able to play with but it didn't take me long to discover that it was a London area TRF and there was no EHT. I took advice from a local radio shop and they told me to forget it and gave me a nice Ekco T231 and another 17" Ultra both of which has easy faults. The T231 needed a LOPT replacement, I can't remember the fault in the Ultra.

After abandoning the 1808 I dismantled it but kept the 3/16 which has rested in my loft since 1963! I was thinking that I was unlikely to find a use for it and am really happy to see Trevor's success. I thought his results with the radar tube looked really good but was very surprised when he called me to report the performance without even needing to boost or run-in the old tube.

Very well done Trevor

Peter

[FERNSEH]

Hi Trevor,
That's absolutely brilliant. It proves these sets are capable of producing excellent pictures.
Must bring the Marconi VRC54 down from upstairs and put it through it's paces. I doubt if it is as good as your set though.

DFWB.

[murphyv310]

Thank you David and Peter for the encouragement
I'll get it fully tidied up, check the alignment and do the frame blocking transformer.
It will be in the living room for the Queens speech on Christmas day, I'll do a video for authenticity and show the top of the cabinet to prove its a real Royal set..... I wonder if the Palace would like it back?

[Lloyd 1985]

Hi Trevor, that's a fantastic picture on that set! It's always nice to be able to fit a tube that surprises you and gives excellent results.

Regards,
Lloyd

[Panrock]

Yes, brilliant - in more senses than one.

Steve

[murphyv310]

Once I've done the final work I'll take some decent photos with another camera. Hope to have it completed by Tuesday. Its going in the spare room between now and Christmas and in the living room on Christmas day.