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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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1st May 2021, 7:18 pm | #1 |
Heptode
Join Date: Apr 2003
Location: Cornwall, UK.
Posts: 986
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HMV 1840 Rescue
This set has been languishing in my ‘pile’ for years. It arrived as a flat pack, at least the tube survived!
I’m lucky that the Emiscope SE 14/17 CRT has very good emission, and now produces a very pleasing picture. The set required all the EMI manufactured wax capacitors to be replaced, and I’ve re stuffed these, as I like to do on all my sets. All the electrolytics have proved serviceable. Most of them were made by BEC, (British Electrolytic Capacitors) and these tend to be well made and have a long life. The LOPT gave me a few problems. This is enclosed in a thermoset plastic tub (along with the EHT rectifier valve) with a rubber top and is bathed in a low melting point wax. It gave the usual saturation problems - diminishing EHT and shrinking width, after being on for a short period of time. The wax was heated and poured out and the transformer removed. I passed a DC current through the overwind for 24 hours or so, and then re assembled it back into the housing. Instead of re using the wax, I filled the container with petroleum jelly, heated enough so that it became liquid. It worked! .......for about half an hour, when cracking and picture disturbances put in an appearance! This turned out to be the winding for the EHT rectifier valve (6W2) breaking down to the transformer core. This was removed and replaced with EHT cable wound in the same manner. The sequence of re filling the transformer pot followed. I think the set deserves the cabinet to be re finished now, it’s in a pretty rough state. There is also damage to the front, brown plastic escutcheon, which is now quite brittle. All the metal threaded inserts to hold screws for the loudspeaker and panel had broken away from the plastic. I’ve managed to glue these back. The knobs, similarity, are extremely fragile and have required some doctoring. So, in addition to the above, the speaker required repair, there was an open circuit inductor which prevented any sound getting through, the metal rectifier was shot and a few of the ‘helter skelter’ wirewound controls needed nursing! If anyone has any good knobs or escutcheon for this set, please let me know. Cheers. SimonT.
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1st May 2021, 7:20 pm | #2 |
Heptode
Join Date: Apr 2003
Location: Cornwall, UK.
Posts: 986
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Re: HMV 1840 Rescue
.......a few pictures of the LOPT assembly. The second picture illustrates the new EHT heater winding.
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1st May 2021, 7:23 pm | #3 |
Heptode
Join Date: Apr 2003
Location: Cornwall, UK.
Posts: 986
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Re: HMV 1840 Rescue
The chassis with the re stuffed capacitors. Hopefully, you won’t see much difference!
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1st May 2021, 8:04 pm | #4 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
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Re: HMV 1840 Rescue
Well done with that one! Almost as nasty as the 1807 with sync and instability problems to say nothing of a very short lived tube. There was always a good one and this must have been one of them. They were mostly scrapped when the tubes failed around 1959/60.
Regards, John. |
1st May 2021, 8:13 pm | #5 |
Nonode
Join Date: Jun 2008
Location: Coningsby, Lincolnshire, UK.
Posts: 2,814
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Re: HMV 1840 Rescue
Did you buy that set from Ikea?! The CRT did well to survive! Picture looks good on it now, well done saving it!
Regards, Lloyd |
1st May 2021, 8:58 pm | #6 |
Pentode
Join Date: Mar 2009
Location: Norwich, Norfolk, UK.
Posts: 228
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Re: HMV 1840 Rescue
Well done Simon, a brave restoration in deed. I liked the idea of using Petroleum jelly for the LOPT, like a jelly pot now. Nice one!
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1st May 2021, 10:06 pm | #7 |
Dekatron
Join Date: May 2003
Location: Edinburgh, UK.
Posts: 3,273
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Re: HMV 1840 Rescue
A great result!
Well done. Peter |
1st May 2021, 10:21 pm | #8 |
Pentode
Join Date: Dec 2009
Location: Chatteris, Cambridgeshire, UK.
Posts: 176
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Re: HMV 1840 Rescue
Excellent and a very worthy restoration, despite all odds. The picture show's just how good 405 can be.
I am with you regarding re-stuffing of wax capacitors. I know opinion is divided, but I hate to see modern types when just a little more effort keeps the chassis looking original. I had fun here below with a HMV 1826, but I was not as fortunate with the Emiscope CRT.... https://www.radios-tv.co.uk/communit...-tvs/hmv-1826/
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Andrew Last edited by PYE 405; 1st May 2021 at 10:32 pm. |
2nd May 2021, 7:49 am | #9 |
Dekatron
Join Date: Mar 2008
Location: Worthing, West Sussex, UK
Posts: 5,185
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Re: HMV 1840 Rescue
I am amazed it survived it's journey, I expect the glue on the cabinet was very weak.
You were certainly very lucky that the CRT was not only intact, but has good emission. These EMI sets were truly dreadful, but I have managed to get all four of mine working well, apart from the low emission CRT's. You have certainly done a good job to get it working so well, I am sure you can get that cabinet to look as good as the chassis! I guess that was one of the last EMI built sets before Ferguson took over manufacture of HMV/Marconi sets. Mark |
2nd May 2021, 8:25 am | #10 |
Hexode
Join Date: Jan 2007
Location: Beckenham, London, UK.
Posts: 373
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Re: HMV 1840 Rescue
Lovely job. I agree that re-stuffing is well worth the effort. I see it's full of the nasty paxolin valve holders that gave me grief on an earlier HMV.
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2nd May 2021, 10:08 am | #11 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
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Re: HMV 1840 Rescue
The failed EY51 heater winding was a stock fault if write ups of the time are anything to go by.
This could be a confusing symptom due to heavy sparking around the CRT coating particularly where it was earthed by the contact spring. Direct TV replacements of Lewisham famous for the manufacture of replacement LOPTs` used to supply an 'open' type LOPT. No rubber gloved surgical operations complete with squelchy jelly to contend with. Obviously they did work once! John. |
2nd May 2021, 10:23 am | #12 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: HMV 1840 Rescue
I converted one of those to 625/UHF in 1966, also rigged up a wired remote with on/off, brightness and volume controls.....bedroom telly.
Lawrence. |
3rd May 2021, 1:58 pm | #13 |
Heptode
Join Date: Jun 2006
Location: Ware, Hertfordshire, UK.
Posts: 988
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Re: HMV 1840 Rescue
Hi Simon,
That's very impressive. Years ago, I purchased my Bush TV11A, when the NVCF was at the NEC. I should have taken the fact that the cabinet had been refinished by the seller as a clue to its damp past. As I attempted to carry it back to the car park, it started to fall apart in my arms. Luckily the wrap around veneer survived as did the polyurethane finish. It all glued back OK, but the damp caused all sorts of nasty electrical faults. I see that the chassis on your set does not scream that it has been stored in very damp conditions. So as suggested earlier, it must have been very poorly glued. A long way from their pre-war cabinets. A great rescue! BTW, how did you re-stuff the red and black plessy electrolytics? Cheers Andy
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www.youtube.com/user/andyvalve100 Last edited by beery; 3rd May 2021 at 1:59 pm. Reason: Missing word |
3rd May 2021, 4:27 pm | #14 |
Heptode
Join Date: Apr 2003
Location: Cornwall, UK.
Posts: 986
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Re: HMV 1840 Rescue
Hello everyone.
Many thanks for all your comments on my set. It has been working very well for a number of hours, but started to play up yesterday. I had to frequently re adjust the Vertical Hold, which would solidly ‘lock’ but then 10 minutes or so later, would again need re adjustment. I changed the PCL83 with a known good NOS valve as a quick test, but the fault repeated the same process. Looking at the circuit, which is almost as simple as it could get, I noticed that R101 is a 5% carbon composition resistor when the norm with this era of electronics would be 10 or 20%, so that was specified for a reason! It did measure slightly out of tolerance, but it seemed to be quite fussy with temperature. A replacement 1.8Meg resistor completely cured the problem! John, with regard to the EHT valves heater winding, I was surprised to see that this was formed of a thick enamelled copper wire rather than a wire which was insulated to withstand a high voltage as is normally encountered. Maybe this is the reason for Un reliability here? The cabinet, whilst very scratched and loosing its finish, doesn’t appear to have suffered long term damp, but the glue has certainly failed for some reason or other. Luckily it was fairly straightforward to clamp and re glue. I did make a couple of errors in my original post. The CRT is an SE14/70 not 17! I did have to re stuff one electrolytic - the red and black Plessey that decouples the Cathode of the EF80 sound output valve. It had dried up completely. Andy, I managed to remove the clear printed tape in one piece so it could be re applied. The yellow under tape is never in a good way on these and is a sticky mess! I then split the two halves with a Craft knife, removed the old innards, and fitted a replacement axial capacitor. I drilled 2 small holes in the ends to feed the new capacitor leads through. The two halves were then glued back together. I found that the yellow label tape from my Brother labelling machine looked good as the undertape, and this is self adhesive anyway! Finally, the original clear printed tape was re applied and a small shot of clear lacquer completed the job. The pictures below shows the process from an earlier project. Cheers. SimonT.
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The honesty of imperfection.......... Last edited by thermionic; 3rd May 2021 at 4:30 pm. Reason: Spelling! |
3rd May 2021, 4:57 pm | #15 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: HMV 1840 Rescue
Hi Simon, does your set have the electrostatic focus CRT? The Emiscope SE14-70 was a near equivalent to the Mullard AW36-21.
My next door neighbour owned and used for six years the 14" console version of the set under discussion. The HMV 1841 was trouble free over it's six years of service. 1956 to 1962. DFWB. Last edited by FERNSEH; 3rd May 2021 at 5:06 pm. |
3rd May 2021, 4:58 pm | #16 |
Pentode
Join Date: Dec 2009
Location: Chatteris, Cambridgeshire, UK.
Posts: 176
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Re: HMV 1840 Rescue
Well ! I have never tried to re-stuff the Plessey type electrolytics.... an excellent job done there and, in future, I will try the same.
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Andrew |
3rd May 2021, 6:38 pm | #17 | |
Heptode
Join Date: Apr 2003
Location: Cornwall, UK.
Posts: 986
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Re: HMV 1840 Rescue
Quote:
Yes, my set incorporates the SE14/70 electrostatically focussed CRT. In this instance MR1, C58, R74 &75 are absent and CRT pin6 is connected to pin10 (first anode) Interestingly, R70 (150K) was also not included in my set. This meant that the brilliance of the picture was excessive at only about a quarter of a turn of the control. I’ve fitted a resistor as per diagram and still have plenty of brightness. Normal viewing is obtained at about half way. Surely this resistor was not omitted on cost grounds was it? Cheers. SimonT.
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3rd May 2021, 6:40 pm | #18 | |
Heptode
Join Date: Apr 2003
Location: Cornwall, UK.
Posts: 986
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Re: HMV 1840 Rescue
Quote:
I’ve done a few of these now and almost without exception, they come apart quite easily. Cheers. SimonT.
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