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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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3rd Feb 2013, 9:39 pm | #1 |
Heptode
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Bush TV 105R 405 line
Following on from: https://www.vintage-radio.net/forum/...ad.php?t=87473
I've started this new thread now that we know what the set is. Having spent a few weeks in the warm, I decided to drag it thro' to the workshop and have a quick play. Doing the usual checking between HT rails and ground, snipping out the mains filter cap, I decided to give it full beans! (HKS style). Nothing drastic, a few clicks and ticks as things warmed up. Then a slight hum thro' the speaker and the line output stage burst in to life. I connected the aurora and got good audio, and a full but rolling picture. I didn't expect to get this much at first light! There are many very sticky waxies and some of the nasty little light brown Hunts caps that crumble into a paste when you touch them. I found the circuit in the R&TV red book 1962/63. I can see this set is going to make a big hole in my capacitor stock. Being full of cold this weekend and feeling lousy, this is as far as I've got so I'll continue the story as I go hopefully later in the week. Greg
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4th Feb 2013, 1:27 am | #2 |
Nonode
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Re: Bush TV 105R 405 line
I had one like this many years ago. Does it have a FM radio tuner on it?
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Simon BVWS member |
4th Feb 2013, 7:32 am | #3 |
Dekatron
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Re: Bush TV 105R 405 line
That looks a very promising start, A full recap should return it to full health.
I always like loft finds, It is a good bet that the set was working fine when stored, so should not need any valves replaced. Good luck with it, I will be watching this thread with great interest. Mark |
4th Feb 2013, 9:02 am | #4 |
Heptode
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Re: Bush TV 105R 405 line
I believe I have a couple of new spare tuner push buttons for that set if you want them. I did offer them on here but had no replies. They sometimes wear if they have been used a lot for retuning. The ones I have are gold tipped but a different colour shaft.
John https://www.vintage-radio.net/forum/...ad.php?t=92915 |
4th Feb 2013, 9:24 am | #5 |
Heptode
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Re: Bush TV 105R 405 line
Thanks for your comments!
Simon, no it doesn't have a radio tuner. John, re the buttons, there is a problem with the existing ones in as much as two of the buttons just seem to be floating and not connected to anything. I could only get one button out of four to tune in the aurora. I need to take the tuner unit out and see what the problem is- if it is due to the buttons themselves being damaged I'll gladly have your spare ones. Greg
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14th Feb 2013, 12:36 am | #6 |
Heptode
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Re: Bush TV 105R 405 line
Made some good progress this evening.
First, thanks to Nicklyons2 for sorting me out with copies of the original Bush service info. Problems were a fast rolling picture that wouldn't adjust and also a flicker, which reminded me of the 240 line HMV/Marconi demonstration at Harpenden a year or two back! So I decided to concerntrate my attentions to the frame oscillator part of the circuit. C80, connecting the grid of one half of the ECC82 oscillator actually gave itself away by getting warm and softening its own wax. It had decided it was now a resistor and was leaky to the tune of just under 13k ohms! Replacing this corrected the oscillator and now a full and rolling picture but no flicker. There is good height, width and brightness. Going through a few waxies now in the line oscillator part of the circuit gradually gave picture stability. Linearity was poor though, as in the first photo. C82 which couples the 'gen lin' pot and the 'top lin' pot was leaky, so this replaced restored a good range of adjustment on both the pots. Looking at the linearity circuits, I always think that they are a bit like the tone controls on an audio amp. I've got a good stable picture now as in the second photo, with some 'cogging' to sort out. This set, although 50 years old, is the most modern (so far) that I've had a go at and is the first with flywheel sinc., etc. So there has been a bit of head scratching as I try and understand how the system works! Only one tuner push button will 'pull out' to twist and adjust the tuning, and even that one is dodgy, which is annoying as test card and tone will suddenly disappear, making me think "What've I done now?' Anyway, all good fun, I think this'll make a nice set without too much more effort! Greg
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14th Feb 2013, 9:24 am | #7 | |
Dekatron
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Re: Bush TV 105R 405 line
Quote:
Your set is a TV105R and so does not have flywheel sync (as a cost-cutting measure). You will notice a rectangular cut-out in the chassis on the right hand side vertical, at the top, near the front. This is where a sync transformer would be fitted in the TV105. Is the circuit you are using for the TV105R or the TV105? They are similar but not the same. For cogging, I would replace the sync coupling capacitor (C73, 0.1uF) on the top of the chassis, with the green wire that goes to the pin 2 of the ECC83 sync separator stage (V9a). It'll be as leaky as a colander! Another change with the TV105R is the use of an EF80, rather than the high gain EF184, in the second vision IF amplifier stage (V4). Regards, Dazzlevision Last edited by dazzlevision; 14th Feb 2013 at 9:33 am. Reason: Added text. |
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14th Feb 2013, 10:00 am | #8 |
Heptode
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Re: Bush TV 105R 405 line
Thanks Dazzlevision, that explains a great deal! The manual I've got is for the 105, my set is a 105R! There were some confusing missing component numbers on the schematic around the frame output area, including the additional transformer which I thought was maybe hiding around the back of the chassis somewhere! It was getting late!
Greg
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14th Feb 2013, 10:09 pm | #9 |
Heptode
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Re: Bush TV 105R 405 line
[QUOTE=dazzlevision;588958 For cogging, I would replace the sync coupling capacitor (C73, 0.1uF) on the top of the chassis, with the green wire that goes to the pin 2 of the ECC83 sync separator stage (V9a). It'll be as leaky as a colander![/QUOTE]
And it was! Thanks for your help. Good results with this set, I still consider myself a novice as far as TV's are concerned but this set has been kind to me. The only components I've replaced are 11 waxies, all in the line and frame sections. Haven't had to touch anything in the RF/IF/AF/power supply sections (apart from snipping out the mains RF filter cap). I need to remove chassis then tube to give it a good clean behind the front glass plate, as there is some muck and a loose bit of vinyl trim to sort. Also to have a look at the mechanical fault with the tuner. Below some period Hancock with bonus TV spottage! Greg
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14th Feb 2013, 11:00 pm | #10 |
Dekatron
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Re: Bush TV 105R 405 line
Looking good
If you can sort the tuner, you are nearly there, there is a great satisfaction in getting these old sets working again. Mark |
14th Feb 2013, 11:08 pm | #11 |
Octode
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Re: Bush TV 105R 405 line
Greg, glad to see the set's up and running pretty well. I'd quite forgotten the 'cut down' specs in the 'R' versions, I believe the 'R' stood for rental; sets built down to a price to maximise rental company profits. With the TV 125 it meant you got dummy buttons instead of a UHF tuner - mind you when it was fitted the valve UHF tuner was only slightly less useless than the dummy buttons!
Nick |
14th Feb 2013, 11:28 pm | #12 |
Dekatron
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Re: Bush TV 105R 405 line
Hello,
The TV125 did have a rental version, namely the TV125R but the differences this time were exclusively cosmetic (a cheaper cabinet; the entire front was a Phenolic resin moulding, not wood and the finish on the top and sides wasn't the deep Polyester varnish found on the TV125 and TV105/TV115). The only reason a UHF tuner wasn't fitted in TV125s or TV125Rs, was that BBC2 started up in 1964 only covering the Greater London area and it was felt that, apart for sets destined for dealers in London, the UHF tuner could be fitted when BBC2 reached the area in which the TV was located. I think the UHF tuner (NSF132 - made in West Germany by NSF, later part of Telefunken) was around 8 guineas. It also reduced the initial purchase cost of the sets and was a common arrangement with all TV manufacturers of that period. I agree that valve UHF tuners had low gain and a high noise figure, but that was simply the limit of valve technology at the time. The likes of Labgear made good money from selling masthead preamplifiers as soon as decent UHF transistors became available, such as the AF139 and AF186. The original rotary UHF tuner supplied in the UHF/625 conversion kits supplied by Rank Bush Murphy for the TV105 and TV115 were made by Philips/Mullard. AudioMagpie; have you replaced the wax capcitor on the line output transformer and the two (IIRC, but may be only one in a TV105R) on the vertically mounted tagboard immediately to the left of the LOPT? This is where the line scan coils connector plugs in. If you haven't, I would do so, as they will be defective and may increase the stress on the LOPT and/or upset both the width and horizontal linearity. Regards, Dazzlevision |
15th Feb 2013, 12:11 am | #13 |
Dekatron
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Re: Bush TV 105R 405 line
Hello again,
I've just had a look at the TV105R circuit and there is a 0.3uF (around 200Vdc working; S-correction) on the scan panel (to the left of the LOPT) and a 0.005uF (around 1000V dc working; LOPT tuning) on the LOPT. In addition, I have noticed that the sync sparator on the TV105R is a PCF80 (pentode section), but on the TV105, it is an ECC83. Regards, Dazzlevision |
15th Feb 2013, 1:03 am | #14 |
Dekatron
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Re: Bush TV 105R 405 line
The attached circuit diagrams show the differences in the line sync arrangements of the Bush TV105 which has flywheel sync and the TV105R with the simple direct line sync.
Information for the TV105 can be found in 1961/2 Newnes R & T book. Evidently there was a 21" CRT version, the TV109. All the other sets in the series have 19" and 23" rectangular CRTs. For some reason most 19" models have the frame grid EF184 valve in the vision IF amplifier yet the large screen versions make do with the conventional EF80 pentode. Another model, the TV105D was fitted with a tone control. I always knew about the existence of the rental set, the TV105, but I never realised that it had a number of circuit simplifications. The cabinet was supposed to be more austere, but really it was just an alternative finish, satin instead of the high gloss of the other sets. DFWB. |
15th Feb 2013, 12:18 pm | #15 |
Octode
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Re: Bush TV 105R 405 line
As Dazzlevision has said it was the staged arrival of BBC2 which partially accounted for the dummy buttons in the TV125; in fact our 2nd batch were 'RU's which had the tuner fitted - I was just trying to add a bit of 'humour' into the proceedings really. However and whatever the reason, I always thought it cheeky and a bit of a cheat to expect a customer who was renting the set (about 10/- a week) to foot the bill for the tuner (£7:10s in our case); to pay for the aerial yes (another £7:10s). This £15 (a week's wage for many) meant almost none of the 'R's ever got converted and were scrapped early. What Dazzlevision might know, and I'm curious, did the Murphy versions V849/879 ever have dummy buttons, all the ones I ever encountered had tuners BUT they were all quite old when they drifted into my care.
The TV 109 was a magnificent looking set in a white plastic case with a very rounded 21" tube ( looked like the ones in early 1960s American TV series); it is one of my great regrets I scrapped off the last of these in the 1980s ... should have kept it.. But being 405 only and no prospect of cheap standards converters at that time it went. Nick |
15th Feb 2013, 1:52 pm | #16 |
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Re: Bush TV 105R 405 line
In the Bush TV section of the 1962/3 Newnes R & T servicing book there is information on interesting variants of the TV105, the models TV106 and TV107. These receivers have FM radio facilities. The dual channel sound IF amplifier handles the standard 38.15Mc/s TV sound and 10.7Mc/s FM radio IF.
Correct me if I'm wrong, but I believe one of the push puttons on the tuner becomes the FM tuner and there is a tuning scale above those buttons. With regard to the TV109. I used to service one way back in '60s which had a strange coloured cabinet. It was a sort of orange. I thought the cabinet was a bit flimsy but it certainly looked good. DFWB. |
15th Feb 2013, 1:56 pm | #17 | |
Dekatron
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Re: Bush TV 105R 405 line
Quote:
I can enlighten you on dummy UHF buttons and the Murphy V8xx series (internally identical to the Bush TV12x series). They did indeed have dummy buttons fitted on the non-"U" suffixed sets and I have at least one dummy moulding in my stores (a.k.a. loft!). I have ionly ever seen one TV109 and it was quite impressive looking and used the same moulded cabinet colour and material as the Bush TV103 and TV113. The rare Bush TV123 also had a moulded cabinet but it was grey (and thre UHF tuner was a rotary type, like the TV105 and TV115 series). The RBM UHF/625 conversion kit for the TV109 was a major affair, as a special EHT rectifer supply derived from the mains was required (in addition to everything else)! Regards, Dazzlevision |
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15th Feb 2013, 9:29 pm | #18 |
Octode
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Re: Bush TV 105R 405 line
Many thanks the Murphy info and the additional bit that a kit WAS available for the TV109 never knew that. It sounds as though it may have been only fractionally easier than building a set from scratch! There were one or two other sets of the era similarly, (in deperation & with deep pocket), convertable.
Regards, Nick |
15th Feb 2013, 11:00 pm | #19 |
Heptode
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Re: Bush TV 105R 405 line
David, thanks for the scans of the 105/105R circuits showing the differences. I'll print off for future ref.
Re the caps on the small scan panel, I will change these when I lift the chassis out, it'll be easier to get at them then. I haven't done a blanket cap replacement, as it was interesting to replace just one at a time, or sometimes two if sharing a termination, then switch on and see what the effect was and gradually see the picture improving. Although not wanting to be accused of 'CCD', I usually find that most waxies, even if they initially seem OK after say 30+ years sleep, will inevitably start to play up now they're back in use! Greg
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16th Feb 2013, 8:32 am | #20 |
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Re: Bush TV 105R 405 line
I suspect that the 'convertable' sets were no more than a marketing ploy.
Of course, manufacturers had to make conversion kits available to support their claims, but how many were actually fitted? |