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Old 23rd Jan 2020, 12:24 am   #1
1100 man
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Default Sobell 1000 DST at long last!!

Yes it's true: I've finally got one!!

I've been looking for one of these sets for at least 5 years, and the closest I've come so far was a couple of years ago when I managed to find the GEC version, the 2000 DST.

From my earliest memories of Andy Pandy, the Flower Pot Men, Finger Bobs etc right up until 1981, (when it was finally replaced with a Pye G11), the Sobell 1000 was the family TV.

It was not in great shape when I took it over in 1981, having had a very long life and frequently repaired by dad. I remember winding an extra turn round the LOPT to feed the EHT rectifier to give it a bit more EHT!

So from a purely nostalgic point of view, I have been looking for one to add to my ramshackle collection of TV's.

There doesn't seem to be many surviving TV's from the '60's, especially dual standards. Most models only seem to survive in single digits or not at all. The TV museum at Dulwich has one (I think) and I believe a forum member also has one, but they are the only two I've found.

Although I scour Ebay regularly, I've never seen one come up for sale before. This one turned up last week and I managed to get it for a not too eye watering amount and it was within a feasible travelling distance.

I collected it this afternoon and have now had a chance to give it the 'once over'. The cabinet is actually pretty good, apart from a small chunk of veneer missing from the top corner which can be repaired. All the knobs have lost their chrome so hopefully I can manage to source some better ones. The VHF tuner knob has fallen apart as has the cam on the back of the tuner that operates the system switch.

Internally it has a good layer of grime & spiders and several flies have emerged since I've brought it into the warm! The cabinet seems free of wood worm & rot which is good news. It has had a lot of work done over the years- there are plenty of vintage capacitor replacements in there, many of which have cracked casings.

Like my GEC version, the plastic of the scan coils has rotted away and turned into a crumbly mess. Also the brass clamp that holds the two halves of the ferrite core together has fractured which I've never seen before on a set of coils.

It's got the same LOPT as the GEC with the hard plastic encapsulated overwind. This is also covered in deep cracks. I will give it a dose of 'passing a current through it to heat it up' treatment and then coat it in transformer varnish to seal it up. That seemed to work OK with the GEC one.

Very unsurprisingly, the CRT reads near zero emission when hooked up to the tester. I've come to expect that from all the sets that have come my way but they always come up OK with a little clean- I'm sure the cathode gets covered in cobwebs! I'll see if it recovers once it gets some use before I rejuvenate it.

There is little point going anywhere near this set with power until the obviously dodgy caps have been replaced and the LOPT dried out & resealed. I'll reform the main smoothing caps and see how they respond.

Access to the PCB's is not great with everything in situ, so I've removed the chassis & CRT so I can work on them more easily.

Anyway, I'm dead chuffed to have finally found one of these sets and look forward to restoring it to full health!

All the best
Nick
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Old 23rd Jan 2020, 1:13 am   #2
Reelman
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Default Re: Sobell 1000 DST at long last!!

Congratulations!

It’s always great to finally get what you been wanting for a while. The GEC version was our family telly around 1968. Fond memories!

Peter
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Old 23rd Jan 2020, 9:12 am   #3
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Default Re: Sobell 1000 DST at long last!!

Hi Nick.

Great set and always a buzz to finally get that long lost cherished set from the past.

You can add another to your list. I picked one of these up a few years ago with the intention of using it as a source of spares for my GEC 2002DST (Electra). I've not robbed it yet as it basically works apart from the usual overwind problems.

Good luck with it and I'm sure the CRT will respond in due course.

Regards,

Mick.
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Old 23rd Jan 2020, 10:39 am   #4
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Default Re: Sobell 1000 DST at long last!!

The fact you had one till 1981 is a testament to their longevity. A dry LOPT, some two-tone capacitors and the high value resistors changed and a bit of care with the print and it'll soon be back to health.
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Old 23rd Jan 2020, 11:05 am   #5
Peter.N.
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Default Re: Sobell 1000 DST at long last!!

I used to rent those out, ex Granada. I found the best way to preserve the print was to unsolder the components from the top of the board, the iron held the print in position through removal.

Peter
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Old 25th Jan 2020, 11:08 am   #6
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Default Re: Sobell 1000 DST at long last!!

Yes Peter. Any attempt to remove the components from the under print side usually resulted in lifted print. Once learned it was quite easy and reliable. John.
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Old 25th Jan 2020, 11:16 am   #7
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Default Re: Sobell 1000 DST at long last!!

Is that one of the sets that uses an EH90 for the FM sound as a locked-oscillator
discriminator. I never thought they were very good on FM sound and often tended to buzz.

John
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Old 25th Jan 2020, 11:44 am   #8
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Default Re: Sobell 1000 DST at long last!!

I think it did John, I don't remember it buzzing - but it was a long time ago.

Peter
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Old 25th Jan 2020, 11:48 am   #9
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Default Re: Sobell 1000 DST at long last!!

Yes, the FM sound demodulator was an EH90, with those underrated Erie 18k and 5k6 carbon composition resistors that slowly crumbled! The earlier chassis to this used a metal oxide Welwyn 18k - value engineering!
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Old 25th Jan 2020, 12:26 pm   #10
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Default Re: Sobell 1000 DST at long last!!

Those pictures bring back memories of retrieving several of these from a skip behind a TV rental shop in the village where i lived (I did ask if i could take them) wheeling them home on the crossbar of my bike and cobbling together a working set for my bedroom, great for Doctor Who or late night Hammer horror films. Very often the faults were just broken dropper resistor sections or dry joints, even though it was a very long time ago I also vividly remember several nasty shocks I received in the process.
Good luck with the restoration, I will enjoy watching this come back to life Kind regards RT
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Old 25th Jan 2020, 4:55 pm   #11
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Default Re: Sobell 1000 DST at long last!!

Quote:
Originally Posted by raditechman View Post
Is that one of the sets that uses an EH90 for the FM sound as a locked-oscillator
discriminator. I never thought they were very good on FM sound and often tended to buzz.
One model used to pick up Radio Moscow in the 49 metre band. I can't remember if it was this chassis, perhaps it was a GEC.
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Old 26th Jan 2020, 11:24 pm   #12
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Default Re: Sobell 1000 DST at long last!!

Quote:
Originally Posted by Welsh Anorak View Post
The fact you had one till 1981 is a testament to their longevity. A dry LOPT, some two-tone capacitors and the high value resistors changed and a bit of care with the print and it'll soon be back to health.
Dad did fix it fairly often during my childhood, but to my knowledge it never needed a LOPT.

Thanks everyone for your various comments & memories- it makes the whole thing all the more interesting

I've spent the day having a bit of a move around and building a second workbench- the main bench still has the Thorn 2000 with it's guts hanging out! It's too heavy & awkward for me to move, so it will have to stay there until I get it finished!

So now I've got somewhere to work, the Sobell has been stripped down into bitesize chunks. This makes cleaning & initial checks much easier, plus enabling various components to be checked/ changed before power up.

The two main PCB's that sit at the bottom tend to get a good layer of filth. As I found with my GEC version, the best solution was a good wash with some Fairy liquid and a stiff paint brush. It's now nice and clean with legible component ID's.

The scan panel that sits under the LOPT housing has been treated similarly. The LOPT has been unsoldered and removed. Both these items were really caked in black grime- I find this tends to be conductive especially as it absorbs moisture.

This set looks like it's had a hard life- many caps have already been replaced as has the mains dropper and main smoothing cap. One section of the dropper is O/C, but conveniently, there is a spare section which is shorted out on the DST version (to take account of the UHF tuner valve heater's). This is the same value as the O/C bit!

The overwind on the LOPT is loose which in itself is not a problem, but there is a winding underneath it with very fine leadout wires. I had problems on my other one with corona between this winding and the core. This one is O/C, so I think the wires have fractured, due to the movement of the overwind. There is green corrosion near the terminals so careful investigation is needed.

Thanks for the warnings about the double sided print- unsoldering from the top side seems to be the way to go.

If anyone has a good set of knobs for this model, I would be very interested! The chrome has gone from mine and the VHF tuner knob is broken!

All the best
Nick
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Old 27th Jan 2020, 11:06 am   #13
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Default Re: Sobell 1000 DST at long last!!

I never understood why that print was so disliked, but I suppose if you tried to remove a component from the underside with a Weller heat gun then you were asking for trouble!
I expect you'll be best to re-replace the carbon resistors and some of the capacitors as they will be showing their age - it's easy to overlook things that have already been done, especially as they might nor be the right values. Besides those and the obvious electrolytics, the components should be OK -and you've got a nice crop of reliable mustards there.
Good luck with the LOPT - delicate work ahead, though thinking of those graveyard parts you had for the 2000, this should be a walk in the park...
Looking forward to seeing it running!
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Old 27th Jan 2020, 12:23 pm   #14
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Default Re: Sobell 1000 DST at long last!!

I think gec were rather proud of it at the time, they were using a deposition technique that put the tracks on rather than etching copper off as i recall, it was very fragile though.
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Old 27th Jan 2020, 1:30 pm   #15
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Default Re: Sobell 1000 DST at long last!!

Easy to see how the sound was sidelined in these though - just look at that apology of a speaker just shoe-horned in there!
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Old 27th Jan 2020, 9:40 pm   #16
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Default Re: Sobell 1000 DST at long last!!

Yes it is small but the sound was adequate for the average viewer in a 12'X9' living room. The example at the museum sounds quite reasonable and was similar to it's contemporaries. The PCL84 gave about 2 watts. The EH90 circuit gave a clean result but was critical when it came to tuning. The PYE 11U series employed a similar circuit.

The problem today is a massive one involving ludicrous multi watt amplifier units pumping through walls and ceilings of flats, terraced, and semi detached houses often late into the night. Little respect today. Bring back the EF91/EF80 as an audio output valve. It gave an incredible account of itself in a large number of chassis. John.
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Old 29th Jan 2020, 11:29 pm   #17
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Default Re: Sobell 1000 DST at long last!!

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Originally Posted by Edward Huggins View Post
Easy to see how the sound was sidelined in these though - just look at that apology of a speaker just shoe-horned in there!
Granted it's a little diminutive, but I suspect it can hold it's own when compared to a modern flat screen TV with it's tiny speakers in a small plastic box!

It was a hard enough job providing a reasonable picture down to a cost, so it's hardly surprising that the sound in most TV's was a bit of an after thought!

I've now had a chance to examine the three main PCB's in detail. Not wishing to be accused of compulsive component changing disorder, I'm willing to give each component a fair hearing before condemning it

I lifted a leg of every blue Dubillier capacitor and every red Hunts one, and applied 250V from my insulation tester. Most had turned into resistors of 100 - 200K. Whilst some of these would still have functioned in the less demanding positions, it seemed prudent to change them.

By way of comparison, I tested one of the 0.22MFD 'mustards'. No measurable
leakage and spot on for capacitance. I wonder if these Philips caps were more expensive at the time? Or was it pure luck that they have stood the test of time so well?

Next task, while I wait for some more 0.1 & 0.01 caps to arrive, is to apply some power via the variac to the 4 main smoothing electrolytics and see how well they reform.

All the best
Nick
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Old 30th Jan 2020, 1:25 pm   #18
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Default Re: Sobell 1000 DST at long last!!

It's always a relief to see those nice Philips mustards sprinked on a board - they're more than likely to be OK. Ditto those silver Philips electrolytics, some wearing a blue coat, from a slightly later era.
Dubilier supplied RS as well, and it's often tempting to ignore these as they've been changed already - no such luck!
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Old 5th Feb 2020, 7:51 pm   #19
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Default Re: Sobell 1000 DST at long last!!

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Originally Posted by 1100 man View Post
If anyone has a good set of knobs for this model, I would be very interested! The chrome has gone from mine and the VHF tuner knob is broken!
I have a large box containing a wide range of knobs for bygone TVs. If you would like to pop in next time you're in Wroxall, you can have a look and see if any of the ones you need are in there.
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Old 6th Feb 2020, 12:01 pm   #20
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Default Re: Sobell 1000 DST at long last!!

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Originally Posted by Vectamart View Post
I have a large box containing a wide range of knobs for bygone TVs. If you would like to pop in next time you're in Wroxall, you can have a look and see if any of the ones you need are in there.
That's great- many thanks. I'll bring back the remains of the knobs I have when I next come to the Island and maybe we can find a match!

Cheers
Nick
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