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Old 2nd Oct 2020, 8:16 pm   #1
davyrocket2
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Default Alba,TC2326.G8

Hello.

I recently collected a 26 inch Alba TV, this came from Neil 29.

He had used his tube tester and the tube seemed to be good, it's a blue labelled Mullard ,the set is dead and appears to have not been used for some time.

The 800mA fuse is blown and all the other fuses test OK.

Any pointers welcome.

Regards David.
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Old 2nd Oct 2020, 9:05 pm   #2
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Default Re: Alba,TC2326.G8

Repaired a few of these and main problems I found were in the following order.

1. Channel switchbank
2. Tripler
3. Lopt

Lots of info in this thread.

The green type tuning capacitor across the line output transistor would now be my first items to receive attention.

Good luck with it.

John.
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Old 3rd Oct 2020, 9:40 am   #3
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Default Re: Alba,TC2326.G8

David

I do hope you have a video of you transporting this very large TV from one side of the country to the other by "shank's pony" and the train.

As for the G8 chassis, as John has said, there are many threads on this set's workings or not and a comprehensive Television article on the subject. Unfortunately, my shack is at the end of a waterlogged garden and so I can't give you further details.

One last point though is of course whether your TV has a single or twin panel IF/Video design although finding out what cause the fuse to blow is another matter.

Good luck

Chris
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Old 3rd Oct 2020, 10:04 am   #4
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Default Re: Alba,TC2326.G8

Ahh

From one of the BVWS threads, "A VERY lucky find indeed", by TV Madness, Television July 1985 and December 1976 are the articles I mentioned.


Chris
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Old 3rd Oct 2020, 10:28 am   #5
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Default Re: Alba,TC2326.G8

Which 800mA fuse? I expect it's the one on the line board, in which case you disconnect the tripler from the LOPT and disconnect the red plug from the line panel.
Plug in and check the 205v at the fuse. Wind it down if you need to. Now switch off and cold check the BU 105s for shorts. Then change the cylindrical green capacitors nearby, even if you like the look of them.
Now replace the fuse and switch on. My bet is it'll blow but not before you've seen a tell tale flash in the LOPT. Then it's time to go hunting!
If you've very lucky and it holds, try the tripler cautiously. Chances are that's faulty.
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Old 3rd Oct 2020, 10:47 am   #6
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Default Re: Alba,TC2326.G8

hello chris no I am afraid I do not have a photos of me collecting it , but Neil 29 helped me get it to the train station. I took a large cardboard box and used parcel tape to wrap it across the tube and a blanket tied around it and rope from poundland to tie onto my trolley. Neil29 had already changed the lopt panel so I concentrated on getting it home safely. My journey was Newport to Reading and then the Reading to Waterloo train changing at Clapham junction, for a London Victoria service.. I was lucky because I boarded a Dover train and changed at faversham for Margate . I departed Newport 14.30,and was back home by 20.15. I have removed the back and found the 800ma fuse blown it was not black just failed the set is dead ,and is there a way to hinge open the chassis ? so I can work on it .I did replace a Tripler on one back many years ago on that one the tripler was arcing and a replacement cured it the tube was tested by Neil29 who said it went into the green section of his tester .I recently purchased a dropleaf table which was in need of sanding and restaining so whilst doing this I carefully lightly sanded the G8s cabinet and restained it there is a piece of wooden edge beading missing and it does not have its stand so any pointers of where to look are welcome there is not much dust but ,I will carefully use a dry paintbrush and hoover and dust from the boards then examine for dry joints.I will take photos but not sure how to upload them regards David Grant.
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Old 3rd Oct 2020, 10:56 am   #7
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Default Re: Alba,TC2326.G8

Hello Glynn yes its the one on the Lopt panel but whether that panel is faulty or the tripler is faulty is unknown because Neil29 had already changed the lopt panel for another one and I have just ordered some 800ma fuses from a well known source ,I think it would be a idea to get hold of a tripler If I knew where to get one ,The tube was tested and is good ,I also think a thyristor and a diac would be a sensible purchase plus the caps you mention ,if you can point me to a source for them I will order some regards David .
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Old 4th Oct 2020, 1:13 pm   #8
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Default Re: Alba,TC2326.G8

the thyristor tests open circuit and I am awaiting fuses to arrive in the post so is the tripler a likely cause of this or could it be another fault and does anyone reading this have a stand please
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Old 4th Oct 2020, 5:01 pm   #9
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Default Re: Alba,TC2326.G8

Thyristors do test open circuit as do diacs, so no problem there. A fault in the PSU will blow the mains fue, not the line stage fuse.
Triplers do turn up from time to time - a five-wire one is what you need.
The capacitors are C545 and 546, both 5.1nF and originally polysteyrene, mounted on the sub-panel with the balancing coil. They need to be suitable for high voltage and appropriate for this use. I'd avoid NOS ones of a similar type as they can and do change value.
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Old 12th Oct 2020, 4:50 pm   #10
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Default Re: Alba,TC2326.G8

I had the 800mA fuses arrive and disconnected the tripler and replaced the fuse below the transformer. There was a slight puff of smoke and the 800mA fuse has blown. Before switching on I tried testing the mains dropper, the bottom section when I did continuity check beeped which seemed to show its OK the top section did not beep so does this mean a open circuit section or other problems?

Regards, David.
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Old 12th Oct 2020, 5:10 pm   #11
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Default Re: Alba,TC2326.G8

I'm not a TV expert, but I would point out that the continuity test on a meter is only designed to test for low resistance ie continuity, not to measure resistance.

I suggest using your meter on a resistance range and comparing the results with the values in the service sheet.

Whether a dropper fault would cause the 800mA fuse to blow I have no idea. I'll leave that to the experts.
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Old 13th Oct 2020, 2:11 pm   #12
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Default Re: Alba,TC2326.G8

As I suggested, start at the beginning. Leave the 800mA fuse out for the moment and see if there's 205v or thereabouts at the fusholder. It's likely the LOPT or tripler has died as the fuse is there to blow if anything south of it is taking too much current.
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Old 13th Oct 2020, 6:30 pm   #13
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Default Re: Alba,TC2326.G8

I agree with Glen , leave fuse out and test voltage on fuse holder it should be
205 volts. As you say fuse blow after tripler was disconnected then the tripler is not causing the fault you have but may still be faulty for other reasons.
next look at the transducer transformer does this look burnt
With set switched off and the fuse out test the two line output transistors (Bu205) for shorts as glen says , check the resistance from fuse holder to chassis if its low try following the circuit to fine out which part is faulty.

As regards the mains dropper on the power supply this must be ok ,if they where faulty you would not have any voltage on the line output panel
the bottom one is 2r2 and the top one is 68r. there is also a 47r resistor on the scan panel again this it ok.
Hope this might help
Derrick
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Old 17th Oct 2020, 11:17 pm   #14
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Default Re: Alba,TC2326.G8

The set is producing 200 volts, so the BU205's both seem OK. Are there other items like the LOPTX which could be causing the short ? I have found a source for genuine G8 tripler, but have not manged to find a LPPTX. The mains dropper has had the connections resoldered and I think when I tested it before that it was old poor solder connections producing high resistance, as it now tests OK. I am also looking to replace the two caps that can cause the HT to go high.

Please can anyone suggest what other items can cause the fuse to blow? There are no obvious signs of burning.

Regards, David.
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Old 18th Oct 2020, 12:27 pm   #15
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Default Re: Alba,TC2326.G8

Quote:
Originally Posted by davyrocket2 View Post
The set is producing 200 volts, so the BU205's both seem OK.
The BU105 line output transistors do not produce the 200V HT, this is done by the thyristor power supply and are fed from this. Together with the Lopt they produce the line scan and around 8KV to feed the input to tripler. Have you tested the transistors with a meter? You will have to unsolder the connections to the base and emitter to check them properly.

Check out this guide to servicing the G8

John.
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Old 18th Oct 2020, 12:56 pm   #16
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Default Re: Alba,TC2326.G8

Yes I have unsoldered the wires and tested them they seem okay they are 205s types . I am working blind so to speak so which is the tranducer and its location ? , the set is very clean . I think from what neil said about the tube testing very good then despite its age it may have been retired early in its life. I have found a brand new ITT tripler and am working on the Idea that a Lopt would be a sensible purchase if I could find one regards David
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Old 18th Oct 2020, 7:15 pm   #17
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Default Re: Alba,TC2326.G8

The transductor (not transducer) will be found on the frame timebase/line oscillator board. It's the one lying flat at the bottom of the chassis nearest to the line output panel - the one with the line output transformer on. To eliminate the transductor from proceedings while finding the reason for the overload, simply unplug plug H, the red one on the aforementioned board near the transductor.

That G8 servicing guide is very useful too.

Good luck.
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Old 19th Oct 2020, 8:56 am   #18
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Default Re: Alba,TC2326.G8

Sorry about the wording transducer /transductor . It must be 45yrs since I worked on a G8. My 80 yr brain must be getting forgetful , could not remember were the said transformer was mounted . As a field eng I liked G8
most of them where repairable in customer house.
Thanks Tazman for the correction

davyrocket2 hope you will be able to fine problem soon

Regards
\ Derrick
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Old 19th Oct 2020, 9:50 am   #19
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Default Re: Alba,TC2326.G8

If the fuse still blows when you unplug the red plug on the timebase panel and the tripler then it's almost certainly the LOPT. Try Donberg and HR Diemen for one or maybe a 'wanted' post on the forum. They do still exist. Even if it's not the LOPT you'll still need one on the shelf! Remember to change the big green capacitors on the sub panel at the same time.
Hope you ordered enough 800mA fuses!
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Old 19th Oct 2020, 12:49 pm   #20
davyrocket2
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Default Re: Alba,TC2326.G8

I just had a offer £12.00 for a genuine ITT tripler and he said he will include 2 mica gaskets and 2 ,BU208S and 2 Bu205s the BU208S are for a Dynatron CTV 22, and he informs me he also has a new 5 wire tripler that has a diode connected with it ,so I am going to be very busy ,I Just now need a Pye 731 ,mains dropper.I have also been told that one of the screws holding the line output panel can get close to the HT printed circuit and cause the 800ma fuse to blow.regards David
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