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Old 7th Apr 2009, 9:14 am   #1
System A
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Default ultra 3500

hi everyone just returned fron another great tcc convention weekend with a 22" ultra bermuda 6714 3500 . I spent yesterday replacing various dried out caps on the power supply . When i switched on there was sound but no line output . on checking the LTBpanel i found a dryjoint on L502. when i sorted that out i was rewarded with a good picture after a few adjustments, however after 10 minutes the picture goes dark then the focus drifts followed by the picture disappearing the the cutout trips with loads of smoke !. If it"s left off for 10 mins the set functions again for a while follwed by the same . I can"t seem to locate where the smoke is coming from and i"m not familliar with this chassis . any ideas would be gratefully received .
regards . Gary .
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Old 7th Apr 2009, 9:25 am   #2
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Default Re: ultra 3500

The 3500 is a modified 3000 chassis.

The Power Supply and Line Output panels are the same, so if you've got another set you can narrow it down. Where does the smoke come from? From behind the set, power supply on the left, LOPT panel on the right.

Change any suspect caps and resolder everything. Try a new tripler too - the focus volts come off it (I think).

Cheers,

Steve P.
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Old 7th Apr 2009, 9:31 am   #3
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Default Re: ultra 3500

hi Steve i tried another LTB board , tripler but i don"t have a working power panel to hand . I can"t see where the smoke is coming from . I would have thought that the power board is ok as theres no overheating there . Ive just tried the set again and the picture was ok for 10 mins . I wonder if the focus unit could cause that sort of thing ? .
regards .gary .
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Old 7th Apr 2009, 9:34 am   #4
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Default Re: ultra 3500

Possible. It's worth a try.

Try swapping capacitors on the Power Panel. And the hard to get at chopper may be breaking down under load?

Cheers,

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Old 7th Apr 2009, 9:39 am   #5
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Default Re: ultra 3500

thanks for those tips Steve i"ll try those and report back .
Regards .Gary .
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Old 7th Apr 2009, 9:44 am   #6
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Default Re: ultra 3500

Hi Gary.

From what I understand, you're saying the fault also occurs with a replacement line timbase unit and tripler. Is that correct?

Also, is its syling anything like my Marconiphone 4714?
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Last edited by Tazman1966; 7th Apr 2009 at 9:46 am. Reason: Added a question
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Old 7th Apr 2009, 9:46 am   #7
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Default Re: ultra 3500

Hi SYSTEM A
Good to see you at another good convention
If the chopper transistor is breaking down
it is worth changing the mica washer as well it is usally
this that causes a problem.
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Old 7th Apr 2009, 9:52 am   #8
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Default Re: ultra 3500

Hi Taz & GEC2110 the problem is still with the tripler and LTB replaced . The styling is the same as your marconi Taz but the cabinet is light teak , it even has it"s original four legged stand with it . I"ll post some pictures up when it"s sorted .
Regards .Gary .
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Old 7th Apr 2009, 9:58 am   #9
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Default Re: ultra 3500

Thanks Gary. Looking forward to the pics.

What happens to the 60V line as measured at F603 on the top of the power board when the symptoms start?

Also when the pic first starts to go dark what happens to the voltage across R907 on the beam limiter sub panel. That might give a clue. It should be around 1.5V.

Are you able to swap out the focus control assembly?
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Last edited by Tazman1966; 7th Apr 2009 at 10:07 am. Reason: Spelling!
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Old 7th Apr 2009, 10:03 am   #10
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Default Re: ultra 3500

as i"ve said the power supply seems to be ok . i"m going to try the set again shortly and try and find where the smoke is coming from . i am beginning to think it"s the focus unit myself . Watch this space !.
Regards .Gary.

Last edited by System A; 7th Apr 2009 at 10:04 am. Reason: spelling
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Old 7th Apr 2009, 10:12 am   #11
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Default Re: ultra 3500

The mica washers on the chopper and LTB OP transistor might be worth looking at.
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Old 7th Apr 2009, 2:25 pm   #12
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Default Re: ultra 3500

Hi
You can always run it with the tripler disconnected and see if it still does its party trick....help to narrow things down.
Glyn
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Old 7th Apr 2009, 3:08 pm   #13
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Post Re: ultra 3500

Hi Gary

The best bet would be to put the boards into their service positions, and switch on, be brave, and sit at the back of the set (with some eye protection) while looking at the boards to work out who is sending smoke signals. Good luck with it look forward to seeing the pics mate
Marcus.
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Old 7th Apr 2009, 11:22 pm   #14
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Default Re: ultra 3500

What have you tried. Earlier on you said you had tried an LTB board and a Tripler, but not a Power Supply. Then later on you said you had changed a Power Supply.

I'm confused. Which is it?

It sounds to me like something is getting warm and breaking down. Either a Tripler, The Focus Unit (linked to tube base - check here too!) or a transistor breaking down. In which case change the transistor and the bits that insulate it.

Cheers,

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Old 8th Apr 2009, 2:33 pm   #15
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Default Re: ultra 3500

Hi Gary.

Just a thought. I've had the following fault a couple of times now, the most recently was yesterday (YES Yesterday!) on a Fergie 3703 fitted with the 3000 chassis. On the Chroma board there is a small 4.7 uF Tanatalum cap across the 30V rail. This can short intermittently producing clouds of smoke from R350 (12R) and shutting the 30V line down and thus the set. As a quick check, simply unplug the multi connector to the chroma panel.

Hope that's of some help.
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Last edited by Tazman1966; 8th Apr 2009 at 3:00 pm. Reason: Added a bit
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Old 8th Apr 2009, 6:39 pm   #16
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Default Re: ultra 3500

In the words of Les Lawry-Johns

"Beware the blue tant"

Keith
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Old 9th Apr 2009, 5:31 pm   #17
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Default Re: ultra 3500

Hi everone the ultra is fixed . it was the focus unit , it was a thick film type bolted onto a paxolin panel . the thick film unit was burning onto the earth pin on the paxolin board . I found one of the older slider type in my junkbox which is working great . Thanks to everyone for their help .
Regards . Gary .
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Old 10th Apr 2009, 5:37 pm   #18
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Default Re: ultra 3500

Hey Gary, that's great news

Have you got any pics of this lovely set?
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Old 11th Apr 2009, 4:32 pm   #19
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Default Re: ultra 3500

I"ll post some pictures of the set when i return home next week taz.
regards .Gary.
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Old 26th Apr 2009, 4:38 pm   #20
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Default Re: ultra 3500

Hi everyone here are the pictures of my ultra 6714 as promised , it continues to work well after replacing the focus unit which was causing the cutout to trip after 10 minutes working .
Regards . Gary .
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