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Grundig CUC2500 doesn't start up

 
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Bodeslight
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PostPosted: Thu Mar 30, 2006 12:21 am    Post subject: Grundig CUC2500 doesn't start up Reply with quote

Hello,

I have an old Grundig T70 1020A with chassis CUC2500.
The problem is that he sometimes doesn't start up.
After switching on the power I can here a few ticks.
I already replaced the IC655 (TDA 3640), C642 (10uF), C661 (47uF), but that didn't changed anything.
Can someone help me fixing this problem?
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PostPosted: Sat Apr 01, 2006 7:37 pm    Post subject: Reply with quote

I don't know this chassis but I had once similar problems with a cuc5511.
Then the problem was a short circuited BU 508A line oscillator.
After replacement the power supply could start up again
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Bodeslight
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PostPosted: Wed Apr 05, 2006 3:01 am    Post subject: CUC2500 (T70-1020A) start-up problems Reply with quote

Anonymous wrote:
I don't know this chassis but I had once similar problems with a cuc5511.
Then the problem was a short circuited BU 508A line oscillator.
After replacement the power supply could start up again


Thanks a lot for your quick response.
I have searched the CUC5511 drawings, and I couldn't find a BU 508A.
There's a BU 290 (T644) that drive's the line transformer.
Are you sure about the BU 508A?
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BBHE



Joined: 08 Feb 2005
Posts: 12

PostPosted: Thu Apr 13, 2006 8:01 am    Post subject: Reply with quote

I have had the same problem.
You can check the psu by soldering the bu508D (T521) out. Then connect a normal 220V light bulp between colector - emitter.
If the tv "starts up", the light bulp lights up. You can now check the different output voltage (195V, 12V, 5V etc). Are they ok the defect is somewhere in the line part.
In my case it whas the BU508D that whas defect.
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Bodeslight
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PostPosted: Thu May 11, 2006 2:29 am    Post subject: Reply with quote

I have checked the PSU with a light bulb like you told me but the light bulb doesn't light up. When I measure the BU508D it seems to be OK.
I think that there's something wrong before the transformer.
Can someone give me some new advise?
Thanks a lot.
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PostPosted: Thu May 11, 2006 5:48 pm    Post subject: Reply with quote

When it starts, check the health of all powersupplies, and replace the filter capacitors of any that have excessive ripple, then check the rectifier diodes. Check for broken solderjoints especially around larger components.
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