Grundig CUC2500 doesn't start up

Bodeslight · Guest

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?

Guest · Posted: Sat Apr 01, 2006 7:37 pm Post subject:

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

Bodeslight · Guest

BBHE · Joined: 08 Feb 2005 Posts: 12

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.

Bodeslight · Guest

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.

Guest · Posted: Thu May 11, 2006 5:48 pm Post subject:

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.