UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Multi-Channel VHF Modulator Design

oldeurope · 4th Mar 2005, 4:24 pm

Hi David,
the problem is the changes of the sync takes place at the DC-restorer
and this is in the IC! So you must look for sync level changes at
the output of the vision demodulator in the TV set.
An eventually reduce of brightness from left to right can you measure
at pin 9 I think.

Kind regards
Darius

PS: The picture shows the input of the cxl's.
the clamp current comes from the LM1881 ony at the sync tips.
So the cap at the input will not be discharged during a line.

4th Mar 2005, 4:24 pm	#45
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: Multi-Channel VHF Modulator Design Hi David, the problem is the changes of the sync takes place at the DC-restorer and this is in the IC! So you must look for sync level changes at the output of the vision demodulator in the TV set. An eventually reduce of brightness from left to right can you measure at pin 9 I think. Kind regards Darius PS: The picture shows the input of the cxl's. the clamp current comes from the LM1881 ony at the sync tips. So the cap at the input will not be discharged during a line. Attached Thumbnails