48 with sinking 12 volt

[jojo]

Can antone shine a light on this problem ,

got a 48 in for repair ,
found loads of memory chip errors reported on a poor b/w screen .
verified 12 volt , which showed 7.3 v

next test showed this ;

12 volt dropped to 3.6 .

third test only gray screen with vague vertical lines ,
and 12 volt dropped to 1.6 v

i assume internal powersupply , but ztx 213 and 650 do measure correct ( compared to 2 others )

[1024MAK]

Yes, well, definitely something wrong with the DC/DC converter or excessive loading caused by a faulty chip (most likely a 4116 or equivalent DRAM chip).

Which issue board? Does it have the DC/DC modification?

Do any of the 4116 DRAM chips get hotter than normal?

Is the +5V and the -5V in spec.?

Mark

[jojo]

When i started this issue 2 for the first time ,
All ram chips remain cold-ish but the screen was missing pixels in the trademark text.

tests revealed a 7.x volt 12 line .

after 3 tests , the 12 v line is at around 1,6 volts.

dc-dc modifications have all been done ( and removed ) situation does not change .

now waiting for the transostors to arrive to change tr4 and tr5