Hameg HM203-6 Repair Question

[SubSonic]

Hi everyone!

Just got time to troubleshoot my Hameg HM203-6 which i got from ebay  .
CH2 was working CH1 not.
I found the culprit. It's resistor R152 (6R81) which sits on the -12V rail (marked in attached photo and schematic).
Look like it's blown as it don't look ok.

EDIT: The faulty resitor reads around 0.725 kOhms

As it seems quite difficult to take the scope apart to get to the bottom side of the frontend board to desolder the resistor and put a new one in i thought about just bodge a 6R81 across the old one. Will this be ok or will the old one have any effects during operation?

Also what do you guys thinks this resistor is doing? some kind of current limiter?

-Markus

[edavid]

The resistor probably blew up because something else is shorted, perhaps C120.  You are going to have to find out what.

[SubSonic]

Thanks for the hint. Just checked and the rail after the resistor is indeed shorted to ground.
I would highly appreciate any hints on how to take the HM203 apart.

[Bored@Work]

I would highly appreciate any hints on how to take the HM203 apart.

Ask Hameg for the service manual. If the service manual doesn't contain that information ask Hameg for the details.