Is my Ch A broken?

If I test Ch B with a 9 volt battery (Setting: DC, 10 v) the trace jumps up and stays there. If I use the same probe plugged into Ch A (Setting: DC, 10 v) the trace jumps up and then quickly decays back to zero. Am I missing something? Is there some other setting I need for Ch A to properly register DC voltage? Does it sound like a hardware problem? (2.6, 1.41, 2.45b)?

Ant suggestions would be greatly appreciated.

is the input coupled for ad or dc ? in the menu

it seems that the S1 in your Quad is not working while you set the couple as “DC”.please recheck as :

  1. open the back cover of Quad and find out the S1.
  2. withe the 9v battery source ,change the setting of couple mode, and check the pin as the attached drawing to see if changes . it should be 9v if your setting is “DC” and 0v if “AC”1111jpg.jpg

Thank you very much for this detailed info. Are there additional instructions on how to open the back. I can get the front cover but that only exposes the LCD screen.

I don’t want to damage this excellent package so any help would be appreciated.


this a vidio for you: … hotostream

Thanks for your help. The internal measurements confirmed what the Quad display was showing. This shows that the QUAD is a very good diagnostic tool - even when used to confirm that QUAD itself is broken.


On My DSO, channel B has the DC mode broken …

How can I fix it ?