On Saturday, May 2, 2020 at 10:57:58 AM UTC+2, wrote:
On Saturday, May 2, 2020 at 9:39:57 AM UTC+2, Bo-Lennart wrote:
Den onsdag 7 mars 2018 kl. 18:25:00 UTC+1 skrev Bo-Lennart:
Have a SENNHEISER UPM 550-1 (audio level-meter). My problem is that -14Vdc from the power-supply board is goes upp and down to nearly 0 Vdc. If I take out the board labeled B15, the -14Vdc is stable. And I can use the instrument as a AC-rms voltmeter. No problem. But something happen the I re-plug the board B15. The B15-board have something to do with the CCIR-filter (I guess). But I need a service manual to find out. Maybe someone out there, know exactly what's wrong here.

Best regards from SWEDEN
Bo-Lennart Karlsson
Falun, SWEDEN


Thank you very much Bo!
We spent some more time looking for the manual the other day and found it for sale on two websites. Since we got a bit impatient and it only was 5$, we just decided to buy it.

So, thanks again for offering your help! I hope you were successful with the work you were doing on your UPM 550

Oh and sorry for the confusion with the email address. Apparently it was shortened by the forum.