Hi, I teared down my new DM3068 as there was problem with intermittently changing button brightness and display contrast. Problem usually disappeared when multimeter warmed up. Sending back would take too long. There was a problem with 1117B-33 vreg ic, sometimes voltage shoot up to 3,7v on it for a short time. As it seems to be no info on the net about what's inside, decided to share my own. Here are some pics:
https://plus.google.com/photos/117212633093763827202/albums/5861950419366571361. At first glance multimeter was well built with good parts, only bad thing was a flux residues on hand soldered connectors and relays. At start I didn't want to remove RF shield, but it was too interesting to look what's there so I gave up to my curiosity
. And curiosity haven't disappointed me. There I found interesting bodge with 2 green wires. It seems that those wires are in parallel with existing traces (at least one, second trace is below IC so not sure). Don't know why Rigol done this, maybe for lower resistance... Also one IC is hand soldered, not sure if it is rework or done for other reasons.
About parts used. All electrolytic caps are nichicon. In digital part there are blackfin DSP, some strange ISP13628D chip, hynix RAM, spansion flash, one Altera MAX CPLD and one MAXII. Davicom DM9000 ethernet controller. Isolation made with AD ADUM 1301 and 1401 digital isolators for data and one PC817 optocoupler for powering on input part. On measuring part there are Ti ADS1256 24 bit ADC, Vref is LM399H from Linear Tech, biggest chip as some others is with marking laser burned off. There also are caddock 1776-C6715 precision resistor divider, meder BE05 reed relay, 3 Matsushita relays and one small axicom relay. Two current sensing SMD resistors are 4 wire and both are hand soldered. Input seems to be well protected, 2 big MOVs and 2 powerful 1400V ceramic spark gaps there.
Greetings from Latvia