When you power it on there are no indicated fault codes, but the issue is whatever mode of measurement the meter is in the display will flash "- OL -" or overload.
I checked the main voltage rails and they seem ok; I briefly looked over the relays but I think I will need to look more closely at the analog input side of things.
...later that afternoon
Well, after a shocking afternoon literally with this unit (lol don't ask!) I managed to narrow it down; so I just reheated a load of pins around the suspect area and it started working! The calibration looks not too bad at all; the sticker on it says the last calibration was 2016 so it should be good!
Btw, if your TIL117 chip is labeled IC307 then you have a later model 7150 (serials 300921 onwards), and if it's labeled IC306 then you have the older version; there are some very subtle differences in the power rail circuit.
All in all very happy! :)
[later that afternoon... ;) ]
Well, the story didn't end there! it looks like I was somewhat premature in my celebrations!!, later that day it started glitching out again with the same issue! I initially started to think it might be a component acting intermittently - that would have been a real nightmare to find and fix; but what I found was after tapping the board in various places I found that it would fix itself, then fault again.
So, I carefully tapped each component and narrowed the issue down to near the front edge of the board; after flexing the PCB very slightly one way I could make it work and by flexing it the other way it would fail; so, I started looking for any broken tracks on the board; the PCB looked ok, so I started tapping each component, then, all of a sudden I noticed the leg on a resistor had separated from the body - so I used my desoldering tool and took it out and replaced it for a metal film one, I tested a few resistors of the same value to get a better even closer match to the original one, but the broken resistor was certainly the root cause of the overload issue.
I left the meter running most the evening and it was fine so I will leave it on for a few days to give it a bit of a soak test.
