Solartron Schlumberger 7151 bench multimeter teardown pics

[iloveelectronics]

This is a 5.5/6.5-digit bench meter from 1988. I don't really need another bench meter but saw a private seller in China selling this for rather cheap and just couldn't help it. Didn't know some of these 7151 meters were actually licensed to be assembled in Shanghai, China. The Chinese text on the back panel says it was designed by Solartron in the UK but assembled, tested, and calibrated in China. It looks like a 1988 vintage judging from the date codes as well as a stamp on the inside of the top housing piece.

Calibration looks slightly out (I didn't check actual specs), based on my Agilent 34461A. It's about 3-5 count out in 5.5-digit mode (30-50 in 6.5-digit) on DCV. Didn't really check the other ranges yet.

So here goes the pictures (click to enlarge):


The Chinese voltage reference is marked as 5.00090V. 6.5-digit mode.


10.00007V. 6.5-digit mode.


Up pops the cover. You can see a date stamp on the dark underside that reads "Apr 1988".










Looks like some leakage and corrosion on the electrolytic caps.


The 3.6V battery measures only 0.57V. Someone corrects me if I'm wrong but I think it's only used for the real time clock?


Another board.






The back panel, with the Chinese text saying the unit was designed in the UK but assembled, tested and calibrated in China.


Everything looks original to me and it doesn't look like it's been repaired or anything so I'm overall pretty pleased with the purchase. But as I said I don't really need it so I'll probably just hang on to it for a little longer and then sell it on for costs+change

[ecat]

I love the case design of these meters, well, assuming the 7151 uses the same design as the 7150+



From here you can rotate the 'top' of the case 180 degrees, so the flat top surface is back at the top. The sides are different heights, arrange the case top so the flat surface is sloping down towards the rest of the meter.




Fold the entire top board over to the left and it is supported by the case top half. Both upper and lower boards are now component side up, all wires are still connected and the meter remains fully functional. So simple, so sweet

[sfiber]

I can see the corosion on the logic board and I dont think its about trimpot or something.When one of the adc chip has a corosion on pins,it changes to adc step size or something and this cause the wrong value on measurement.

[Wytnucls]

Nice catch Franky.
Here is some info about its specifications:

[free_electron]

Oh no .. A varta-leak-a-battery.. Swap that thing immediately. If it bursts it'll eat half the board.

Notice, on the analog board, the cpu with the eprom stacked on ots back ? Probably either a national semi COP4 or COP8 series or an early mostek/ST chip

-edit- oh wow .. A hitachi 68xx . Never knew they did piggyback ...

[iloveelectronics]

Oh no .. A varta-leak-a-battery.. Swap that thing immediately. If it bursts it'll eat half the board.

Thanks for the tip. I reckon the two 2200uF caps next to it need replacing too.