Maplin Gold DVM M 510 EC - UK Vintage Radio Repair and Restoration Discussion Forum

Ed_Dinning · 29th Aug 2019, 10:30 am

Hi Folks, has anyone details of circuits of this meter, which uses the Intersil ICL7106 CPL chip.
It reads about 30% of what it should on both AC and Dc volts, but fine on Ohms; current ranges not checked but new PP3 fitted

Thanks, Ed

MrBungle · 29th Aug 2019, 11:02 am

Look for any leaky electrolytic caps. That's usually what knackers the Flukes around that era. Also check voltage dividers up front (just plug another DMM on ohms mode into the volts when it's off and check it reads around 10 meg). Also look for damage to the main switch.

hysteresis · 29th Aug 2019, 2:20 pm

In the absence of the actual multimeter's circuit diagram, the circuits provided in the ICL7106 datasheet and application notes may help:

https://www.renesas.com/eu/en/www/do...106-07-07s.pdf

https://www.renesas.com/eu/en/www/do...note/an046.pdf

Ed_Dinning · 29th Aug 2019, 8:32 pm

Thanks guys, this one looks pretty pristine inside,clean and no signs of overheating, so it needs a closer look.

Ed

Biggles · 29th Aug 2019, 8:49 pm

Has the 7106 got a reference voltage input on one of the pins? could be worth checking that is correct if it has. I would have thought that the ohms range would be affected at the same time though. Maybe the presumably very high value input divider resistor chain has drifted high. With some DVMs I have seen copper track creepage on the PCB contact pads under the rotary switch. Worth a check if you are brave enough to dismantle the switch what with the usual springs/tiny ball bearings etc!
Alan.

29th Aug 2019, 10:30 am	#1
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Maplin Gold DVM M 510 EC Hi Folks, has anyone details of circuits of this meter, which uses the Intersil ICL7106 CPL chip. It reads about 30% of what it should on both AC and Dc volts, but fine on Ohms; current ranges not checked but new PP3 fitted Thanks, Ed

29th Aug 2019, 11:02 am	#2
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Maplin Gold DVM M 510 EC Look for any leaky electrolytic caps. That's usually what knackers the Flukes around that era. Also check voltage dividers up front (just plug another DMM on ohms mode into the volts when it's off and check it reads around 10 meg). Also look for damage to the main switch.

29th Aug 2019, 2:20 pm	#3
hysteresis Tetrode Join Date: Feb 2007 Location: Liverpool, Merseyside, UK. Posts: 99	Re: Maplin Gold DVM M 510 EC In the absence of the actual multimeter's circuit diagram, the circuits provided in the ICL7106 datasheet and application notes may help: https://www.renesas.com/eu/en/www/do...106-07-07s.pdf https://www.renesas.com/eu/en/www/do...note/an046.pdf

29th Aug 2019, 8:32 pm	#4
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Maplin Gold DVM M 510 EC Thanks guys, this one looks pretty pristine inside,clean and no signs of overheating, so it needs a closer look. Ed

29th Aug 2019, 8:49 pm	#5
Biggles Rest in Peace Join Date: Feb 2004 Location: Hexham, Northumberland, UK. Posts: 2,234	Re: Maplin Gold DVM M 510 EC Has the 7106 got a reference voltage input on one of the pins? could be worth checking that is correct if it has. I would have thought that the ohms range would be affected at the same time though. Maybe the presumably very high value input divider resistor chain has drifted high. With some DVMs I have seen copper track creepage on the PCB contact pads under the rotary switch. Worth a check if you are brave enough to dismantle the switch what with the usual springs/tiny ball bearings etc! Alan.