Icom IC-H10 running memory battery down - UK Vintage Radio Repair and Restoration Discussion Forum

SiriusHardware · 19th Oct 2017, 7:32 pm

I've just dusted off my trio of Icom IC-H10 VHF Hi-Band PMR handhelds, for which I still have the programming software (DOS, of course) and the official programming interface which is basically just an RS232-TTL level converter.

They are roughly about 25 years old. Still fairly neat albeit quite oversized and heavy by modern standards. I think there was supposed to be a UHF version, the IC-U10, as well, but I've never seen one and I don't know if they were ever used in the UK.

On checking them over I was surprised to find that one beeped madly at me, indicating that it had forgotten its programming. This was unexpected as I re-celled the main battery packs and fitted new Lithium memory retention batteries quite recently, back in 2014. All still worked immediately after I'd done the work. The other two sets still appear OK.

When I replaced the coin cell which does a similar job in my TS-50 Amateur HF radio quite a few years ago there was a caution in the service manual which said that the radio must be power-cycled on/off immediately after replacement of the battery otherwise the battery would run down very quickly.

Is there a similar rain dance which has to be performed in order to get the IC-H10 into the correct internal battery management mode? I've done a post-battery-change CPU reset (basically, hold a couple of the side buttons down and turn the set on) and then cloned the channel programming from one of the other H10s into it. I can turn it off, leave it off for a while, turn it back on, it still remembers the programming so the new memory retention battery is obviously doing what it should, at least in the short term.

orbanp1 · 21st Oct 2017, 3:58 pm

A quick glance into the manuals (OM and SM) did not reveal any push button sequence to reduce backup current, though it was just a cursory look...
I would measure the backup battery current, as you have more than one unit, you can compare them.
If the current is higher, I would check the backup circuit.
The service manual is available on the elektrotanya web-site:
https://elektrotanya.com/icom_ic-h10.../download.html
If the current is higher, I would start by checking out C2, 6.8uF, 6.3V, on the "Logic Unit" (pg. 11, pg. 35).
Eventually I would check the backup current draw of the processor chip.
If the chip draws the excess current itself, then I think there is not much you can do short of replacing the chip.

Good luck, Peter

orbanp1 · 21st Oct 2017, 7:21 pm

Some more things that you could check:
D3 diode assembly in the "Logic Unit" separates the backup power from the +5V. The diode from the +5V could be leaky.
For the processor to go into the standby mode, and draw only 0.1uA, the INT4/P00 input (pin 27, see pg. 12 in the SM) has to be in the low state. Do check if that pin is indeed at 0V when the radio is powered off.
Also have a look at the datasheet of the uPD75108A processor, of which a version is used in your radio:
http://www.datasheetarchive.com/pdf/...ry=UPD75108AGC

Peter

SiriusHardware · 21st Oct 2017, 10:42 pm

Hello Peter, thanks for the detailed response to my question, for taking the time to consider possible faults and avenues for diagnosis and for finding that service manual, all very much appreciated.

I got the radios out again because they were needed for a specific task for which they are currently being used, so I can't grab them back just at the moment.

Measuring the standby current against that taken by the other two sets is a good idea but not trivial, owing to the way the radios are put together - the lithium battery is between a 'sandwich' of PCBs in the extreme upper part of the set and so to disconnect one end of the batteries to make current measurements requires a significant amount of stripdown.

The PCBs are interconnected via fairly fragile brown ribbon cables which are integral parts of the PCBs themselves, which makes me instinctively reluctant to dismantle the two 'good' sets without good reason as these ribbon cables could easily be damaged just by bending them around.

The radios spend long periods of time in storage unused and short periods in use, as they are now.

I think what I'll do is make a note on next year's calendar to check the battery voltage on the suspect set at about this time next year - the voltage is easier to check than the current, as the battery +ve can be reached with a needle probe when only the front casing is removed. If, at that time, the battery voltage has decreased significantly, I will know I do have a battery drain problem and will investigate along the lines you've suggested.

19th Oct 2017, 7:32 pm	#1
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Icom IC-H10 running memory battery down I've just dusted off my trio of Icom IC-H10 VHF Hi-Band PMR handhelds, for which I still have the programming software (DOS, of course) and the official programming interface which is basically just an RS232-TTL level converter. They are roughly about 25 years old. Still fairly neat albeit quite oversized and heavy by modern standards. I think there was supposed to be a UHF version, the IC-U10, as well, but I've never seen one and I don't know if they were ever used in the UK. On checking them over I was surprised to find that one beeped madly at me, indicating that it had forgotten its programming. This was unexpected as I re-celled the main battery packs and fitted new Lithium memory retention batteries quite recently, back in 2014. All still worked immediately after I'd done the work. The other two sets still appear OK. When I replaced the coin cell which does a similar job in my TS-50 Amateur HF radio quite a few years ago there was a caution in the service manual which said that the radio must be power-cycled on/off immediately after replacement of the battery otherwise the battery would run down very quickly. Is there a similar rain dance which has to be performed in order to get the IC-H10 into the correct internal battery management mode? I've done a post-battery-change CPU reset (basically, hold a couple of the side buttons down and turn the set on) and then cloned the channel programming from one of the other H10s into it. I can turn it off, leave it off for a while, turn it back on, it still remembers the programming so the new memory retention battery is obviously doing what it should, at least in the short term.

21st Oct 2017, 3:58 pm	#2
orbanp1 Heptode Join Date: Nov 2009 Location: London, Ontario, Canada Posts: 675	Re: Icom IC-H10 running memory battery down A quick glance into the manuals (OM and SM) did not reveal any push button sequence to reduce backup current, though it was just a cursory look... I would measure the backup battery current, as you have more than one unit, you can compare them. If the current is higher, I would check the backup circuit. The service manual is available on the elektrotanya web-site: https://elektrotanya.com/icom_ic-h10.../download.html If the current is higher, I would start by checking out C2, 6.8uF, 6.3V, on the "Logic Unit" (pg. 11, pg. 35). Eventually I would check the backup current draw of the processor chip. If the chip draws the excess current itself, then I think there is not much you can do short of replacing the chip. Good luck, Peter

21st Oct 2017, 7:21 pm	#3
orbanp1 Heptode Join Date: Nov 2009 Location: London, Ontario, Canada Posts: 675	Re: Icom IC-H10 running memory battery down Some more things that you could check: D3 diode assembly in the "Logic Unit" separates the backup power from the +5V. The diode from the +5V could be leaky. For the processor to go into the standby mode, and draw only 0.1uA, the INT4/P00 input (pin 27, see pg. 12 in the SM) has to be in the low state. Do check if that pin is indeed at 0V when the radio is powered off. Also have a look at the datasheet of the uPD75108A processor, of which a version is used in your radio: http://www.datasheetarchive.com/pdf/...ry=UPD75108AGC Peter

21st Oct 2017, 10:42 pm	#4
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: Icom IC-H10 running memory battery down Hello Peter, thanks for the detailed response to my question, for taking the time to consider possible faults and avenues for diagnosis and for finding that service manual, all very much appreciated. I got the radios out again because they were needed for a specific task for which they are currently being used, so I can't grab them back just at the moment. Measuring the standby current against that taken by the other two sets is a good idea but not trivial, owing to the way the radios are put together - the lithium battery is between a 'sandwich' of PCBs in the extreme upper part of the set and so to disconnect one end of the batteries to make current measurements requires a significant amount of stripdown. The PCBs are interconnected via fairly fragile brown ribbon cables which are integral parts of the PCBs themselves, which makes me instinctively reluctant to dismantle the two 'good' sets without good reason as these ribbon cables could easily be damaged just by bending them around. The radios spend long periods of time in storage unused and short periods in use, as they are now. I think what I'll do is make a note on next year's calendar to check the battery voltage on the suspect set at about this time next year - the voltage is easier to check than the current, as the battery +ve can be reached with a needle probe when only the front casing is removed. If, at that time, the battery voltage has decreased significantly, I will know I do have a battery drain problem and will investigate along the lines you've suggested.