TV IR Remote That Eats Lithium Batteries Fixed
My brother phoned me that he had a strange problem with the IR remote control of his Ziggo Settop TV Box. He inserted new 3V 2025 Lithium batteries a couple of times (his remote has 2 of them in parallel for more current) but after a day or 2 his remote no longer worked and the lithium cells were drained.
So I picked it up at his home and got home to examine it but couldn’t find anything wrong with it. No shorted components and no strange current consuming problems. And no bad measuring resistors or semiconductors either. I also used my external 30V 10A power supply set to 3V and set to a low short max current to test the remote. No problem there either! And I also checked the IR signal on my oscilloscope. It was just fine!
I also used 2 new CR2032 batteries, although my brother apparently had used CR2025 batteries, but they afterwards also were suddenly drained after just a day or 2! Again also without hardly having used the Humax compatible remote. At home I could control my about 9 years old 37 inch Samsung TV with it, so I was easily able to test it.
My only conclusion here was that the IR Motorola chip marked with code MC9S08RD32DWE now just consumed more energy at certain moments than it normally did which will be hard to fix. Although the remote on the external 3V power supply set at a max current of about 0.220 Ampère only showed a measured current in use of only 0.01A! So when a key was pressed the remote just needed about 10mA! There simply were no other components that caused any problem here like the normally shorting SMD mounted capacitors that would be explaining causing this current eating situation. And logging the current over time possibly could have recorded the exact moment.
Anyhow this is the datasheet of that microcontroller: http://www.datasheetcatalog.com/datasheets_pdf/M/C/9/S/MC9S08RD32DWE.shtml
It was logical to assume that the IR remote consumed energy even at times when it wasn’t used. I already had a solution for this problem! An easy fix to solve this unusual problem which I had encountered in other battery operated devices before too!
Although my brother already had ordered another universal IR remote for his Settop Box it took long to arrive and he still couldn’t use his TV Receiver Box. But after my fix he already was able to use his original remote again without any worries! Below a close up of the controller and its pcb.
Below the good quality gold contacts that show that this board was a decently made design!
Nothing was found that would point to the cause of the fast draining batteries!
What is the solution to fix the problem you would ask? I simply cut the + pole track to both battery holders, connected two tin 0.1mm wires to a small switch that I mounted in the front case of the remote. Below some examples of spare part switches I had in stock for this kind of repairs.
Most of the switches were just too big or had a too high contact resistance of around 150 Ohm, so those were not useful in this case. But I found one that was just right!
This way the batteries were only connected to the circuit when the push button was pressed and when the remote was needed.
A small hole was easily made and the perfect push button switch was found and glued on the inside with hot glue. Next photo shows the professional result.
In above photo on the right below the Ziggo tekst (our Cable provider’s name) the new added small button is added to the remote. And my brother was happy with the professional looking result!
I have many hot glue ‘pistols’ but the one in the photo below is probably the most professional I have that is capable in gluing rather large surfaces easily!
After a few days I asked my brother if the problem this way was really solved and he convinced me it was!
It is always nice to have fixed something at almost no costs. Especially when it at first also seems to be unfixable!
Albert van Bemmelen, Weert, The Netherlands.
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Note: You can read his previous repair article in the below link: