Need help with Repairing a Sony Digital Paper Ereader - Page 1
Forum section: electronics / projects

author: Technobabble_
author_rank: Regular Contributor
timestamp: February 06, 2021, 02:41:19 am
content: Hello,A few years ago I bought a Sony DPT-RP1. I loved it. I used it almost every day for reading and note-taking. Now, Sony has discontinued support for the $#$& product line. My tablet won't charge, even though the light comes on. When I plug in the tablet, the charging light stays on for a minute, then flashes intermittently. I took it apart (see photo below), and measured 3.3 volts DC over the battery. There are four leads; I assume the two white ones are for a sensor?Here's what I'm thinking:Disconnect the battery and hook up a lab power supply with the proper voltage and current settings to make sure the rest of the tablet is OKTrickle-charge the battery using a lab power supplyReplace the battery with a two-lead one, and short the two white wires to trick the tablet into thinking the battery is OK.Try my luck on an Aliexpress supplier that claims to have replacement batteriesIs there anything I'm missing, or that you recommend I try first?

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 06, 2021, 03:35:01 am
content: Try connecting a bench power supply set to 4.1V with a current limit of 1A or less to the red and black wires and let it sit for a few minutes or so. If it is then able to power up, see if charging from USB works.Also check what appears to be a supercap (that thing that looks like a smaller battery), I'm not sure why a tablet would need such a large supercap given the battery is not intended to be swapped by the user.

author: Technobabble_
author_rank: Regular Contributor
timestamp: February 06, 2021, 04:47:11 pm
content: Why do you recommend trying the tablet at 4.1v instead of 3.7v?

author: Technobabble_
author_rank: Regular Contributor
timestamp: February 06, 2021, 05:07:17 pm
content: Edit: I may have posted this to the wrong forum. @Dave can you please move it?

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 06, 2021, 06:37:21 pm
content: Quote from: Technobabble_ on February 06, 2021, 04:47:11 pmThe usual charge voltage is actually 4.2V/cell but derating that to 4.1V reduces the stress on the battery.

author: Renate
author_rank: Super Contributor
timestamp: February 06, 2021, 07:28:41 pm
content: I'm guessing that the white wires are a 10k thermistor, that's very common.If the power supply gets you going you've got lots of room to hook up any replacement battery.

author: Mantou85
author_rank: Newbie
timestamp: April 18, 2024, 02:36:19 am
content: I found this post on Google and disassembled my Sony Digital Paper. I have two AliExpress replacement batteries. I attached the replacement batteries to the reader and it does boot. However I get an error that the tablet cannot charge and the temperature is too high. Based on what I've read above the white wires are the thermistor.How would I go about troubleshooting how to make the battery compatible with the device or am I SOL? I could buy an adjustable DC Power Supply to try the aforementioned.Sony has been a great tool for our business and, sadly, they discontinued support.

author: moffy
author_rank: Super Contributor
timestamp: April 18, 2024, 09:45:13 am
content: Quote from: Mantou85 on April 18, 2024, 02:36:19 amTry different value resistors between the two white wires until you find something that clears the temperature error, you could start with 10k as suggested by Renate.P.S. If you use, say a 50k pot you could adjust it to get the right resistance value.

author: Mantou85
author_rank: Newbie
timestamp: April 20, 2024, 02:26:25 am
content: Quote from: moffy on April 18, 2024, 09:45:13 amCan you please translate this to a newbie? What type of device could I use to perform these tests.

author: moffy
author_rank: Super Contributor
timestamp: April 20, 2024, 03:12:44 am
content: Quote from: Mantou85 on April 20, 2024, 02:26:25 amUse something like this:https://www.jaycar.com.au/50k-ohm-linear-b-single-gang-24mm-potentiometer/p/RP3516Connect the center pin to one of the outside ones, then wire the two connections to the two white wires, adjust the potentiometer until the error clears.