Microcontroller blown its top off! - Page 1
Forum section: electronics / repair

author: CambridgeMart
author_rank: Regular Contributor
timestamp: August 18, 2018, 01:21:23 am
content: I have an airconditioner that has packed up; the problem is clearly with the controller board, there's a big hole blown in the top of the microcontroller package! I would guess that the board is beyond repair. Even if I could replace the microcontroller, I don't have the code to reprogram it. In case you're interested, it's an Ariagel TE160, very similar to the DeLonghi PAC400. The replacement boards are unobtanium, so I either need to repair this or somehow come up with an alternative. The unit is a split system, so there's a compressor, 2 fans and a condensate pump to look after, plus the infra red remote control to deal with; how hard can that be?

author: Rerouter
author_rank: Super Contributor
timestamp: August 18, 2018, 01:46:46 am
content: Break down the problem and it gets easier, Identify the inputs, (definatly a temp sensor in the indoor unit, possibly some current sensing to the outdoor unit), last one I dealt with had the functional diagram of the outdoor unit under the wiring cover, just had a common nuetral, a wire for the pump, a wire for the fan and a wire for I believe the expansion valve.Beyond that its like any other electronics project, do the magic between input and output.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 18, 2018, 01:51:30 am
content: If youre good in any arduino programming, there's some projects flying around, you could create your own processor board

author: floobydust
author_rank: Super Contributor
timestamp: August 18, 2018, 04:34:33 am
content: MCU with the top blown off is usually a big overcurrent, from a shorted mains triac or failed (capacitive) power supply.There is an open-souce IR remote-control project of air conditioners using Arduino or ESP8266;Arduino Midea air conditionerYou would just need temp and fan control code added, to make it a master instead of slave.Arduino librarieshave device control too.

author: amyk
author_rank: Super Contributor
timestamp: August 18, 2018, 04:38:48 am
content: The MCU in these systems is normally powered by a capacitive dropper, and when the dropper capacitor fails shorted, this is what happens.At a minimum you could turn the system into manual control by using switches for each of the components (I'm assuming the relays survived, but you should check) --- watch out for mains isolation.Post a picture (both sides) of the control board if you'd like assistance reverse-engineering it. They're usually only 2-layer and through-hole so not very difficult.

author: abraxa
author_rank: Frequent Contributor
timestamp: August 18, 2018, 08:11:37 am
content: Quote from: CambridgeMart on August 18, 2018, 01:21:23 amHmm, is that so? A quick google search found this:https://www.ereplacementparts.com/delonghi-pac400-portable-air-conditioner-parts-c-122345_122354_122898.htmlhttps://www.ereplacementparts.com/control-board-p-696934.htmlhttps://vdocuments.site/te-160.htmlshows a really very similar drawing, so just like you said, I'd say one is a rebranded version of the other.

author: CambridgeMart
author_rank: Regular Contributor
timestamp: August 18, 2018, 04:38:14 pm
content: Quote from: abraxa on August 18, 2018, 08:11:37 amThe controller shown is nothing like the controller in the TE-160, I don't know if they revised the design at some point.

author: CambridgeMart
author_rank: Regular Contributor
timestamp: August 18, 2018, 04:41:42 pm
content: The Arduino controller sounds like a solution; I have plenty of Arduino projects under my belt already.The PSU in this is a transformer isolated supply, but a couple of loads are driven by triacs driven via a ULN2004, so a shorted triac could have done the damage; a number of +5V traces were vapourised as well, so a large current has definitely flowed through the 5V rail at some point.

author: Mr. Scram
author_rank: Super Contributor
timestamp: August 18, 2018, 04:46:23 pm
content: What caused the microprocessor failure? Replacing it is no use without fixing that first.

author: CambridgeMart
author_rank: Regular Contributor
timestamp: August 18, 2018, 04:48:55 pm
content: Both triacs measure <200 Ohms between MT1 and gate, so that could well be the reason.