D Link ADSL Signal Drops Frequently during POWERCUT- Using Inverter


Jun 29, 2012

My case:
Have a DLINK 2640T Wifi Router cum ADSL Modem for my BROADBAND Connection (BSNL)

This which works fine with normal electricity (ADSL remains static; Even with normal voltage fluctuations)
BUT when power goes off (thank to OUR Power cuts ), and home Inverter takes over, the ADSL signal drops periodically in say some 1-2 minute intervals, making it almost useless to use internet (i.e due to constant disconnection and reconnection )

DLINK 2640T comes with an AC 220V to AC 12V 1.2Amp Simple transformer adapter. (This comes from a firm named AMIGO ITE Ltd. and costs friggin 450 bucks. These get burnt if there is a good voltage spike)
My UPS is of PowerCom, single battery OFFLINE type (the normal common ones) which is 10 times better than other normal cheap UPS brands at my place
(I hope people replying know whats d difference between offline and online)

After lot of testing, i have come to conclusion that its the INVERTER issue. Even though the inverter i got is of a good brand- Good quality SINE WAVE one (microcontroller based), i feel the voltage still fluctuates more than normal for modem to keep the adsl signal static)

My Options:
I read all over internet regarding other people having such issues: and there were few reasons and solutions provided
Few thread were:

1) USE SMPS based 12v Yellow output and put that DC input into Modem. Given the fact that it has a rectifier built in, DC will pass as such and only requirement amount i.,e 1.2Amp would be withdrawn.
Also as i had GOOD quality (Costly Cooler master SMPS), the quality of supply would be good (interference; noise etc would be less)
BUT When i did that, the ADSL drops regularly in both normal electricity & inverter feed

I tried measuring voltage levels in both Normal Electricity & Inverter Feed in both 12v DC Output SMPS Molex & 12V AC Output DLink Adapter for finding a reason.

Normal Electricity FEED CASE
SMPS -> 12.3
DLINk Adapter- > 13.8

SMPS -> 12.2
DLINk Adapter- > 11.9-12.0

- There is indeed higher range in Adapter case & pretty constant in SMPS case (As expected)
- Further voltage is higher than 13V in DLink adapter normal electricity case, i.e the only time when the ADSL doesn't drop. Does that mean Static ADSL needs 13V to work. Inverter Voltage never came close to 13v
Is voltage the reason here? Guys having good electical knowledge kindly help?
Further is there any way, i can increase the voltage at molex end from 12.2 to 13.2V or something like that...using some resisters, etc ..just to check (Sorry i have forgotten quite a physics now)

2) USE SMPS based wall adapter which is not linear like default dlink adapter and switched mode will correct the issue.
here a guy used some oswal adapter and i was never able to find any for 9v even,,,forget the 12v.

Anyway, as people have told that as long as amperage is not less than the required (can be higher) and voltage is same, i can use any adapter.
So to check whether these smps based will work, i plugged in my TATASKY 70-240V AC to 12V DC 2.5Amp SWITCHED mode adapter.
In this case, ADSL dropped even with normal electricity feed.

I searched online but never found any 220V Ac to 12v AC or DC 1.2Amp SMPS adapter.
I found a 220V Ac to 12v DC 1.5Amp SMPS adapter but i am not sure whether that will work (Seller also not sure) . I may be just spending on useless adapters.

3) Use a stabilizer.
Well only one person online said so, i tried, using a AUTOMATIC 0.5 KVA Stabilizer, the same we use with our refrigerators.
ADSL constantly dropped on INVERTER feed as before.

Few things to be noted here:
- Firstly, given the fact that there is no issue at all with my adsl signal when there is normal electricity completely rules out any issue with my adsl line or SNR ratio and other stuff.
- Some people also talked about other things providing interference to modem line. I tried removing landline wire & modem to an isolated place and then checking things. Same adsl drops on inverter.
- Secondly, of course i don't plan to change my INVERTER, just for the sake of testing my adsl ***. So not an option. Going to other people's places to find out is fine but very few have adsl broadband
- Thirdly, i am really at wits end to halt my online activity due to constant power cuts and load shedding . One can plan power cuts and work accordingly but this load shedding shits a load on everything else (of course ADSL drops here)
- Also does this has anything to do with INVERTER's earthing?
- Interesting thing i found out is, during the early 5-10 minutes of power cut, the ADSL doesn't drop. After that time, it starts dropping regularly as explained at top. Is that pointing to the fact that early on inverter is fully charged or something and provides better voltage? Any other equipment used at home with inverter works fine all the time.
- Also pertinent to mention here that ADSL signal is fine with UPS supply when normal Electricity feed & Inverter is turned off. That gives me an idea that ONLINE UPS (no relay based stuff) will prolly solve the issue. I need to cross check though as a good brand ONLINE UPS like of APC would cost me >600 USD (30000INR)
- Kindly share your thoughts or experiences . also help me find the solution. I am really feeling desperate due to this.

I am new to post here and but i promise i will reply INSTANTLY.
I am trying to ask this on various forums too.