Modem ADSL Link issues; Need solution and AC DC Guidance

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  #1  
Old 06-30-12, 01:15 AM
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Unhappy Modem ADSL Link issues; Need solution and AC DC Guidance

Hello
I have a DLINK 26740-T ADSL+Wifi Modem for my broadband and the
issue is the ADSL signal link drops regularly in 1-2minute intervals, once the power goes off and home invertor jumps in.
Gievn the fact that there are too many power cuts at my place, its pathetic to browse internet with supply of invertor.
(I have a good Sine wave invertor ..but still the issue)

There is no issue at all with normal electricity and UPS power supply (ADSL is fine)

The default adapter which comes with modem is AC 220V to AC 12V 1.2Amp Simple transformer adapter.

I heard following options as solutions but none worked:
1) Using SMPS 12v molex supply into my modem..i tried but ADSL drops even with normal electricity supply.
I was told that even though molex is DC output, my modem has rectifier buit in and if dc is fed into ac, there is no problem. Modem will withdraw 1.2amp itself.

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

INVERTER FEED CASE
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 electrical knowledge kindly help?


2. Using stabilizer , as inverter supply can fluctuate causing adsl signal blink
I tried ..but still no help

3. Using SMPS based adapter.
I tried with 220AC to 12V DC 2.5Amp adapter..butADSL drops even with normal electricity supply too
I cant find any 220AC to 12DC 1.2Amp SMPS adapter..only 1.5Amps one... Can i use it..will it fry my modem?


Please help
 

Last edited by DlinkMan; 06-30-12 at 01:46 AM.
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  #2  
Old 06-30-12, 02:53 AM
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Can i Use 12V AC 1Amp adapter for a modem requiring 12V 1.2Amp?

I already have a major issue with my modem detailed here
http://www.doityourself.com/forum/co...-guidance.html

Though this is concerned with modem only..they are bit different and straight questions...
1) Can i Use 12V AC 1Amp adapter for my modem requiring 12V AC 1.2Amp?
2) Can i Use 12V AC 1.5Amp adapter for my modem requiring 12V AC 1.2Amp?
3) Can i Use 12V DC 1.2Amp adapter for my modem requiring 12V AC 1.2Amp?
(As per this link,
How can I connect my modem power supply to the molex connector? - Digit Technology Discussion Forum
DC will go in as such and rectifier circuit built into modem will not have any issue of 12v DC or 12AV is put in)

Kindly explain why "no " or yes"

Thanks
 

Last edited by DlinkMan; 06-30-12 at 03:31 AM.
  #3  
Old 06-30-12, 03:56 AM
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The Dlink may need more than the 11.9 that is supplied by the inverter or the 12v from the SMPS. Because the Dlink has a built-in rectifier, it could be losing another .7 volts through a diode which would put it at or under the minimum voltage required for the device.

Have you tried plugging the Dlink's power supply into the UPS with the UPS plugged in to the inverter?

Another option is to find a 220v to 13 or 14 volt transformer for use with the inverter.

Are you sure the inverter is a pure sine wave and not a "modified sine wave" inverter? Many electronic devices won't work or will work erratically with a MSW inverter.
 
  #4  
Old 06-30-12, 04:09 AM
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1. Maybe. The transformer will probably power the device, but it may get too hot and eventually fail due to heat. If you decide to use this adapter check it frequently for heat build-up.
2. Yes. Current is not "pushed" by the transformer. Instead, the device will draw the current (amps) that it needs.
3. Yes. However, as I mentioned in the other thread, the internal rectifier may drop the voltage to the point at which it is too low for the device to operate reliably.

A power supply of 13 or 14 volts may solve your problems. See if you can get your hands on a laptop-style power supply that's rated for 1.2 (or more) amps at 13.8 volts.
 
  #5  
Old 06-30-12, 10:37 AM
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Thanks for reply RICK ( i posted this issue with more details in about 7 major forums till last day and u replied 1st)
So voltage is the issue? as i was just guessing . Was not sure.

Have you tried plugging the Dlink's power supply into the UPS with the UPS plugged in to the inverter?
When i say adsl drops using inverter, i mean the same setup, PC & modem into UPS and Ups into normal electrical port, which provides inverter supply when main power goes off (The only advantage of quick automatic switchover of inverter over a generator ..else i hate the former)

Given the fact that i have a offline UPS (the common one) and not an online one(Cost is almost 10 times), AFAIK former have a relay based network i.e current flows directly to load when UPS is powered by any electricty (mains or inverter) else it switches to UPS battery circuit. So i don;t think there would be any difference if i use the load directly to invertor point (which further might be harmful as inverters are not for stuff like computers, which may shutdown when mains comes & goes, if i do so)

Another option is to find a 220v to 13 or 14 volt transformer for use with the inverter.
Indeed i was thinking the same but believe me its very difficult to find even 220 to 12C Ac of exact 1.2Amps (as required by modem by default)
I have never heard of 12 or 14v. Just 9V, 12V, 16V, 18V like that !
To be frank, i feel the best possible option for me would be in a way i could increase that 12v molex supply from SMPS (which is firstly Switched type and secondly a high grade product) to 13 or 14 V as you say.
But dont know how to make up for that 0.7 volt increase
Also i am not sure what would be the effect on modem with 14v as i am not clear about amperage and voltage relation here. Some say modem will withdraw current as required. Some say Voltage will increase at adapter output if it is rated less than required amperage..causing issues etc
Kindly explain

Are you sure the inverter is a pure sine wave and not a "modified sine wave" inverter? Many electronic devices won't work or will work erratically with a MSW inverter.
Though its not a very new inverter (bought some 3 yrs back), it was advertised sine wave (microcontroller based). I am not sure how to find exact details. I will try website of the manufacture and model details , once again.
Any easy way to find, what it is EXACTLY?
 
  #6  
Old 06-30-12, 10:44 AM
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Thanks for clarifying RICK

So you mean anything like 13-14V and rating of >=1.2Amp ( i repeat >= 1.2Amp) would probably would be fine and would not cause harm to modem?

BCoz even if i somehow find a laptop based supply (I think all are the SMPS variety and not linear ones), Matching amperage to 1.2 is surely impossible. They would surely be >2 Amps or so.
Getting into search mode now.
I would continue now on the other thread.

Thanks again
 
  #7  
Old 07-01-12, 06:26 AM
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The power supply's amp rating can be equal to or greater than the device it is powering. The device won't pull more current than it needs. A 2-amp power supply will work fine.

Voltage is another story. It should be matched to the device. Most devices are built to work within a 10% tolerance for over/under voltage conditions, which means 10.8 to 13.2 volts on a 12-volt device. However, your modem's power supply is actually 13+ volts, which means it may not be a 12-volt device.
 
  #8  
Old 07-01-12, 06:49 AM
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Can you post the make & model of the inverter?

If you have access to an oscilloscope you can look at the waveform it produces.
 
  #9  
Old 07-01-12, 07:31 AM
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I understand a bit now.

But how come you are so sure that my modem's default adapter is 13+V?
As per its labelled specs, its 220V Ac to 12V AC 1.2Amp
Further as per my modems official datasheet (NAME : DLINK 2640T), it requires a 12V 1.2Amp external power adapter
Here is the link. Kindly see
http://global.dlink.com.sg/site_pdtp...L-2640T_ds.pdf
I have the whole manual link too, but not sure that will help,

You said most devices are with 10% tolerance, then why this brick of mine is not working with 12V DC from molex connector of my SMPS (which i am realy interested in as SMPS regulates/protects whole PC components and are kind of safe hands? (given we take away 0.7 to 0.8V away from it (as you said once)..it is still 11.2 V going in)
 
  #10  
Old 07-01-12, 07:36 AM
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Well i just searched online... in detail
here is the model details i got
Home Solutions | Digital UPS | Chic
And to my bit of surprise it lists ..its MODIFIED sine wave
So is that the issue?

Many electronic devices won't work or will work erratically with a MSW inverter
So what are my options now?

 
  #11  
Old 07-02-12, 03:48 AM
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See if it runs on a car battery. Seriously. A lead acid car battery puts out over 13 volts at full charge, and will last for hours pulling only 1.2 amps. A basic battery charger may not have problems with the generator. You may be able to charge it while it's powering the modem.

Don't keep a lead acid battery in the house, though.
 
  #12  
Old 07-02-12, 03:55 AM
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If the modem has a rectifier it means that there are four diodes inside; two on each "leg" of the incoming AC. Each diode drops the voltage .7 volts and two are active at any given time = 1.4v drop. Just a guess ...

I've merged these threads.
 
  #13  
Old 07-02-12, 09:36 AM
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Rick, thanks for replying
But you are confusing one main thing, IMO

I am overall using 2 things in tandem simultaneously.: and COMPUTER UPS +Home inverter (Details of which i posted in last post)

The Computer UPS used a 7V 7.2AH battery and is for short voltage fluctuations mainly. Inverter concerned here uses Lead battery (local but known to be good brand) indeed. (Earlier when i bought it it came with SMF Battery which i later replaced later on after its life)

So Computer+ modem load all goes to UPS > which goes to a socket powered by Inverter.
(In my case, i do not use GENERATOR anywhere)

Well it has to have a rectifier as my default its a AC to Ac adapter and Modem has to use DC in circuits right?

Anyway, till know i have been able to reach/filter the issue to INVERTER's type of AC (MSW) in this case
Voltage can also be a issue BUT if i go and fetch a AC to 13.5 AC 1.2Amp+ Adapter (which is not easy to find except getting a custom-made; I only can find 15V ones or 18v ones) The problem would be ,,,how would my Modem handle the extra volts when normal mains supply comes back? Wont high voltage fry it?

I mean when inverter's Voltage is converted to less than 12V by default adapter, the modem doesn't work properly. Inverter must be supplying less than 220V to Adapters primary circuit..thats why secondary of 12V is falling below 12 V right?
So accordingly when mains will throw few more than 220V, the secondary on adapter would prolly send > 14V ..causing issues right?

So in that case using a 13.5V Adapter (which itself is a chase to get one) is not logical or a solution..right?




and probably the issue will be sorted if i change over to Pure sine wave inverter or a Online UPS itself (the latter solution will be costly but perhaps end all the issues (including good backup)
 
  #14  
Old 07-03-12, 04:20 AM
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Try connecting the modem directly to the (fully charged) lead acid battery. Disconnect the charger and anything else from the battery first.

Also, find a friend who has a true sine wave inverter and see if your modem runs on it. You won't have an internet connection but you should be able to determine if the modem cuts off.
 
  #15  
Old 07-04-12, 04:15 AM
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Well to clarify again..
Modem Power never goes off, whether its mains or inverter feed (Its the ADSL signal LED...which drops)
Probably bcoz Inverter's switchover circuit is good/quick and further, even if not, modem is attached to UPS (along with other computer load)..& UPS is plugged into one of the inverter's output socket (Inverter supplies 1 fan +1 light each and every room & electrician has kept 2 sockets too for normal usage in most rooms)

find a friend who has a true sine wave inverter and see if your modem runs on it.
Thats easy but whats the point after i informed above.
Finding a friend with same adsl broadband and sinewave is difficult. Thats what i was thinking about.

Anyhow... i am getting too suspicious to the fact that MSWave of Inverter is indeed the culprit rather than relatively ~0.5 low voltage from inverter than mains. (These inverter manufactures also advertise consumers to buy pure sine wave inverters to run all equipment (all equipment like word they dont use on other non-pure wave models)

As an all time solution..
Now i am considering a ONLINE UPS itself for my computer load(which is about 10 times as costly than normal singe battery offline UPS; reason for delaying to buy it)..
as firstly ALL supply will come from Online UPS itself and it will be surely pure sine wave 12V AC ( I am looking for international quality brand like APC; Lower crest factors too (as someone informed))
unlike OFFLINE ups which switchover to supply and thats how INVERTER's quality of output is involved in my case.
&
secondly, it will be another means of better backup (which won't put much load on home's inverter )

Thanks for replying again rick.
Regards
 
  #16  
Old 07-04-12, 05:01 AM
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All this time I have been responding as if the modem itself was shutting off, but after re-reading your first post I see that it is only the DSL signal that gets dropped. What threw me off track was the SMPS not powering it.

Are you able to maintain the link when connected directly to the battery, and with nothing else connected to the battery?
 
  #17  
Old 07-04-12, 06:08 AM
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another post coming after this ..writing on pdA

well then you wasted your precious time responding and mine too ...replying to troubleshooter :P

Indeed Computer's SMPS 12v molex connector (yellow and black ground connection) was not able to keep ADSL alive (It does power on too). In that case, even when there is normal mains fed to computer's UPS..ADSL never remains static. Further may be as someone else informed on another forum ..not an good idea supplying DC power to a AC modem (as it required 12V ac as per specifications. The guy talked of diodes going dead sooner or later..even if that works)

Anyway..
 
  #18  
Old 07-04-12, 06:24 AM
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Ok i tried powering it thru inverter only and no other load on latter. Results prolly stand out
I measured voltage across that inverter socket too with a cheap digital meter n here r results ( I checked for 5 min each )

Only modem load --- ADSL static, 247-248V (245-252V)
Switched on UPS on same socket (using extension)- ADSL drops as before ,259-260V (258-264V)

The voltage range is brackets what I got on digital.meter when I switched red and black wires of multimeter between power socket's 2 holes i.e. phase n neutral. That has larger range as you can see. Not sure what that means

So final judgement Rick ? Voltage is the Actual issue.?
The fact that ADSl used to remain static early on for 1.2 minutes when mains used to go off..also means charged battery (& thus inverter ) sends better voltages early on for few minutes.

So we have found out th REAL reason?



EDIT
WAIT WAIT..
Why the hell i am getting larger voltages when adsl is dropping? This is surely confusing! I thought we should get lower voltages ..when more load is there on inverter ? What am i missing ? Is adsl drop due to higher voltages?
 

Last edited by DlinkMan; 07-04-12 at 06:41 AM.
  #19  
Old 07-07-12, 12:15 AM
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......................Rick?
 
  #20  
Old 07-07-12, 09:11 AM
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Dlink, have you tried sending a PM to Rick?
 
  #21  
Old 07-07-12, 09:35 PM
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Nope.. not as yet.
Should i ?(I have seen some people getting offended by that; as its already being discussed here)
 
  #22  
Old 07-08-12, 04:06 AM
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I'm here. Life in the real world got a bit busy for the past couple of days. I am at a loss, however, to further suggest or explain why the modem is dropping out after a couple of minutes.

Have you tried connecting it to a fully charged battery that isn't connected to anything else?
 
  #23  
Old 07-08-12, 08:54 PM
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Hi rick. Hope everything is fine.
Yes, as i explained in post 18, i tried connecting only modem to the inverter (taking all other home load off inverter)
I measured voltage across that inverter socket too with a cheap digital meter n here r results ( I checked for 5 min each )

Only modem load --- ADSL static, 247-248V (245-252V)
Switched on UPS on same socket (using extension)- ADSL drops as before ,259-260V (258-264V)
The voltage range is brackets what I got on digital.meter when I switched red and black wires of multimeter between power socket's 2 holes i.e. phase n neutral. That has larger range as you can see. Not sure what that means
On inverter load, ADSL never dropped (not for 5-10 minutes i checked) & i think will not drop till i keep using it for a long time(discharging a lot of inverter battery)
When i Switched on UPS on same socket, ADSL started dropping just like usual (the main issue)
By "Switching on the UPS on same socket", i mean adding addition load along with modem i.e. UPS getting power from inverter too & charging itself (& thus increasing the load; I didn't power on the PC and monitors, connected to UPS sockets though; which will of course add more load to inverter)

So i hope things are now clear enough for you to understand? So what do you think is the issue?
(The only reason i see for adsl not dropping on full load (even PC powered on) for early 1-5 min... is probably early on battery is able to provide good backup, due to charge but later voltage dies down than the required)


 
  #24  
Old 07-09-12, 03:20 AM
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It is obviously not responding to the modified sine wave of the inverter. That's why I suggested a big battery to power the modem during your sessions. Charge the battery with the inverter when you're not using the modem.
 
  #25  
Old 07-09-12, 03:46 AM
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Rick, sorry for being a regular bugger
BUT
i think you are still not able to understand whats my power setup is like. (it may be different in my country (in south ASIA) than yours)
Kindly read below once again and then try to imagine what i am trying to my posts lately.

All Computer load (Modem CONCERNED, Monitors, CPU, GPU, HDD, SSD's Etc) Is plugged into a single battery UPS (Single battery; Sealed ; 12v 7.2Ah). Its kind of local power backup for PC components and stuff. Kindly dont confuse UPS with Inverter (if you are doing so)

This UPS is plugged into a Wall port which is powered by a home (MSW) Inverter, powered by a Lead Acid Tubular battery (needing Distilled water regularly), kept at an isolated corner of house (fume prevention)

This inverter is plugged into into house's mains power supply for charging the battery when mains is "LIVE". Otherwise it just powers 1 light +1 Fan +1 5Amp Socket in each room of the house.(One of the sockets is in use in our case)

When i tested (details of which i posted before) Inverter battery is charged to 80%-90% (its impossible to charge to 100% percent as mains keeps going off and On due to power cuts)
Firstly, i switched off all lights and fans and sockets powered by that home inverter. Then switched the Mains OFF
Then plugged out the modem adapter from PC UPS & directly plugged into one inverter powered socket.
RESULT: On only modem load --> ADSL static (>5-10 minutes; NO issues),


Secondly, kept modem plugged in & plugged UPS socket too (i.e Powered on the UPS too) on same socket (using extension switch). (PC load is still not there i.e. PC is switched off, just its UPS is switched on. So indirectly that means UPS's battery is charging off inverter's supply )
RESULT: On both modem + UPS load ---> ADSL drops continuously as before ,259-260V (258-264V)

Voltage In socket: 247-248V (245-252V)
(voltage range is brackets what I got on digital.meter when I switched red and black wires of multimeter between power socket's 2 holes i.e. phase n neutral.)

have you understood this all before and i am repeating myself or
i am able to express myself clearly now?


So does it mean that Voltage decreases more than required when more load (UPS) is connected and So the ADSL drop issue?
If yes, why the voltage readings in sockets increase on larger load?


 
  #26  
Old 07-10-12, 04:03 AM
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Yes, I understand what is happening, and I can't definitively explain why it is happening.

I've heard some tales of issues caused by improperly-wired plugs (pins reversed) on 240-volt devices, but I can't see how that could affect a modem running off a transformer.

It is possible that the UPS could be backfeeding a noise element onto the inverter's power output that the modem doesn't like, which may also explain the voltage increase.

My suggestion would hopefully treat the symptom and ignore the cause: See if the modem works when connected to a separate, dedicated battery. If it does, use it that way and charge the battery when you're not using the modem. At that point you're also one step closer to finding the cause.
 
  #27  
Old 07-10-12, 06:31 AM
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Yes the modem works (adsl doesn't drop) "when connected to a separate, dedicated battery." i.e. connected to home inverter (with all other load disconnected), as i explained in 1st scenario in last post.

The fact that i can't spend another 350-400$ or so (spent on home inverter+battery) just for powering the modem i think the option i see is buying a 2nd offline UPS (which won;t cost me more than 30$-50$...like the current one) & powering the modem through it.

So, at last, my options/solutions are:
1) New OFFLINE UPS for modem (which will remain disconnected from inverter supply; when mains are off)
2) NEW (& ofcourse costly) ONLINE UPS, for my whole computer & modem ), which is way different in working and better than offline UPS (current one) & will cut off inverter's wave or issues altogether as load connected to it always gets power from its batteries.
3) Getting a 220V to 13.5V >=1.2Amp AC adapter for present modem (As advised to me in another forum which will make sure modem gets the required voltage. There they think bcoz of MSWave of inverter, peaks and troughs are extreme causing issues)
4)Gettin a F**kin new modem altogether .... probably the one which requires DC input (as many good DC Switched mode power supply are there and probably better than the linear based stuff)
Any options you have in mind regarding a ADSL cum Router cum wifi .. good model (i read more good stuff about Cisco and netgear only)

I have 2 last questions
1)Based on previous findings....can you explain whether ADSL drop is due to to higher voltage or lower voltage?
2) If you are not sure about whether that was lower or higher voltage.... What logically should output from inverter supply...when higher load is connected to it.. voltage should increase or decrease.

Kindly reply to all point wise, if possible.

Regards & thank once again for bearing with me.
 

Last edited by DlinkMan; 07-10-12 at 08:39 AM.
  #28  
Old 07-10-12, 07:47 AM
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when connected to a separate, dedicated battery." i.e. connected to home inverter (with all other load disconnected),
If it is connected to the inverter it is not connected directly to the battery. Connected directly to the battery means just that no inverter, nothing but the battery. If it has a built in transformer that steps down the 220 to 13v Ac then you need to find a way to connect at the same point where the 13v DC goes to the modem. Or at least that is the way I keep reading what Rick is saying. If it uses an external power supply that puts out 13 volts be it AC or DC then the battery plugs in where the power supply normal plugs in. If it is 13 volts AC polarity shouldn't matter. If the power supply puts our DC then you need to make sure the polarity is correct.
 
  #29  
Old 07-10-12, 08:38 AM
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@ ray
The modem gets 12v AC from a simple transformer like power adapter for functioning (as per specifications). It has no built-in transformer
I am not sure when rick told me to connect that directly to battery.

If it uses an external power supply that puts out 13 volts be it AC or DC then the battery plugs in where the power supply normal plugs in.
You mean i should connect 12V Lead acid terminals and connect it to 2 wires of a pin like connector (like most modems have)?
If yes, is that just for checking purposes?
If yes, what exactly is the purpose of this checking?
(bcoz what i have learnt till now its a bad decision supplying DC voltage to a AC requiring modem; Some Diodes will give the ghost sooner or later)
Further i am not that techy guy (fear electric shocks/ damaged equipments more), i am not sure i can do that.
 
  #30  
Old 07-10-12, 09:00 AM
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Modern electronics do not run on AC. The modem does not run on AC. It runs on DC that the diodes change AC to. All the diodes do is convert the AC to DC so if DC it just passes through. The warning you got about premature diode failure makes no sense to me but wait for Rick to confirm.
 
  #31  
Old 07-10-12, 09:38 AM
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Well i have understood by now that MODEM (and other most electrical equipment ) work on DC

Regarding the diode thingy, this is what a techy has to say on another forum.
(I don't he/she was lying)
Do not connect an SMPS output to the AC input of an appliance. The AC input voltage of 12V is actually having a peak of about 17V, when the AC voltage is measured to be 12V. SMPS 12V DC output can never give that voltage, and would have shutdown well before reaching that kind of high voltage by the Overvoltage circuitry.
More importantly, the current goes goes thro' different paths (diodes) during positive and negative cycles of AC. With a DC input, the current is always thro' one path, which means double the current flows thro' one path and nothing in the other path. In these days of cut throat competition, the diodes are definitely not rated for double the current and will blow after a prolonged usage (if you are lucky).
SMPS 12V output is spec'd at +/-10% as against +5V which is +/-5%. +5V is normally primary rail which is regulated, and, +12V gets regulated indirectly with a wider margin.
 
  #32  
Old 07-10-12, 11:07 AM
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With a DC input, the current is always thro' one path, which means double the current flows thro' one path
Wrong IMHO. If the modem draws 3 amps it draws 3 amps. That doesn't change. There will be a 3 amp flow through the diode regardless of whether it is AC or DC. I suppose you could split hairs and say it draws a slightly less amps at maximum peak inverse voltage because of the slightly hight voltage but that is probably minimal and canceled out as any effect by voltage variations from transformer to transformer and variation in home actual voltage. Not an expert but that part of his explanation doesn't make sense to me.
 
  #33  
Old 07-11-12, 05:28 AM
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Thanks, Ray.

In an AC circuit the current alternates between positive and negative either 50 or 60 times per second (depending on the standard in your country). If the AC current is 1.2 amps, it passes first through one side of a diode bridge (rectifier) and then the other. If you connect a DC source to the rectifier instead of an AC source, only one side of the bridge will continuously handle the current, which is still 1.2 amps. It does not handle double the current. However, since it is now working full time instead of half the time, it may heat up. This should still not cause any issues in a properly designed supply, because the same amount of heat would be dissipated by both sides working. A properly designed supply would have an adequate heat sink.

As for peak voltage: AC voltage is measured by the root-mean-square (RMS) method, which works out to about 70% of the peak. A 12-volt AC supply is actually putting out peaks of around 17 volts. After it is rectified and filtered to reduce ripple, the peak voltage is still there (as ripple) until a load is connected to the supply, at which time the voltage drops.

DlinkMan, how did you connect it to the 12 volts supplied by the SMPS output? Isn't that DC?
 
  #34  
Old 07-11-12, 10:15 AM
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"DlinkMan, how did you connect it to the 12 volts supplied by the SMPS output? Isn't that DC?"
Yes i did connect it to SMPS when i didn't knew diode issue (not u r saying its not an issue either; i am still unsure). WHY i connected it to SMPS was thinking that may be the voltage fluctuations of inverter's supply are causing the ADSL drops and as i have a good quality COOLERMASTER SMPS for my PC, it would provide better 12V DC to my modem
I read about this in one forum. I used cut wire & output connector of an OLD (fried) default AC Adapter of same modem for the same. I connected it to MOLEX Connector of SMPS with yellow wire and black wire out of total 4 options in molex.
ALAS, things didn't work out even from that high quality almost static SMPS 12v Supply. ADSL almost never remained static. Neither on Inverter's supply to UPS nor on Mains !

Thats why i asked the following
You mean i should connect 12V Lead acid terminals and connect it to 2 wires of a pin like connector (like most modems have)?
If yes, is that just for checking purposes?
If yes, what exactly is the purpose of this checking?
 

Last edited by DlinkMan; 07-11-12 at 10:45 AM.
  #35  
Old 07-12-12, 05:40 AM
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Yes it's for testing (troubleshooting) but if it works and doesn't heat up beyond being warm to the touch you've treated the symptom. You can then use it while you continue to troubleshoot. You're one step closer to solving the problem.
 
  #36  
Old 07-12-12, 01:16 PM
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Well, as explained, it didnt work at all. The adsl never remained static. which either means DC voltage input is not liked by modem or it needs actually more than bit over 12v
 
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