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Naomi netDIMM board battery replacement

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Category: Technical
Forum Name: Tech, Maintenance & Repairs
Forum Description: Need Help? Ask Here
URL: http://www.ukvac.com/forum/forum_posts.asp?TID=356839
Printed Date: 24 May 2017 at 8:36pm


Topic: Naomi netDIMM board battery replacement
Posted By: big10p
Subject: Naomi netDIMM board battery replacement
Date Posted: 07 Mar 2017 at 8:34pm
From what I've read, the battery fitted to the netDIMM boards only work for a few days before going flat, so by 'replacement', I mean a power supply (preferably UPS) that will keep the game/data loaded on the DIMM, even if the cab isn't used for a couple of weeks.

This would be great for my dedicated Shootout Pool cab, as it would mean the ranking tables don't get wiped every time the cab is turned off. It would also shorten boot up time a fair bit.

I found http://forums.arcade-museum.com/showthread.php?t=302266" rel="nofollow - this thread on KLOV that discusses a solution, but I'm no electronics whizz, so don't fully understand how to build it. Has anyone build something like this, and can give a few pointers on exactly how to make one? Or even better, does anyone make and sell them?

Cheers



Replies:
Posted By: terminator2k2
Date Posted: 07 Mar 2017 at 10:03pm
Just taken this from my Daytona USA 2 thread in the make section, I did this on my chihiro , I can't find the original thread though....

well just a small update.....ive been doing the battery backup mod as done by a few members on here....
pictures not the best.....This will be mounted on the rear of the cab in the empty space....



Posted By: terminator2k2
Date Posted: 07 Mar 2017 at 10:09pm
It uses a 12 v battery and a ups backup system. This is charged by a 15 volt dc supply.....it then goes to a voltage regulator which steps the voltage down to 7.2v which the original battery was rated at....a diode is fitted on the output to stop any voltage leaking back to the battery mod from the chihiro.....

I use a mains adapter with built in timer , so the 15v adapter only charges the battery for 2 hours a day....and not continuously......


Posted By: big10p
Date Posted: 07 Mar 2017 at 11:23pm
That looks like just the setup I'm after. I didn't realize it's a well-known mod, as nothing came up when I was searching for info (except the link I posted).

I still don't quite understand exactly what all the components are, and how they're wired, TBH. If I build something like this, I want to be sure I know what I'm doing, and not make something that's either going to damage my Naomi/netDIMM, or create a fire hazzard! It would be really useful if you could post some links to all the bits I need ( http://www.ebay.co.uk/itm/Leoch-LP12-7-0S-12v-6-5ah-Lp-Series-Agm-Lead-Acid-Battery-/361852179596?hash=item544012148c:g:gg4AAOSw5cNYgiPt" rel="nofollow - think this is the battery you used? ), and go in to more detail about how to wire it up.

Cheers!


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Posted By: obcd
Date Posted: 08 Mar 2017 at 8:43am
Basically, the original lithium 7.4V battery is removed and replaced by a 12V gel PB accu. On the picture, it looks like a 7AH type, but other types can work as well.
 
As the Naomi needs 7.4V, a step down converter is used to change the 12V accu voltage to 7.2V.
This is a module you can buy premade.
 
When the Nedimm (Naomi) is turned on, it sends voltage to the lithium accu to charge it. This behavour is blocked with a diode between the output of the step down converter and the Netdimm accu connection.
 
Third thing that you need is a charger for the 12V gel accu. That's again a premade module. It limits the charging current that goes to the battery. It needs a 15V input voltage. (The input voltage must be higher than the battery voltage)
 
The original netdimm battery has 3 contacts. The black is ground. The red is the output voltage and the blue is a thermistor (or ntc?) to measure the battery temperature. It's function is to stop charging the lithium batteries if they become 2 hot. The wires go to a small pcb that sits on top of the batteries. Normally such pcb should prevent deep discharge of the battery pack as such can damage lithium batteries. It should also stop charging them if the voltage has reached 4.2V (1 cell) Further, it should do some load balancing to ensure both cells are charged equally.
 
It has been described in detail for a chihiro 3 "outrun 2 sp" setup. When the netdimm batteries on that run flat, it loses it's high scores and network setup. (and the game code itself obviously)


Posted By: terminator2k2
Date Posted: 08 Mar 2017 at 9:49am
Heres a thread :

http://www.ukvac.com/forum/outrun-2-sp-battery-back-up-modification_topic341050_post862147.html?KW=#862147" rel="nofollow - http://www.ukvac.com/forum/outrun-2-sp-battery-back-up-modification_topic341050_post862147.html?KW=#862147

theres links on that thread to get the stuff needed on ebay.....

Is the battery in the Naomi the same as the chihiro? ive never messed with a naomi net dimm so wouldnt know...




Posted By: seanr28
Date Posted: 08 Mar 2017 at 10:40am
Originally posted by terminator2k2 terminator2k2 wrote:

Heres a thread :

http://www.ukvac.com/forum/outrun-2-sp-battery-back-up-modification_topic341050_post862147.html?KW=#862147" rel="nofollow - http://www.ukvac.com/forum/outrun-2-sp-battery-back-up-modification_topic341050_post862147.html?KW=#862147

theres links on that thread to get the stuff needed on ebay.....

Is the battery in the Naomi the same as the chihiro? ive never messed with a naomi net dimm so wouldnt know...



yes they are the same batteries used.


Posted By: big10p
Date Posted: 08 Mar 2017 at 11:39am
Cheers for the info, fellas. Somehow I missed the schematic in the link I posted, when I scanned through the posts.

Chris: from your pics, looks like you haven't fitted any fuses? I also can't see where you've fitted the diode?


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Posted By: terminator2k2
Date Posted: 08 Mar 2017 at 12:52pm
Originally posted by big10p big10p wrote:

Cheers for the info, fellas. Somehow I missed the schematic in the link I posted, when I scanned through the posts.

Chris: from your pics, looks like you haven't fitted any fuses? I also can't see where you've fitted the diode?

The diode is on the output of the regulator and soldered to the wire , then insulated with a bit of heat shrink..possibly why you cant see it...

Fuses.....yes i missed them out , but im going to fit 1 between the battery and the micro ups....

generally speaking the power supply (charger) should have it own internal  fuse, and the fuse on the output will only protect against short circuits in the cable run , or from the naomi/chihiro (which should be very rare  unless you put too much voltage through it imo)

Fit them for peace of mind......

you will get a 0.6v drop across the diode this is normal......so my regulator is set to 7.8v - 0.6v = 7.2v

ive also seen mo's post about the voltage being over 9v once connected to the chihiro and the chihiro powered on .....i think this would be normal as the chihiro would be trying to charge the original battery.....The only way to really find out would be to check the voltage on a good battery in a chihiro , with the chihiro running.....i would say it would roughly the same......




Posted By: big10p
Date Posted: 08 Mar 2017 at 1:58pm
I see - thanks. I think I will just do the same as you. What type/rating of fuse is needed, between the battery and micro UPS?

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Posted By: terminator2k2
Date Posted: 08 Mar 2017 at 5:15pm
This is what i got:

http://www.ebay.co.uk/itm/200933520834" rel="nofollow - http://www.ebay.co.uk/itm/200933520834
http://www.ebay.co.uk/itm/332063048494" rel="nofollow - http://www.ebay.co.uk/itm/332063048494
http://www.ebay.co.uk/itm/232128214645" rel="nofollow - http://www.ebay.co.uk/itm/232128214645
http://www.ebay.co.uk/itm/151146839962" rel="nofollow - http://www.ebay.co.uk/itm/151146839962

you could possibly source the battery closer to home unless you trust batteries in the post.....the seller on ebay was only 10 minutes away from me....

for the fuse , i would go with a 5amp fuse....shouldnt need anything higher.....


Posted By: richmal
Date Posted: 08 Mar 2017 at 6:41pm
If you do this modification to the dimm board battery do the games load any faster?
Just wondering


Posted By: big10p
Date Posted: 08 Mar 2017 at 7:09pm
Originally posted by terminator2k2 terminator2k2 wrote:

This is what i got:

http://www.ebay.co.uk/itm/200933520834" rel="nofollow - http://www.ebay.co.uk/itm/200933520834
http://www.ebay.co.uk/itm/332063048494" rel="nofollow - http://www.ebay.co.uk/itm/332063048494
http://www.ebay.co.uk/itm/232128214645" rel="nofollow - http://www.ebay.co.uk/itm/232128214645
http://www.ebay.co.uk/itm/151146839962" rel="nofollow - http://www.ebay.co.uk/itm/151146839962

you could possibly source the battery closer to home unless you trust batteries in the post.....the seller on ebay was only 10 minutes away from me....

for the fuse , i would go with a 5amp fuse....shouldnt need anything higher.....
Thanks for that. One last question. Big smile Do you know what size the crimp connectors (yellow ones, in your pics) are? They look like they're bigger than ones I have in stock, so will have to order some.

Originally posted by richmal richmal wrote:

If you do this modification to the dimm board battery do the games load any faster?
Just wondering  
Should load plenty faster, as the game is held on the netDIMM. It then just gets loaded onto the Naomi when it's switched on. Should basically be like having a cart of the game. Smile


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Posted By: terminator2k2
Date Posted: 08 Mar 2017 at 7:15pm
Originally posted by richmal richmal wrote:

If you do this modification to the dimm board battery do the games load any faster?
Just wondering

it keeps the last game in the dimm memory , so no need to keep loading the game on bootup.....

if you change the game, you still have to load it into memory.....so no it doesnt make loading up any faster,  it just saves your last game.....

it helps folks like me that run 1 game permantley in a cab...or if you dont change that often...




Posted By: terminator2k2
Date Posted: 08 Mar 2017 at 7:20pm

Quote
Thanks for that. One last question. Big smile Do you know what size the crimp connectors (yellow ones, in your pics) are? They look like they're bigger than ones I have in stock, so will have to order some.

i dont sorry.....i found them in my box of bits and bobs LOL


Posted By: big10p
Date Posted: 08 Mar 2017 at 7:26pm
Originally posted by terminator2k2 terminator2k2 wrote:


Quote
Thanks for that. One last question. Big smile Do you know what size the crimp connectors (yellow ones, in your pics) are? They look like they're bigger than ones I have in stock, so will have to order some.

i dont sorry.....i found them in my box of bits and bobs LOL
Gotta love boxes of bits and bobs. Big smile No worries, I might just order a set of assorted ones.


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Posted By: big10p
Date Posted: 18 Mar 2017 at 12:07pm
I've almost finished building and fitting this, but the diodes I ordered must have got lost in the post, or something. Confused Now I'm having trouble finding somewhere else that sells the diode - even RS don't seem to have them. Do I have to use a 1N4008 diode, or will something else do?


Posted By: big10p
Date Posted: 18 Mar 2017 at 2:06pm
Looks like I have a few 1N4007 diodes on an old chassis. Will they do?


Posted By: obcd
Date Posted: 18 Mar 2017 at 4:36pm
1N4007 is fine. The last number is just the reverse breakdown voltage. In your case, it should withstand 7 - 8V. The 1N4007 can handle up to 700V if I remember well.


Posted By: big10p
Date Posted: 18 Mar 2017 at 4:38pm
Originally posted by obcd obcd wrote:

1N4007 is fine. The last number is just the reverse breakdown voltage. In your case, it should withstand 7 - 8V. The 1N4007 can handle up to 700V if I remember well.
Cheers!


Posted By: big10p
Date Posted: 18 Mar 2017 at 7:02pm
Hmm, something odd is happening...

I read 7.2v on the regulator output terminals, on mains power and battery power, but the voltage I read after the diode goes up to around 9v, when using mains power - how can this be?! Confused Maybe I'm just tired and starting to see things...


Posted By: terminator2k2
Date Posted: 18 Mar 2017 at 10:40pm
Originally posted by big10p big10p wrote:

Hmm, something odd is happening...

I read 7.2v on the regulator output terminals, on mains power and battery power, but the voltage I read after the diode goes up to around 9v, when using mains power - how can this be?! Confused Maybe I'm just tired and starting to see things...

With the naomi powered off is the voltage 7.2v after the diode?

with my chihiro on i get roughly 9v after the diode....powered off it reads 7.2v  , i think this is just the naomi/chihiro charging voltage for the original battery....

if your original battery is ok, remove the new battery/charging system and try putting it back as it was with the original battery  with the naomi on and check the voltage again just to compare.....


Posted By: obcd
Date Posted: 19 Mar 2017 at 8:10am
It's difficult to compare it with the old battery as that one will charge. So, it will basically form a load on the charging voltage. The new charging system has no load as the diode prevents current from going into that direction. You shouldn't worry about the 9V. It's normal. The voltage of a charged lithium cell can go up to 4.2V. 2 such cells in serie are 8.4V. The 9V is just above that voltage. Their is a small pcb on top of the batteries that has a thermistor to measure the battery temperature and some electronics for BMS and charge control. So, basically, when the batteries are fully charged, the charging voltage is cut off to prevent over charging and damaging the batteries. Also, when their voltage becomes 2 low (fully discharged) they are disconnected to prevent damage of the batterie cells.


Posted By: big10p
Date Posted: 19 Mar 2017 at 12:26pm
So, is feeding around 9v into the Naomi OK, then? I tested without plugging into the Naomi and was just surprised to read 9v output when the mains adapter was powering the system, but 7.2v when running on battery power.

I think I must have a fundamental misunderstanding of what's happening. The regulator is outputting a constant 7.2v (whether powered by battery or mains), yet - somehow - the diode seems to up the voltage to around 9v when mains power is used.


Posted By: obcd
Date Posted: 19 Mar 2017 at 1:40pm
When the naomi is turned on, it's producing the 9V to charge the battery that was original there. Even if you disconnect the regulator from the dimm board, you will measure 9V on the dimm board connector when the system is on.
The diode is there to prevent that voltage to go to the regulator.


Posted By: big10p
Date Posted: 19 Mar 2017 at 2:13pm
Yes, I get that, but I'm getting 9V from the plug that connects to the Naomi DIMM, when it's not plugged into the Naomi (and the Naomi isn't even on). I think I better double check the readings today.


Posted By: obcd
Date Posted: 19 Mar 2017 at 5:12pm
Ok. I misunderstood that. So you have 7.2V on one side of the diode and 9V on the other side?
Maybe your meter battery is on it's way out and that is causing wrong readings.
If the diode is placed correctly, you should measure 0.6 - 0.7V lower on it's kathode. So, that should be 7.2 - 0.6 = 6.4V maximum.
To compensate that voltage drop, you might need to set the voltage a little above that 7.2V
 


Posted By: big10p
Date Posted: 19 Mar 2017 at 6:17pm
Originally posted by obcd obcd wrote:

Ok. I misunderstood that. So you have 7.2V on one side of the diode and 9V on the other side?
Yes, that's right.

Quote Maybe your meter battery is on it's way out and that is causing wrong readings.
I thought that may be the reason, so replaced the battery with one I found in a drawer, but got the same readings. So, maybe that was flat, too - or my meter is faulty. It's just weird that I only get the high reading when the UPS is being powered by the mains adapter. It reads OK when powered by the battery.

Anyway, I dug out my old meter, and I'm getting the correct/expected readings using that! I'll get a new battery for my 'good' meter and see if that sorts it.

Quote If the diode is placed correctly, you should measure 0.6 - 0.7V lower on it's kathode. So, that should be 7.2 - 0.6 = 6.4V maximum.
To compensate that voltage drop, you might need to set the voltage a little above that 7.2V
I seem to be getting a .4V drop across the diode, but I guess that may be because I'm using a 1N4007, which has a lower rating than the 1N4008?

Cheers!


Posted By: obcd
Date Posted: 19 Mar 2017 at 7:27pm
The voltage drop depends upon the current passing trough the diode.
If it's unconnected on one site, it's only the current of your meter that will flow trough it.
On a good diode, it should never exceed 0.8V. The 1N4007 can handle up to 1A. Your meter current is maybe 1 uA.


Posted By: big10p
Date Posted: 19 Mar 2017 at 7:45pm
I see. Thanks.


Posted By: big10p
Date Posted: 20 Mar 2017 at 8:13pm
OK, I've finally got everything connected up and switched on. All looks good, and no strange readings, now the system is connected and under load. Here's a few pics...

After removing a couple of unused PSUs (for the hopper and hopper controller PCB) from the base board, there was just enough room to fit the UPS system next to the sound amp:


There's a convenient recess in the back of the cab, so I fitted the mains adapter there, making it simple to unplug, if/when I need to shift the cab:


And here it is, installed and working in the cab:


So now (fingers crossed), no more net booting or loss of high scores or ranking tables! Smile

Thanks for all the help, fellas! Thumbs Up


Posted By: terminator2k2
Date Posted: 20 Mar 2017 at 11:44pm
nice job.....i have my ac adapter on a timer plug , and let it charge for 2 hours a day just to make sure its keeping the battery charged up....


Posted By: big10p
Date Posted: 20 Mar 2017 at 11:58pm
Originally posted by terminator2k2 terminator2k2 wrote:

nice job.....i have my ac adapter on a timer plug , and let it charge for 2 hours a day just to make sure its keeping the battery charged up....
Yep, I'm doing the same. Smile I figure 2 hours a day should be plenty to keep it topped up.


Posted By: Rone
Date Posted: 21 Mar 2017 at 6:38am
never seen such a backside style at a sega racing mashine...


Posted By: big10p
Date Posted: 21 Mar 2017 at 11:23am
Originally posted by Rone Rone wrote:

never seen such a backside style at a sega racing mashine...
Racing machine? It's a Shootout Pool cashcube cab.



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