little Naki project

[Laxeybobby]

1 hour ago, karri said:

It sounds that you don't get the amps. My guess is that the power pack has some hidden resistance and the voltage turns into heat on its way to the Lynx. Bad wires?

 

Even 6V should be enough if you can provide some 500mA of current.

How would I test for this?

In replacing the batteries, all I did was desolder the wires from the start and end of the group of batteries. (Old batteries are yellow)
I know that there is a resister in the wiring but I left that alone. 
Once I soldered the new batteries (blue) together I just resoldered the wiring as it was. (If that makes sense)

Edited September 4, 2020 by Laxeybobby
Uploaded pictures to help

[Laxeybobby]

Problem is I don’t have enough knowledge to fault find the issue. 
Both my Lynx 2’s have the new LCD screens so should be less draining on the batteries. 
Is there anyone on this group in the UK that is electronically minded that could easily solve the issue. I’m happy to post the pak and pay for return postage? 

[+karri]

The problem is in the short black wire. It is very thin. It is not properly soldered. I can see the strains sticking out in the photo. Also I wonder what the resistance might be from the short black wire to the Lynx connector. It should be around 0 ohms.

[Laxeybobby]

4 minutes ago, karri said:

The problem is in the short black wire. It is very thin. It is not properly soldered. I can see the strains sticking out in the photo. Also I wonder what the resistance might be from the short black wire to the Lynx connector. It should be around 0 ohms.

I’ll have a go a replacing that wire today. 
From the batteries that wire goes to two resistors (band colours brown black brown) they inturn connect to the charging socket. 

[+karri]

My guess is that there is just one resistor that limits the current by which you charge the batteries. In parallell with the resistor I believe there is a diode that allows you to get the current to the Lynx when you are playing using batteries only. If this diode is broken then the current will only flow through the resistor and the Lynx does not power up.

 

When you connect external power my guess is that the power goes directly to the Lynx and it always powers up. At the same time there is probably a small current going towards charging the batteries. The diode prohibits the big current to flow to the batteries from the external power.

 

I may be wrong. This is how I believe it works. So I would test the diode with a multimeter. The current should flow easily from the battery to the Lynx and just a little through the resistor from the Lynx to the battery.

[Laxeybobby]

1 hour ago, karri said:

My guess is that there is just one resistor that limits the current by which you charge the batteries. In parallell with the resistor I believe there is a diode that allows you to get the current to the Lynx when you are playing using batteries only. If this diode is broken then the current will only flow through the resistor and the Lynx does not power up.

 

When you connect external power my guess is that the power goes directly to the Lynx and it always powers up. At the same time there is probably a small current going towards charging the batteries. The diode prohibits the big current to flow to the batteries from the external power.

 

I may be wrong. This is how I believe it works. So I would test the diode with a multimeter. The current should flow easily from the battery to the Lynx and just a little through the resistor from the Lynx to the battery.

Are you referring to the battery pack or the internals of the Lynx?

I’ve taken a picture of the wiring in the Battery pack and there are just two parallel resistors 100ohms each resistor which gives a resistance value of 50ohms. 
There is no diode. 

[+karri]

Thanks for clarifying. So the long white wire will go directly to the Lynx. There must be some magic in the power socket that works as a switch then. When you plug in power the short white wire is disconnected from the long white wire and when you remove the plug it is connected.

 

The resistors are there only to limit the loading current when the power plug is inserted.

 

So the next question is to check if this switch mechanism in the socket is broken. It could be dirty and have a large resistance.

[Laxeybobby]

54 minutes ago, karri said:

Thanks for clarifying. So the long white wire will go directly to the Lynx. There must be some magic in the power socket that works as a switch then. When you plug in power the short white wire is disconnected from the long white wire and when you remove the plug it is connected.

 

The resistors are there only to limit the loading current when the power plug is inserted.

 

So the next question is to check if this switch mechanism in the socket is broken. It could be dirty and have a large resistance.

Firstly thanks for your continued help. 
So I’ve looked at the power in socket and it looks just like a socket. Couldn’t see anything that would suggest some form of electronic switching. 
(Tried to provide a closer picture)

The resistance is 50 ohms created by the two 100ohm resisters in parallel. They are in series to the negative of the battery group and the pin that feeds the negative that would go to the Lynx. 
I’ve also put my ohm meter from that pin to the negative part of the plug that would be inserted into the Lynx and that gives zero ohms. 
My volt meter states that the batteries as a group are at 8.5v (I’m not sure what voltage they should be at all fully charged but as they are 1.2v, 24000mAh each I’m assuming that voltage is ok) 

 

I just don’t know enough about electronics to know what’s going wrong. 
I think I’m just going to give up on it.