Lynx I No power from Battery

[Izen]

Hi everyone,

 

I'm attempting to repair a Lynx I that has a broken battery compartment where the cartridge door snaps on (so the door won't close). I replaced the battery compartment with a replacement and I'm getting no power on the system. Works on the AC adapter, but can't get it to run with batteries. I checked the replacement with a multimeter and batteries and I'm getting 9V. I've tried de-soldering and re-soldering to no avail. Any suggestions? Thank you!

[+Stephen Moss]

I am not sure exactly what you did to replace the battery compartment, however if it involved de-soldering the original connector and soldering it onto the ne compartment are you sure you connect it and thus by extension the batteries the correct way round and are fully charged?

 

If you are certain of both those things then the ground connection for the battery voltage passes through two inductors and a switch within the power connector. Have you tried measuring the resistance between TP16 and Pin 7 of U6 with the batteries and AC adaptor removed?

If you measure close to 0 ohms with your meter leads connected in both directions then the connection is good and you can eliminate that as a possible cause. However, if you measure infinite resistance then there is an open circuit somewhere, could be a bad solder joint on the battery connector or a problem with the switch in the power socket but chasing the continuity through will reveal where the problem is.

 

If you can eliminate the ground connection as the source of the problem, look at the positive side, measure the resistance between the positive connection on the battery connector (the one mounted on the PCB) and TP15, if you measure close to 0 ohms the connection is good, if you measure infinite resistance the connection is bad, probably a bad solder joint on the batter connector.

 

At least that is where I would be looking as the rest of the circuitry is common to both battery and AC adaptor.

 

 

 

[Izen]

I'll need to check, thanks!

 

Yes, I de-soldered the old wires from the old battery compartment and soldered on new wires that are attached to the new compartment. Batteries are fully charged and are placed in the correct way. I'll need to pull the meter out again to check the different areas you mentioned. Thanks!

[Izen]

Ok, so I checked with my multimeter. Pin 7 of U6 and TP 16 give 0 ohms. I tried the positive connector from the PCB where the battery connector is soldered and got 2.7 ohms. This means I should try resoldering to get to 0? Thanks so much for your help.

[+Stephen Moss]

You say you are measuring 2.7ohms between the positive battery connector and TP16, was that a typo as it should have been TP15 or is that where you actually measured? I know there are difference between component numberings between the Lynx 1 and 2 but from the schematics I thought the TP's were the same.

That said I could not actually find TP15 on my Lynx 2 and had to measure between the battery connector and R74 and I measured 0 Ohms so that is definitely what you should be reading.

 

I would not have thought 2.7 Ohms would be sufficient to stop the Lynx working as that would be a 2.7v drop at one amp and I doubt the Lynx is consuming that much current, but it may be enough to prevent the Lynx turning on if the voltage is to low so you can try re-soldering the battery connector and see if that helps.

 

 

If that does not help measure the voltage between at the battery connector (both on the compartment when disconnected from the Lynx and at the connection to the Lynx PCB when connected) and at Pins 7 & 14 of U6, I would expect you to measure the same voltage at all those places.

 

[Izen]

Yes, that was a typo! Sorry. From pin 7 to TP15 was 2.7 ohms. I'm going to try soldering again. I've done it so many times with this, but another time can't hurt.

[Izen]

So I feel stupid. I tried soldering again. Worked before I closed it up. Closed it up and nothing. Opened again and noticed the negative terminal, where soldered to the PCB was lifting. I think when Ive been closing the shell it must be pulling too much on the wire. Im going to keep trying the system, but I hope this is it. Thanks for your help!

[+Stephen Moss]

If you overheat a pad when soldering it can melt the glue that sticks the copper to the fibreglass substrate causing it to lift, creating a weakness/intermittent joint usually where the pad meets the track.

 

Sounds like when under tension the cable is lifting the pad creating an open circuit, but when not under tension enough of a connection is re-establish to power the Lynx. You could try repositioning the wire so that it is not under tension when the lynx closed up, or getting a longer piece of wire (7/0.2 or 0.22mm² should do) so that it is not under tension when closed.

Because, there now appears to be a weakness where the negative connection attaches which may eventually fail altogether you may want to consider reconnecting it somewhere else such as the cathode (end with black line) of D19.

[Izen]

Thanks! Appreciate all your help!

[Passive Matrix]

I just picked up a Lynx 1 with the same problem. Works fine on AC but nothing on DC. I replaced the power jack with a new one but nothing changed. I played a game for a few minutes on AC while the batteries were still inside and I noticed they got considerably warm which worried me a bit. I'm thinking of replacing all the common failure points in the power circuit and replacing all the caps. Is there anything else I should do or check before I go ahead with the new caps and power parts?

[+karri]

One very common cause is that the two last batteries inside the compartment are stuck. So when you take out the batteries you only get 4 batteries. Not 6. After a few years the remaining 2 batteries start leaking and getting very hot.

[Passive Matrix]

One very common cause is that the two last batteries inside the compartment are stuck. So when you take out the batteries you only get 4 batteries. Not 6. After a few years the remaining 2 batteries start leaking and getting very hot.

I used 6 fresh batteries and the battery compartment looked fine with no corrosion or anything like that. Is it possible for AC power to reach the batteries if a component it faulty?

[+Stephen Moss]

Have you measured the voltage across D18/C66, the point where the battery compartment attaches to the PCB & across between Pins 7 & 14 (diagonally opposite corners) of U6 to establish if power from the batteries is reaching key parts of the PCB? If not I would start there.

 

Positive voltage from the power unit will always reach the positive terminal of the battery pack via D11 as both positives are permanently ties to the +9V rail. The 0V connection is switched via the power socket. When the power supply is inserted into the power connector the switch contact between pins 2 & 3 of the power connector should be opened thereby disconnecting the battery 0V connection from the main power in 0V and that of the power supply.

Consequently if you have replaced the power connector with an exact replacement and it is operating correctly there are only two possible reasons why the AC power would be getting to both terminals of the battery pack, a short circuit of D19 & a solder short between pins 2 & 3 of the power connector either of which is effectively the same as the switch remaining closed.

 

However, if you have replaced the power connector with wrong part (same size but switched differently) or you have the correct part but it is defective (essentially keeping the switch closed) that may be the reason for the issues you are reporting. Unfortunately I do not have access to my Lynx until Monday so I cannot check which pins are 2 & 3 however I believe these were the ones used for both the Lynx 1 & 2 (the top one worked on my Lynx 2), the pins are shown from the underside of the PCB. So if you have multimeter make, remove the batteries and power plug and ensure there is no resistance (a reading near 0 ohms) between pins 2 & 3 then with the power supply plug inserted (but power unit off) I would expect a reading or either around 1000 or infinite/very high resistance between pins 2 & 3 depending on which pin is commented to the COM lead of your multimeter.

[GadgetUK]

I also noticed on the MK1 Lynx, what happens is rechargeable batteries dont make a good connection (they are a bit shorter I think - by a tiny amount). So when rechargeables are in there it wouldnt work. I solved that by stretching the contacts a bit on mine.

[Passive Matrix]

So I managed to fix this problem with minimal effort. Somebody had already been inside this unit and had soldered the battery compartment to the motherboard incorrectly. The positive wire was connected to the pad intended for ground and vise versa. I just had to reverse the wires and the Lynx powered up from batteries just fine. There was definitely a short going on before I fixed it because whenever I put fresh batteries inside it they got noticeably warm.

 

Stuff listed as junk on eBay can often be fixed with the smallest adjustments.

[power]

So I managed to fix this problem with minimal effort. Somebody had already been inside this unit and had soldered the battery compartment to the motherboard incorrectly. The positive wire was connected to the pad intended for ground and vise versa. I just had to reverse the wires and the Lynx powered up from batteries just fine. There was definitely a short going on before I fixed it because whenever I put fresh batteries inside it they got noticeably warm.

 

Stuff listed as junk on eBay can often be fixed with the smallest adjustments.

 

never underestimate the ability of someone to break something then sell on ebay.

 

checkout this PS4 video I watched last night - the amount of stuff wrong with the unit is astonishing. The ebay seller of course lied through their teeth.