Another Lynx 2 "No Power" Troubleshooting Question

[SkydivinGirl]

Hey everyone!

 

I recapped a non-functional Lynx 2, which had some minor leakage and corrosion around some caps, and I replaced the power components with Console5's rebuild/refresh kit.  I'm still not getting power.  I read through as many posts here as I could on the subject but wasn't able to make any progress.  Here's what I've done.

 

- Verified the start button functionality.

- Jumpered the cart port so it thinks there's a cart in the slot.

- Measured voltages.  I have 9V coming from the battery terminals (hooked up to a bench power supply).  I don't have a power cord so connecting to the battery terminals was the easiest solution.

-- Testing from TP16 to PIN 14 on U6 shows the 9V from the battery supply.  I am unable to get readings from the other pins on U6.  For example, PIN 1 is 0V.

-- Testing the 5V rail returns 0V.

 

From my limited knowledge, I'm thinking U6 may be bad.  I'd really appreciate any information anyone may have that could help.

 

Thank you,

 

Heather

[+-^CrossBow^-]

Solder some clipped leads off some caps or wires to the vias/leads where C41 is. Set your bench supply to +5 and attach it to those leads you soldered in off C41. Put a game in it and then power on your supply to see if the Lynx starts up and plays normally at that point. If so, then it is likely to be an issue with U6. I've had to replace that little guy at least once in a Lynx II sent to me for service about 2 years ago I think?

[SkydivinGirl]

Thank you SO much for taking the time to reply to my question.  It really is appreciated.

I wanted to try applying 5V but wasn't sure about the best connection point.  Looking at the schematic and your suggestion makes sense to me.  I hooked up to those locations and the system lit right up! Everything seems to be working perfectly.  I had already ordered a replacement U6 before you replied so I'll wait for that to come in and swap it out.  I'll share a few pictures here once I'm done.

Thank you!

Heather

 

[+Stephen Moss]

16 hours ago, SkydivinGirl said:

Testing from TP16 to PIN 14 on U6 shows the 9V from the battery supply.  I am unable to get readings from the other pins on U6.  For example, PIN 1 is 0V.

Check the continuity between pins 2 & 3 of the power socket as it could be a problem with the GND connection (although I would expect all pins of U6 to read VCC rather than 0V), if that is the problem and it lies with the power connector it will read open circuit when it should read short (without an AC power unit connected).

Alternatively if it is a GND problem it may just be with the continuity between TP16 and Pin 7 of U6, you could try checking it with a meter but the pressure from the meter probe in pin 7of U6 while doing so may "make" any bad solder joint resulting in it looking ok, so it may be worth re-soldering pin 7 just in case there is a bad connection there and then check the continuity to try and eliminate that as the problem. 

 

[SkydivinGirl]

Hi Stephen! Thank you so much for the additional troubleshooting tips.  I had replaced the power connector with the new one from the Console5 kit.  I did test it anyways and it was fine.  I had tested continuity throughout the power circuit, including the points you mentioned.  Power never came back, even when putting pressure on Pin 7 of U6 but, you are right, I could have re-flowed the chip just to verify that wasn't the issue.  I have a large microscope and didn't see any issued visually, but re-flowing it would have been better.

 

I did receive the replacement U6 and installed it and the system is working perfectly.  Thanks again for everyone's help. :)

 

Heather

[+-^CrossBow^-]