Lynx II Wont turn off?

[SnowDome_]

I have a problem hopefully someone will be able to help me with. I recently obtained a lynx II sold as not working for repair, after purchasing new capacitors and the voltage regulator kit from console5 i was thankfully able to get it running again.

Except for one strange issue, once batteries are inserted the system powers on instantly and cannot be powered off without removing the batteries. I don't believe the flex connector for the buttons is the issue as all other buttons work perfectly, as well as testing it without the flex cable connected to which it still powers on instantly. My concern is if this could possibly be damaging the system, or be a greater issue altogether. 

 

Unfortunately i am very inexperienced with any troubleshooting or repairs besides what i have tried mentioned above, if anyone has any ideas or suggestions i would greatly appreciate it. 

Thank you

[SnowDome_]

So after getting advice from a member here and reaching out to https://www.best-electronics-ca.com/ , he believes that a faulty 'U6 4069' is most likely the issue. Does anyone know a suitable replacement part that i could purchase new, or would i need to salvage that from another lynx? 

 

Thanks for any help

[+Stephen Moss]

If you have simply replaced the original parts to repair it there are two things I would look for...

a) Has someone used that damn awful headphone Ground bodge to try and get it working. If so that completely bypasses the MOSFET and will result in instant power on, as well as the system running from 9V. If it exist remove it immediately, look for a wire that appears out of place running from somewhere near the speaker to somewhere near the battery connector. 

b) A problem with U6, which in conjunction with a few other components forms the power On/Off latch. If you have a Multi-Meter start by measuring the voltage between pins 7 & 10 of U6, you get 9V the Lynx should be Off, of you get 0V that would turn the Lynx on. This problem has come up before, I suggest using the Forums search facility the sear the Lynx forum for Power On / Power Off problems, you should find helpful information on testing in those.

[SnowDome_]

11 hours ago, Stephen Moss said:

b) A problem with U6, which in conjunction with a few other components forms the power On/Off latch. If you have a Multi-Meter start by measuring the voltage between pins 7 & 10 of U6, you get 9V the Lynx should be Off, of you get 0V that would turn the Lynx on. This problem has come up before, I suggest using the Forums search facility the sear the Lynx forum for Power On / Power Off problems, you should find helpful information on testing in those.

Thank you for the reply, i believe U6 is the issue as you and some others have mentioned now.
Do you happen to know a suitable replacement for that part? From searching i've seen a few possible replacements mentioned but no answer if the parts are correct. The 2 parts i've seen mentioned here are CD4069UBM and BU4069UBF-E2. If you or anyone else knows if these are working replacements for U6, or where to find them i would greatly appreciate it.

 

Thank you

[+Stephen Moss]

Having looked at the datasheets and measured the size of the device in my Lynx I would go for the CD4096UBM (Texas) the other one doe not appear to come in the correct package size and so may not fit.

Just changing U6 without first absolutely establishing that it alone is the cause of the problem might not solve the problem, for example it may be that a bad connection on the capacitor or a bad capacitor means that that pin 11 is not initially held low at power up as it should be.

[SnowDome_]

10 minutes ago, Stephen Moss said:

Having looked at the datasheets and measured the size of the device in my Lynx I would go for the CD4096UBM (Texas) the other one doe not appear to come in the correct package size and so may not fit.

Just changing U6 without first absolutely establishing that it alone is the cause of the problem might not solve the problem, for example it may be that a bad connection on the capacitor or a bad capacitor means that that pin 11 is not initially held low at power up as it should be.

Thank you for that info. I was suggested to try replacing u6 after a few back and forth emails with bestelectronics. 

I've done a full replacement on the capacitors and have reflowed all points to rule out that problem. Aswell as replaced the parts included in the console5 voltage regulator kit. Hopefully I'm close to figuring out this problem.