dead lynx II?

[haightc]

So awhile back I my belove lynx stopped turning on.

A couple weeks ago I replaced all the caps, mosfet and zener diode. Didn't turn on but I didn't realize the lynx II didn't turn on without a game in. Originally I was hoping to bring my lynx with me on vacation, but now I am back. Plugged in a game and the lynx turned right on with a brilliant white screen. I think I got used to how dim and washed out had became over the years. Well my excitement was quickly dashed as it then a wash of pixels sweep acrost the screen and speaker spit out a crackel. Now once more I find myself with a lynx that will not turn on.

 

Any ideas what went wrong or what the issue is?

[haightc]

Here is my motherboard

[haightc]

Prior to powering on the lynx I saw 5v at tp15 now it shows less than 1, perhaps another diode?

[haightc]

I picked up a dead lynx on ebay for reference. I tested some of the diodes, looks like both have shot D10 diodes. I would guess the zener is bad on the other as well. I need to double check the orientation. The other motherboard shows resistance both directions, so I can't implicitly see if my initial orientation. I plan to check base to test point to leg continuity to make sure my initial placement was correct. Ideally I would be able to repair both lynxs, but I would be happy with just have one resurrected. Is my initial orientation correct?

[+Stephen Moss]

What do you mean by shows resistance in both directions?

Although they can be partially blown Diodes generally either go sort or open, of it measures nearly 0 ohms in both direction it is short, if not you will need to remove it to be certain as while in circuit you are not necessarily only measuring the diode as current could also be flowing though parallel paths in other circuit componets giving a false measurement.

[Andromeda Stardust]

The Zener circuit on Lynx consoles is a ticking time bomb. If the Zener fails open, you get the full DC 9+ V across the entire motherboard which fries everything. In this case, the Lynx is pretty much toast. I've had a Lynx fail on me in storage. Worked in 2007, dead w/ white screen in 2012. Replaced it in 2014. I should probably replace the power circuit in my new Lynx 1 as well as it's probably a ticking time bomb just like the old one.

[haightc]

In the case with a traditional diode, your resistance you be zero as current is able toe flow thought the diode. I you flip it, you should have a significant resistance as the current shouldn't be allowed to flow the opposite direction. However since D10 in this instance shows the same resistance on both sides why know the diode is not functioning properly. Zener's however would still register some resistant that would depend on the intended voltage drop, in both case the delta in ohms was relatively small, especially when compare to a brand new replacement.

 

I replaced the zener and a few caps on the second lynx and it turn on immediate as well as the power LED when plugged in. So obviously more power circuit repair is required, I have order some more caps and MOSFETs, but I'll go through all the diodes in the mean time and replace what I can as required while I wait for parts to arrive

[markeemark]

In the case with a traditional diode, your resistance you be zero as current is able toe flow thought the diode. I you flip it, you should have a significant resistance as the current shouldn't be allowed to flow the opposite direction. However since D10 in this instance shows the same resistance on both sides why know the diode is not functioning properly. Zener's however would still register some resistant that would depend on the intended voltage drop, in both case the delta in ohms was relatively small, especially when compare to a brand new replacement.

 

I replaced the zener and a few caps on the second lynx and it turn on immediate as well as the power LED when plugged in. So obviously more power circuit repair is required, I have order some more caps and MOSFETs, but I'll go through all the diodes in the mean time and replace what I can as required while I wait for parts to arrive

Hi, where to you order the diodes and zener diodes from? Thanks.

 

Mark

[haightc]

Amazon/eBay