Dipski

Thanks guys, it does appear to have gone over-voltage and cooked it as I've measured over 8V on the RAM chips (doesn't seem to be any voltage regulation). I'm curious as to why there's no response using a DC adapter. I can see seemingly normal voltages coming into the system with the DC adapter connected (still unregulated though) - however it doesn't power up the screen from the DC adapter but does with batteries. I believe the root cause of the problem is probably the original power adapter that came with the Lynx, I measured the output voltage at 13.8V. I was using a new power adapter and hadn't plugged it in to the old one but I imagine its previous owner would have plugged it in recently and turned it on. I'm reluctant to do any more testing on it with voltage applied as potentially some chips could still be ok for salvage and I'd prefer not to kill everything on the board, so I've gone through the thread Stephen Moss linked above and checked U6, checked the resistors and the diodes and didn't find any problems. that leaves me with the capacitors (which look ok and at a brief test all seem ok) and testing the transistors (no shorts at first inspection). I didn't see anything on the screen with the backlight disconnected - not too surprising knowing the voltages that have gone through the system. It would be nice to work out what has failed to allow the 8-9V through.

Hi guys, I've got an Atari Lynx II that wasn't powering up. I wired the negative battery terminal to the negative on the headphone jack and it loaded up - great! That was for about a minute or two, I turned it on and off, put a game cart in and was noticing a lack of sound and a funky smell coming from it and then the system goes to a plain white screen hasn't come up with a picture (or sound) since. No problem I figured I'll open it up and use a power adapter to power it so I can work out where the problem might be without juggling batteries - alas it doesn't power on from the DC socket. Seems strange that it's not taking power from there as there's not much between the DC socket and the battery terminals I guess I'll look at the solder joints on the socket. Anyway, regardless of the DC socket I'm still faced with the Lynx giving a plain white screen - has anyone come across this and is it likely to happen if the 5V line is under-voltage or is it going to be more serious? The capacitors look ok but I guess I'll look at them first and check the 5V while juggling the batteries

Hi Folks, I'm a long time reader first time poster. I've been fixing a bunch of Atari 2600's and these days I remove the RF modulator add AV output before switching a system on and that was done to the system I'm currently stuck on also. The machine in question is a 4 Switch PAL unit and when switched on produces a black screen. After warming up a little that black screen has some game colors sprawled horizontally across, and switching on & off can lead to a different toned sound coming through the audio. So the problem is an odd one, the game cartridge isn't loading but the fault changes/improves slightly with warming up with the system producing some isolated horizontally streaked color & occasional random monotone sound. My first thought was that one of the main chips was faulty, so I removed and replaced each of them - no improvement. I checked the 7805 output, power to the chips and data across them which all seem to be ok. I checked the electrolytic capacitors which all tested ok and checked for any cut or damaged traces and found none. I checked for out-of-spec resistors, checked for open/shorted board caps and found none. I replaced the crystals which made no improvement. Thinking it must have related back to power I replaced the 2200uf Cap, 7805 Regulator, Power Socket and 4.7uF Electrolytics. I also replaced the 2N3904 and 2N3906's. No change. There is one point of note on this 2600 in that it doesn't have a piece of circuitry that is present on my other 4 switchers - even those with the same board revision. The A204 chip which sits on the upper right side of the board on my other systems is not present (from the factory) with no provision for its installation. I assume it's just a particular revision of the board that doesn't have the A204 for some reason. This machine also has a second 4.7uF electrolytic next to the red-plastic mounted coil (removed with Q201 as standard for AV mod). I hate to give up on a challenge like this one, but aside from a systematic replacement of every component on the board I'm out of ideas - has anyone come across anything like this before?