Rossoe

Thanks for testing your Lynx - Is this the orientation re Base, Emitter and Collector?

Sure, I kind of expected to have issues with the first Lynx, as I'd tried to install a BennVenn screen and blown a diode on MB etc. but opening a 2nd working Lynx and getting similar figures threw me off! if the 2nd one also has a broken transistor on Q8 it's impressive it still works ok? Is there a chance you can get different readings when testing transistors in circuit vs out of circuit?

ok so what's going on with the figures I'm getting - Q7 & Q8 definitely don't match up to each other? if they break or malfunction can they behave in odd ways like this? both transistors have been changed out for new parts using kits sold to re-do the power circuit. So to avoid confusion I opened a second MKII Lynx which has never been opened before and checked the same parts - Figures are similar to the first machine with Q8 behaving more like an NPN ??

For sanity sake can someone please confirm that Q7 is PNP and Q8 is a NPN? Looking at schematics here - https://wiki.console5.com/tw/images/7/79/Atari-Lynx-II-Schematic-%28Hayato%29-C104247-6-29-90.png and both look like they should be PNP - but the figures I've recorded suggest otherwise? I'm fairly new to electronics so not totally confident of my analysis. Lynx in question is a Mrk II - C104424-001 Below are the figures I get with my multimeter in diode mode - power off. Q7 PNP? Q8 NPN?

Mine does have the copper sheet over the entire back, some seem to only have a small section around the cart slot, I had not thought to cover the caps at the back! the copper sheet seems to have a plastic backing, but I guess there is always a risk that it could puncture through with sharp legs. Zener is definitely the right way round as I made sure the black stripe is facing the metal shield as per instructions.

That's a relief re the power supply, I'm complete beginner re electronics - so didn't know how to test it appropriately! what is the best way to test a power adapter before plugging it into Lynx? I think that silver line on diode is there on another one I have spare as well (see pic below) I'll attempt that 5v across C41

Ah yes, that's a part that is required to be removed as part of the BennVenn screen install.

Ah damn it - I just checked the power adapter and it's reading 14.5v at 6.8a using multimeter! I'm assuming that's what might have fried something on my Lynx? Any chance the zener diode may have offered some protection? and is there a risk that the BennVenn is toast as well? I opted for the diode to be installed for power circuit protection on that as well.

So my poor MkII has had some troubles - and I'm fearing I've damaged something serious! I need some help confirming what I should try next. First the unit was sent for recapping - came back and screen faded immediately on boot up, Thought it was screen issue, so bought a BennVenn replacement, along with new mosfet (Q12) installed those, but screen still faded as soon it turned on. Inspecting board I noticed 3 caps placed with incorrect polarity! so I changed them out myself for new one's. Screen still did the same however I could see slightly more this time, but as soon as I turned brightness wheel it faded to black - much like video below of a user with similar issue. I also noticed another user with same issue: I decided to replace all the power components as highlighted below, after changing the diode, transistors and resister nothing changed, after switching the mosfet I got a garbled screen for a second and some crackling noise from speaker when powering on! I switched off, then re-seated cart and powered on again and noticed a tiny bit of smoke - I did not see where it was from, so immediately switched off and now I'm nervous what to do with it! I've had a look at all components and can't see any burnt area's, I have not opened the metal plate over the main chips. My main worry is if I've blown Mikey and Suzy. I'm not sure how to check Diode in circuit but using Diode mode on multimeter - positive on Anode shows 0.26v, whilst positive on cathode shows 0.649v

Hi I have damage on 2 connectors on my Lynx II likely from soldering iron after a recap job - Are the ribbon connectors actually available anywhere? does anyone have a spare per chance from a dead donor machine ? I'd be very interested if anyone does.

Thanks for you advice guys, I'll see if I can repair - it'll test my soldering skills, I just picked up a hot air rework station to help me as I did not enjoy prying off the Mosfet!

I need the following to replace potentially damaged one's: C16 - (50v 1uf) C23 - (35v 10uf) C33 - (2.2uf 50v) I'm interested in caps that don't stand a chance of leaking well into the future - Do polymer capacitors matching above specs fit in the Lynx per chance ? I'm in the UK -^CrossBow^-

sorry typo - I meant to say "surely the negative of caps are not supposed to be connected to hole clearly marked as positive??"

Oh Jesus, I'm not great at electronics but just having a closer look at the caps that were redone - surely the negative of caps are supposed to be connected to hole clearly marked as positive?? Is that not going to be giving me some strange affects? and also will that have damaged the caps - or am I ok to unsolder and put back in the correct orientation?

Hi Stephen, Yes I have to move it quick otherwise it never show's much on the screen - I can almost get it to stay but only at an extremely dim level, it'll only flash up like it shows in the video by winding dimmer wheel completely to the right and then back to full left again. I'll try and check voltages shortly, as I've ordered a 6 AA battery pack to wire in for testing purposes.