protek Posted June 21, 2014 Share Posted June 21, 2014 I'm waiting for a Lynx II that I bought from ebay to arrive to me in the next couple of weeks. I bought it as "does not power up", so it's going to be a fixer upper. I've been doing some reseach regarding the fault finding and I think I have a pretty good understanding about the steps to take. A few questions though. In case the Lynx powers up with the jump wire to the headphone socket ground, is the TP15 the proper point to test the 5V rail? Also, where on the motherboard I can find the zener diode that regulates the voltage down to 5V? I take it's best to change it all the same? Are there any specs? Anything else to consider? Thanks! Quote Link to comment Share on other sites More sharing options...
Uzumaki Posted June 22, 2014 Share Posted June 22, 2014 (edited) Most likely a transistor is blown: http://console5.com/store/3055e-n-channel-mosfet.html (not my store, not getting paid to promote it) Try that one first if it powers up with the jumper. Do check the caps for any odd shape or coloration, it could be failing. Edited June 22, 2014 by Uzumaki Quote Link to comment Share on other sites More sharing options...
protek Posted June 22, 2014 Author Share Posted June 22, 2014 Most likely a transistor is blown: http://console5.com/store/3055e-n-channel-mosfet.html (not my store, not getting paid to promote it) Try that one first if it powers up with the jumper. Do check the caps for any odd shape or coloration, it could be failing. Thanks! The shipping prices of Console5 are a tad high for a single mosfet. I found this part from Farnell: http://fi.farnell.com/fairchild-semiconductor/mtd3055v/mosfet-n-smd-to-252/dp/1471066. According to this site: http://noel.feld.cvut.cz/hw/st/3650.pdf it should be compatible with STD12N06. I should be able to get that part locally. Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted June 23, 2014 Share Posted June 23, 2014 I'm waiting for a Lynx II that I bought from ebay to arrive to me in the next couple of weeks. I bought it as "does not power up", so it's going to be a fixer upper. I've been doing some reseach regarding the fault finding and I think I have a pretty good understanding about the steps to take. A few questions though. In case the Lynx powers up with the jump wire to the headphone socket ground, is the TP15 the proper point to test the 5V rail? Also, where on the motherboard I can find the zener diode that regulates the voltage down to 5V? I take it's best to change it all the same? Are there any specs? Anything else to consider? Thanks! Yes use Tp15 as a test point to check the 5V is correct once the Lynx turns on, use TP16 as your 0V reference point. What exactly is this fudge with the jump wire the "Headphone Socket ground"? I have seen this mentioned several times, with reference to the circuit diagrams here on AA exactly where is it going from and to? Why is it referred to as the "headphone socket ground", is it not the same a ground for the rest of the system? It may be a way of getting the Lynx to work but it sounds like a bodge that gets around the real problem without actually fixing it with no proper understanding of what it is doing or why. Who came up with this "fix" and are they electronically competent coming to that conclusion through a reasoned thought process or do they know nothing about electronics and just stumble across it by accident? Have you done tests that have lead you to determine that the Zenner is the source of the problem and if not why are you jumping straight to the Zenner as the source of the problem when it could be with Q11, L6 or U6 and associated components that comprise the power on/off latch? Quote Link to comment Share on other sites More sharing options...
protek Posted June 23, 2014 Author Share Posted June 23, 2014 Yes use Tp15 as a test point to check the 5V is correct once the Lynx turns on, use TP16 as your 0V reference point. What exactly is this fudge with the jump wire the "Headphone Socket ground"? I have seen this mentioned several times, with reference to the circuit diagrams here on AA exactly where is it going from and to? Why is it referred to as the "headphone socket ground", is it not the same a ground for the rest of the system? It may be a way of getting the Lynx to work but it sounds like a bodge that gets around the real problem without actually fixing it with no proper understanding of what it is doing or why. Who came up with this "fix" and are they electronically competent coming to that conclusion through a reasoned thought process or do they know nothing about electronics and just stumble across it by accident? Have you done tests that have lead you to determine that the Zenner is the source of the problem and if not why are you jumping straight to the Zenner as the source of the problem when it could be with Q11, L6 or U6 and associated components that comprise the power on/off latch? I've yet to done any tests as I've not received the Lynx yet. I'm just trying to plan out a working procedure to find the fault. Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted June 24, 2014 Share Posted June 24, 2014 Best to start at the beginning and work in from there, so the first three things I would check in order are... 1) Power On/Off latch (U6, 4069 & associated componenets) - if you have not already done so look at http://atariage.com/forums/topic/225348-lynx-1-onoff-issue/ where I have already covered some of this ground 2) Power On/Off Transisitor (Q11 MTD3055E) 3) Resistor & Zenner diode used for for +5V supply regulation Quote Link to comment Share on other sites More sharing options...
protek Posted June 24, 2014 Author Share Posted June 24, 2014 Thanks, Stephen! Those instructions look pretty systematic to follow. Quote Link to comment Share on other sites More sharing options...
protek Posted July 13, 2014 Author Share Posted July 13, 2014 Received the Lynx II the other day. Haven't opened it up yet but I tried it with an external PSU. The power LED faintly lits briefly but nothing else happens. Quote Link to comment Share on other sites More sharing options...
protek Posted July 13, 2014 Author Share Posted July 13, 2014 I opened up the Lynx. I noticed that TP15 is located under a big heat sink, which has been soldered into the motherboard. I connected my PSU and tested the latch chip voltages from pins 10, 11, 12 and 13. Presumably in off state as I didn't have the top connected, neither 10 nor 13 gave 5V, when measured. All the pins were neither 0.1V or -0.1V. Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted July 14, 2014 Share Posted July 14, 2014 What voltage were you getting at 10 and 13, it should be close to the supply voltage (9-12 volt) measured with respect to ground (TP16). As is said in the post linked to above if those voltages look correct they should swap around when the on button is pressed and stay that way until the off switch is pressed. If that also looks correct then look at the second stage, U6 pins 1, 6 & 8. on the off state pin 1 should be at the supply voltage, Pin 6 & 8 at about 0V, as with the first stage these voltage should swap once the power on switch as been pressed and stay that way until the off switch is pressed You can forget about TP15 for now as that is the +5V rail once the Lynx is on but that will never happen if the problem is in this stage. Quote Link to comment Share on other sites More sharing options...
protek Posted July 14, 2014 Author Share Posted July 14, 2014 (edited) I can double check but I'm pretty sure the voltages at 10 and 13 were 0,1V or thereabouts. Definitely not nowhere near 9 to 12 volts, when I measured them in relation to TP16. Edited July 14, 2014 by protek Quote Link to comment Share on other sites More sharing options...
protek Posted July 14, 2014 Author Share Posted July 14, 2014 I rechecked the voltages. Pin 10 was 0,11 volts and pin 13 was -0,11 volts. Quote Link to comment Share on other sites More sharing options...
protek Posted July 16, 2014 Author Share Posted July 16, 2014 One question: do I need to have a cartridge connected in order to get a supply voltage for U6? Looking at the Lynx schematic, I see that the VDD pin is connected to the cartridge port. Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted July 19, 2014 Share Posted July 19, 2014 Voltage for the 4069 does appears to come from the cartridge port but I cannot see how it gets there, you should have a cartridge inserted. Certainly my Lynx will not stay powered on without a cartridge inserted, if I try the power light flicks on for a second and then goes off. Quote Link to comment Share on other sites More sharing options...
protek Posted July 19, 2014 Author Share Posted July 19, 2014 (edited) Hmm, makes me wonder. The Lynx was sold as non working but I'm starting to think that the seller may have not tested it with a cartridge. I'm waiting a cartridge to arrive to me. I'd better test it with a cartridge before I do anything else. Edited July 19, 2014 by protek 1 Quote Link to comment Share on other sites More sharing options...
protek Posted July 26, 2014 Author Share Posted July 26, 2014 I got a California Games module. The Lynx indeed boots and the game can be played but the screen is corrupt as per picture. Quote Link to comment Share on other sites More sharing options...
protek Posted July 26, 2014 Author Share Posted July 26, 2014 Mine is actually similar to this topic: http://atariage.com/forums/topic/180129-lynx-ii-lcd-with-horizontal-stripes/ Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted July 28, 2014 Share Posted July 28, 2014 Well that is one problem solved however with Power, Data and Clocking to consider there are to many options to try and guide someone through so I do not think I can help you much (if any) further. There are 6 clock signals going to the display and it is possible that some of them are either not functioning or not reaching the display. They can be found at either R95 - R100 or Pins 1, 2, 10, 11, 12 & 13 of U7 (74HC04). Although it is possible to measure these voltages the results would be unreliable as DVMs are not capable of giving accurate answers for changing signals above 60Hz. If you want to try it a reading of near 0V or 5V would be suspicious and around 2.5V may be ok however that would not be a conclusive test, you really need to check the signals with an Oscilloscope and/or Logic analyser to get an accurate view of what is happening. Without access to a Oscilloscope or Logic analyser you best bet would be to remove an re-insert the flexible circuit strip connecting the display to the PCB case it has come loose/there is a dirty contact at the PCB connector however, it is unlikely that connectors that age were ZIF type and so the flexible circuit may be a tight fit and difficult to remove and re-insert so if you try this be careful not to tear it when pulling it out. Quote Link to comment Share on other sites More sharing options...
protek Posted July 28, 2014 Author Share Posted July 28, 2014 Thanks, Stephen. The ribbon connector is ZIF. It's still a pretty tight fit and I'm not quite certain that I got it properly inserted. It's snuggly there and it doesn't come loose, if I tug it gently but the contacts are slightly exposed, when the ZIF connector is closed. Is it supposed to be that way? The narrower ribbon is completely covered. Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted July 29, 2014 Share Posted July 29, 2014 (edited) I have only used the regular type FFC connector and so not had any first hand experience of the ZIF type therefore I am not certain what you should see when the ZIF lock is in place. When you say the contacts are slightly exposed I assume you are referring to those on the flexible circuit, on the regular FFC connectors I have encountered when correctly inserted there is generally very little (maybe 0.5mm) if any of the contact area on view although some cables may have a longer contact area. All things being equal I would expect the cable to go in by about 5mm so if there is at least 5-6mm of contact area and the cable has gone in roughly that far you are probably ok. You could try looking at the connector case, if you see a slight line a couple of millimetres from the back end that is probably where your cable will stop therefore holding the cable up to that may be a guide as to how much contact area you think would be visible from a correctly inserted cable All I can say without comparison to another Lynx is that if the amount of contact area on view is consistent across the width of the connector and the connector has a good grip on the circuit then you are probably ok. Edited July 29, 2014 by Stephen Moss Quote Link to comment Share on other sites More sharing options...
protek Posted August 6, 2014 Author Share Posted August 6, 2014 (edited) I now have a working Lynx II. I decided to get another faulty Lynx from ebay. It was indeed faulty as it wouldn't power up even with a cartridge inserted. It had a healthy screen however, so I transplanted the motherboard from the original into the new one. It turned out that some of the buttons in the new weren't working either so I had to open it up once more, move the LCD into the old case top and put it together. Now it's working perfectly. I have to see, if I could get at least the other motherboard working. Edited August 6, 2014 by protek Quote Link to comment Share on other sites More sharing options...
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.