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Stephen Moss

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About Stephen Moss

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  • Birthday 12/20/1970

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    Cambridge, United Kingdom
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    American Football, Golf, Electronics, Programming, Sci-Fi, Indoor Climbing

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  1. I think there was some misunderstanding here, I was referring to the power pins of U6 as the symptoms you were describing were suggestive that one of its power pins was not connected. It would not hurt to check continuity through the GND rail, just to be sure. Generally, continuity seems to be OK from the above with the exception the you have specified some continuity which is a resistance measurement as voltages. So I am a little puzzled as to why you are not reading the correct voltage at TP15. Maybe you just have a bad connection to TP15 in which case you could try measuring to the top end of R74, or R75 and see what you get there. You are measuring this as a DC voltage right? If you were measuring it as AC that could also explain the apparent lack of voltage, if you were measuring at as DC try it with Battery power. With the COM lead of your meter on Pin 7 of U6 you should measure the same battery voltage at Pin 1 of the battery connector, Pin 14 of U6 and TP15.
  2. First, as the old saying goes, "if it ain't broke, don't fix it". That aside, you did not indicate if the listed voltages are when the Lynx is off (as in after the power source is connected & the On button has not pressed) or after the On button was pressed which makes it a little difficult to be certain which (if any) voltages are correct not knowing which state to compare them against. However, the following pins of U6 should be connected and therefore at the same voltage... 2 & 3 4, 5 & 9 6 & 8 10 & 13 11 & 12 but you measurement with DMM common on GND shows that is not always the case suggesting that either you have some bad solder joints, made an error in your measurements or there is a problem with U6 (assuming you had a cartridge inserted). Your measurements with the DMM common on pin 7 of U6 are a little more consistent in terms of pins that should be at the same voltage are but you are reading essentially no voltage anywhere, that suggests to me that you may not have a good power connection connection to U6. Try performing a continuity test from the power pins to the battery terminal to verify, if that is part of the issue from the measurements given I think it more likely the problem lies with GND connection than VSS but best to check both. But take into account that the meter probe contact may create the connection so try to use as little pressure as possible on the pins, alternatively try re-soldering them. You also state that TP15 is 0V, that should never be the case unless there is a brake in the power rail. Once a power source is connected TP15 should either be 12-14V (PSU and Lynx off) or 9V (PSU Lynx On/Battery, Lynx on or off) when measured with respect to power GND (left of Q12 on the schematic). If you were measuring with respect to the single point GND (right of Q12) then I would expect a reading of 0V if taken while the Lynx is off. You also mentioned connect the Drain and Gate powered the Lynx are you sure it was Drain and Gate rather than Source and Drain? How the latter would work is obvious but not something i would suggest doing for long as the entire system will be running at 9V. Whereas with Drain and Gate I cannot see where there would be a sufficiently high current path to GND for that to work.
  3. There will always be a little heat generated while on, even if not plugged into the Jaguar as there will be current flowing through the primary of the transformer, more heat will be created when drawing current from the power unit, it is inherent in the design as 3 to 4 watts of power is being created inside a small unventilated enclosure. Consequently it is normal for them to get warm when in use, even feel hot, but provided it does no get too hot to touch it is probably OK and the longer you use it the warmer it will get. If you open the jaguar and the measured output voltage with the Jaguar running is approximately 9V that would be a reasonable indicator that it is operating as expected. The first thing to check when you have on audio output is that the output voltage from REG1 is 5V DC and that it is getting to pin 8 of U4 (audio output amplifier)
  4. Stephen Moss

    Team Tap

    Could just be a bad power connection (Solder Joint or broken wire) to the 5V pins of the 74H244 or 74HC154. Without a solid power supply they could be drawing power through the input pin, if they do that as the pins change state due to button press or controller row strobe the lose enough power for correct operation which results in either no or random output. If you still have the defective one, want to investigate and have access to a multi-meter you might want try checking the voltages to those IC's, for U1 pin 24 is 5V, pin 12 is GND, for U2 pin 20 is 5V and pin 10 is GND. With the text in top of the device the correct way up and reading left to right they should be the top right and bottom left respectively.
  5. They are covered by normal Copyright law, which essentially gives the author of any original work the Copyright to that work once the work is started. As I recall there is no distinction between Complete and unfinished/works in progress, otherwise someone could plagiarise your work and get a copy out ahead of you if the laws only applied to finished/commercially released items. The question then becomes one of how did it appear on the internet? If it was initially uploaded without the copyright holders permission that and any subsequent distribution would be illegal. If the copyright holder uploaded it for people to try/keep free of charge then they still retain Copyright to the work, if they specified either at time they made it available or subsequently that others may not host/otherwise distribute copies then doing so would be an issue. Otherwise, I don't think there is an issue with another party hosting/distributing copies (provided it is a verbatim copy and not modified/repackaged in any way or charging for something that was initially released without a fee) where the author has not indicate any prohibition to doing so as they can claim they were unaware of any such prohibition, although it is always polite to ask the copyright holders permission before doing so in order to be certain it is permitted rather than to assume it is. The above is different to the author releasing it a Public Domain (PD), if the author openly declares it to be PD then they are relinquishing any Copyright they have in regard to the work and so anyone can then do as they wish with it, if no PD declaration is made by the author then they retain the Copyright to the work in question until the expiration of the legal set Copyright period.
  6. I don't have any experience of the Game Gear but all computer systems need three key things to operate which should be the first things to check for... Power - if power is not getting to part of the circuit or to all power pins on a device (particularly the processor, VCC & GND) then nothing will work. Check every power pin on a IC and connector but only the first component to which any point marked 5V or 35V is connected on the various sub-circuits otherwise you will be there for hours if you check it gets to every component. I would start at 5-3 DC-DC converter and the voltages on CN1. Clock (Xtal) - difficult to check without an oscilloscope but a reading other than 5V or 0V on a DVM (multi-meter) is a likely indicator that the clock is running. Check it gets everywhere it needs to. Reset - Resets are normally active low (0V, indicated by a line above it), it should be that at power one but quickly rise to 5V after a short delay to allow the power supply to stabilise and then remain there unless a manual reset is performed with the power on. Check it is correct everywhere it goes to. So unless you get any better advice form someone experienced in Game Gear repair who may know specifically where to look I suggest you start by checking the items above as best as you can.
  7. If the component references match those of a standard controller then with the keypad rubber membrane removed if the problem no longer exists it may have been a stuck button due to membrane misalignment during assembly. However, if the issue still remain I suggest measuring the voltage between pin 10 (GND) and pins 13 (Input) and 7 (Output) of the 74HC244. With no controller buttons pressed... 1) Both the 74HC244 input and output pins are at 5V = pullup resistor & 74HC244 operating correctly, problem may be open circuit between pin 13 of the 74HC244 and pin 14 of the controller plug 2) Pin 13 at 5V but pin 7 at a lower voltage = possible failure of 74HC244 or external short of pin 7 to GND 3) Pin 13 at 0V = possible short to GND or open circuit to R6... a) If you can measure 5V at each end of R6 then you may have an open circuit between R6 and Pin 13, try reflowing the solder joints of R6 & pin 13 then perform a continuity test if case of a cracked PCB track. b) If you can measure 5V across R6 then a short to ground is likely. c) If you measure 0V at each end of R6 then you may have an open circuit 5V to R6, try reflowing the solder joints of R6 then perform a continuity test in case you have a cracked PCB track.
  8. I would check the voltage regulator first measuring the input and output voltage with a multi-meter, normally you should read about 9V DC going in and 5V DC coming out, centre pin is ground Also try the finger test or use freezer spray to see if the TIA, ROIT or 6502 are getting very hot very quickly
  9. Maybe I am not quite understanding what you are doing but with both component and S-Video are not the video and audio separate? Therefore I am confuse as to how the splitter fits in to this unless you are using it backwards to combine two Audio feeds from different devices/cable into a single pair out inputs on your AV equipment. If you are attempting to use a splitter to connect the two audio cables into one that is probably where you problem lies, as the splitter probably has resistors on each "output" or inputs as you would be using them which combined with the input impedance of the AV equipment is creating a potential divider and thus reducing the input signal levels. If that is indeed the case them the simplest solution would be to use a Double Pole Double throw switch to manually switch between input cables.
  10. Those measurement suggest that neither the cap is shorted or the pull up resistor is open circuit. Next I would measure the pin 14 voltage both with and without a controller connected... a) A reading of approximately 5V in both cases confirms all is well with the primary input stage. b) A reading of either 0V or something much lower than 5V in both cases could suggest a problem with U20 (or possibly C81 that only appears when power is connected despite the result of the resistance test) c) A reading of approximately 5V without a controller connected and either 0V or something much lower with it connected would be suggestive of a potential controller issue. If, having measured that voltage you determine the outcome as being either a or b above then I would check the following... With the power on I would expect you should read approximately 5V at pin 2 (input) of U20 (pin 10 is GND), as the output at pin 18 is being switched for the controller reads I cannot be certain of what measurement you would get. But I would not expect either 5V or 0V. The readings should be approximately the same both with and without a controller connected. With the power off you should read approximate 10Kohms between pin 18 of U20 and Pin 16 of RP7.
  11. If the Jag is detecting a * and # press there is no software method of clearing that. The game software will only be coded to read the port, I doubt it have been written to include possible error correction as it would be difficult to identify a hardware error from a user input error. If you have a SkunkBoard or GameDrive you could try running the controller test program by Matthias Domin which you can download from here (scroll 3/4 of the way down) to see what controller buttons that reports as being pressed to help confirm or dismiss these suspicions as the source of the problem. In regards to it being Jaguar hardware problem is most likely to be the result of a short or open circuit somewhere, you have to first perform the resistance test I mentioned previously tests, start at the beginning of the signal chain and then work along. Alternatively, if you do not have access to any test equipment (i.e. multi-meter, logic probe (easy to build) or Oscilloscope) you must have access to a soldering iron to have re-capped it, in which case you could initially try reflowing and adding a little solder to all the controller socket solder joints as it may simply be a case of having a bad solder joint or two there.
  12. I am assuming that means that the LCD & Backlight are not currently getting any power, which could explain the previously mentioned current draw of 500mA (missed that earlier) when I would expect almost twice that going from the AC adaptor specs. If you were powering it from the AC adaptor like that then it is likely it was running off around 12 volts instead of 9 which could explain why things were heating up when using it. Unless there is a need to do otherwise I personally prefer to measure all voltages referenced to the main supply GND as it is a known fixed voltage. You can use the single point ground as ground for measurements of the "5V" sections of the circuit provided you are certain the power stage is operating correctly otherwise it is an unreliable and variable reference point.
  13. I am sure you would of had the Com lead of you multi-meter at appropriate point to be measuring 5V and not 9V and so the fact you are measuring 9V suggests that the power GND and Single point ground are shorted. Assuming that is the issue and it is not caused by the horrid headphone ground hack or a solder splash my first suspects would be Q11 but as you have already changed it and several other associated components twice I would suggest looking it at short of L6, but I personally would be looking at problem with the switching Oscillator (U6, Q13, C37 & R54) because if that is not oscillating it would give the impression of a short as the resistance of L6 and Q11 would be negligible. Unfortunately, I will not have access to my Lynx or any equipment to provide any oscillator frequency or modulation depth measurements for comparison until September. If you have an oscilloscope to hand take a look at pins 1, 2, 3, 4, 5, 6, 8 & 9 of U6 and see if they appear to be oscillating or are static at either 9V or 0V (depending on the pin being probed) with the GND of the Oscilloscope to main ground (left of Q11 in the schematic). Otherwise the voltage reading you will get if it is oscillating with a multi-meter will be determined the frequency of you your multi-meter sampling but if there is no oscillation again you should get fixed readings of either 0V or 9V.
  14. I am not sure how/where you are thinking of fitting it but you cannot simply just connect it in to the same place on the PCB as Q12 as... a) The 5V parts of the Lynx circuit the relative to the 9V power rail not the battery/power pack ground, so the "single point ground" as it is called on the schematic is actually floating at 4V (9-5) relative to true ground. b) The only 9V source on the PCB pads of Q12 is its gate voltage which is a switching signal itself and so not a good source for regulator, plus you cannot draw enough current from the outputs of the output pins of the 4069 that provide that signal to power the rest of the circuitry anyway. There are ways of fitting an alternate regulator circuit and I recall seeing posts on the subject before, unless someone posts some links to previous posts on the matter in reply I suggest you use the forums search mechanism to try finding them, although I do not guarantee that any instructions you find are necessarily the correct way of doing it. Also, if you are not already aware of it DC-DC converters conventionally use high frequency switching which can create a lot of electrical noise, unless the output is very well filtered there is the potential that such noise may produce noticeable and unwanted affects in the audio and video outputs.
  15. Sounds like you might have a bad solder joint somewhere and that probing and moving the PCB has resulting in a better connection (for now).
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