lulrik Posted June 18, 2014 Share Posted June 18, 2014 my method, called me if it is false MJE210 it a transistor type of PNP right ? If the transistor is PNP type, current will flow when the black lead of the multimeter is to the base, and that the red wire is in contact with the emitter or collector. right ? 2N3904 it a transistor type of NPN right ? If the transistor is NPN type, current will flow when the red lead of the multimeter is to the base, and that the black wire is in contact with the emitter or collector. right ? I said if my values are not clear enough and does not allow an analysis of problem Quote Link to comment Share on other sites More sharing options...
lulrik Posted June 18, 2014 Share Posted June 18, 2014 gray cylinder that looks a diode is conducting in any case, so I can not manage to know if it was a diode, a zener diode or something else Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted June 20, 2014 Share Posted June 20, 2014 with luck, I has it: D : http://fr.farnell.com/metrix/ax0503a/alimentation-stabilisee-ax503/dp/3430893 for our method : (front view) _____________ | | | | | 7805 | | | | | | | --------------------- || || || || || || || || || || || || 9v GND 4.5 or 5.5v my assembly is good ? I unsoldered Q9, Q10 and 7805 and the Zener diode and I give new PS: I have numerous pieces of diode detached home, how I could choose the right one? Yes those are the voltages you should have. The Zenner Diode has to be a 4.7 or 5.1 volt, 500mW (0.5W) Zenner diode, if it is not a Zenner the circuit will not operate correctly. The circuit diagram lists the Zenner as being either a 1N5230 or a 1N5231 respectively or you can use a suitable equivalent. my method, called me if it is false MJE210 it a transistor type of PNP right ? If the transistor is PNP type, current will flow when the black lead of the multimeter is to the base, and that the red wire is in contact with the emitter or collector. right ? 2N3904 it a transistor type of NPN right ? If the transistor is NPN type, current will flow when the red lead of the multimeter is to the base, and that the black wire is in contact with the emitter or collector. right ? Although measuring the junction resistance will may indicate if the junction is blown it does not easily indicate if it is partially blown that is why measuring the hFE is a better test. Set the meter to the hFE setting and insert the transistor into the relevant (NPN/PNP) part of the circular socket on the left of the Meter. As I said previously I would expect your to get a hFE reading of around 100 - 180(max) for the MJE210 and 100 - 300(max) for the 2N3904. gray cylinder that looks a diode is conducting in any case, so I can not manage to know if it was a diode, a zener diode or something else If you have removed it from the PCB what does the silk screen underneath it say? If the silk screen labelling matches that of the circuit diagram then... if it is an Diode it should be labelled CRx If it is an Inductor it should be labelled FBx If it is an Resistor it should be labelled Rx If it is an Capacitor it should be labelled Cx where x is a number If it is a Diode then set the meter to the Diode ( -|>|- ) test setting as it is in the image above, as I previously stated with the meter leads connected one way round you should get a reading of 800 -1200, when connected the other way around you should read infinity (1 on the left of the display), if you get the same reading both ways round, i.e. either infinity or 0 then it has blown. Quote Link to comment Share on other sites More sharing options...
lulrik Posted June 26, 2014 Share Posted June 26, 2014 Yes those are the voltages you should have. The regulator works, I its voltage The Zenner Diode has to be a 4.7 or 5.1 volt, 500mW (0.5W) I have zener diode, but I do not know how to recognize them because it comes from older devices. I'm looking for if I will buy. Although measuring the junction resistance will may indicate if the junction is blown it does not easily indicate if it is partially blown that is why measuring the hFE is a better test. Set the meter to the hFE setting and insert the transistor into the relevant (NPN/PNP) part of the circular socket on the left of the Meter. As I said previously I would expect your to get a hFE reading of around 100 - 180(max) for the MJE210 and 100 - 300(max) for the 2N3904. When I put the transistors in the Hfe, nothing happens ... I've tried everything. With transistor 7800 or from other btw If you have removed it from the PCB what does the silk screen underneath it say? If the silk screen labelling matches that of the circuit diagram then... if it is an Diode it should be labelled CRx If it is an Inductor it should be labelled FBx If it is an Resistor it should be labelled Rx If it is an Capacitor it should be labelled Cx where x is a number for me "gray cylinder" is zener diode is we were talking about earlier, right? On the PCB its place is : L3 If it is a Diode then set the meter to the Diode ( -|>|- ) test setting as it is in the image above, as I previously stated with the meter leads connected one way round you should get a reading of 800 -1200, when connected the other way around you should read infinity (1 on the left of the display), if you get the same reading both ways round, i.e. either infinity or 0 then it has blown. apparently he died Quote Link to comment Share on other sites More sharing options...
lulrik Posted June 26, 2014 Share Posted June 26, 2014 I bought another Atari 7800 works, I hope to have the same mainboard. I open tomorrow. You action requests to do? Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted June 27, 2014 Share Posted June 27, 2014 I do not think that the grey cylinder is a Zenner Diode if it is labelled L3, if it was a diode if would probably begin with D and not L as typically D = Diode and L = Inductor, they should have the same labelling on the schematic as the PCB but apparently not in this case! If the hFE test shows nothing either you are doing something wrong or the transistor is blown. Make sure you have the EBC pins in the correct EBC holes and on the correct side of the tester (MJE210 = PNP, 2N3904 = NPN) If you have another 7800 then put the components back in (make sure to get the transistor in the correct way around) & just compare voltages on the 4013 D-Type Latch, 2N3904 and MJE210 between the two units, where you get a difference should indicate where the problem is. Quote Link to comment Share on other sites More sharing options...
lulrik Posted June 28, 2014 Share Posted June 28, 2014 I think there was a misunderstanding in ^ ^ gray cylinder is the zener diode for me from the beginning ... sorry I did not have understanding So you ... forget the test of the zener diod :S saw it was gray, I thought it was a diode. But it may be FB2 on the shematic I try with full transistor home. I think my multimeter does not work for the measure hfe, I have a METRIX MX22 but I think it does not hfe If you have another 7800 then put the components back in (make sure to get the transistor in the correct way around) & just compare voltages on the 4013 D-Type Latch, 2N3904 and MJE210 between the two units, where you get a difference should indicate where the problem is. I'll try Quote Link to comment Share on other sites More sharing options...
lulrik Posted June 30, 2014 Share Posted June 30, 2014 (edited) New !! I think we are progressing !! I think MJE210 is dead and that he simply does not switch when you press the ON switch. Right ? You think that I need to test weld MJE210 (new) on the old console to see what happens? Edited June 30, 2014 by lulrik Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted July 2, 2014 Share Posted July 2, 2014 If the new MJE210 is either one you have ordered or removed from a working 7800 then I agree it does look like the original may be dead, so fit the new one and see what happens. Quote Link to comment Share on other sites More sharing options...
lulrik Posted July 2, 2014 Share Posted July 2, 2014 I'll try to reseal the components, I will give new Quote Link to comment Share on other sites More sharing options...
lulrik Posted July 2, 2014 Share Posted July 2, 2014 I tested it works !!!!!! I just buy a MJE210 for a console I also will buy other items in case there have a problem again thank you hugely !!!!! I'll probably make a tutorial to learn how to repair and change the components that we are posed problem, I put it on my website. . you can see pictures of my Atari on my website : http://lulrikgames.canalblog.com/albums/atari_7800/index.html I'll keep you posted for more and thank you again Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted July 3, 2014 Share Posted July 3, 2014 (edited) Happy to help bring another Atari console back to life. I am already working on a guide to solving power on/off problems with the 7800 as well as ones for the Lynx and Jaguar which I hope save me a lot of time in the future. By all means make your own tutorial if you want, however it may be better to leave these things to people who know more about it as we could have reached this conclusion in half the number of posts had you followed my initial instructions! Edited July 3, 2014 by Stephen Moss Quote Link to comment Share on other sites More sharing options...
lulrik Posted July 4, 2014 Share Posted July 4, 2014 (edited) I am already working on a guide to solving power on/off problems with the 7800 as well as ones for the Lynx and Jaguar which I hope save me a lot of time in the future. cool! let me know: D By all means make your own tutorial if you want, however it may be better to leave these things to people who know more about it as we could have reached this conclusion in half the number of posts had you followed my initial instructions! You are right I refrain again thank you EDIT : a little help for french : http://www.gamopat-forum.com/t70800-resolu-atari-7800-qui-refuse-de-s-allumer his is the French version of the problem, but less complete Edited July 4, 2014 by lulrik Quote Link to comment Share on other sites More sharing options...
mmervine Posted July 4, 2014 Share Posted July 4, 2014 Glad to see that you got your 7800 working again!!! Quote Link to comment Share on other sites More sharing options...
uveprom Posted January 7, 2015 Share Posted January 7, 2015 I have this problem with my atari 7800,,,7800 startup requires system be turned on twice?did you know where is the fail ?i did change 4013 and nothing happened ! Quote Link to comment Share on other sites More sharing options...
SIO2 Posted January 19, 2015 Share Posted January 19, 2015 I am working on a couple of 7800s at the moment. Both will not turn on due to dirty switches. I have ordered some new switches but being impatient, I noticed that one type of switch can be cleaned. If you have the switches with the clear plastic covers and the rivets in each corner, you can cut the mushroom head off the rivets, lift the cover, remove the cap and the dome. Then clean the dome with a scouring pad. Clean the contacts inside the switch with a knife or screwdriver if they even need it. Then replace the parts back into the switch. The clear plastic cover should snap back into place well enough to hold the switch cap in. If you accidentally zing a cover to the nether regions as I did, just put some tape over the cap. The cover just keeps the dirt out and keeps the cap from falling out if you turn the machine upside down. Tape will work. If you have the revision A board with the grey switches, I guess you are out of luck. those look pretty solid. Quote Link to comment Share on other sites More sharing options...
uveprom Posted January 25, 2015 Share Posted January 25, 2015 I have this problem with my atari 7800,,,7800 startup requires system be turned on twice? did you know where is the fail ? i did change 4013 and nothing happened ! problem solved! Quote Link to comment Share on other sites More sharing options...
lulrik Posted January 25, 2015 Share Posted January 25, 2015 Good ! what is the problem ? Quote Link to comment Share on other sites More sharing options...
alortegac Posted December 13, 2015 Share Posted December 13, 2015 I have a similar situation with a 7800 that will not turn on...it was working and then it shut itself off and could not restart it again.......it was dead. By following this and other discussions, I replaced the 7805, MJE210, Q9, Zenner diode, R53 and power button. And the 7800 did not work consistently. I made the console to turn on for a little while and then it would shut itself off again..back to dead!. However, when on it was not working properly. I was not able to get any 2600 game to display correctly, only 7800 games would start up sometimes, and I was getting garbage in the screen... I thought maybe the new 7805 was not good, so I put back the original one. I replaced the MJE21, Q9 and the diode again. Well, now the strangest thing has happened, I connected it to the power and try to turn it on, an electronic smell, not burnt just a bit of smell....and BOOM! It is now working perfectly, I tested it for hours....and does work all functions all games, pause, reset , any 7800's and 2600's games. THERE is one problem though......it cannot be not turned off.....so I replace the power button again and nothing,,,,it just does not power OFF. ANY IDEAS will be appreciate it. thanks!!! Quote Link to comment Share on other sites More sharing options...
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