Jump to content

Photo

Atari 5200 2 port power issue


48 replies to this topic

#26 SignGuy81 OFFLINE  

SignGuy81

    Dragonstomper

  • 591 posts

Posted Thu Jul 6, 2017 4:12 PM

Also I want to know if you are checking this with or without a cartridge plugged in?



#27 Jpc18 OFFLINE  

Jpc18

    Space Invader

  • Topic Starter
  • 18 posts

Posted Fri Jul 7, 2017 10:55 AM

SignGuy81 there is no game inserted. I lifted legs on c130 and c43 and the input is .938.



#28 DavidMil OFFLINE  

DavidMil

    Moonsweeper

  • 377 posts
  • Location:Kingwood, Texas

Posted Fri Jul 7, 2017 2:29 PM

 

DavidMil am I supposed to be ohming these two on q6 and q7 with power plugged in or not. I think we are not plugging power back up for now so that nothing gets fried.

 

 

NEVER try to get an ohms reading with the power on!  You can do bad things to your meter and or your board.  The input voltage for VR1 goes through

Q6.  If Q6 has failed VR1 won't get enough power to enable regulation.  Q6 doesn't have to be shorted to be bad.  If raising one leg of the caps doesn't

make any difference, I would check the resistance between E and B and E and C on Q6 and compare them to similar reading on Q7.  When you had the

voltage on did you check any of the VCC readings on the chips? 

 

DavidMil



#29 Jpc18 OFFLINE  

Jpc18

    Space Invader

  • Topic Starter
  • 18 posts

Posted Fri Jul 7, 2017 2:51 PM

DavidMil I did not check vcc on on the chips. Q6 4.1 E and B. E and C 153. Q7 4.0 on E and B. 279 on E and C. If I keep the probes there though it seems they would continue to climb. This test is also with the legs still off, I wasn't sure if it mattered.



#30 SignGuy81 OFFLINE  

SignGuy81

    Dragonstomper

  • 591 posts

Posted Fri Jul 7, 2017 4:13 PM

As far as Q6 and Q7 goes, as I was mentioning before, there is no direct connection from the emitter, base, or collector to ground so therefore if the transistor is shorted(the only kind of problem the transistor could have that would cause a short to show in something parallel with it) it will not show a short or the near short(close to 1 ohm) you are seeing between the input and ground of VR1.  You need to follow the input trace from the voltage regulator and make sure you don't have a bridged solder joint somewhere or something.    I would also still remove the transistor anyway(Q6) completely to help narrow down and find the short on the motherboard though.


Edited by SignGuy81, Fri Jul 7, 2017 4:15 PM.


#31 DavidMil OFFLINE  

DavidMil

    Moonsweeper

  • 377 posts
  • Location:Kingwood, Texas

Posted Sat Jul 8, 2017 10:24 PM

Ok, we've been telling you to do a lot of things, so can I get you to recap (list) what components have lifted legs or have been removed totally?  Also when you are ohming

things out, where are you putting the ground lead?

 

DavidMil



#32 Jpc18 OFFLINE  

Jpc18

    Space Invader

  • Topic Starter
  • 18 posts

Posted Mon Jul 10, 2017 8:15 AM

Signguy81 in the pic this is where I followed it to. On the input trace pic 1 bottom side of the board going right and up to the solder point leads to the topside and these. L9 and then runs over to c129 pic 2. On the input side again bottom side of the board following the trace downward, it leads to c37 I think that's what it says and the other which I can't read it's covered. See pic 4. Looks good I believe. Pic 1 got turned upside down somehow sorry.

Attached Thumbnails

  • IMG_8350.JPG
  • IMG_8351.JPG
  • IMG_8355.JPG
  • IMG_8356.JPG

Edited by Jpc18, Mon Jul 10, 2017 8:16 AM.


#33 Jpc18 OFFLINE  

Jpc18

    Space Invader

  • Topic Starter
  • 18 posts

Posted Mon Jul 10, 2017 8:19 AM

DavidMil, I'm measuring from the Input side and center, which should be ground correct? Pics of what I lifted.

Attached Thumbnails

  • IMG_8352.JPG
  • IMG_8353.JPG


#34 DavidMil OFFLINE  

DavidMil

    Moonsweeper

  • 377 posts
  • Location:Kingwood, Texas

Posted Mon Jul 10, 2017 10:40 AM

And VR1 is still Removed Right?

 

David



#35 Jpc18 OFFLINE  

Jpc18

    Space Invader

  • Topic Starter
  • 18 posts

Posted Mon Jul 10, 2017 11:35 AM

Davidmil that is correct.



#36 SignGuy81 OFFLINE  

SignGuy81

    Dragonstomper

  • 591 posts

Posted Mon Jul 10, 2017 3:38 PM

I'm glad you posted that pic.  The first one up above showing where VR1 is.  The silkscreen is wrong.  I and O labels are backwards which has been throwing the whole troubleshooting off.  The short must be on the output side if you were checking it by the "I" label on the board.  Looking at the front of the regulator from left to right is Input, Ground, Output in that order.  The silkscreen labeling is backwards due to an error apparently.  Also you can confirm what I'm saying by the schematic where C43 is across the Input and Ground of VR1, just as in the picture, they just have it labeled wrong on the board.


Edited by SignGuy81, Mon Jul 10, 2017 3:40 PM.


#37 SignGuy81 OFFLINE  

SignGuy81

    Dragonstomper

  • 591 posts

Posted Mon Jul 10, 2017 3:47 PM

Might sound like a lot of work but lift one pin of C122, C37, C36, and C119 so we can see where to trace the short from there(if it isn't one of the caps themselves).  If not one of the caps I want to see if it is on the 5VA, 5VC, or the VCC1 line and removing one leg of each cap will tell us.  Plus L10 forgot that, and L7 have to have one leg lifted on those as well to isolate.


Edited by SignGuy81, Mon Jul 10, 2017 3:49 PM.


#38 DavidMil OFFLINE  

DavidMil

    Moonsweeper

  • 377 posts
  • Location:Kingwood, Texas

Posted Tue Jul 11, 2017 1:31 AM

Might sound like a lot of work but lift one pin of C122, C37, C36, and C119 so we can see where to trace the short from there(if it isn't one of the caps themselves).  If not one of the caps I want to see if it is on the 5VA, 5VC, or the VCC1 line and removing one leg of each cap will tell us.  Plus L10 forgot that, and L7 have to have one leg lifted on those as well to isolate.

Before you do all that I would suggest that you do a fast voltage check and see if you are still loosing power (not getting 12V on the MB) with VR1 removed.  If the voltage is good at this

point you will know for sure that the problem is beyond VR1.  If it's still low, kill the power and do and ohms test between either L7 or L10 and ground.  If you're not getting a very low reading

(a few ohms or less) at one of these points, I would think that we need to look elsewhere.  I just had a thought...  Look in the cartridge socket and make sure there are not any bent connectors

or small loose metal objects (like maybe a solder ball).  VCC1, CI1, and CI2 all got to the cartridge socket, and create a short potential.  CI1 and CI2 are right next to the ground connector in

the cartridge socket.

 

David



#39 Jpc18 OFFLINE  

Jpc18

    Space Invader

  • Topic Starter
  • 18 posts

Posted Wed Jul 12, 2017 7:46 AM

May be a delay as i'm busy at work and home. To signguy81 and Davidmil, I'm trying to locate these numbers and have found a few. To answer your first question for now, that has already been tested a few posts back. still 1.2 volts at the connector socket with VR1 removed and the two legs on C43 and C130. Should get a break or two today to locate and test these things.



#40 Jpc18 OFFLINE  

Jpc18

    Space Invader

  • Topic Starter
  • 18 posts

Posted Wed Jul 12, 2017 10:29 AM

To Davidmil, i have checked L7 to ground where the center pin for VR1 was if that is correct and got .931. I also checked L10 to the same ground and got similar results. It was .930. Cart connector pins are not touching and i used an air hose to dislodge any thing inside of it. As far as the VCC1, CI1, CI2, not finding them on the schematic.



#41 DavidMil OFFLINE  

DavidMil

    Moonsweeper

  • 377 posts
  • Location:Kingwood, Texas

Posted Wed Jul 12, 2017 12:46 PM

As far as the VCC1, CI1, CI2, not finding them on the schematic.

 

Look on page 2-27 of the schematics (Fig. 2-12)  This is the power supply/distribution section of the schematics.  Look at the base of Q6 and Q7.

CI2 is connected to Q6 via R57, and CI1 is connected to the base of Q7 via R58.  R57 and R58 are large resistors on the right edge of the board.

Do you not have pages 2-27 and 2-29?  I can put them out here for you.  2-29 is a picture of the top of the MB with part numbers listed for each

component.  VCC1 is connected to the output of VR1.

 

David



#42 Jpc18 OFFLINE  

Jpc18

    Space Invader

  • Topic Starter
  • 18 posts

Posted Wed Jul 12, 2017 3:02 PM

Davidmil, yes signguy81 posted a link. I see the R57 via Q6, I flipped the board over to follow the trace up to what looks to be a dead end (see pic 3). Now on the other hand with R58 via Q7, I traced it all the way to the bottom of the cartridge slot as you've stated (see pic 2). As for VCC1, I see that point. I think the biggest issue with looking at these is I can't under stand the schematic as you guys do (see pic 1). In the microscope nothing appears to be touching. Sorry for the dirty fingers, I had some work to do and the plane was dirty. I have a couple schematics I use and can understand installing the wiring for switches, breakers, and clean power in boxes, but it's simplified and this is a little more complex. Everytime I upload pics they get swapped around.

Attached Thumbnails

  • IMG_8369.JPG
  • IMG_8368.JPG
  • IMG_8367.JPG

Edited by Jpc18, Wed Jul 12, 2017 3:08 PM.


#43 DavidMil OFFLINE  

DavidMil

    Moonsweeper

  • 377 posts
  • Location:Kingwood, Texas

Posted Fri Jul 14, 2017 10:35 PM

Davidmil, yes signguy81 posted a link. I see the R57 via Q6, I flipped the board over to follow the trace up to what looks to be a dead end (see pic 3).

 

 

CI2 goes to pin 36 of the cartridge slot.  You can ohm it out to make sure.  Put one lead on the side of R57 closest to the heat sink and the other on pin 36 of the

cartridge socket.  I'm going to tell you that the 5200 schematic is not the easiest to follow.  From what I'm looking at (via the schematics), power is on VR1 even

when the power button is off.  SignGuy81, would you agree with that? 

 

David



#44 SignGuy81 OFFLINE  

SignGuy81

    Dragonstomper

  • 591 posts

Posted Sun Jul 16, 2017 1:53 PM

 

 From what I'm looking at (via the schematics), power is on VR1 even

when the power button is off.  SignGuy81, would you agree with that? 

 

David

 

 

Not always, depends on whether or not a cart is inserted.  The 4013 chip and cart inserted both play a role in this.  If you look at VR2 side of things, where  Q8(NPN) is, that gets power to the base from Q9(another NPN which the collector is tied to the unreg supply) which gets its base power from the 4013 chip.  Basically once Q8 is turned on, it sends ground through the jumper of CI1 and CI2 to make the PNP transistor(Q6) turn on.  So without a cart VR1 shouldn't power up and it shouldn't power up until pin 13 of the 4013 chip is high and a cart is inserted.  And VR2 can power up with just pin 13 of the 4013 high, supplying base power to Q9 which does the same then for Q8 which then supplies the ground to base of Q7(PNP) for VR2. 



#45 DavidMil OFFLINE  

DavidMil

    Moonsweeper

  • 377 posts
  • Location:Kingwood, Texas

Posted Sun Jul 16, 2017 7:00 PM

 

 

Not always, depends on whether or not a cart is inserted.  The 4013 chip and cart inserted both play a role in this.  If you look at VR2 side of things, where  Q8(NPN) is, that gets power to the base from Q9(another NPN which the collector is tied to the unreg supply) which gets its base power from the 4013 chip.  Basically once Q8 is turned on, it sends ground through the jumper of CI1 and CI2 to make the PNP transistor(Q6) turn on.  So without a cart VR1 shouldn't power up and it shouldn't power up until pin 13 of the 4013 chip is high and a cart is inserted.  And VR2 can power up with just pin 13 of the 4013 high, supplying base power to Q9 which does the same then for Q8 which then supplies the ground to base of Q7(PNP) for VR2. 

 

SignGuy19 is correct, without the cartridge installed and Q9 powered on, Q8 won't turn on and give a path to ground for Q6 and Q7.  Jpc18 did you ever lift one leg of the four caps 

and two Ferrite Beads (C36, C37, C119, C122, L7, and L10)?  This will tell you which of the three 5Volt power rails (5A, 5B, VCC1) has the short.  To avoid any miss-readings, I would raise

the legs of L7 and L10 that are connected to the large trace that connects the two inductors on the top of the board. 

 

David



#46 Jpc18 OFFLINE  

Jpc18

    Space Invader

  • Topic Starter
  • 18 posts

Posted Mon Jul 17, 2017 10:25 AM

If Q6 is R57 then i probed leg E as seen in one of the 3 pics. I actually probed it thouh on the bottom side of the board and pin 36 on the cartrige slot. I get 4.893. I have not cut any other legs per signguy81's request to do so yet. The red probe indicates the E leg, which should be R57. The black probe is on pin 36 in one of the photos.

Attached Thumbnails

  • IMG_8396.JPG
  • IMG_8397.JPG
  • IMG_8398.JPG


#47 DavidMil OFFLINE  

DavidMil

    Moonsweeper

  • 377 posts
  • Location:Kingwood, Texas

Posted Mon Jul 17, 2017 2:26 PM

Jpc18, Please forgive me but I have to ask:  You are on ohms and not kilo ohms scale right?  The way you have the probes set there, you

are reading across the E-B (Emitter, Base) junction of Q6 and through R57.  If you are reading 4.893 ohms, you have a serious problem there.

 

David



#48 Jpc18 OFFLINE  

Jpc18

    Space Invader

  • Topic Starter
  • 18 posts

Posted Mon Jul 17, 2017 2:41 PM

Davidmil, yes ohms. I'm sorry i thought 57 was Q6, after looking at the schematic i see R57. 330.6 is the read out.



#49 DavidMil OFFLINE  

DavidMil

    Moonsweeper

  • 377 posts
  • Location:Kingwood, Texas

Posted Mon Jul 17, 2017 5:50 PM

Jpc18, Please forgive me but I have to ask:  You are on ohms and not kilo ohms scale right?  The way you have the probes set there, you

are reading across the E-B (Emitter, Base) junction of Q6 and through R57.  If you are reading 4.893 ohms, you have a serious problem there.

 

David

 

I forgot to mention that R56 is 4.7K (which you are also reading across) and when you add R57 into the reading you would get about 5K ohms.

Close enough to the 4.893 that you were reading (if you had an auto ranging ohm meter).  You may want to check across R56 alone to see what

you are reading.  If it's not close to 4.7K, I would raise one leg of R57 and check it again.  We are getting side-tracked from your short problem

though...

 

David


Edited by DavidMil, Mon Jul 17, 2017 5:50 PM.





0 user(s) are browsing this forum

0 members, 0 guests, 0 anonymous users