Author Topic: Atari Audio/Regulator II Problem...Please help (Read 7857 times)

Mikew88 · « **on:** March 16, 2006, 10:36:53 pm »

Heya,

I have a AR II -02 board and i have a little problem. The board was
running fine at the beginning. I had to take out the board for a while
because i cleaned the inside of the cab. When i put the AR II back in,
-5 and +12 we're gone...No biggy, i put in a rebuilt kit and thought
that would take care of it...nope sure didn't, -5 and +12 are completly
dead. The 7905 and 7812 are working propperly, and i have checked all
joints on the ar II aswell as the wiring to look for cracks/loose
wires. Didn't find anything. Any suggestions that might get this board
running again?

grantspain · « **Reply #1 on:** March 17, 2006, 02:13:34 pm »

I know your gonna say i'm being stupid but you did connect all the plugs back on correctly,you say your regulators are running ok-i guess you metered the outputs on these and you have -5 and +12(there or there abouts),are there any fuses or fusible resistors on the pcb?

Mikew88 · « **Reply #2 on:** March 17, 2006, 03:29:36 pm »

yes the connectors are connected the right way... since there is only one way to hook them up. The regulators are working because i tested them with an ohmmeter. I dont get -5 and +12 anywhere. But what i did notice was that when i leave the bottom connector that feeds the voltages for -5 and +12 unplugged...nothing changes, meaning theres no voltages going through there. Now i gotta figure out why.

Mike

grantspain · « **Reply #3 on:** March 17, 2006, 03:53:59 pm »

well first thing you gotta prove is that you have input voltage onto that board,maybe from a transformer or a psu,if you posted a photo of your board i could probably tell which is needed,to me its sounds like you have a fuse blown somewhere or a cable broken.it don't sound like a major problem to me.bet it turns out to be something really daft.

Mikew88 · « **Reply #4 on:** March 17, 2006, 10:03:01 pm »

Ok this is what i have so far...All voltages are there except for 36VAC, 36 goes straight into the AR 2 which is needed for the lower half of the board, thus my problem. I tested 36 before the fuse block, and yup its there, tested 36 after the fuse block, nope, its gone. The fuse in there is not blown, but rather under rated. Now i replaced the fuses for the 36 volt line, and upon start up, it blows. Ya think ya got the answer, then another problem occurs...

Mike

grantspain · « **Reply #5 on:** March 18, 2006, 12:23:04 pm »

first thing to do follow the 36v wires and disconnect them from each termination point(unplug them),then switch on your machine,bet the fuse don't blow,then reconnect each plug one by one whilst switching off and on your machine until the fuse blows,the board that is causing your fuse to blow will have a bridge rectifier(4 diodes) and your regulators,for the fuse to blow straight away on power up means you have a dead short to ground and the only things that will cause this are diodes,transistors and caps-so its time to get your meter out and check those componants on the problem board.

RayB · « **Reply #6 on:** March 19, 2006, 01:20:29 pm »

Umm, did you re-connect the GAME BOARD? You will not get any voltage readings if there is no game board connected.

Mikew88 · « **Reply #7 on:** March 20, 2006, 01:09:37 pm »

Hey,

Yea the game board is connected. I believe there is a majot short in here somewhere. As the +5 and gnd test point have continuity, as do almost all others. Something is really screwed up.

Mike

grantspain · « **Reply #8 on:** March 20, 2006, 01:49:54 pm »

If i had your fault this is exactly what i would do.
disconnect all boards voltage plugs
check all fuses,replace if blown
turn on machine and check a/c voltages on transformers are correct
plug in psu board only
does the fuse blow-yes fault on psu board
does fuse blow-no,plug in each board one by one until fuse blows
remove board and check diodes,transistors
remember you will always get some continuity from 5v to com because of componants like caps.
always make sure fuses are the correct rating,if you underate by too much the fuse will blow anyway
usually a good sign to see if you have dead short is when the fuse blows right away on power up.

cw · « **Reply #9 on:** March 20, 2006, 03:06:29 pm »

he seems to have a dead short across all the test points on the board....

thats with it pulled out and on a bench..seems very strange

grantspain · « **Reply #10 on:** March 20, 2006, 03:51:28 pm »

Must be reading the board incorrectly,a dead short 0 ohms across 5v to com could only be plug upside down or regulator dead short,its sounds alot more simple than that,i still think its a diode(bridge) on the audio board.The 36v must go onto the audio board,if its a/c then into a bridge rectifier,smoothing cap then a small transformer,then voltage regulators,smoothing caps again, then off to audio ic.Hope its not just a 12v bulb holder shorting(seen that before)

Mikew88 · « **Reply #11 on:** March 20, 2006, 04:21:57 pm »

Heya,

Me an cw have been trying to figure this out for quite some time now. I did some tests before and it HAS to be the ar 2. I bought brand new fuses 3A 250V. Exactly the ones i need. Put em in and powered the game on, and they immediatly blew. This was with the P9 connected to J9 on the ar 2. K well those fuses are history, popped in fresh ones leaving P9 disconnected (Plug that carries the 36VAC) and everything went ok. Besides the lack of 36vac and no -5 and +12. I guess this would indicated that i have a majot short somewhere in the area where the 36 volts flow in. The capacitors are all inserted the correct way. But im not sure if the diodes work anymore...

Mike

grantspain · « **Reply #12 on:** March 20, 2006, 04:33:14 pm »

get your meter on each diode read across on diode test or ohms- should not read dead short anywhere(0 ohms)

Mikew88 · « **Reply #13 on:** March 20, 2006, 05:01:18 pm »

I will test the diodes as soon as i get home from school....which will be in about 1 1/2 hours.

Mike

Mikew88 · « **Reply #14 on:** March 20, 2006, 06:25:57 pm »

ok...none of the testpoints or diodes have a dead short. They all have resistance. The diodes for example are at around 10k ohms. Not sure where this puts us right now.

Mike

grantspain · « **Reply #15 on:** March 21, 2006, 01:24:58 pm »

the only sure way to meter a diode is lift one side out of the board and then you should get a reading one way only,is there any chance you can get the schematic of that board on this thread,it may be possible to identify possible causes.
You say your game was good before you cleaned the cab then you got problems,well you have got retrace everthing you did,you may have shorted some wires,trapped something-its really easy to do.

RayB · « **Reply #16 on:** March 21, 2006, 02:51:20 pm »

Just occurred to me. Why is this in "monitors/video" rather than in "Arcade"?

Mikew88 · « **Reply #17 on:** March 21, 2006, 08:24:10 pm »

I guess the problem started out with a shaky monitor on my warlords, this is probably caused by the Ar 2 so i guess i just took it from there. Sorry i didn't post it in the arcade section

. I don't really think i shorted anything outside the Ar 2, Leaving everything disconnected such as the monitor, coin door, and control panel results in the same problem. And i never messed around with the game board in a way to mess it up. Well here are the results i got from the diode were about .40 on each.

And here is a link to the Crystal Castles Schematic Package that has the Ar 2 schems in it.
http://gamemanuals.net/download/ba497ce73be49d0818b9d921e31589ec/Crystal%20Castles%20(SP-241%201st%20Printing)%20[Schematic%20Package].pdf

Thanks
Mike

D_Zoot · « **Reply #18 on:** March 21, 2006, 08:58:27 pm »

let me see if I have been following the story so far:

The fuse that feeds the 36v to the AR2 blows, only when the AR2 is plugged in. If you disconnect the game board the fuse still blows, right (an AR2 will output with no load, but expect higher than normal voltage output)? If it doesn't blow with the game board disconnected, then you have a game board problem.

Ok, so if it is the AR2:

Right now I am holding an AR2 and looking at it.

Ok, there isn't that much on that side of an AR2, you really have only a few of things that would cause this.

CR5-CR8 (the rectifier diodes) sound ok. You are measuring .40v on each diode in one direction and nothing when you reverse the leads, right? If so, the diodes are ok.

Make sure the 7905 has an insulating sheet between it and the heat sink. Use your meter and test for a short between the tab of the 7905 and the heat sink, if so inspect the insulating sheet for holes or tears.

Next would be a bad regulator IC, you can't test them with a meter, the only way to test a regulator IC is in-circuit, which you can't do in your case. I would remove each regulator one at a time and recheck to see if the fuse blows again. Q8 is the 7812, Q9 is the 7905. Remove one at a time, recheck, if the fuse still blows, move on to the other one.

Lastly, you could have a shorted cap.

That's it, there's nothing else on the board to go wrong.

If you get really stuck, I'll look at the AR2 for you and either fix it or exchange it, let me know if it comes to this and I'll send you my address.

Good luck!
D

Mikew88 · « **Reply #19 on:** March 21, 2006, 09:56:43 pm »

Heya,

Thanks for the info.

7905 is isolated from the Heatsink. The game board is fine as the fuse still blows with the ar2 connected.. Basically the ar2 itself can be connected. Except of P9 in J9 of the ar2, thats what will cause the fuse to blow on start up. It could be the regulators, but something tells me that it isn't as the board did the same thing before the rebuilt kit, BobRoberts told me that he hadn't had a bad regulator in 50 years...so i dont know if could be the regulators but its worth a try. Shorted cap...they are all soldered in the correct way not sure how it could short anywhere. Ill give the regulators a try tomorrow, and will report back.

Thanks
Mike

cw · « **Reply #20 on:** March 22, 2006, 07:34:42 am »

mikey and I have looked at every cap on that side of the ar2... they all look good..

grantspain · « **Reply #21 on:** March 22, 2006, 01:54:07 pm »

with only the ar2 board 36v(no other plug) only connected does it still blow the fuse?

RayB · « **Reply #22 on:** March 22, 2006, 02:24:03 pm »

Dumb question: Are you sure you're putting in the correct rating of fuse?

cw · « **Reply #23 on:** March 22, 2006, 03:32:23 pm »

yes he is.... 3a sb 250v... that was one of the first things to check...

Mikew88 · « **Reply #24 on:** March 22, 2006, 04:26:24 pm »

Well i haven't really checked with ONLY P9 connected...But when i leave P9 disconnected its fine, once its connected it blows, thought it would be pretty obvious that the issues are dealing with wherever the 36vac line is going into which would be the diodes and then the rest of the circuit.

grantspain · « **Reply #25 on:** March 22, 2006, 05:17:49 pm »

not always,there can be a problem further on your circuit which is confusing the issue,first isolate the faulty area e.g the ar2 board then isolate the area of the board which is causing the problem,there are situations where possibly a short further on the circuit will cause your 36v to blow,by only plugging p9 you prove without a shadow that the fault lies on the ar2 board and not after,once the board has been isolated as the fault area then you start by metering the a/c to d/c area of the board,like i said the only true way to meter a diode is lift one side and then read the diode.I can't get the diagram to load on my pc so i am working blind,but you have a dead short on one of you voltage lines to common and more than likely its on the a/c side because its blowing the fuse on the a/c side.

Mikew88 · « **Reply #26 on:** March 22, 2006, 07:01:54 pm »

Alright...This is gonna sound totally loopy, but the ar 2 works again...I noticed there was a size difference in a few caps and it prolly slipped my mind. Upon checking over every cap again, C31 and C23 were mixed up. Now....could this be an active reason why the board blew the fuse? I still can't believe that it works again/how it works again/how stupid i was.

.......

grantspain · « **Reply #27 on:** March 22, 2006, 07:11:28 pm »

You know this is what i was saying about retracing your steps,it only takes one mistake and you have a whole load of crap on your hands,i hope it works ok now,also maybe you have learnt a bit more about fault finding so this has been a good experience,anyway enjoy

Mikew88 · « **Reply #28 on:** March 22, 2006, 07:13:14 pm »

This has been a GREAT experience

Ya gotta love it when you finally get something working by trying and trying and trying...Thanks to everybody who helped on this one.

Mike

grantspain · « **Reply #29 on:** March 22, 2006, 07:19:31 pm »

Even after 20 years in the industry i still get a massive buzz fixing a fault,it makes you feel good,don't matter how silly the fault its good and thats why i love my job

Mikew88 · « **Reply #30 on:** March 22, 2006, 10:09:05 pm »

Yup thats how i always feel, and thats how it should feel, that way you know you have fun doing these kinda things. I've been in this hobby for only a few years, but my collection has grown, and hopefully it will keep growing


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