Road blaster power supply question.

THEDJ

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Hi all

I am rebuilding a power supply for a atari road blasters

Where does the red/white wire that runs from the audio req to the ? (maybe power supply)

It says CT on the schematic


also do i not need to hook up the +sense and -sense

see photo


Thank you
chris
 

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It goes to the isolation transformer. The wire coming out of the transformer looks white with a pink stripe on my game but the pink might be a faded red.

Here is a pic from the manual of the wire (circled in red):

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Here is a pic from my game:

attachment.php


The cut red/white and brown/white wires at the bottom of the photo above are the sense wires. The game works fine without them.
 

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The CT stands for Centre Tapped - In this case 12VAC Centre Tapped. The red, violet, and white/red wires combine to supply 12VAC CT from the transformer to the Audio PCB assembly.

And yes, you need to hook up the +sense and minus sense (to the main PCB).
 
Ct wire

Sorry, i didn't understand what you said about the ct wire.

i know the other 2 wires connect to the +12v on the switcher power supply.

not sure where the ct wire goes, I know it does not goto to the +12v(game does not boot)

maybe a ground?

also on the +sense and -sense

do i just connect them to the +5 (switcher) and the ground.

One final question.

there are 2 red led lamps on the main pcb.

when i turn on my game, the lower one lights, and starys lit.

the upper one blinks a few times, and stays off.

my game turns on but the graphics are all cut up, and there is no sound, just a few pops from the speakers.

thank you.

chris
 
Sorry, i didn't understand what you said about the ct wire.

The "CT" wire is the wire from the isolation transformer circled in red on the pictures I posted. It should be the white wire with a red or pink colored stripe sticking out of the transformer.

i know the other 2 wires connect to the +12v on the switcher power supply.

I assume you are referring to the other wires from the Audio II PCB that are red and violet. If you look at the diagram in your first post, you will see "F2" and "F3" which stands for fuse F2 and fuse F3. These two wires are 12v AC ! This is not the same as the 12v DC on the switching power supply. This may be the cause of your sound problems. The "CT" wire is part of this AC circuit too which is why it also goes to the transformer but it does not need to have a fuse like the red and purple wires.

There should be a Red +5V DC wire and a Brown DC Ground wire on the switching power supply as in my picture. The +12v DC is not used at all.
 
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Your right.

Your right.


The 12 v red, and violet are ac not dc.

I had them hooked to dc. (on the switcher)

my transformer is not the original, so i was only using it for the monitor.

I am not sure if my transformer has 12 vac legs on it, or where to hook the ct wire as well, since it is not the original transformer.

Also is the red led lamp in the upper right corner of the pcb on or off, when power is on?


Thanks

chris
 

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The LED (red light) at CR3 is not on but the LED at CR5 is on when the game is running normally. I do not know for sure if CR3 should blink because I cannot see it when I turn it on or plug it in. I can not seem to find the normal status listed in the manual anywhere. On some games, it can work as an error code.

There could be a trick to getting the Audio II board to work without the 12v AC but I am not sure how. You may just have to track down an original transformer. I know that the Audio II board converts the AC to regulated DC for the main PCB so the game itself might not work properly without the 12v line. I bet you could splice in a +12v DC line from the switcher between the Audio II board and the Main PCB at P101. This would probably not help much with the audio but it might get the board to boot.
 
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I'm struggling to understand why you're not running the 3 wires to where they should be - which is the audio board (not the switcher). You posted a picture of the relevant part of the schematic which shows you where on the audio board these go. The audio board is waiting for 12.5VAC CT from those three wires. Why not give it a try?
 
my transformer is not the original, .........

I am not sure if my transformer has 12 vac legs on it, or where to hook the ct wire as well,
Ah. I see. From your original post it wasn't obvious that you weren't using the original transformer .... so I've been looking at this backwards.

Anyways .... in answer to your question `where does the CT wire come from?' - it doesn't. It's an output from the transformer. Or would be if you had the original. I take it that you're not using a like for like replacement?

How do you know that you're getting 12VAC from the transformer that you are using? Do you have the correct schem for that transformer? If so, you need to check the outputs. Post a pic or a link if you like.
 
Transformer

I have found an extra pole position power brick, i may just try to use it, i know it has the power for the monitor, and the 12vac for the audio req 2 board.


How many amps is the 12vac ?


Thanks

ck
 
Are you sure that the Pole Position power supply will give you the 12VAC? The schematic suggets that it wont.

Anyway, 12VAC isn't going to cut it. You need 12VAC CT.
 
On to the next problem.

I had to buy a step down transformer.

Now the game boots up, and i have sound. but the picture is all blocky, and cut up.

So its time to search the boards for that problem.

maybe need to reseat the chips.


thanks for all the help guys.

chris
 
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