Atari bridge rectifier from Bob Roberts

jumpman

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This is probably a dumb question but I'm still learning my way, I ordered a new bridge rectifier for a MC PS from bob roberts I haven't replaced it yet because I didnt know which wires to hook to where. the bridge has 4 terminal tabs to which I need to hook 4 wires, Does anyone know off hand what color wires to hook to where?
I will post pics later tonight when I get off work if that will help.
thanks
 
it should be marked with + and - It can be on the molded part looking down from the top or printed very small on the side. match up those signs with the ones on your original.
 
Most are marked + only. Some have all four poles marked.
Some are not marked at all but + is indicated by a flat side on one corner. If its a square one the negative will be diagonal across from the + and the other two are ac. If it has inline pins the two middle are AC and negative on the opposite end from +.
 
i better post pics just to be sure:
the original has a white w/ black stripe and a black w/ white stripe going into the side marked "Line"
The Load side has a solid white and black coming out. I just want to make sure which wire to hook to the +, and to make sure the + side is also the Line side. Thanks for your help!
 

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Ahhh, your trying to replace a line filter with a bridge rectifier :)
Maybe you should find someone to work on your game...or at least help you.
Flip that power brick over and see if the bridge is mounted on the bottom side.
 
Ahhh, your trying to replace a line filter with a bridge rectifier :)
Maybe you should find someone to work on your game...or at least help you.
Flip that power brick over and see if the bridge is mounted on the bottom side.

No I wasn't trying to replace a line filter, I just didnt see any other parts that looked like what I got from bob, I was just looking for something that had 4 wires hooked to it so I assumed that was the bridge rectifier. I will have to look at some manuals to make sure what Im looking for. There is a rectifier board attached to big blue, is it near that?
 
It's on the Power Transformer 'brick'.

Here it is viewed from the bottom.

normal_CIMG1649.JPG



It's on the bottom of this

normal_CIMG1644.JPG
 
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If you don't even know where it is or what it is,how do you know it's bad?:eek:

thanks for the pic, now I know what Im looking for.

I dont know if its bad, I was trouble shooting non working ps, so someone recommended since I was ordering a big blue that I might as well order a bridge rectifier too. I only replaced big blue and it worked, so I never bothered to replace the bridge. It was bothering me that I couldnt even find where it was so I asked incase I need to replace one someday. For now I will not mess with it since its not broken, unless someone recommends I do. Thanks for the help guys!
 
Missile Command, like other Atari games from about 1980 and earlier, does NOT use a bridge rectifier in the power assembly. Instead, it has two large diodes on a small circuit board that is screwed directly to the bottom of the "big blue" filter cap. In the manual, it's listed as "rectifier p.c. board assembly."

Bob Roberts does sell a replacement for those two diodes if yours are bad, order:
"P600A Across Atari Big Blue Cap PCB (2 needed)2/ $2.00"

The transition from the two-diode (half wave) to four-diode bridge (full wave) rectification seems to have happened around 1980-81.
 
I don't mean to hi-jack this thread but I've replaced my rectifier with the one from Bob's kit and now the PS does not work at all. I'm pretty sure I put it in right. I have pictures of before and I put the replacement in the same way. Ideas?

I also replaced Big Blue and all fuses in the Tempest PS. Thanks
 
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Missile Command, like other Atari games from about 1980 and earlier, does NOT use a bridge rectifier in the power assembly. Instead, it has two large diodes on a small circuit board that is screwed directly to the bottom of the "big blue" filter cap. In the manual, it's listed as "rectifier p.c. board assembly."

Bob Roberts does sell a replacement for those two diodes if yours are bad, order:
"P600A Across Atari Big Blue Cap PCB (2 needed)2/ $2.00"

The transition from the two-diode (half wave) to four-diode bridge (full wave) rectification seems to have happened around 1980-81.
Sorry to drag this thread up, but can anyone confirm that 2 x P600A are indeed suitable replacements. The original diodes are MR750 (semi conductors), the P600As are solid state. Other than that the specs match (6A, 50V). Thanks for any advice, I need to replace these diodes.
 
Sorry to drag this thread up, but can anyone confirm that 2 x P600A are indeed suitable replacements. The original diodes are MR750 (semi conductors), the P600As are solid state. Other than that the specs match (6A, 50V). Thanks for any advice, I need to replace these diodes.

I've used the P600A's from Bob Roberts successfully in Asteroids and Lunar Lander games.

Also, when I haven't had P600A's on hand, I've substituted 6A2's.

Can compare specs:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MR750-BPMS-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P600A-E3/54-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=6A2DICT-ND

As far as I'm concerned, pretty much any beefy diode rated at 6A and 50V (or better) will work fine.
 
Sorry to drag this thread up, but can anyone confirm that 2 x P600A are indeed suitable replacements. The original diodes are MR750 (semi conductors), the P600As are solid state. Other than that the specs match (6A, 50V). Thanks for any advice, I need to replace these diodes.

Yes, they are good subs.

Ed
 
For those unfamiliar, it works out this was because a bridge rectifier is nothing more than 4 diodes arranged in a square. As long as AC goes in on opposite corners, DC comes out the remaining two corners. (see pic)

To identify the terminals on an unmarked full wave rectifier, use your a meters continuity test. First, select two opposite terminals as your AC terminals. It does not matter which two as long as they are diagonal from one another. This leaves you with only two terminals to test. These are your DC terminals. Next, connect your meter's black (-) lead to either of the AC terminals. Now, test both DC terminals with your red (+) lead. The + DC terminal will show continuity, the - terminal will not. You can remember this later by looking at the probe. If you are testing with a + probe, you will get continuity on the + terminal. Conversely, if you reverse the leads and connect + to an AC terminal, you will be testing for the - terminal.

To identify the DC terminals on an unmarked full wave rectifier, use your a meters continuity test. First, select the two opposite terminals marked as as your AC terminals. This leaves you with only two DC terminals to test. Next, connect your meter's black (-) lead to either of the AC terminals. Now, test both DC terminals with your red (+) lead. The + DC terminal will show continuity, the - terminal will not. You can remember this later by looking at the probe. If you are testing with a + probe, you will get continuity on the + terminal. Conversely, if you reverse the leads and connect + to an AC terminal, you will be testing for the - terminal.

If all that sounds difficult to remember, there is an easier way. Supply AC power to it (without a load on DC). Use your voltmeter to check the opposing DC terminals. If + and _ leads are hooked up properly, the voltage value will be positive. If it is negative, your leads are reversed.

@Ben - Test your install with the instructions above. You may have installed properly, but the old vs. new pinouts changed.

The original diodes are MR750 (semi conductors), the P600As are solid state

"solid state" is an old term used to denote devices that used all semiconductors and no tubes. It's not used much anymore, but can was often used interchangeably with semiconductor. If the specs match, carry on. Since rectifiers are very simple devices, all you really need are diodes that can handle the same voltage and current.

Missile Command, like other Atari games from about 1980 and earlier, does NOT use a bridge rectifier in the power assembly. Instead, it has two large diodes on a small circuit board that is screwed directly to the bottom of the "big blue" filter cap. In the manual, it's listed as "rectifier p.c. board assembly."

The transition from the two-diode (half wave) to four-diode bridge (full wave) rectification seems to have happened around 1980-81.

Are you sure that's a half wave rectifier? You can use a center tap transformer and make a full wave rectifier with just two diodes. I'd love to see a schematic and/or pic if you have one handy or can point me to a link.
 
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Haven't got a link to the schem, but yeah, on Missile Command it's a 16.5VAC CT.

The outer rails run through the diodes. The diodes run straight to the Big Blue cap, where they are joined by the centre tapped voltage (at negative on the big blue).

I think .....
 
'm betting you have a full wave rectifier based on your description. On Ken's diagram, place your big blue filter cap where RL and continue both legs on to your actual load. If that matches, it's a 2 diode full wave.
 
To identify the terminals on an unmarked full wave rectifier, use your a meters continuity test. First, select two opposite terminals as your AC terminals. It does not matter which two as long as they are diagonal from one another.

According to that diagram you can't just pick two opposite terminals as AC. The AC terminals have to be between the two diodes pointing the same way.
 
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