Level42
New member
Why people replace perfectly good working bridge rectifiers (or diodes) is beyond me....they don't wear out or anything.....
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Atari bridge rectifier from Bob Roberts
- Thread starter jumpman
- Start date
SuperSprint
Well-known member
Great catch. All these years, and I never noticed that... At work, I'll update in a bit.
tb lilley
Member
Well yeah, but they do occasionally go pop. Which is why I need some new ones. Believe me, if they were fine I'd leave them well alone!
Not to hijack this thread, but the discussion has brought up a question...
I have and Asteroids Deluxe with a working power supply. I got the Atari ps rebuild kit from Bob because I had read that big blue should be replaced as a preventivie measure. So, I figured I'd just get the entire kit, which included the rectifiers and fuse block.
Given that I have a working power supply should I just replace big blue and not bother mucking with swapping out the rectifers and fuse block?
Or should I not even bother with big blue since it's all working right now and just hang onto the parts until it does fail?
I have and Asteroids Deluxe with a working power supply. I got the Atari ps rebuild kit from Bob because I had read that big blue should be replaced as a preventivie measure. So, I figured I'd just get the entire kit, which included the rectifiers and fuse block.
Given that I have a working power supply should I just replace big blue and not bother mucking with swapping out the rectifers and fuse block?
Or should I not even bother with big blue since it's all working right now and just hang onto the parts until it does fail?
Riptor
Well-known member
No they dont wear out, they burn up. Bridge rectifiers fail more often than you think. It does help to know how to properly test them so you dont throw away money replacing them when they are not bad. They are simple to test with any multimeter that has diode setting.
G-P-E
Well-known member
Most often the case - it it works, don't mess with it.
But, capacitors going bad can take other components with it...occasionally.
Leave all alone except the cap. Look at the cap to see if it is original. Check date code - should give you a good idea as to age. If you find something like "7943" - that means 43rd week of 1979...real old.
As a rule, caps are considered old at the 10 year mark. However, there are always exceptions to every rule. Some caps were just made better than others and don't dry out nearly as fast. Some had little use and less dryout occurs due to lack of use (heat). Others... just give up the ghost early. Heck, many Chinese caps give up the ghost before they're used. If cap is made by Lelon ... save some time and toss it in the trash now.
For big blue - if in doubt and it appears to be older than dirt, change it. It is an easy change with little chance of mucking things up. Just make sure to not reverse the polarity!!
Rectifiers, etc -- these provide ample opportunity to make things worse than they are. If it works, leave them well alone.
Ed
Awesome, thank you!
G-P-E
Well-known member
This thread finally has me asking -- are Bob's caps made by Richey Capacitor (Nashville, TN)?
A few months back, I special ordered a couple cases of 27000uF, 25V screw terminal caps from Richey Capacitor. When they were shipping, I got a call from Richey -- they said they accidently marked the caps with the caption "Big Blue". They also said the reason they did this was because another person that ordered at the same time as me wanted them marked as "Big Blue". Richey never said who the other customer was but I suspect Bob... I can't think of anybody else that it could be. Just curious.
Ed
A few months back, I special ordered a couple cases of 27000uF, 25V screw terminal caps from Richey Capacitor. When they were shipping, I got a call from Richey -- they said they accidently marked the caps with the caption "Big Blue". They also said the reason they did this was because another person that ordered at the same time as me wanted them marked as "Big Blue". Richey never said who the other customer was but I suspect Bob... I can't think of anybody else that it could be. Just curious.
Ed
Riptor
Well-known member
Yes, Bob sells Richey caps. At least I know his "big blue" is.
tb lilley
Member
Interesting question. I'd change the big blue, because it's easy to do (5 minute job) and it's worthwhile. As for the rest ..... dunno really .... as long as the fuse holders are nice and tight, and clean, I'd probably not bother. I'd probably leave the rectifier alone too. That said, I can see an argument for replacing the whole lot while you're working on the power assembly anyway - and having new ( hopefully reliable) parts in there.
tb lilley
Member
I'm struggling with this ......
New diodes bought - P600As. Old diodes desoldered, new diodes soldered in.
Question: which way round are these sodding diodes supposed to go in?
I read that the cathode band indicates which way they should face. I took the cathode band to mean the grey coloured band that runs round one end of the diode.*
When I put them in the board, the band is facing the marks that are circled in the pic that ive linked below:
http://i143.photobucket.com/albums/r121/tb_lilley/aa34363d.png
Question 2: What happens if they are put in the wrong way round? I ask as I'm getting the right voltage, but with polarity reversed ........
Grateful for any help. I've been poncing about with this for 10 days and in the process have learnt to make a pretty decent job of soldering. And I've burnt my thumb. Determined to see this through though ......
New diodes bought - P600As. Old diodes desoldered, new diodes soldered in.
Question: which way round are these sodding diodes supposed to go in?
I read that the cathode band indicates which way they should face. I took the cathode band to mean the grey coloured band that runs round one end of the diode.*
When I put them in the board, the band is facing the marks that are circled in the pic that ive linked below:
http://i143.photobucket.com/albums/r121/tb_lilley/aa34363d.png
Question 2: What happens if they are put in the wrong way round? I ask as I'm getting the right voltage, but with polarity reversed ........
Grateful for any help. I've been poncing about with this for 10 days and in the process have learnt to make a pretty decent job of soldering. And I've burnt my thumb. Determined to see this through though ......
G-P-E
Well-known member
First is a minor issue, those are not P600A's...those are MR750's. No biggie as they can have the same voltage/current rating.
Next, important issue - it looks like you have the cathodes oriented to the left (away from the cap). I don't have a board like that so I cannot verify... but the photo looks like the diode orientation illustration (what you have circled) is going to the right. Can't tell as the picture quality isn't good enough. Can you get a better picture posted?
Putting diodes in backwards can have disastrous results to your new cap.
Ed
tb lilley
Member
Cheers Ed. Appreciate the advice. I did put them in back to front. I've now rectified (excuse the pun) the mistake and all is now right. When they were in the wrong way I was getting a negative voltage instead of +ve, and ground was also reversed. Everything upside down.
Anyway, somewhere along the line I've taken out the +5v on the AR2. S'ok as I have a spare. Cheers again.
Anyway, somewhere along the line I've taken out the +5v on the AR2. S'ok as I have a spare. Cheers again.
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