Recently started having reset issue on my White Water, which quickly evolved into the game not booting. I've not very good with board work, but I think I have traced the problem to this bridge rectifier. In reverse direction all others null out, but this one does not. That certainly could cause these issues, correct? Is there anything else I should replace, while I'm replacing this one?
Anyone? In the forward direction the resistance is about 500, so the reverse isn't wide open, but my understanding is this should be null.
Quoted from Tuukka:You can't test the rectifiers while in circuit. If you have problems with game resetting, replace BR2 and C5.
First, thank you for the reply. Second, is that true? I was following the PinWiki. I just wasn't sure if any variance was acceptable or if it was null or replace.
https://pinwiki.com/wiki/index.php?title=Williams_WPC#Failed_Bridge_Rectifier
It's hard to tell from the pic exactly but it looks like you may have your meter leads going in a direction that does not tell you much about a bridge.
When DMM testing diodes do "black on band".
When its a complete rectifier package it seems backwards but... red lead on - and then use black lead probe both AC pins for ~0.600v . Then go black lead on + and read lead probe both AC pins for ~0.600.
Most common way a bridge fails is shorted which will result in 0.00v test. Some will fail open reading open circuit. When there is caps in circuit your DMM leads will charge up the cap and effect reading, but you will still be able to detect a shorted bridge.
While it does seem possible that there is fail mode where bridge rectifier gets "weak". I don't know if one diode voltage drop drifts or whatever, but I have seen voltage come up after a bridge change in different systems. I would exhaust other culprits before replacing the bridges unless you get a sure fail reading. I would suspect connectors first. Measure volts dc at different points in the power chain. See if the voltage reading drops the further from the voltage regulator you test. Like if the +5v is a quarter volt less on the MPU then near the v-reg on driver board, its probably connectors.
Quoted from barakandl:It's hard to tell from the pic exactly but it looks like you may have your meter leads going in a direction that does not tell you much about a bridge.
Sorry, it was hard to do with one hand while taking a picture. What I'm showing here red on AC and black on negative. It's the last step in the PinWiki.
Quoted from barakandl:When its a complete rectifier package it seems backwards but... red lead on - and then use black lead probe both AC pins for ~0.600v . Then go black lead on + and read lead probe both AC pins for ~0.600.
Most common way a bridge fails is shorted which will result in 0.00v test. Some will fail open reading open circuit. When there is caps in circuit your DMM leads will charge up the cap and effect reading, but you will still be able to detect a shorted bridge.
In that open direction I get between .5 and .7 on all diodes. In the closed direction I get a null reading on all diodes except for this bridge rectifier.
Quoted from lpeters82:Second, is that true? I was following the PinWiki. I just wasn't sure if any variance was acceptable or if it was null or replace.
https://pinwiki.com/wiki/index.php?title=Williams_WPC#Failed_Bridge_Rectifier
In-circuit, you can test if the rectifier is open or shorted, but you will not be able to see if it fails under load. It is a cheap component to replace, so if any doubt, put in a new one. But take care when unsoldering, not to damage the circuit board thru holes.
Quoted from Tuukka:In-circuit, you can test if the rectifier is open or shorted, but you will not be able to see if it fails under load. It is a cheap component to replace, so if any doubt, put in a new one. But take care when unsoldering, not to damage the circuit board thru holes.
Okay, I don't think I would have the equipment to test it under load anyway.
I don't know the answer to the bridge rectifier question, but upon a third inspection of the roms, one of the pins was bent. Perhaps a secondary problem, but things are working great now.
Quoted from lpeters82:I don't know the answer to the bridge rectifier question
Did you ever figure this out as I'm getting readings as well. Here's the pinwiki steps:
1. Place your DMM into "diode test".
2. Put the black lead of your DMM on the "oddball" lead of the bridge rectifier. This will be the lead that isn't oriented the same as the others (as with the
"spade" type of bridge) or the lead that prevents the four legs from forming a square (as with the "wire lead" type of bridge). This will also be the DC
positive lead of the bridge.
3. Place the red lead of the DMM on each of the adjacent legs, one at a time.
A reading nominally between .5 and .7 should be seen (this represents the voltage drop across the bridge's internal diodes).
4. Swap locations of the red and black leads. A reading of "null" should be seen.
When I do the "swap" in step #4 for this and the next steps (on DC neg lead) I do get readings, not zero???
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