No 5v WPC

[robm]

Hey guys,

Got a Judge Dredd that has had most boards repaired by Ken (Skybeaux) except the power driver board - went to put the repaired boards in, and no bootup - have discovered there is no 5V present.

Replaced BR2 and c5, and put in jumpers between these two components
Tested all traces from pins 1 and 2 of J101 to F113 to BR2, c5 to the LM323 and they all test fine
Test all traces that go out from BR2 and C5 - all test fine (tested twice)
Get 10v AC between 1 and 2 of J101
Get 10V AC from pin 1 101 to F113
Get 10v AC from pin 1 101 to top right leg of BR2 - can't test any others with the board installed
Get 10V AC to d3

I'm thinking the problem almost has to be the LM323 voltage regulator, but thought this was quite rare - any other suggestions?

Thanks

Rob

---------- Post added at 05:45 PM ---------- Previous post was at 05:27 PM ----------

OK, just managed to get some more info

Tested the + output of BR2 and it is briefly at 1.5vDC when you put the lead there, then drops down to 0.5v dc

This is a new BR - could it be faulty or something else the problem?

---------- Post added at 06:02 PM ---------- Previous post was at 05:45 PM ----------

Next bit of the puzzle

On two of my other pins (Shadow and Black Rose) the 10V AC to F113 is measured between F113 and pin 2 of 101 whereas on JD its between F113 and pin 1 of J101...

Is there something a bit back to front here - i don't know enough about AC?

[beaky]

set your multimeter to AC and test that you have voltage on the 2 ac leads on the bridge.
then set your multimeter to DC and then check the + -  leads on the bridge.

also make sure you have soldered both sides of the pcb to the legs on the bridge in case the solder throughs have been damaged.
make sure that the bridge is polarised correctly (I.E. the 2 ac pins are in the correct place and the + and - are in the correct space)

the AC for BR2 comes from pins 1 & 2 on J101 and via F113

pin 1 on J101 goes to F113 then to the top right pin on BR2 (A.C)
pin 2 on J101 goes straight to the bottom left pin on BR2 (A.C)

Check that F113 is not faulty, there have been quite a few people who have been caught out with fuses that look fine but are faulty.

Check that you have continuity from the - on BR2 to the - Pin on C5. Do the same with the + pin on BR2 and the + pin on C5. You will have to remove the board for this.
let me know what the results are and we will go from there.

[robm]

Beaky,

I struggle to get the leads of the multimeter to all the legs of BR2, so thats why i seem to only be able to test AC (10V) at the top right, and +DC at top left (which is only 0.5V)

The two bottom legs seem just too difficult to get to when its in the machine.

F113 is definitely fine as i removed it to test it with continuity

I might just pull it apart again and quadruple check the traces

[beaky]

Beaky,

I struggle to get the leads of the multimeter to all the legs of BR2, so thats why i seem to only be able to test AC (10V) at the top right, and +DC at top left (which is only 0.5V)

The two bottom legs seem just too difficult to get to when its in the machine.

F113 is definitely fine as i removed it to test it with continuity

I might just pull it apart again and quadruple check the traces

I have edited my above post with some things to check with the board out
this is what I added
Check that you have continuity from the - on BR2 to the - Pin on C5. Do the same with the + pin on BR2 and the + pin on C5. You will have to remove the board for this.
It sounds like you have a  bad solder through in the area u are working on. either on the bridge or the cap

[robm]

Desoldered BR2 and c5 again - the new bridge tests fine out of circuit and was definitely installed correctly

Without the components installed there is continuity from + BR2 to + C5 also -BR2 to -C5.  I had put the jumpers in here anyway, so this problem should have been avoided.

I get continuity from pin 1 J101 to top right of BR2, and pin 2 to bottom left of BR2.

I also get continuity from the -BR2 and -C2 to any other GND spot on the board, including one smaller trace on top of the board that goes to just below the LM323.

That said - the solder through pads on BR2 are not present on the bottom side of the board BUT - i put the jumpers on to overcome this problem (for the top traces that go back to the + and - of BR2), and i get continuity when i test wherever the underside traces go.

The solder through pads on BR2 are all pretty good.

Are there additional jumpers to/from C5 i should be looking at?

[Strangeways]

Stock standard rebuild for the power driver board - all caps and BRs with jumpers. I do this for all DMDs I restore or recondition. I install the jumpers regardless of the condition of the mounting holes, as I usually don't know the history of the board / previous repairs.

http://aussiepinball.com/index.php?topic=2969.45

(Page 4)

[Mr Pinbologist]

Stock standard rebuild for the power driver board - all caps and BRs with jumpers. I do this for all DMDs I restore or recondition. I install the jumpers regardless of the condition of the mounting holes, as I usually don't know the history of the board / previous repairs.

http://aussiepinball.com/index.php?topic=2969.45

(Page 4)

That info will come in very helpful Nino  
I have a Twilight Zone here that i'm repairing/shopping out, it needs a few connectors redoing/repinning on  the driver board so i'll do all that while the board is out of the machine (1st one i have worked on!). It currently works fine but the caps/bridges have never been changed, and i have been instructed by the owner to do anything i think is neccessary on the game, and he'll pay whatever it costs to have it in tip top shape.

[Strangeways]

I might start a proper guide in the relevant section. Beaky has an excellent repair log on his driver board as well.

I'll tidy it up and create a new thread.

The cost for parts is just over $30 - and that is great insurance for a perfectly working game for years to come. Greg (RTBB) carries all the parts to rebuild the driver board.

[beaky]

Ok, if you follow Nino's advice and fit jumpers to all the above then the next thing to do is check the +5 volt without a load. (also make sure you have changed C4)
I usually do this on a bench test but you can do it in the machine by only connecting the correct plug to J101.
next test the +5 volt rail and see if you have +5 volts.
If you don't and everything is fine before the regulator then the regulator is cactus.
If you do then you will need to put a load on the +5v rail to make sure it still works under load, I do this with a 906 wedge lamp. (pins 4 & 5 0n J114, see photo below)
If the lamp lights up (it will only be dim) you still have between +4.9v and 5V then your reg is fine. If the voltage drops below 4.85 then the +5 reg is faulty.
If the reg has tested ok then power down the machine and hook up all the plugs then power up again. if you don't have +5v then there is a short or a faulty component on one of the other boards.

[robm]

OK, Followed Nino's guide exactly, replaced all 5 BRs and Caps - although i did not change c4 as i don't have one here at home. Put all his pictured traces in and......

Same thing

Then i put another driver board in, and everything works perfectly - so its definitely a board issue.

I keep thinking its something at the input part of the circuit as when i measure DC volts from GND to the + of BR2, i'm only getting 0.5V - it should be much higher than this - is this the clue to solve this or just a red herring? (even though there is continuity from pins 1 and 2 of 101 to the AC lugs of BR2)

Thanks

Rob

[beaky]

OK, Followed Nino's guide exactly, replaced all 5 BRs and Caps - although i did not change c4 as i don't have one here at home. Put all his pictured traces in and......

Same thing

Then i put another driver board in, and everything works perfectly - so its definitely a board issue.

I keep thinking its something at the input part of the circuit as when i measure DC volts from GND to the + of BR2, i'm only getting 0.5V - it should be much higher than this - is this the clue to solve this or just a red herring? (even though there is continuity from pins 1 and 2 of 101 to the AC lugs of BR2)

Thanks

Rob

If you have the jumpers on and you have 10 volts AC going into the bridge but nothing coming out of the bridge the only thing left is the bridge.
have you tried a different bridge?
just check for continuity again from the GND on the bridge to the Gnd else where on the board.
there is nothing else i can suggest now that you have followed Neno's repair guide. 
If you can't find out what is causing the problem send it down and i will sort it out for you.

[robm]

Double checked - there is continuity to GND from BR2

Thats the strange thing - i did try another new BR, and it tested fine before installation, but once its in, it tests strange ie: on diode test, 0.2V one way, 0.8V the other between the same sets of legs on the bridge...

[Strangeways]

Your 5V only needs BR2 and C5 replaced.

Check Connector J101, Pins 1 & 2 in particular. Look for tarnished connectors / pins
Check the Fuse Holder for F133. The fuse should clip into place. Just for something a but different, change the fuse. I've seen fuses cause issues like this. Check the fuse holder has no dry joints.
Continuity between one side of the BR must be Grounded (looks like it is ok)
Check C5 is correctly installed and jumpered
Check pin 1

Other possible culprits

C9 - Could be shorted
Q1 - LM323 has a short between pin 1 and 3

For kicks and giggles

Just wondering if something is dragging down the 5V. Remove  J114, J116, J117 & 118.

Report back !

[Skybeaux]

If your leaning towards the regulator being faulty after double checking everything else , try swapping one out of another board into it , at least that way you can rule it out as the problem.

[robm]

I don't think anything is dragging down the voltage as i tried with only J101 connected.

I've had a look and pin 1 of J101 does look a bit dull compared to the others - the plug is fine as its working with the other board - but i might replace the header pins.

Its about 15 degrees here and  too cold for this girly queenslander to head out tonight to the shed and try it in the machine, and i've got some serious renovations to get into over the weekend - will prob check back in, later on the weekend.

Thanks very much for the assistance so far

On a good note - the boards Ken repaired for me (sound, display and CPU) are all working sweet - thanks mate!