[BUILD] CAPI Dual VPR & 51x Floor Box PSU~Official Support Thread

Could it be a wiring error? I would remove the wires from the DC output header and check the PSU voltages again. You can check the 48V on the PSU side of the fuse.

Hi Jeff,

Really appreciate all the help you've given with this project. Sorry for the inexperienced questions, but you did mean the JP1 connected wires (see picture)? Because I tried removing them and retesting with the multimeter, but this time I got a reading of 0.008V on the 48V terminals. Could this mean my wiring between the PCB (JP3) and the toroidal transformer is incorrect? Thanks again!

Steven

Well, if the 48V LED is not illuminated, the fuse is most likely out. I would check for DC on BOTH sides of the fuse.

Thanks Jeff.  The F1 160mA fuse was blown. After replacing it the 48V was coming through, until the replacement fuse blew as well. If I leave the PSU turned on, the fuse seems fine. The fuse seems to be blowing after turning the PSU on/off a few times. Any ideas why this is happening? Thanks again!

Did you follow what I said above about disconnecting the cable and so on? We have no idea what you have plugged into or not plugged in the PSU/rack etc etc. Too many variables to just start guessing.

I believe so, but as I'm sure you can tell, I'm too inexperienced to fully comprehend what you're saying. I disconnected the cables from the JP-1 section (what I have assumed is the DC output header), and tested each side of the blown fuse. One side reads 48.6V and the other side reads -16.4V. The PSU is not plugged into the rack, just plugged into a standard wall outlet. 

Don't want to waste your time Jeff. Maybe I should hire an electrician for help...  :-[

4D Audio said:

One side reads 48.6V and the other side reads -16.4V.

Click to expand...

No way, you must be using a wrong measuring reference.
Is the lack probe connected to your star ground?
Do you have continuity from (with anything disconnected) from your IEC safety ground to your star ground to Pin 1 & 2 on your XLRs? Continuity to both of the 2 way screw terminal (JP2-1 and JP2-2) on the PCB?

Hey Silent Arts thanks for the help! Yes the black probe is connected to the star ground. I am not 100% sure what continuity in electronics should suggest, but I assume it means a path for current to flow that does not split, or divide? I do have the IEC safety (green/yellow wire?) connected straight to the star ground. And both JP2 terminal wires are connected straight to the star ground. I am unsure of the what the Pin 1 & 2 XLRs are. I have attached pictures. 

Guess it's only one pic per post...
The other side of this fuse reads 48.6V

I see the wires for the DC cable are still connected to the output header. I am thinking you have a short or error in the wiring. Remove all of the wires from the JP1 header and measure the output voltages again.

Oops! Sorry Jeff, I tried reconnecting those after I replaced the 160mA fuse, which btw I need to buy a few more of . After removing the DC output wires again, now I have a 0.01V reading on the fuse. Still 48.6V on the other side.

Yes of course, because the fuse is blown. At least there is no -16V. This confirms that you have an error in the cable, connector(s) or rack. Something  after the PSU.

Ok thanks for your help! (and patience). That's a BIG relief. Looks like I have some troubleshooting to do. Also, where can I buy some new fuses? Can't find them on your site.

Hello,

Greetings from Berlin. Aaron here. I am a long time lurker but finally registered user. I built my 51x during the gdiy "blackout" andhave most certainly made some errors i.e. fuses are blowing when I switch the floor PSU on. I've checked my transformer & IEC wiring against the pics here in the list and AFAICT, I'm hooked up ok. Like I said however, I'm blowing fuses though.

I haven't found a troubleshooting guide yet. If it exists can someone point me in the right direction?

Many thanks.

Aaron

Which fuses? That can be a clue. The biggest mistake folks make on these is over tightening the positive regulators to the heatsink sides. That shorts them out thru the sill pads.

Hi and thanks for the quick response. The fuse in the IEC socket blew, I checked and saw that I had a 2.5 in instead of a 1.25. I replaced it and it blew again.

Shall I loosen/remove the heatsinks still?

Attached pic of IEC wiring.

Ah. I would triple check all of the mains, primary and secondary wiring. A direct short somewhere on the secondary side of the toroid would cause this. You could try to find it by probing for DCR at the JP3 AC inlet headers. Do this with the secondary wiring disconnected from the JP3 header and DO NOT CONNECT TO AC SOURCE.

Hey, thanks for that. Sorry to be dim but, can you provide more detail. If I remove the 11 wires from J3 where are my test points?

tgr said:

Hey, thanks for that. Sorry to be dim but, can you provide more detail. If I remove the 11 wires from J3 where are my test points?

Click to expand...

There are 10 wires to remove not 11. You will probe for DCR between the AC entry points for each sections diode bridge. Take a look at the schemo. For example, JP3-5 and JP3-6 are for the -16V rail. If these 2 AC entry points are somehow "connected" or shorted together (somewhere), it will near immediately take out the mains fuse when you power up. You most likely have one (or more) shorts between the pairs of AC entry points on the JP3 header.

Got it. Thanks for your time.

I tested all the pairs and, just in case, I tested the permutations i.e. 1 to 2, 1 to  3.... 5 to 1, 5 to 2 ... etc.

No shorts. Next steps?