[Old Man Mike]

My Oracle Diversity Controller suddenly started doing a continuous switching between receivers. This unit had worked well for more than a year. Replacing it with my backup Oracle proved that something had gone bad. Looking inside the box I found a solder ball that had lodged between pins 1 and 2 of the MAX4313 video multiplexer chip:



Since this was the first time I opened the box, the solder ball must have been rolling around inside all this time. I thought that removing it would fix the problem but it seems to have caused permanent damage. Pin2 is tied directly to +V and pin 1 is an input for switching the video so I assume the part driving that pin is damaged. The pin appears to be driven from pin7 of the LM1881 chips.

With the open collector output on pin7, I suspect the transistor blew out in one of the LM1881 chips. I'm hoping someone familiar with the Orcale design will provide a confirmation of my troubleshooting. Without a schematic it is difficult to determine why the Odd/Even frame output is used to control the multiplexer although I suspect it might be a clever OR approach to allow switching on the video frame boundry.

OMM

[Mr.RC-Cam]

Sorry to hear about the problem. Pin 7 of the LM1881 is unused. If you have found that pin 7 of the LM1881's is connected to the MAX4313, then that is not good and would be something to check out.

MAX4313 pin 1 is driven by the microcontroller. If you can manually switch between the two video sources then the stuck solder ball did not harm the MAX4313 or microcontroller's control signal.

Please send it in for repair. Just use the contact form at dpcav.com and request an RMA. But before you do that, check your wireless receivers' video signals one more time. Excessive video tilt or awkward video levels will cause endless rapid switching.

[Old Man Mike]

Mr.RC-Cam, on 01 February 2010 - 08:40 AM, said:

Sorry to hear about the problem. Pin 7 of the LM1881 is unused. If you have found that pin 7 of the LM1881's is connected to the MAX4313, then that is not good and would be something to check out.

Well I thought it was most strange that the odd/even field would be used. The fast switching signal on the MAX4313 looked just like the signal from pin 7 of the LM1881 and I jumped to that conclusion, especially after seeing the open collector drive on that output which would likely fail if briefly shorted to the regulated supply voltage.

Mr.RC-Cam, on 01 February 2010 - 08:40 AM, said:

MAX4313 pin 1 is driven by the microcontroller. If you can manually switch between the two video sources then the stuck solder ball did not harm the MAX4313 or microcontroller's control signal.

Yes, I can manually switch between the two video sources. It stays steady on the selected source until the normal time period is up and then goes into the near 30 Hz constant switching. I even took the PIC controller from the bad Oracle and put it in the good Oracle. It worked fine so I know the PIC is not bad.

Mr.RC-Cam, on 01 February 2010 - 08:40 AM, said:

Please send it in for repair. Just use the contact form at dpcav.com and request an RMA. But before you do that, check your wireless receivers' video signals one more time. Excessive video tilt or awkward video levels will cause endless rapid switching.

I must not have been clear:

1) Exchanging the Old Oracle with the New Oracle results in perfect operation. The New Oracle performed just like the Old Oracle did before before it failed.

2) This test is using a lab setup with a directly connected -60dBm signal and equal splitter feeding the two receivers. Video picture and Video levels are perfect.

If I can't fix it myself, I'll just buy another. Besides, it might be interesting to reverse engineer the design to see what improvements could be made.

OMM

[Mr.RC-Cam]

Quote

If I can't fix it myself, I'll just buy another.

Since all it would cost you is the shipping charges, it seems like buying another would be wasted dollars; The savings could be spent on cool FPV stuff.

All it takes is a RMA request from www.dpcav.com. I work there, so I know you will be given very good support on such issues.

[Old Man Mike]

Mr.RC-Cam, on 01 February 2010 - 01:41 PM, said:

Since all it would cost you is the shipping charges, it seems like buying another would be wasted dollars; The savings could be spent on cool FPV stuff.

All it takes is a RMA request from www.dpcav.com. I work there, so I know you will be given very good support on such issues.

I did not realize that you worked there although I've noted that they sell some of the nice designs you did (like the Low Pass filters). However, I bought this unit from Range Video, not dpcav. Does that change things? Also, would it be possible to receive feedback on what failed?

OMM

[Mr.RC-Cam]

Quote

I bought this unit from Range Video, not dpcav. Does that change things? Also, would it be possible to receive feedback on what failed?

Not a problem. Just visit www.dpcav.com and click the contact link. Include a description of the problem and report that the Rx's video signal quality/levels have been verified. Please be sure to include the serial number and any information you feel is important.

An RMA number will be issued so you can return it for repair. Turn around times are usually only limited by the shipping/travel times.

Most importantly, don't ship it with the little evil solder ball. The last thing you need is for it to get lodged in some unseen place and cause more cruelty.