IPM Module Failure

After rebuilding using the other IPM module and additional FET's, we experienced a second very loud failure as seen in this short video. The camera runs at 15 fps and the explosive incident is only visible, very brightly, in one frame.

Extension Assembly for IPM Module

To facilitate repair and testing, we've turned the heat-sink/IPM module on its side, added another heat-sink on top for external FETs, and temporarily mounted this to the Y sustain board. During testing, we encountered a failure (visible short on die) in one FET on the remaining healthy IPM module. We are now hand wiring high power discrete FETs (two seen on the left in this photo) taken from the other TV externally to substitute for the on-module devices. In one test, we experienced a very loud and spark-filled explosive failure destroying the remaining on-board FETs, some surface mount resistors, and the external FETs. We've rebuilt this assembly with the other IPM module and additional high power FETs; test results shortly....

Pop Goes The Plasma

It is hard to consider the odds but within a 5 day window, we obtained two LG 50" plasma tvs from the local transfer station (120 pounds each!). From what we've been able to read on-line, these models have a class problem with early failure (within 9-24 months) of the IPM modules on the Y and Z driver boards. The near universal problem description is a "pop" followed by loss of picture but with sound still available. This photo shows the likely source of the pop: two large dies mounted on the primary Y module surface have clearly failed catastrophically. If you double click on the image, you will see an interesting close up of the surface and the explosive nature of the phenomena-nice craters. The good news is we were able to harvest another identical and healthy IPM. Our challenge is extraction and re-installation on the boards. We have found it very difficult, requiring very high heat to remove the modules, in some cases damaging the fragile top traces and surface mount components. We removed the same module on the Y board out of the second LG TV and found all four transistors had failed in a similar fashion.

High Current 12 VDC Supply

This is a new power supply built from a transformer and rectifier (mounted on the aluminum heat sink) taken out of an industrial control-timer of some kind. The black transformer is a heavy duty winding that appears to be rated at over 11amps on the secondary. In this first use, we were able to drive 8 amps through an electrolyte solution of sodium bicarbonate and sodium chloride in a new electrolysis cell with four aluminum bar electrodes. Of course we had to test for flammability....