I've got a 3-tap kegerator and I've had one of the kegs ruin consecutive batches. 6 weeks ago I kegged a Tripel and a Pale Ale. The Pale Ale is great, but the Tripel spoiled. 1.5 weeks ago, I kegged a Wheat in the same keg as the Tripel and it spoiled.
I sanitize everything carefully with StarSan each batch. I soak the keg parts and beer lines in SS.
The Wheat was pressurized to 30psi to force carb, and the gas and beer lines were disconnected. 2 days later I had found that the CO2 had leaked out (but wouldnt the beer still be under a CO2 blanket?). I attached sanitized gas and beer lines and let it carb for a week. When I tried it a week later, I found it was spoiled.
The spoiled beer turns brown like a brown ale and has a slight smell and sickly sweet/acrid taste.
Any advice on how I can find the source of contamination and eliminate it?