Won't Power on & Standby LED blinks

A New Fix to the 6-blink Won't Power-Up problem:

Although the last addition to this thread appears to be a few years old, I'm hoping there are still a few die-hard Sony WEGA Trinitron KV-40XBR800 fans out there who haven't yet departed with their set for what appeared to be unsolveable Power-on problems. If so, I hope you can benefit from this post. I purchased my Sony 40" Flat Screen in 2004 when my wife and I reposted to Tampa Florida with the military. I loved my set and thankfully had the foresight to purchase the extended warranty, which introduced us to the 2 IC chip replacements that this thread discusses several times for IC6501 and IC8001. The technician that came to repair our 6-blink no-power-on problem, told us that he had replaced these two chips but he didn't install the chip socket for future replacements. Sure enough, almost 3 years later, I followed the instructions listed through this thread and installed the chip sockets and new replacement chips that I was able to find reasonably through E-Bay. Well, just about 2 years later, which was about a year ago, the TV began the problem again, but this time, the 2 new chips did NOT solve the problem. At this point, I presume most folks would have ended the relationship with this TV, but with my previous electronics background, coupled with having a father who owned a TV repair shop in Kissimmee Florida, I decided to dig deeper.

Our diagnosis and further discussion in this reply are based on the use of the actual Sony TV Service Manual, which I was able to find for free from a few different web-locations.

We started by analyzing the self-diagnostic error circuit which is actually responsible for sending the low-voltage signal responsible for telling the start-up relays to either shut down or not come on at all. I probably shouldn't admit that we tried the smoke-test first and provided ground to one side of the start-up relay, which is deprived when an error signal comes through the self-diagnosis circuit. Well, no smoke, the TV started up, we then removed the ground jumper from the relay, and the set stayed on. That told us that our problem was likely some sort of spike on initial start-up. Unfortunately, what we began to figure out was that with this particular problem, the 2 IC chips that were typically going bad and being replaced, were actually acting as fuses, being the first real components to give out, but as the TV grows older and the real culperate component continues to degrade, replacement of the 2 IC's is no longer enough to mask the problem. We were able to work our way back into each of the 4 main circuits that feed the self-diagnostic error circuit and bingo, a bad capacitor on the output of the secondary windings of the main power transformer which provides the 135v on the D-Board. Capacitor C6556 is a 33 uf / 160v capacitor meant to clip or chop the spikes that come off of the transformer when it first starts up...well, when this capacitor starts to go bad, it allows voltage spikes through to the +B Over Voltage Protection (OVP) circuit, and sure enough, our capacitor was degraded, not bad enough to keep the set from running once it's turned on, but definitely enough to allow a spike to activate the +B OVP error input to the Self-Diagnostic Circuit. We grounded the input signal that the bad capacitor caused to the +B OVP circuit and no-more problems. The TV starts up with no problems and the error codes are gone. We chose a capacitor of about 50 uf and 200v capacity to cover the slightly higher spikes that we presume had caused the capacitor to degrade too quickly. We presume the capacitor was a bit underated, leading to these sets typically showing the 6-blink +B OVP error which lead to the 2 IC chip replacements throughout the years.

The result is, after waiting almost a year to get to the troubleshooting and repair, a beautiful display that this set was so well known for. Will it last forever, absolutely not, but at least we found the main culpurate that caused so many of us the frustrations of numerous repairs over the years.

I hope this is still helpful to some and will be happy to provide a bit more detail regarding the numerous components that we had tested and some that were needlessly replaced along the way as we determined the actual solution to this problem.