Miscellaneous fixes for various things

Some people like doing those crazy sudoku puzzles. I like debugging and fixing broken things. Below are notes from random fixes I've performed where I haven't had time or ambition or interest to create a separate page with pics, etc.

Problem: Unit is stuck in CW mode, buttons don't work. Reset does not help. Radio diagnostics show a stuck bit for the tuner. Hmmmm.
Solution: The UPD8255AC I/O chip has a stuck bit on the output. Part isn't new but found a NOS replacement stateside for less than $5. Cut out the old part, desolder the old legs, replace. Problem solved.

Problem: Low receive sensitivty for narrow FM.
Solution: In my case I found that CF2002, a ceramic filter in the FM demod section had failed. Toko ALFYM450F=K. You can narrow this down because it's only in-line for narrow FM receive, and the service manual shows voltages on both sides of the filter. One side was in-spec, the other side (input, if I remember) was zero volts. Yaesu has replaced this with a different part number, my cost from Yaesu parts was $0.61 each with less than $2 for shipping.

Mon May 6 14:33:19 CDT 2013

Update: Turns out that KD0FER had a deaf VX6R...searched the forums...ended up here...and then realized the he knew me. We took a look at his radio over lunch and I was confident it was the same problem. Super deaf on NBFM receive. Just fine on WBFM receive. I brought some tools and my extra filter and we went for the repair. Another success!

Ok, lots of stuff can go wrong here...

Problem: starts OK, bad performance (can't get above 1500RPM) for maybe two minutes after first start of the day. But not at all after it's warm.

Troubleshoot:Disconnect upstream O2 sensor. Better?

Solution:If disconnecting the upstream O2 sensor makes things better, replace upstream O2 sensor. This is a heated O2 sensor and the computer relies on the readings from this sensor for air/fuel mixture. You get bad values from the sensor until it warms up by virtue of being in the exhaust stream which takes a few minutes. Once it warms up, it's fine. If you disconnect the front O2 sensor, the compute runs off an internal air/fuel map and things aren't optimal but they're better than with a bad sensor.

The front O2 sensor isn't bad for replacement, you can put a standard O2 sensor socket over the sensor and a breaker bar will fit atop. Hit the sensor with penetrating oil and then push at the breaker bar with your foot. Remove/replace. Done. Mon Aug 13 11:22:47 CDT 2012

This page last modified Mon Aug 13 09:30:52 CDT 2012 by timc!