Epilogue: R59 looked good visually, but fell apart when tapped. Cannot trust appearances.
Box from Mouser arrived today. It took me about 90 minutes to replace five resistors (I'm slow). Replaced the finals. Powered up, everything looked good. Finals neutralized easily. Full power available. All is well again. By measuring the voltage drop across my new 5% R59, it seems my meter reads 20 mills low. Who knows how accurate it was before. I have not played with R58 yet. While the T-4XC was sick, I used my TR-3 and a near junk RV-3 to work S04R. My thanks again to Garey for the R59 idea and his service CD. And thanks to all for the other things to check and your support. 73, Bob WW3QB --- On Sun, 4/12/09, Garey Barrell <k4...@mindspring.com> wrote: > From: Garey Barrell <k4...@mindspring.com> > Subject: Re: [Drakelist] I Fried my T-4XC > To: drakelist@zerobeat.net > Date: Sunday, April 12, 2009, 12:52 PM > Bob - > > You've gotten a lot of good suggestions. The Bias > supply is always the first suspect in this sort of problem, > but you say it is ok. > > One thing I haven't seen is to check the meter shunt > resistor, R59. This is a 3.3 ohm, 1/2W resistor that > is located on the relay board under the chassis. This > resistor is almost certainly damaged, usually going up in > value, causing the meter to read way high. When you > replace it, you need to calibrate it using the resistor R58 > which is located up on the slide switch behind the LOAD > control. > > You will need to replace the cathode resistors, the screen > resistors and certainly need to check the RF chokes. > > 73, Garey - K4OAH > Glen Allen, VA > > Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs > <www.k4oah.com> > > > > Robert Ladden wrote: > > I had an unfortunate accident. I was using my T-4XC in > CW. I finished but left it in CW mode. I was doing something > else in the basement (where the shack is) when I heard a > fizzle. I saw the T-4XC turn off. I ran to it and saw the > 6JB6's fade from orange. The keyer did something bad, and I > was not paying attention (never leave it in CW mode). Not > good, but I have several spare 6JB6's. The fuse in the AC-4 > blew. I replace the fuse and the 6JB6's and it powers up > again. I try to neutralize the finals on 10m but get little > output and high current. Not good. I try on 40m and it does > tune, but at .4 on the meter I get low output. Trying the > load control gets full output, but pegs the current meter > and I cannot dip the plate. I quickly turn it off. > > Cathode resistors test inline at 16 and 30 Ohms. Needs > replacing, but probably not the source of this problem. > Tuning is too weird. > > There is no obvious burns on the chokes or anywhere > else, but I fear for the bandswitch back there. Hard to get > a good look. > > Is there more I can check? Or is it time for an expert > surgeon? > > > > 73, > > Bob WW3QB > > > > _______________________________________________ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist > _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
