If physical shock won't find it you can frequently use thermal shock - some need cooling to locate, others need heat.
The simple way is to get a can of freeze spray and zap one component at a time. However this does get expensive in a hurry. Aerosol canned ethyl chloride is a specialty item and priced as such. You also need to wash the zapped parts with alcohol when you are done - cheap brands of freeze spray have other things than propellant and ethyl chloride in them, and the contaminants can corrode certain alloys on component leads. Or if you know someone who has a cylinder of CO2 you can hook one side of a oxy-acetylene cutting torch rig to it and use the CO2 to cool one component at a time. I spent several years doing component level repair as one member of a tech group of 26.... we took care of over 1,000 items from over 75 manufacturers at NASA / JPL. We had a dozen full sized workbenches and someone was always working on something - from IBM mainframe tape drives to surveillance video cameras to 1443 line printers to NBS-based clocks. We abandoned the freeze spray a few months after we stared using it because of the corrosion on certain alloys of components. The CO2 worked great as a coolant, but the cutting torch handle assembly was unwieldy and got heavy after an hour or so. One of the guys whose brother worked in the welding shop set us up with a solenoid valve on the tank feeding a pinpoint nozzle. We mounted that on a old burned up soldering gun. The trigger switch controlled the solenoid valve. Heat can be provided by a hair dryer on high setting, and the hot air run through a metal funnel (wrapped in a towel to protect your hands) so that only the component of interest gets zapped. Mike WA6ILQ At 01:10 PM 11/25/04, you wrote: >Jeff, I have a Mastr II station. A NHRC 3+ as the controller and >your DAD board. In the audio chain I'm also using a GE channel guard >board. The 3+, DAD board and CG board are in the same enclosure with >feed thru caps. I have disconnected the receiver and left the Pll >exciter audio hooked up. When I ground the PTT line no audio comes >thru except crackling and static, and it comes and goes. The PA is >not in line, the exciter is running alone into a dummy load. I've >tapped and wiggled all components and I can not find a spot where I >can get it to stop or start. I hope I've covered everything. > >Happy Thanksgiving to you and the group also....Jim km0k > > > >--- In [email protected], Jeff Otterson ><[EMAIL PROTECTED]> wrote: > > Yes, possibly a bad capacitor anywhere in the audio chain. > > > > What else do you have connected up? A receiver? > > > > Happy Thanksgiving! > > > > Jeff > > > > > > > > At 11:09 AM 11/25/2004, you wrote: > > > > >--- In [email protected], Jeff Otterson > > ><[EMAIL PROTECTED]> wrote: > > >Jeff, I disconnected the audio line to the exciter. NO Noise, so > > >then I disconnected the audio from the Rx. The noise was still > > >there. The only thing left is the NRHC 3+ controller. What would > > >generate noise there, Bad Cap? What should I look for? Tnx...Jim > > > > > > > > > > Bad capacitor in the audio stage? > > > > > > > > Jeff > > > > > > > > At 09:39 AM 11/25/2004, you wrote: > > > > > > > > > > > > >Hi group! > > > > >I have a vhf pll exciter that is very noisy, by that I mean > > >scratchy > > > > >sounds on the carrier. When I unplug the PA and run the >exciter > > > > >alone with no audio into a dummy load I get this noise, so I >know > > >it > > > > >is coming from > > > > >the exciter. I cleaned all the contacts that the audio and > > >bandpass > > > > >boards plug into and also the edge connecter plug, ICOM etc. > > >Touched > > > > >all posts with a touch of new solder, but still have it. > > > > >I even swapped audio and bandpass boards to no avail. So I > > >replaced > > > > >it with another exciter, and this one is a > > > > >lot quieter. What would cause this exciter to generate noise? >I > > > > >modified the Band Pass Filter from G2 to a G1 and replaced the > > > > >aluminum slug with a ferrite one. I would like to fix this >one if > > >I > > > > >can as they are hard to come by. Is there any suggestions >where I > > > > >should start looking? Has anyone else had this problem? >Thanks in > > > > >advance. > > > > > > > > > >Jim KM�K Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
