[Hallicrafters] Help with SX-42

[Edward B Richards]

Thanks, Barry;

That is EXACTLY my problem. Same wafer. I have it isolated so I know it
is leakage across the insulation. Lots of good tips. Thanks again.

73, Ed Richards K6UUZ


On Mon, 9 Aug 2004 03:24:12 GMT "Barry H" <barry_hauser at juno.com> writes:
> 
> Hi Ed
> 
> Have you seen all the info at 
> http://www.antiqueradio.org/halli07.htm ?
> 
> Scroll way down the page and there's the account of A. B. Bonds 
> about this or very similar situation.
> 
> A bad cap may have caused arcing and the wafer or rotore may be 
> carbonized.  If so, you may be able to scrape away enough of the 
> char to remove the short -- or "accidental resistor."  If you can 
> see the blackened area -- with a flashlight, you may be able to 
> scrape it with an Xacto knife or similar tool.  
> 
> Another thing they say is that the dirt buildup can cause shorting 
> and arcing on that bandswitch.  The carbon track might be on/around 
> the rotor, or it might be on one place on the wafer and the shorting 
> action is occurring through the wiper(s).  
> 
> There is also mention of reparing a broken wafer -- something about 
> raising up the bandswitch by unsoldering some of the leads.  Maybe 
> you could use that technique to get at the switch without removing 
> it.
> 
> I suppose the short could be in some other component giving you that 
> reading -- you might have to disconnect one or more leads to isolate 
> the wafer and rotor to check that.  
> 
> Whatever -- I suggest going to that link and give it a read through 
> if you haven't seen it before.  Hope it helps.
> 
> Anybody ever hear from A. B. Bonds lately?
> 
> Barry
> 
> 
> Hi, it's me again;
> 
> I won't say how many days I spent looking for a short in subject. I 
> found
> B+ on the 2nd RF amp control grid (hard on 6AG5's). After 
> deciphering the
> schematic which shows each bandswitch wafer in 2 places with only 
> one row
> of contacts, some making to the front rotor and some to the rear 
> rotor
> and some to both, I found 500 ohms leakage from the front rotor (2nd 
> RF
> grid circuit) to the rear rotor (1st RF plate circuit) on wafer 
> 1H-1HH.
> It looks impossible to work on it in place and just as bad to get 
> the
> wafer out. Has anyone run across anything like this, and what did 
> you do?
> Any suggestions for getting the wafer out? Drill out the rivet and 
> pull
> the center flat shaft out the hole in the back of the chassis? Any 
> advice
> will be much appreciated.
> 
> 73, Ed Richards K6UUZ
> 
> 
> 
>