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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Sat 08, 2003 1:03 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 16
Location: W. St. Paul, MN USA
Help! The shadowmeter on my Philco is not working properly. I can only get the meter to deflect a very small amount when tuning. The radio is aligned, the tubes are good, and the set works great. The vane rotates freely in its socket. I measured about 1900 ohms of resistance on the shadowmeter coil and a voltage drop on the coil of between .5 to 2 Volts when tuning. Any help would be appreciated.<P>------------------<BR>


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Sat 08, 2003 1:19 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1827
Location: Sanford, North Carolina
Hi Phil,<BR>try this site, it's not mine , it's Chucks<BR> <A HREF="http://www.philcorepairbench.com/tips/svctip01a.htm" TARGET=_blank>http://www.philcorepairbench.com/tips/svctip01a.htm</A> <P><P>------------------<BR>Rick Dippolito<BR>THE PHILCO RESTORER at<BR> <A HREF="http://hometown.aol.com/philcorestorer/myhomepage/index.html" TARGET=_blank>http://hometown.aol.com/philcorestorer/myhomepage/index.html</A>


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Sat 08, 2003 4:18 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 16
Location: W. St. Paul, MN USA
I've tried that site; it helps, but I'm trying to avoid rewinding the coil.<BR><P>------------------<BR>


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Sat 08, 2003 5:35 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 31642
Location: Livermore, CA
Hi Phil<P> Even though the radio plays tubes may not have full emission? Stronger AVC voltage causes tubes to draw less current. This current change is what drives the shadow meter. Since your shadow meter isn't open it's probably ok. Try different RF & IF tubes if you have them. For greatest effect you will need an antenna.<P>------------------<BR>Norm


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Sat 08, 2003 8:23 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 16
Location: W. St. Paul, MN USA
Good suggestion, but alas, to no avail. I swapped out the tubes and still no change.<BR><P>------------------<BR>


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Sat 08, 2003 12:03 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3836
Location: Malone, New York USA
Hi Phil,<P> I usually leave these questions to be answered by better minds than mine, but I'll take a "crack" at it.<P> IF aligned at 470 khz?<P> Meter vane returns to rest across light beam by itself, after manually deflecting and release? (magnet issue)<P> Coil measures 1900 ohms resistance.<BR> Poor memory here says that is OK compared to known good one I tested a while ago.<P> Plate and screen grid voltages:<BR> Both RF AMP and DET.OSC. tubes show same voltages on published socket voltage data.<BR> Both SGs at 80 v, both Plates at 215 v.<BR> No signal. Are these OK?<P> Scheme for this shows me coil operates from current created via difference of plate voltages of these two tubes with received signal.<P> Out of ideas for now.<P> Good luck,<BR> Den<P>------------------<BR>


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Sat 08, 2003 6:08 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1827
Location: Sanford, North Carolina
Hi Phil,<BR>I notice in one of your replies you say your trying to avoid rewinding the coil. I don’t believe that there is anything wrong with the meter itself !!<BR>When you aligned it, did you fallow the instructions in the PHILCO service bulletin number 257 ?? This set does NOT align like the others and also did you fallow the shadow meter instructions in that same bulletin ??<BR>Also I notice that in your reply to Norm, you did not say anything about the antenna !! <BR><P>------------------<BR>Rick Dippolito<BR>THE PHILCO RESTORER at<BR> <A HREF="http://hometown.aol.com/philcorestorer/myhomepage/index.html" TARGET=_blank>http://hometown.aol.com/philcorestorer/myhomepage/index.html</A>


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Sat 08, 2003 6:55 pm 
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Posts: 17544
Location: Somers, CT
Did you recap the set? A leaky cap in the AVC line can cause this problem by limiting the AVC voltage swing. <P>Also, did you try doing the mechanical alignment for the shadowmeter coil as detailed in Riders or on Chuck's website?<P>I'd start with the mechanical aligmnent. BTW, if a set is playing fine, the tubes are rarely the cause of problems. Capacitors are the prime suspects, resistors generally second.<P>Pete<P>------------------<BR>


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Mon 10, 2003 8:35 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 16
Location: W. St. Paul, MN USA
Plate and screen grid voltages:<BR> Both RF AMP and DET.OSC. tubes show same voltages on published socket voltage data.<BR> Both SGs at 80 v, both Plates at 215 v.<BR> No signal. Are these OK?<P>Interestingly, no. Both plates are around 245v and SG's at 40v. Hmmm... 40 volt differences both times, this warrants further investigation. Unfortunately, I both tired and ill.<P>Thanks for the suggestion<P>------------------<BR>


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Mon 10, 2003 8:37 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 16
Location: W. St. Paul, MN USA
When you aligned it, did you fallow the instructions in the PHILCO service bulletin number 257 ?? <BR> <BR>Yes and no. I'll explain later, I'm not feeling well. Thanks for the heads up.<P>------------------<BR>


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Mon 10, 2003 3:13 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 160
Location: Florida keys
Hi, the last one of these chassis i did, a large number of the resistors had to be replaced. after recapping, the set worked, but not as well as i expected, sensitivity or sonically, and the shadow meter also had inadaquate deflection. I had bid the restoration not planning replacing 30 resistors, so i remember it well. the circuit is a bit convaluted around that meter too. I would check every resistor, no way around it, measure each incircuit, if measuring high, replace, if measuring lower than it should, unhook one end, then measure again, replacing if high or low. I bet you will find a number of way off ones, and the meter will end up working correct. if after checking the resistors there was still a problem, i would measure avc, possibly weak sensitivity due to something like an open winding on a coil could also cause inadaquate signal strength through the reciever, but like i said, first i would go after the changed value resistors. good luck, that is a complicated chassis, and if i remember right, some of the parts are really deep in.<P>------------------<BR>


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Mon 10, 2003 7:28 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 333
Location: Vienna, VA USA
Hi Phil,<BR>I have restored several shadow meter sets and trying just about everything was never able to get them to deflect as fully as I would expect them to. I have even had to rewind two of the coils and can suggest that if you will have to go that route, to use the bobbin rewind feature on a sewing machine for that purpose. It works quite well.<BR>George<P>------------------<BR>George Guma


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 Post subject: Philco 37-660 Shadowmeter
PostPosted: Nov Mon 10, 2003 9:25 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 16
Location: W. St. Paul, MN USA
like i said, first i would go after the changed value resistors. good luck, that is a complicated chassis, and if i remember right, some of the parts are really deep in.<P>[/B][/QUOTE]<P><BR>yeah, you remember right, the chassis is a bit ...strange. I have certain four letter words that would describe the underside of this set, but I won't use them here. I am currently checking the resistors, but the process is slow. <P>Thanks for the idea.<P><P>------------------<BR>


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