The DR-7 has two 5-volt regulators - U9033 and U9034, bolted to the frame of the radio. U9033 feeds the counter, U9034 the display. Both are fed from the +12. Easy to check, easy and cheap to replace.
Also suspect are those pesky oxidized Molex pins and connectors. Especially suspect if the rig has been in storage for 20 years. Also check the +24v from the PS board, this is vital to the VCO. It's normal for the -5v to read low. 73 -Jim On Mon, 22 Mar 2010 13:51:39 -0400, Garey Barrell wrote: >Chris - > >First step is to determine if the problem is the receiver or the counter. > >Are you able to tune in a signal on the receiver? > >4.67V is too low on the 5V line. It should be less than 0.2V more or >less than 5.00 V. Possibly leaky electrolytic caps. > >73, Garey - K4OAH >Glen Allen, VA > >Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs ><www.k4oah.com> > > >Chris Hughes wrote: >> Hi all >> Before I start pulling things apart ..my TR7 counter display >> has locked up accept for the last 2 numbers which are rapidly changing >> and not responding to any controls , the 10 volt line is spot on but I >> can only get 4.67 volts on th 5 volt line ? this radio was locked up >> in storage for 20 years but its been working well up untill a couple >> of months ago any idears ....Chris ZL2UKT >> >> > >_______________________________________________ >Drakelist mailing list >[email protected] >http://mailman.zerobeat.net/mailman/listinfo/drakelist -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! "Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime." HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://radiojim.exofire.net http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
