[Drake] TR-7 Problem Update
Michael Russ
[email protected]
Sun, 30 Dec 2001 16:35:26
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<P>I'm not a repair tec by any means and I'm sure some ellse will answer you, but if not. Do you still get these same readings when your band swithch is set in the 40 meter position ? Might want to check a few other bands for comparison. Look for something that is not common in the 15 meter position on the circuit. If all else fails You can contact J frost at R.L. Drake company. He can get you started in right direction.</P>
<P> mike</P>
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<DIV></DIV>
<DIV></DIV>>From: "David M. Nance" <[email protected]>
<DIV></DIV>>Reply-To: [email protected]
<DIV></DIV>>To: [email protected]
<DIV></DIV>>Subject: [Drake] TR-7 Problem Update
<DIV></DIV>>Date: Sat, 29 Dec 2001 14:04:57 -0500
<DIV></DIV>>
<DIV></DIV>>Many thanks to several of you for suggestions. I located my service
<DIV></DIV>>manual and; although I'm a vacuum tube guy in a microchip world, I
<DIV></DIV>>decided to do some voltage checks.
<DIV></DIV>>
<DIV></DIV>>I checked the transceiver power supply board (#21). Here is what I
<DIV></DIV>>found:
<DIV></DIV>>
<DIV></DIV>>Pin 21/9: 13 vdc (this is the supply to the board so this should
<DIV></DIV>>eliminate the PS-7 as the problem)
<DIV></DIV>>
<DIV></DIV>>Pin 21/11: slight deflection of meter on 3 volt scale (this is the +5
<DIV></DIV>>volt regulated output)
<DIV></DIV>>
<DIV></DIV>>Pin 21/10: +0.4 vdc (this is the +10 volt regulated output)
<DIV></DIV>>
<DIV></DIV>>Pin 21/2: 0 vdc (should have read +25 vdc)
<DIV></DIV>>
<DIV></DIV>>Pin 21/1: 0 vdc (should have read -5 vdc)
<DIV></DIV>>
<DIV></DIV>>Pins 21/4, 5, 6, 7, & 8: all pins read less than 0.3 vdc
<DIV></DIV>>
<DIV></DIV>>Looking at the schematic and reading the circuit description on the
<DIV></DIV>>power supply board, I would suspect Q2101, Q2102 or U2101. They create
<DIV></DIV>>the 10 volt regulator circuit from which all other voltages are derived.
<DIV></DIV>>
<DIV></DIV>>Am I on the right track? Are there any resistance readings I can take
<DIV></DIV>>to make sure there is not a short circuit somewhere. From the circuit
<DIV></DIV>>description it appears there is some protection built in which would
<DIV></DIV>>shut things down (Q2103?) I don't have any of the extender boards
<DIV></DIV>>(don't even know if there was one for the power supply board) so I'm at
<DIV></DIV>>a bit of a loss as to where to go from here.
<DIV></DIV>>
<DIV></DIV>>
<DIV></DIV>>-------- Original Message --------
<DIV></DIV>>
<DIV></DIV>>I've been enjoying my "new" TR-7 for the last three months. However,
<DIV></DIV>>this morning while having a QSO on 75 the digital display went blank and
<DIV></DIV>>now it won't transmit or receive. My suspicion is the power supply
<DIV></DIV>>board in the transceiver, since the FA-7 fan still works and the meter
<DIV></DIV>>and analog dial lights are still working.
<DIV></DIV>>
<DIV></DIV>>If this helps, the TR-7 did the same thing a few days ago, but only for
<DIV></DIV>>a split second. I suspected then I was going to have problems.
<DIV></DIV>>
<DIV></DIV>>Since I have had little experience with the TR-7, I thought some of you
<DIV></DIV>>on the list might have some ideas as to where I should start looking.
<DIV></DIV>>All of my service experience has previously been on tube rigs.
<DIV></DIV>>
<DIV></DIV>>Thanks,
<DIV></DIV>>
<DIV></DIV>>David Nance - W4SSE
<DIV></DIV>>[email protected]
<DIV></DIV>>
<DIV></DIV>>
<DIV></DIV>>-------- Original Message --------
<DIV></DIV>>
<DIV></DIV>>I've been enjoying my "new" TR-7 for the last three months. However,
<DIV></DIV>>this morning while having a QSO on 75 the digital display went blank and
<DIV></DIV>>now it won't transmit or receive. My suspicion is the power supply
<DIV></DIV>>board in the transceiver, since the FA-7 fan still works and the meter
<DIV></DIV>>and analog dial lights are still working.
<DIV></DIV>>
<DIV></DIV>>If this helps, the TR-7 did the same thing a few days ago, but only for
<DIV></DIV>>a split second. I suspected then I was going to have problems.
<DIV></DIV>>
<DIV></DIV>>Since I have had little experience with the TR-7, I thought some of you
<DIV></DIV>>on the list might have some ideas as to where I should start looking.
<DIV></DIV>>All of my service experience has previously been on tube rigs.
<DIV></DIV>>
<DIV></DIV>>Thanks,
<DIV></DIV>>
<DIV></DIV>>David Nance - W4SSE
<DIV></DIV>>[email protected]
<DIV></DIV>>_______________________________________________
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