Drake TR3 Smoked Resistor
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I'm working on bringing a Drake TR3 back to life. During power up I noticed smoke coming from below the chassis. I quickly powered the TR3 off. I turned the TR3 upside down, front panel facing me, and found a 1/2W resistor that had overheated. The picture below shows the location of this resistor. Does anyone know the resistor's value and where on the schematic it's located? The Yellow shaft is used as a pointer and the Black arrow is also pointing to the resistor. It's to the "Left" of the audio transformer and between the 2 small PC boards. I need to determine what that resistor is so I can find it on the TR3 schematic then track down what caused it to over heat. The TR3 was in "receive" when the resistor overheated. There was no audio heard in the speaker. The 8 pin remote VFO plug was in place with pin 2 connected to pin 8 as shown on the TR3 schematic (the RV3 was not plugged into the remote VFO socket). Any help would be appreciated. Please reply direct to my email address. 73 Mike W5RKL |
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Mike, I¡¯d look around that area for a shorted capacitor. I had some smoke a few years ago that was caused by a shorted SM cap. It should be fairly easy to find.? Steve Wedge, W1ES Time flies like an arrow. Fruit flies like a banana. Sent from for iOS On Thu, May 1, 2025 at 20:30, Mike W5RKL via groups.io <mikew5rkl@...> wrote:
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Mike, In my TR-3 that is a 3.3K ohm resistor that bridges across the two PCBs.? I've had this same resistor meltdown on a TR4 and the culprit was one of the capacitors in the capacitor can.? Start by replacing that can with one from Hayseed hamfest or with discreet capacitors under the chassis.? Poke around at the other capacitors and look for signs of bloating, oozing goo, or crispy and brittle.? The rest are less likely to be a problem than the can capacitors but I have found bad ones in the past.?? Barry KJ5GQM
On Friday, May 2, 2025 at 08:27:23 AM CDT, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
Mike, I¡¯d look around that area for a shorted capacitor. I had some smoke a few years ago that was caused by a shorted SM cap. It should be fairly easy to find.? Steve Wedge, W1ES Time flies like an arrow. Fruit flies like a banana. Sent from for iOS On Thu, May 1, 2025 at 20:30, Mike W5RKL via groups.io <mikew5rkl@...> wrote:
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