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JR-310 restoration |
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1. |
During the visual observations I found that most of the electrolytic capacitors and wire are damaged in this unit. I replace all the electrolytic capacitors with new once and rewire most of the parts with new 20 S.W.G cables. |
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2. |
Previous owner of this unit install MF-455-10AZ mechanical filter into this unit and I keep it as it is. |
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Bottom view of restored JR-310 receiver |
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3. |
V3 (6CB6) IF stage pentode is missing in this unit and I plug new RCA 6CB6 into this socket. |
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4. |
UC1306J AF amplifier module is badly damaged and I replace most of the components in this module. Output transformer is in usable state and I clean it up and fix it again. |
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Top view of restored JR-310 receiver |
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5. |
During the initial runs unit may not produce any output and later found that issue is related with V2 6BA6 tube. After replace it with new tube unit starts to work again. |
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6. |
S-meter is not shown any deflection and this issue is fixed by rewiring the VR4 (500Ω S-ADJ potentiometer) related connections. Time to time VR4 readings are not smooth and I fixed it by cleaning the potentiometer control with isopropyl-alcohol. |
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After above steps receiver starts to work again and it support AM, SSB and CW modes. This receiver has 3.5, 7, 14, 21, 25 and 50MHz operating bands and sensitivity is around 1µV. |
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TX-310 restoration |
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7. |
Compare with JR-310 this unit is heavily damaged. Replace most of the electrolytic capacitors with new once. During the visual inspection I found that terminals of two neon lamps (NE-2) are corroded and disconnected from the PCB. I replace those with new NE-2 neon lamps. Other than that large amount of wires, resistors and few disc capacitors are replaced. |
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Bottom view of restored TX-310 transmitter |
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8. |
UC1004J board is completely damaged and most of the components are not in the PCB. I remove the PCB from chasse, remove all components, clean-up the board and re-solder the PCB with new components. |
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S2001 final stage vacuum tube and high voltage area of TX-310 |
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Then I check S-2001 final stage connections and plate choke related connections. In HV area nothing is damaged and in good condition because of its protective grill-cover. |
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10. |
During the initial test runs I got smoke from rear side of the transmitter and I found that R7 (4.7K) resistor is burned. Reason for this issue is bad 6AQ8 tube. This R7 resistor is burn because of short circuit between anode and grid of the 6AQ8 tube. R7 is replaced with 4.7K 2W resistor and V1 (6AQ8) is replaced with commonly available ECC85 tube. |
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Top view of restored TX-310 transmitter |
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11. |
After the above fixes I got no indication at RF meter mode and later found that the defect is in final 12BY7A tube. I replace both 12BY7A with new tubes and after that unit start to work on both CW and SSB modes. |
