01-06-2018, 08:41 PM
I am working on re-caping a 640 and ran across a discrepancy. Under the replacement parts section part 44 is listed as 3615-DU which is a dual .05uf ungrounded block cap. The actual part used in the radio is a 3615-DG which is grounded. I did not look closely when I pulled out the guts but I assumed that the two caps shared pin 1, which is grounded. If this is the case than the schematic as drawn is not correct as it shows that the pair of caps connect to the 78 cathode, not ground.
Is the schematic wrong? Could the dual caps share pin 3 which would allow the schematic to work as drawn but this goes against the dual caps I have worked on before and what is shown in Fig 1. If the the 3615-DG was used by accident vs the ungrounded part I would expect that the 300 ohm resistor would have a lead wire going to the chassis for the ground, it does not, it uses pin 1 for the ground suggesting that the 3615-DG is the correct part to use.
[Image: https://i.imgur.com/GtoNvCJ.png]
[Image: https://i.imgur.com/zatNwzH.png]
Is the schematic wrong? Could the dual caps share pin 3 which would allow the schematic to work as drawn but this goes against the dual caps I have worked on before and what is shown in Fig 1. If the the 3615-DG was used by accident vs the ungrounded part I would expect that the 300 ohm resistor would have a lead wire going to the chassis for the ground, it does not, it uses pin 1 for the ground suggesting that the 3615-DG is the correct part to use.
[Image: https://i.imgur.com/GtoNvCJ.png]
[Image: https://i.imgur.com/zatNwzH.png]
