Wards Airline 62-9060 diode rectified SE 6v6 amp high B+

Discussion in 'Amp Tech Center' started by Pup Tentacle, Jul 6, 2017.

  1. Pup Tentacle

    Pup Tentacle Tele-Holic

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    Any one ever seen one of these before? Single ended 6v6 with one 12ax7. Diode rectified with 6" speaker. All the voltages are very high. I found a schematic online showing 400vdc on the plate of the 6v6. When it's first switched on the voltage is around 540vdc on the 6v6. This drops to about 450vdc when the tube heats up. Filament voltage is around 7.5vac without the 6v6 installed, I have not checked filament voltage with the output tube in.
    The schematic does not show an AC input voltage but the front panel says 120vac. Schematic does show 720vac across the PT but I measured about 840vac. It appears to be the original PT but I couldn't find it with a web search. I think the amp is late 1960's and if I'm reading the transformer codes properly it was built in mid to late 1968. Output trans #'s - T2640 5246744 PT - 330 T3037 5246821
    Any info on this amp would be greatly appreciated. DSCN8907.JPG
     

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  2. slider313

    slider313 Tele-Afflicted

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    Wire nuts on the power cord is a very bad idea. The heater voltages should be determined with all tubes installed. The 450v plate is slightly high but knowing what amount of current the 6V6 tube is drawing would help.
     
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  3. Silverface

    Silverface Poster Extraordinaire Ad Free Member

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    So is the bolted ground wire. It needs to be soldered directly to the chassis.

    The filament voltage will only read correctly with all tubes installed.

    My concerns are both the initial high plate voltage and the high transformer voltage. The "running" plate voltage would be OK otherwise - but the transformer output and the "surge" from the rectifier indicate to me that the PT is either the wrong one or is failing.

    there's no way to ID the amp from a partial chassis picture - need to see the whole chassis, control panel and cabinet, as the true "point to point" wiring on these amps varies quite a bit, and the schematic is a pretty generic type I seem to recall was used for other Valco models.

    What voltage did you read between the center tap and diode?
     
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  4. Pup Tentacle

    Pup Tentacle Tele-Holic

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    The wire nuts are from a before picture. Its the 540vdc start up voltage that concerns me. The original tube was dissipating 118%. The JJ 6v6 I was using for testing purposes was at 135%.
     
  5. Pup Tentacle

    Pup Tentacle Tele-Holic

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    I think this amp had the power switch on the volume pot and an indicator lamp where the power switch is now.
     

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  6. slider313

    slider313 Tele-Afflicted

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    Cut a hole in the chassis, install and wire up a rectifier tube socket. Use a 5Y3.
     
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