EH Scott Radio Enthusiasts

The Fine Things are Always Hand Made

Please refer to the photos section of the site where I loaded five photos of a Scott published wiring diagram and schematic for an early Philharmonic Power-Amp chassis (dial pointer set with 83-V tubes).

I am asking for someone here on the site to confirm something I believe is a factory wiring error.  The wiring diagram for the Power-Amp chassis shows connections for C-71 and R-42 that I believe are not consistent with the schematic.  To be clear, the wiring diagram has two R-42's and two C-71's.  The one C-71 that is shown in the wiring diagram as being connected to the union of R-43 and R-43, I believe is not properly wired.  I believe it should be connected to the left most R-43 (left side) at the junction of C-69 (to be consistent with the schematic).  In addition, the R-42 that I believe is not wired correctly is the one that is shown connected to a single R-43 (right side at the junction of C-69) and it should be connected to the union of the two R-43's (to be consistent with the schematic).

My chassis wired as the wiring diagram shows, but I belive the schematic suggests it should be otherwise.

Please give it a look and let me know what you think.

Regards,

Igor

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Igor:

This is a common wiring error in the Philharmonic power amplifier chassis.  It was likely to have been caused by a requested change in the physical arrangement of components around the terminal strip and poor communication between those making subassemblies (terminal strip with components attached) and those installing the subassemblies.  The miswire does not have a significant detrimental effect on sound quality or performance therefore the Scott Radio Laboratories, who must have known about the error, did not do anything about it.  I rewire the circuit as indicated on the schematic.

Norman

Norman,

 

Thank you for your reply.

 

Are you aware of any other common wiring errors in early Philharmonics.  I have not found any others, having started in the Power Amp chassis, now through the 2nd IF stage on the radio chassis.

 

I have not found any resistor that has drifted outside of 5% from nominal value, which I think is remarkable.

 

Thank you,

 

Igor

Igor:

The only other miswires that I can recall in Scott chassis were from collectors taking shortcuts or not paying attention when rebuilding the chassis.  With the exception of the military and post-war Scott models, I have found that the resistors used in most Scott chassis are much more stable that those used on radios of their contemporaries.

Norman

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