EH Scott Radio Enthusiasts

The Fine Things are Always Hand Made

On Aug. 15, I made edits to this post; deleted words are shown as strikethrough and added words are shown in red.  Specifically, while I assumed that the set socket was on the left side (as per Riders 14-26) since most of my amp had this configuration, it was actually on the right side (as per Riders 14-19).  Thus, the wires on the lug of elect. cap #1 are correct, and the dangling wires should go to the positive terminal of that cap.

 

I recently acquired a Scott Allwave 23.  Tuner chassis serial number is H-504; amplifier has a hand-written number (maybe in magic marker) of J 591 (unsure if this latter number helps).  Except for one replaced capacitor, the tuner chassis seems complete and original.  However, I need help with the wiring of part of the amplifier.  First off, the amplifier is the same as the diagram on Riders PAGE 14-26, except that it has many components on the top of the attenuator (same as shown on the amplifier diagram on Riders PAGE 14-19). 

My specific problem lies with the three electrolytics (listed as C5 on Riders 14-26); the one for 100 mfd (C1 on 14-26) is fine.  The three cans on top of the amplifier are identical, but the markings on are cans are 4 mfd, 600 V (the description on Riders 14-26 list each as 30 mfd; I don’t yet have a clear copy schematic, but one from Nostalgiaair may have different values).  Except for the wiring of these electrolytics, the wiring seems complete and original.

Attached is a picture of part of the amplifier; for reference purposes, the three electrolytics can be referred to as #1 at top of picture and #3 at bottom of picture.  Also, the choke connections are referred to as #1 at the top thru #4 at the bottom.  There is nothing connected to the positive terminal of any of the three components.  There are three wires to the lower lug (at 7:00 o’clock position) of electrolytic #1 – the orange wire comes from component C# 3 (on page 14-26); a green/tan wire goes to speaker set socket #6 (all socket numbers are based on the diagram on the schematic, with socket #5 as grounded and going around clockwise); and a green/wire goes to the middle lug of R1 (between rectifier tube sockets on page 14-26). 

There is a .05 cap shown in the picture between C3 and C4 (page 14-26) on the left side.  A one lug terminal strip has been added on the chassis; the ungrounded lug has the following connections – orange wire to speaker set socket #1 and a green/tan wire from choke connection #3.  The other end of the cap has a wire connected to speaker set socket #7. 

Also, there is a dangling connection shown in the 2:00 o’clock position of electrolytic 2.  One wire (maybe slate color) is from choke connection #2, and another wire (tan/green) goes to speaker set socket #2.

Can anyone tell me with how the three electrolytics were originally wired?  Or has someone added new electrolytics and not stuffed them in the cans, so that they can help me?  Also, should I use the value of the electrolytics shown on page 14-26 (i.e., 30 mfd for each of the three)? 

If you think you can help, but need more description, please ask.

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Someone has removed the original filter capacitors, probably for upgrading the appearance of a set they intend to keep, and replaced the holes with the 4-mfd, 600-v capacitors.  Given the fact that they did not replace the original capacitors, they did not intend to restore this power supply.  The filter capacitors should be 30-mfd, 500-volt if available, 450-volt if not.  Wires connected to the lower lugs of the replacement capacitors are probably original.  Be aware that only the middle capacitor has the case at ground potential.  The two outside capacitors should be insulated from the chassis using fiber washers.  More later if I have time.

Norman

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