[DKinYORKpa]

I just removed the cap/tar box , part # 108,  located under the bass/AC switch at the front of the receiver chassis. I carefully noted the location of the 3 wires. Now that I'm ready to re-stuff the box with two .1s and a .7, looking at the schematic for guidance, I'm confused. On the chassis, the ORANGE and the WHITE-BLK-TR wires go to the same lug and the BROWN wire goes to another lug. At first this made sense, but why aren't the ORANGE and the WHITE-BLK-TR just one wire? In other words, why aren't there just 2 wires coming out of the box?

[img][Image: http://i191.photobucket.com/albums/z309/...u5mxu.jpeg][/img]

[Phlogiston]

Maybe that is not a factory cap?

I have seen this. A duel cap built with separate leads can be used in more radios. I have also seen the grounds tied together.

[DKinYORKpa]

That doesn't help me....lol....the two .1s are grounded together and soldered to the cap box. The schematic then shows one leg of a .1 tied to one leg of the .7, so that's my brown wire. The schematic then shows the other .1's leg tied to the other side of the .7. But I have an orange wire and white with black trace leaving the box and going to the same lug. What am I missing?

[DKinYORKpa]

OK, so you're saying that in the box, the one leg of the .1 is the white with black trace and the leg of the .7 is the orange, right? So in essence, I could have just 2 wires leaving the box by tying them together in the box?

[SteveJB]

Those caps are for the discriminator. I had the same issue when I restored mine. It took a while to figure it out.  In the end I just followed the schematic and it worked out fine.  It probably has more to do with how that box was constructed when it was made.

It has been several years so I can't comment on the colors of the wires, just follow the schematic.  I did not restuff. I believe the 38 116's I restored had the same issue.

Steve

[DKinYORKpa]

My restoration is headed towards completion. The plug on my AC cord is a (first one for me) fused plug. It's old and nice looking and seems like a good idea. The fuses are old and kind of corroded and I'd like to replace them. They are marked 3A. Does anyone know the wattage for this unit? I can't recall where I saw it listed. And they would be slo-blo, correct?

[morzh]

2A is enough. Slowblow (time lag) is fine.

[Radioroslyn]

As a rough guide figure about 1.5 amp per 100 wts  of load. An old toob TV draws 200wts @120vac fuse it with a 3 amp fuse.

Terry

[DKinYORKpa]

BTW, here is the modern (after market) version of my old fused plug. Common glass fuses push into the 2 holes. Both legs are fused.

http://www.ebay.com/itm/Fused-AC-Plug-fo...xyu1BTkbFL

[DKinYORKpa]

Well gang, after a total recap, 2 candohm rebuilds and fingers crossed, by some miracle it works! Sort of. AM sounds great, tunes fine but there is absolutely nothing on the SW bands, not even a click-sound from spinning thru the bands. Nothing with volume full. Dead air. Suggestions? (I did some contact cleaner the best I could)

[klondike98]

Hi DK, I merged your series of 38-690 questions into a single thread to keep the subject all together. Unfortunately I can't help with the actual SW question but do wish I had a 38-690

[Ron Ramirez]

The SW oscillator coils would be the first suspects, although the band switch may need some DeoxIT as well.

P.S. Thank you, Bob, for merging the threads

[DKinYORKpa]

OK, hanging out around the SW Osc. coils, I noticed something. Resistor #44, 4K 1 watt, becomes too hot to touch when I switch to SW. On AM (which works great), it measures 220VDC in and 170V out. On SW, it measures 175VDC in and 32V out. What does this point to?

[img][Image: http://i191.photobucket.com/albums/z309/...4qcap.jpeg][/img]

[Radioroslyn]

+1 Ron
I'm thinking if your lucky (well not that lucky) you got 3 bad osc coils. This may account for the high drop across your 4K resistor as the osc tube wouldn't be oscillating (higher screen current).

Or if you are unlucky you may have a bad band switch. If that is the case maybe a terminal is shorting to something else when it's on the SW bands. Or something in the metal part of the bandswitch is shorting to one of the contacts, like where the shaft goes though the wafers.

If it does turn out to be either you may what to consider getting a spare rf deck to swap with this one. I think the ones from a 37 or 38-116 will work in it's place. Ron could help on which ones will work just to be sure.

Seems like I remember BAD posting about a '116 or 690 that just about all of the osc coils where bad.

GL
Terry
ps. Henry had or has a 37-116 parts set in the for sale.

[Ron Ramirez]

I'm thinking you may have a burned carbon track in your band switch, in the oscillator section. Which of course is not good news.

Either that, or something is shorting B+ to ground to drop your B+ voltage that much when the band switch is in one of the SW positions.

Some careful resistance measurements (with the set of and unplugged) might reveal the source of the trouble. I would measure resistance between the B+ line (both sides of resistor (44) and from there up to the oscillator "plate" or grid #2 of the 6A8G oscillator tube) and chassis ground with the set in all four of the SW positions. Also take these measurements in the AM position as a reference.