116X Revisited - Printable Version

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116X Revisited - Radioroslyn - 06-10-2018

All this chatter about the 116X got me busy again on mine. Sometime back I did a pretty complete overhaul on the set but after I was done it still had some issues that needed to be addressed.

Noise in the audio. W/the volume down you could hear a hissing and an occasional pop. It was intermittent. Reminds me of what a leaky coupling cap can sound like. Was thinking that it could be a noisy resistor, bad driver transformer or noisy tube. Pulled out the 42 and all was nice and quite. Same w/the 77. Not so w/the 37. Replaced the 77 and all is well. Got lucky this time.

Dial calibration off. Had removed the dial speed reduction to reclean and lub for a 2nd time. When I did so I didn't get the dial back on exactly where is should be. When I did the alignment the tracking was very good, within a few kc on the bcb but now it's 15kc or so off. At fiddling around for a bit I figure it's the set screw in the front that loosen the dial from the tuning cap. The rear screw locks the 2 sp drive to the tuning cap. Was able to reposition the dial to where it need to be.

Hum in the audio. Haven't really addressed this issue but I'm thinking that the 6A3's aren't balanced. I have a few spares. It's not very noticeable  but w/the volume all the way down it can be heard. It maybe just the nature of using these directly heated tubes in the output stage. Balance pot helps but doesn't get rid of it completely.

Hot power transformer. This too is something yet to be sorted. After it's been on for several hours it's hot to the touch. It's like touching a black car roof on a hot sunny day. You can do it but it smarts. And not weeping any wax. Hv and bias voltage look good so I think there isn't an excessive load but need to get my hands on an ac amp meter to be sure. Line voltage here pretty moderate @118v.

I was in a bit of a wrestling match w/the chassis to get in back into the cabinet. It's kinda heavy and the pt was still hot. Just couldn't seem to get that last 1/4" in, till I realized I had left the tuning knob on it DOH!!!!!

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RE: 116X Revisited - PhilcoPhan1936 - 06-10-2018

When I did the restoration of my 116PX, I noted that the main power transformer also gets hot to the touch. There is a little wax that has leaked out onto the wires coming out of the transformer underneath, but it's not excessive. I did build a bucking transformer, and run it through that, and it does help. I think it runs around 109-110v. It still gets warm after a couple hours of use, but not like it did without the bucking transformer.  
I have yet to service my 116B models. Since they are a similar 11-tube chassis (I think the output tubes used are different), I'm curious to compare if the transformer on the 116Bs will run as warm as the 116PX.  

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RE: 116X Revisited - morzh - 06-10-2018

Terry

You will not earn a Pulitzer. You put the whole process in one post and 6 paragraphs. Where's the action, where's the drama, I ask you, where's the wild yearning for unattainable!
I give you +1 for "smarts". Most people would just say "burns or stings".

But you need to strech the reading pleasure.

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RE: 116X Revisited - Radioroslyn - 06-10-2018

As you may know typing isn't my 1st language I much prefer the spoken word .

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RE: 116X Revisited - Radioroslyn - 06-10-2018

Hi Jeff
The transformer in the 116X is a bit beefier vs the 116B. The specs for the rectifier tubes being 250ma vs 125ma max output. I would think that in the 116B that the 80 is running at abt max dissipation. Don't remember if the transformer get hot or not. I need to get back to my 116B. I got it working well but need a fair amount of cabinet work and the rubber washers under the tuning cap. Gosh it was a year ago! http://philcoradio.com/phorum/showthread.php?tid=16833

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