Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

38-116 Code 125 Tube Heater Circuit Issue
#3

I'm glad to hear that the heater circuit is ok.  The socket voltage diagram I have shows 6.3 vac at both heater pins; so, I thought something was amiss.

The plate-to-plate voltage with the rectifier tube (5Y4G) removed measured 723 vac.  I'm using a digital multimeter.  The + side of cap 120 (and 121) is 275 vdc; supposed to be 315 vdc based on the diagram I have.  

I'm wondering if I have misconnected something with the new electrolytic caps.  For cap 123A I had installed a 10 mfd rated at 160 volts (with + side going to chassis ground).  The voltage rating on the original can was labeled as 50 volts.  But after a couple minutes of operation, I heard a small pop and saw a wisp of smoke.  That cap had apparently overheated and discharged a small amount of oily residue.  I've replaced it with a 12 mfd rated at 450 volts (closest one I had at higher voltage rating).  I've attached a couple photos showing how I installed the new caps.  I tried to mark on one photo how I interconnected the - sides of 120, 121, and 123 with the + side of 123A.

I noticed that the socket voltage diagram shows a 60 vdc measurement for the 10 mfd at 50 volts cap.  Seems like that cap's voltage rating is too low.

Thanks for taking the time to help me with this!
Larry


Attached Files Image(s)
       


Messages In This Thread
RE: 38-116 Code 125 Tube Heater Circuit Issue - by LarryFS - 09-21-2019, 11:19 AM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
My collection presentation
This article has been completely updated and finished. The beginning of a portable collection.Vlad95 — 11:49 PM
Philco 50-295 antenna connections
Thanks Rod, That makes perfect sense. Is there a way to edit my post? It's a Philco 50-925 and not a Philco 50-295. D...keith49vj3 — 09:55 PM
Philco 50-295 antenna connections
C is for an external speaker.RodB — 08:39 PM
Philco 370LZ chair side not a 71LZ
Can you send a couple of pictures?slford310 — 07:11 PM
Philco 370LZ chair side not a 71LZ
Thank you for the reply. After much studying I figured it just sat there and you have to open the top and pull up and/o...Villager61 — 06:42 PM
Philco 370LZ chair side not a 71LZ
Sorry, I haven't gotten to this project yet, so I don't have the answer, but I bet one of the experts on this site does....slford310 — 05:54 PM
Value of capacitor
That’s what I thought, but when I’m undoing 50 years of “repairs” it never hurts to check. Thanksbridkarl — 04:03 PM
Value of capacitor
According to AI, "Yes, you're reading that correctly. A .005 capacitor typically refers to 0.005 microfarads (µF), ...HowardWoodard — 03:57 PM
Value of capacitor
I’m having to replace this audio coupling cap between the plate of a 6F6 and a phone jack. The parts list just says .005...bridkarl — 03:45 PM
Philco 50-295 antenna connections
Shoot, just realized that the blue wire connecting to the top of the tuning cap can't go to terminal D since that's on t...keith49vj3 — 01:20 PM

[-]
Who's Online
There are currently 2584 online users. [Complete List]
» 1 Member(s) | 2583 Guest(s)
Avatar

>