Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

Low volume on Belmont Model 6D111
#1

Hello, Mama, It's Georgie. Your son, from the money every week. I can hardly hear you! Is Terry available?

   

Working on a Belmont 'bullet' model 6D111 series A

   

Here's a link to the Nostalgia Air version of the schematic, so it can be opened as a PDF and enlarged:

http://www.nostalgiaair.org/pagesbymodel...002220.pdf

Despite a complete recap...micas included, all new resistors, new 1 meg volume control / switch, and trying two sets of all new tubes, the set only plays at barely above a whisper with the volume all the way up. Tracing through the schematic didn't offer any glaring errors. Everything checked out to be where it should be.

Tonight I got out the signal generator and injected an audio output signal to see where I'm losing volume. Here's what I found:

1) Audio signal at CT of volume control loud and controllable (but NOT if you just touch it with a screwdriver) without the use of the SG)

2) Audio signal to Pin 2 (Grid) of the 12SQ7 is loud

3) Audio signal to Pin 6 (Plate) of the 12SQ7 is LOW

4) Audio signal to Pin 5 (Grid) of the 35L6 is LOW

5) Audio signal to Pin 3 (Plate) of the 35L6 is DEAD (no noise)

Checking voltages (All to B -, as per schematic):

Pin 3 (Plate) of the 35L6 is 107 VDC (should be 90)

Pin 4 (Grid) of the 35L6 is 91 VDC (should be 70)

Pin 8 (Cathode) of the 35L6 is 4.7 VDC (should be 4.3)

Pin 8 (Cathode) of the 35Z5 is 126 VDC (should be 112)

Pin 5 (Plate) of the 35Z5 is 116 VAC (should be 110)

Pin 6 of the 12SQ7 (Plate) is 58 VDC (should be 40)

Pin 2 (Grid) of 12SQ7 is - .6 VDC (should be 0)

It seems the problem is in the audio output section somewhere, but I have not found a smoking gun. Do you have any thoughts on where to look, Terry?

It doesn't appear the output transformer is open (I get around .4 ohms on the secondary and around 200 ohms on the primary). The set receives stations across the dial but most are barely audible save for the strong local station which can be heard at with the volume pot turned 3/4 open.

Greg V.
West Bend, WI
Member WARCI.org


Messages In This Thread
Low volume on Belmont Model 6D111 - by NostalgiaRadioTime - 10-07-2018, 10:33 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
HiFi (Chifi) tube amp build - but my own design.
It's the other forum. I'm also in DIY, but mostly read there. Honestly, I kinda jumped into this without much thought to...TV MAN — 10:43 AM
Philco 71 Code 125
Hello,  I am in need of a schematic for this radio. Mine has the three separate circular tube shields and a shadow me...dconant — 08:06 AM
Stromberg Carlson 1500 Squeal
And life just keeps getting more complicated.dconant — 07:57 AM
54C Complete Teardown/Rebuild
Hello Roy, here is this one sincerely Richardradiorich — 12:45 AM
54C Complete Teardown/Rebuild
Richard, Had grabbed it already but thank you just the same.  I find myself wanting to find some way to block out the...glyphmon — 12:03 AM
54C Complete Teardown/Rebuild
Hello roy, here is a link to the schematic . Sincerely Richardradiorich — 11:54 PM
54C Complete Teardown/Rebuild
Richard, The Silvertone 2014 also is a transformerless set, so I am incorporating a 1:1 600 ohm audio isolation transfo...glyphmon — 11:37 PM
Preliminary work on wife's Silvertone 2014
Did an alignment today which was interesting.  IF alignment went great, almost all was already spot-on.  Adjusting on th...glyphmon — 11:35 PM
54C Complete Teardown/Rebuild
The main problem with adding a Bluetooth input is that this set lacks a traditional power transformer to isolate it from...radiorich — 11:19 PM
54C Cabinet Refinish
I started stripping this cabinet before it got super chilly out because I knew I wasn't going to be able to work on ...glyphmon — 11:18 PM

[-]
Who's Online
There are currently 1760 online users. [Complete List]
» 1 Member(s) | 1759 Guest(s)
Avatar

>