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

Echophone model s3 no sound
#1

Working on the 5 tube version (three 24's, a 45 and 80) of the 1930 Echophone, this one is a model S3:

   

My chassis appears to be the "improved" schematic version on the bottom.

I replaced all of the caps, save for the two .02 mfd's (I wanted to replace the "tar boxes" and then see if I could coax some sound out of it). I also read a thread on ARF where Norm suggested changing c14 and c16 to 10 mfd electrolytics and eliminate c15 to improve sound and reduce hum, so that's what I did.

So, after trying several tubes, I'm still getting no sound. My voltages are quite erratic as well (See the chart below...I used the mouse to "color" in red the values I'm getting...hence the hen scratching that looks like a 4 year old wrote it Icon_smile )

   

Trying to inject a signal, I get noise that's controllable with the volume control across both the long and short antenna terminals. On the grid of the output tube I get noise, but no noise on the plate of the output tube. On the plate of the detector tube I get noise, but no noise on the grid of the detector tube. The resistors are a bit high (save for the 2 meg which is reading 5 meg) but none are open.

The choke measures about 400 ohms, so that's not open. Speaker field and output transformer are good.

Anyone (paging Terry) have any thoughts on where to zero in on first? It seems to be a relatively simple 5 tube radio but very ancient in design (it has a multi tap, open air transformer that looks pretty scary in itself but it still putting out voltage and not drawing any amps).

Greg V.
West Bend, WI
Member WARCI.org
#2

Did you connect the - side of c-14 to the chassis?
Does it ave the original spkr that has a tap in the field coil winding?

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
#3

>>Did you connect the - side of c-14 to the chassis?

No, the neg side is going to the choke and transformer.

>>Does it ave the original spkr that has a tap in the field coil winding?

It's a Jensen speaker that looks to be a replacement, but it DOES have the tap in the field coil. That checks out good.

Greg V.
West Bend, WI
Member WARCI.org
#4

How much - voltage do you have from the ct of the hv winding to the chassis? Need abt -50v. With -1.7v on the grid of the 45 the plate current is going to be pretty high. Disconnect one end of the C-5 and see with the - voltage increases. If C-5 is leaky that will apply + voltage to the grid of the 45, not good.

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
#5

I jumped the gun a bit and should've just went ahead and replace the two .02 caps and the resistor bank. That revealed an open 1 meg resistor, a bad solder joint at the non-grounded .02, and some bad solder joints around the speaker plug. Happy to report she is singing tonight and actually sounding pretty good for an 89 year old radio. Voltages are there where they should be now. What a strange power transformer, though. Just by moving the fuse between terminals 84 to 85 or 85 to 86 you can go from 110 volts to 125!

Greg V.
West Bend, WI
Member WARCI.org
#6

The 2nd .02 (goes from from the output trans to gnd) could be reduced in value to brighten up the sound a bit, to .01 or .005 mfd.

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco 91 Speaker Replacement
The spider is glued on the cone and so is the voice coil. I think you can use a cotton swab dipped in acetone and carefu...RodB — 02:42 PM
Restoring Philco 37-604C
Yes I saw that. If I knew, I'd probably try to arrange for getting it myself. But I have just got one. Which does not m...morzh — 01:44 PM
Philco 38-2 Automatic Tuning
When you push the lever, you are supposed to rotate the disk to the desired station. Then the magnetic tuning will acqu...morzh — 01:42 PM
Philco 38-2 Automatic Tuning
I figure out the muting from another picture that helped. Now I need to know how the automatic tuning works. When I push...dconant — 12:11 PM
Philco 91 Speaker Replacement
How would I go about removing the spider from the cone?dconant — 12:04 PM
Philco 38-2 Automatic Tuning
Hello, I am having trouble getting my automatic tuning to stay unmuted. If I play with the tuning handle I can get it to...dconant — 10:51 AM
Does anyone make photofinish replacements?
Here’s the link to the DIY photofinish section of our site: klondike98 — 09:46 AM
Delco car radio Peko vibrator converstion issues
Hi Richard, Thx for posting the schematic.  As I remember as a kid, these were great performers for the time, likely...MrFixr55 — 08:56 AM
Delco car radio Peko vibrator converstion issues
hello mr Fixr, The Electro  Powersupply that I am powering the radio with has a huge choke plus a 10,000ufd electrolyti...radiorich — 10:58 PM
Delco car radio Peko vibrator converstion issues
How about putting a choke in the power supply? The big cap was likely an attempt to stabilize the DC. Kids who cre...MrFixr55 — 09:19 PM

[-]
Who's Online
There are currently no members online.

>