Echophone S-4 Help Wanted
Posts: 122
Threads: 22
Joined: Dec 2013
City: Meridian, ID
I have the set fully assembled, non-working, with a couple of issues impeding my progress.
[Image: https://farm8.staticflickr.com/7925/3288...940f_z.jpg]
The overriding issue is too-high voltage. At 115VAC, the plate voltage for the 245 is over 300v, and over 700v for the rectifier. So, I'm doing my testing now at 60v or 75v and all the other voltages seem higher than expected-- except the filament voltages, which are all good.
[Image: https://farm8.staticflickr.com/7902/3288...31fa_h.jpg]
(Direct link to image: https://flic.kr/p/S6JA4f)
Is the transformer putting out too much voltage, or is it likely that I have made some wiring mistake? I've checked all the wiring several times, and it all seems OK except I'm uncertain about the RF transformers, but I'll ask about that later.
Thanks for looking,
Henry
Posts: 1,419
Threads: 71
Joined: Oct 2007
City: Linn Creek, MO
Henry, make sure you are using the high voltage tap on the power transformer.
Steve
M R Radios C M Tubes
Posts: 122
Threads: 22
Joined: Dec 2013
City: Meridian, ID
Steve,
I had the line connected to lug 81, 115V on the schematic. I moved it to lug 82, 125V. Is that what you meant? At 115VAC, the 245 plate voltage was 345V. Here's a full description of the transformer outputs at 60VAC, extrapolated to 120VAC.
[Image: https://farm5.staticflickr.com/4819/3289...6ded_c.jpg]
Posts: 1,419
Threads: 71
Joined: Oct 2007
City: Linn Creek, MO
Yes, the line should connect to 80 and 82. If connected to 81 all voltages will increase about 10 percent.
Steve
M R Radios C M Tubes
Posts: 122
Threads: 22
Joined: Dec 2013
City: Meridian, ID
Hm-m-m. Voltages did indeed increase, but the problem is that the B voltage is already too high. The 245 plate should be some between 150v and 250v. It's 345v at normal line voltage. Except for filament voltages, a quick check seemed to show all other tube voltages were too high as well.
Posts: 2,118
Threads: 112
Joined: Jun 2010
City: Medford OR (OR what?)
Are you testing this unloaded, that is, with one or more tubes removed?
"I just might turn into smoke, but I feel fine"
http://www.russoldradios.com/
Posts: 122
Threads: 22
Joined: Dec 2013
City: Meridian, ID
First let me say that I finally realize how the high-low voltage taps work--that is by changing the ratio between the primary and secondary. Before I couldn't see how going to the high voltage tap would decrease the transformer output.
I am testing with all tubes in. Fully loaded. But my test results have been so inconsistent that I switched to a different multimeter. The meter didn't make any difference. What I can see now is that when power is first on (Again, at 60VAC) the 245 plate voltage rises from zero to about 135 volts in a few seconds, then slowly reduces to 107 over a period of 2-3 minutes. I'm keeping it on now for 20 minutes to be sure that it stays at 107. If that stays steady, I check again at 115VAC, and if I get the expected 210v at the plate, then I'll proceed with the rest of the voltage tests, and if the radio still doesn't talk, then I go to my next issue.
That y'all so much.
Posts: 122
Threads: 22
Joined: Dec 2013
City: Meridian, ID
Further testing of the 245 plate voltage is more confusing (I keep checking the 245 because they're expensive and I'm afraid of killing it.) At 60VAC, the plate voltage quickly rises to about 110, then over a few minutes it decreases. After 20 minutes it's down to 70v.
BUT, when I ran it at 115VAC, the plate voltage started at 220v and over time, it increased until I stopped at 400v.
After reviewing all the wiring again, including the speaker and speaker plug connections, the only thing I'm unsure of is my wiring for the antenna coils, RF coils, and the potentiometer. First question is, what kind of RF coils do I have. I've assumed that they're the original flavor--not the later models with Litz wire.
[Image: https://farm5.staticflickr.com/4880/3288...d84f_c.jpg]
Of course, I have no idea what the descriptions mean. With the connections I've made, here are the coil resistances. Does it make sense?
[Image: https://farm8.staticflickr.com/7883/3288...ce72_c.jpg]
One inconsistency is that I disconnected one of the Bakelite caps, and it isn't 50pF as indicated on the schematic. If my cap tester is right, then it's less than 10pF.
Users browsing this thread: 1 Guest(s)
|
|
Recent Posts
|
|
54C Complete Teardown/Rebuild
|
| I don't think that I have encountered a 12Z3 before, curious how it uses one of those but includes a #43, which is a 25 ...Arran — 02:17 PM |
|
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 |
|
Who's Online
|
There are currently 1430 online users. [Complete List] » 1 Member(s) | 1429 Guest(s)
|
|
|
|

|