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40-145 speaker issue - Printable Version

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40-145 speaker issue - OldRestorer - 03-12-2015

Ok,

  I am currently working on a 40-145 chassis and have finished the recap. I turned her on and she lit up and no smoke so that good but no sound at all. 

Now when I first put it on the bench I checked all the tubes. All of them were bad and the speaker cone was pushed out. Did the radio blow possibly before I got it? I am thinking that the speaker is bad so here is my first question!

In stoopit terms, How do I check the speaker. If I am using the VTM, Where do I put the leads? there are multiple wires on the speaker so which is which?

Next question:
I did not have a 7Y4 to replace the bad one. Could that stop the radio from getting stations?

I know you guys will figure this out.  Icon_mrgreen

Kirk

RE: 40-145 speaker issue - sam - 03-13-2015

kirk
whats the first thing mike would tell you to do
http://www.nostalgiaair.org/PagesByModel/330/M0013330.pdf

http://tdsl.duncanamps.com/show.php?des=7Y4
I don`t think it will work if 7y4 is bad 

I could be wrong  but I also don't know what dotted line means off switch
sam

RE: 40-145 speaker issue - Radioroslyn - 03-13-2015

Kirk
Soooo how do you know ALL of the toobs are bad??? They don't light up? Tested them in a toob tester? Checked the heater w/an ohm meter? Haha I made a little rhyme.
Tis very unusual for all to bad.
Just because the paper cone on the speaker out, not quite sure what that means it shouldn't stop it from making any sound at all.
The 7Y4 is the rectifier without it you will have no HV hence no nothing.


Sam
The little dotted line means that it is physically connect to. The OFF/ON sw is physically connected to the volume control. Not electrically. Same as the tuning condenser.


Terry

RE: 40-145 speaker issue - OldRestorer - 03-13-2015

I checked all the tubes in the toob checker Icon_smile

I guess I need a 7Y4 and then I can re-test.

I know Mke would say look at the schematic but it does not say "how" to test the speaker.

Kirk

RE: 40-145 speaker issue - sam - 03-13-2015

kirk
I know Mike would say look at the schematic but it does not say "how" to test the speaker.
use a 9v battery listen for click sound

terry
ok thanks for info
sam

RE: 40-145 speaker issue - morzh - 03-13-2015

Koik,

Here's how.

1. Buzz across the field coil. Should be 1.7 kOhm.
2. Take your variac, preferrably plugged via isolation xfmr into 120V outlet. Set it to 20VAC output. Connect the output to your output xfmr PRIMARY. Turn it on. Take a small magnet, not too strong, the type you could hold in hand without it flying out and gluing itself to the speaker pole, as it can damage coil or cone - hold it firm, and move it towards the voice coil fom the front. Again, do not let it out. You should hear the 60 Hz buzz when you close enough. Another way is just to tempirarily place small magnet right to the top of the pole, but then you will need to take it off and it is inconvenient once it is there since the voice coil is around. You could try a very strong magnet from the back of the pole, might work too.

All this is for you not to have to power the Field coil.
So, if the FC is 1,700 Ohm and the spiecker hums, it is good electrically.

RE: 40-145 speaker issue - OldRestorer - 03-13-2015

Buzz across the field coil. Should be 1.7 kOhm

1. Ummmm, where do I put the leads of the VTM? there are a few wires so I dont know.

2. So I plug in the radio, 120v and then hold a magnet close to it and I should hear buzzing?

Just come over and help me, lol

Kirk

RE: 40-145 speaker issue - sam - 03-13-2015

Just come over and help me, lol

Kirk

mike
did you ask him if he even has a variac were talking kirk here
just hop on over only in next state Icon_e_wink

RE: 40-145 speaker issue - morzh - 03-13-2015

Kum'n'over, we'll have a beer without mold and I'll test it for you fer free. Icon_lol
Plus I will teach you where to put meter pobes, I have an impression you sticking something else and in some wrong place too. Icon_lol


OK. On a serious note, does your speaker plug look close to how 20/70/90 plug look? 4 prong thing?
Typically, if it is, then here's a link

http://www.philcoradio.com/tech/speaker.htm

WHich means ther are three wires. You stick your ohmmeter across the two lower fat pins as on the drawing, and this is FC 1.7k
The right fat and right thin one are the xfmr primary, about 600 Ohm.
The cone and VC integrity is checked as I said before. You need either to enegize the FC or use perm magnet.

RE: 40-145 speaker issue - Radioroslyn - 03-13-2015

Mike
His speaker has no plug it's solder in.
Kirk
To measure the field coil measure the resistance from pin 7 of the 7Y4 to pin 3 of the 7B5.
The measure the primary of the output transformer measure resistance form pin3 of the 7B5 to pin 2. Should read a few hundred ohm.
Very unusual for the VC or the transformer secondary to be bad. The set isn't going to do much at all till you replace the 7Y4
Terry

RE: 40-145 speaker issue - OldRestorer - 03-16-2015

Well, I got the tube but no miracle  Icon_mad

This sucks Icon_lol

I have it on broadcast but what are the buttons? is one for broadcast?
I have tried SW and all the push buttons and BC with all the push buttons and get nothing from the speaker still

Kirk

RE: 40-145 speaker issue - Radioroslyn - 03-17-2015

Measure dc voltage from + pin7 of the 7Y4 to- chassis. Should have about 200v. Measure  dc voltage from pin2 of the 7B5 to chassis. Should have 180vdc but I'll  bet you don't.
Terry

RE: 40-145 speaker issue - OldRestorer - 03-17-2015

Will do that today

kirk

RE: 40-145 speaker issue - OldRestorer - 03-17-2015

I get 270 from the 5y4 and 160 from the 7b5.

RE: 40-145 speaker issue - morzh - 03-17-2015

Is the rect tube wired different? 5Y4 and 7Y4 are not the same. Also, they have different filament voltage (5V and 6.3V respectively).