The PHILCO Phorum
Need help on 40-180 chassis - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Need help on 40-180 chassis (/showthread.php?tid=20079)

Pages: 1 2

RE: Need help on 40-180 chassis - BillT52 - 06-07-2019

OK, just got everything back together and did what morzh said to do. So with the signal generator hooked up to the antenna screw thru a .1 cap and volumn all the way up I put 40 AC volts of signal to the plates. Then I connect the voltmeter to the secondary side of the OT and had at times .7 volts  max and it would drop to 0 and fluctuate from 0 to .7 volts. So looks like my problem is the transformer is not putting out. I will be looking for a replacement. Learning experience for me so thanks mortzh. I'll know more how to test these in the future. Once I find another I'll post the results.

RE: Need help on 40-180 chassis - morzh - 06-07-2019

Bill

Yes the secondary fluctuating if the primary is steady is not good.
However, at 0.7V AC you should've heard a fairly loud signal. Maybe a fluctuating but still.

Have you measured the resistances of the primary halves?

RE: Need help on 40-180 chassis - BillT52 - 06-07-2019

224 ohms on one side and 197 ohms on the other which is close to what the schematic calls for: 240 & 210. I've yet to get any signal out of the speaker. The weak signal I can hear comes from the output trans and it fluctuates with moving the dial on the signal generator so I know thats the signal I'm feeding in.

RE: Need help on 40-180 chassis - morzh - 06-07-2019

Are you sure the connection of the xfmr to the speaker is good?

RE: Need help on 40-180 chassis - BillT52 - 06-08-2019

Yes I have checked that. Made sure no break in the plug at the end of the wiring harness. So one side of the trans secondary is to chassis ground, other to speaker voice coil. made sure all connections are the same as original trans I took out.

RE: Need help on 40-180 chassis - Radioroslyn - 06-08-2019

Hi Bill and welcome to the fray, 
If you need an output transformer here is a reasonably priced one.  https://www.tubesandmore.com/products/transformer-output-8-w

GL w/your project.

RE: Need help on 40-180 chassis - morzh - 06-08-2019

Yes theirs are way more reasonably priced than Hammonds. About 1/3 of the price.

RE: Need help on 40-180 chassis - BillT52 - 06-08-2019

Thanks for the link. I may try that one. Haven't had any luck finding an old one in my stash that would work. Price is better than others I've seen. Hopefully that will take care of it.

RE: Need help on 40-180 chassis - Radioroslyn - 06-08-2019

You may want to check the resistance of the spkr's voice coil just to be sure it isn't open. I don't see it very often but it does happen. To do this disconnect the output transformer's secondary from the voice as it will influence the measurement. Should see a very low resistance of a few ohms.

RE: Need help on 40-180 chassis - morzh - 06-08-2019

Terry

He said he took the speaker and tested it with another radio.
This is the only reason I haven't suggested it so far, else I'd do the same.
Also this is why I asked about the connection from the xfmr to the speaker.

RE: Need help on 40-180 chassis - Radioroslyn - 06-08-2019

>He said he took the speaker and tested it with another radio

My brain must have skipped over that part. That's assuming I can read, sometimes that's questionable! [Image: https://philcoradio.com/phorum/images/smilies/icon_lol.gif]

RE: Need help on 40-180 chassis - BillT52 - 06-25-2019

Update on my problem with this 40-180 chassis. Went ahead and got the new output trans that Radioroslyn suggested. Did not solve the problem but I could hear sound thru the speaker a little better but very weak. Felt I had checked all that I could so I contacted a member of one of our local clubs that has been doing this for years. Took it to him and he was stumped for maybe 15 minutes. First thought it might be the switch on the push button for tuning but it was OK. Had output from the new trans when measured at the trans but not so much at the voice coil so he tried a jumper from the chassis to the voice coil and BAM, that was it! He said he had come across this once before. THe speaker I was using was not the exact one but from another Philco. His explanation basically was that the field coil was a little different and was not connected to the ground from the wiring harness. So simple fix was I ran a 5th wire from the voice coil to the ground screw on the chassis and all is well. Maybe this will help anyone else with a 40-180 that needs another speaker.
Thanks to all that offered help on this.