CT-2 radio motorboating sound - Printable Version
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco-Transitone Auto Radios (https://philcoradio.com/phorum/forumdisplay.php?fid=7)
+--- Thread: CT-2 radio motorboating sound (/showthread.php?tid=4206)
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco-Transitone Auto Radios (https://philcoradio.com/phorum/forumdisplay.php?fid=7)
+--- Thread: CT-2 radio motorboating sound (/showthread.php?tid=4206)
CT-2 radio motorboating sound - Jay - 01-26-2012
I have replaced all the caps including the filter caps, but none of the ceramic ones. I get a motorboating audio sound that has a frequency change with the changing of the volume control level. I can hear a faint station in the background. Has anyone had this problem with this chasis and can lead me in the right direction to fix the radio?
Jay
:
Re: CT-2 radio motorboating sound - Radioroslyn - 01-26-2012
Check 14. All connections should show a low resistance to ground. Like less than 30 ohms.
Terry
Re: CT-2 radio motorboating sound - Jay - 01-27-2012
What is #14?
Jay
:
Re: CT-2 radio motorboating sound - Jay - 01-28-2012
Has anyone got a set of voltage readings on various tubes in the CT-2 chassis. I hate the Ryder schematics. I suppose they were OK in the days long ago when everyone was working on these radios at least once week. They probably had voltge readings written down in a book. I am used to using Howard Sams schematics and service sheets. I am spoiled, I guess. Any help along this line will be appreciated.
Jay
Re: CT-2 radio motorboating sound - Radioroslyn - 01-29-2012
It's on the Rider diagram #14 is the oscillator coil.
Terry
Re: CT-2 radio motorboating sound - codefox1 - 01-29-2012
Schematic here with plenty of voltage points. Bear in mind these were taken with meters of the day that somewhat loaded down the circuit, so you may get higher readings. Not much of a voltage divider tree here. So start here.
http://www.nostalgiaair.org/PagesByModel/125/M0014125.pdf
Re: CT-2 radio motorboating sound - Radioroslyn - 01-29-2012
CF Wrong set his is a car radio CT-2 not the PT-2 table radio.
Terry
Re: CT-2 radio motorboating sound - Jay - 01-29-2012
That reference brings up a Philco PT2 chassis with totally different tubes and a lot lower B+.
I would like to see voltages for the CT2 chassis if anyone has such.
I have 205 VDC at the first filter cap and 193V at the second filter cap. I guess that is normal for this chassis?
The rersistance to ground at 14 is less than 30 ohms at all 4 connections.
As I turn up the volume, the motorboating sound turns into a fairly smooth humming sound.
Re: CT-2 radio motorboating sound - Radioroslyn - 01-30-2012
HV sounds OK. Starting at the rf amp tube with the set on start pulling the tubes in order mixer, IF amp... Until the motorboating stops. That will tell you which stage is the problem.
Terry
Re: CT-2 radio motorboating sound - codefox1 - 01-30-2012
7estatdef Wrote:CF Wrong set his is a car radio CT-2 not the PT-2 table radio.I need new glasses.
Terry
Re: CT-2 radio motorboating sound - BILL - 01-30-2012
PT- 2 is a 1935 Packard, I restored one once, These old Transitones had oscillator troubles sometime you can repair them by rewinding and finding the brake, but this sound like a power supply problem go though the work you did double check, a drop of soider in the wrong play can give you fits,I've done it!
RE: CT-2 radio motorboating sound - autoradiotech - 11-13-2012
do you have the first filter cap hooked with nthe neg lead going to the pwr trans sec CT? these Philcos had the CT going to a choke and the other side of the winding was grounded to get nbias voltage for the audio tubes, the first filter had the neg lead going to the trans. CT and the second filter neg lead to ground, the filters were common pos.
RE: CT-2 radio motorboating sound - codefox1 - 11-14-2012
I think you gents are onto something. Often the chassis is not the most negative point in the voltage divider, and there is a filter capacitor that has it's positive leg to the chassis, and negative side to the center tap of the power transformer. Get this wrong, and the set will not work. Either that or you are operating the radio in a marina.
RE: CT-2 radio motorboating sound - Conelrad - 11-14-2012
Ha!
DG