Truetone Model 1035
11/4/2007 7:43:08 PMBill Cook(55540:0)
I have a Truetone model 1035. It is a battery powered 4 tube model (1N5, 1H5, 1A7 and 3Q5. I haven't been able to locate a schematic for it but have found several similiar models. I have taken care of the power requirements, replaced all the tubes (checked them with my tube tester), checked all the values of the capacitors, and replaced the filter capacitor. There is something wrong with the tuning portion of the circuit around the 1A7. I also checked for open resistors and cold solder joints. Being a battery power radio the components all look great. I am unable to get anything out of the 1A7. I also tested power on the appropriate pins of the tubes. Just experimenting I took my RF generator and placed it close to the radio and actually got a tone out of it at 455 KC. Anybody have any ideas? The tuner seems like it is not even there! Really appreciate your thoughts!
11/4/2007 8:05:54 PMBill Cook(55542:55540)
:I have a Truetone model 1035. It is a battery powered 4 tube model (1N5, 1H5, 1A7 and 3Q5. I haven't been able to locate a schematic for it but have found several similiar models. I have taken care of the power requirements, replaced all the tubes (checked them with my tube tester), checked all the values of the capacitors, and replaced the filter capacitor. There is something wrong with the tuning portion of the circuit around the 1A7. I also checked for open resistors and cold solder joints. Being a battery power radio the components all look great. I am unable to get anything out of the 1A7. I also tested power on the appropriate pins of the tubes. Just experimenting I took my RF generator and placed it close to the radio and actually got a tone out of it at 455 KC. Anybody have any ideas? The tuner seems like it is not even there! Really appreciate your thoughts!
11/4/2007 8:52:51 PMZ-(55547:55540)
:I have a Truetone model 1035. It is a battery powered 4 tube model (1N5, 1H5, 1A7 and 3Q5. I haven't been able to locate a schematic for it but have found several similiar models. I have taken care of the power requirements, replaced all the tubes (checked them with my tube tester), checked all the values of the capacitors, and replaced the filter capacitor. There is something wrong with the tuning portion of the circuit around the 1A7. I also checked for open resistors and cold solder joints. Being a battery power radio the components all look great. I am unable to get anything out of the 1A7. I also tested power on the appropriate pins of the tubes. Just experimenting I took my RF generator and placed it close to the radio and actually got a tone out of it at 455 KC. Anybody have any ideas? The tuner seems like it is not even there! Really appreciate your thoughts!
I think a good buddy had a similar problem a good while ago. IIRC, it had to do with the plate resistor being off-specs but you may ask him -John Bartley- about it. You can reach him on ARF. I'm sure you know him if you read there.
11/4/2007 10:30:41 PMTerry Judkins(55550:55547)
::I have a Truetone model 1035. It is a battery powered 4 tube model (1N5, 1H5, 1A7 and 3Q5. I haven't been able to locate a schematic for it but have found several similiar models. I have taken care of the power requirements, replaced all the tubes (checked them with my tube tester), checked all the values of the capacitors, and replaced the filter capacitor. There is something wrong with the tuning portion of the circuit around the 1A7. I also checked for open resistors and cold solder joints. Being a battery power radio the components all look great. I am unable to get anything out of the 1A7. I also tested power on the appropriate pins of the tubes. Just experimenting I took my RF generator and placed it close to the radio and actually got a tone out of it at 455 KC. Anybody have any ideas? The tuner seems like it is not even there! Really appreciate your thoughts!
:
:
Check the oscillator coil for continuity. Also the trimmer capacitor or tuning may be shorted. You may have to disconnect the coil for testing. I had an open coil in a similar RCA portable and rewound it successfully.
:
:
Check the oscillator coil for continuity. Also the trimmer capacitor or tuning may be shorted. You may have to disconnect the coil for testing. I had an open coil in a similar RCA portable and rewound it successfully.
11/5/2007 7:24:42 AMBill Cook(55551:55550)
I checked the coils for continuity but I did it while still in the circuit. Also the tripper capacitors....great ideas. It has to be something in that area.
Thanks!
11/5/2007 9:38:43 PMEdd(55588:55551)
I no findee 1035 either,but.....
I do find 6 other True-tone chassis' that use that same tube lineup, for a possible like chassis referencing :
With these notable differences,
The D2621, and D3630 have an extra RF amp tube included in their design, so it shouldn't be them.
The D2663 and D2762 both use VARIABLE INDUCTOR tuning instead of a dual variable tuning condenser.
That leaves the D3619 using a dual variable tuning capacitor AND (1) 35Z5 in the AC power supply portion.
And the D3635 is also using a dual variable tuning capacitor WITH a pair of 35Z5's in its power supply portion.
And you did mention "filter" capacitor, therefore, that would be associated only with the latter two, as all but 1
of those others were battery only sets.
I also would suspicion mixer portions local osc circuit, since your 455 signal booms right on through the sets
RF portion.
I think your in circuit test of the osc coil would have been OK, as my references show it to be capacitively
solated from being able to make any shunt with any other circuitry.
Are we considering that the osc grid resistor is OK ? and that your mixer tube is receiving high enough B+
in its supply circuitry, or it might just react in the like manner of a later set using an 1R5, tube and not oscillate.
73's de Edd
:I checked the coils for continuity but I did it while still in the circuit. Also the trimmer capacitors....great ideas. It has to be something in that area.
:
:Thanks!
11/6/2007 8:02:39 AMBill Cook(55596:55588)
:I fixed it! I found a schematic with the exact tube lineup but it was a stewart warner. The circuits were virtually identical except that the Truetone used the 3Q5 taking advantage of the centertap on the filaments so there was 1.5 volts across both halves of the filament. Anyway...the problem was a tiny open in the oscilator coil. It was so fragile so I carefully disconnected the wiring and pulled the can out and then pulled the coil out of the can. There it was a hairline open. I found it by measuring the voltages on the pins of the tube. B+ actually runs through the coil to the plate of the 1A7. When I took my measurements before I had the schematic I mistakenly measured on the good side of the coil and assumed that it would be the same on the pin at the tube. Bad mistake on my part! Oh well live and learn...thank you all for your input. I usually do 8 to 10 radios a year, repair and restore cabinet for friends and family. Usually just breaking even so it is more of a hobby than anything but I need to pick up the pace a little bit....my basement is filling up with radios!
:
:
:
:I no findee 1035 either,but.....
:I do find 6 other True-tone chassis' that use that same tube lineup, for a possible like chassis referencing :
:
:With these notable differences,
:
:The D2621, and D3630 have an extra RF amp tube included in their design, so it shouldn't be them.
:
:The D2663 and D2762 both use VARIABLE INDUCTOR tuning instead of a dual variable tuning condenser.
:
:That leaves the D3619 using a dual variable tuning capacitor AND (1) 35Z5 in the AC power supply portion.
:
:And the D3635 is also using a dual variable tuning capacitor WITH a pair of 35Z5's in its power supply portion.
:
:And you did mention "filter" capacitor, therefore, that would be associated only with the latter two, as all but 1
:of those others were battery only sets.
:I also would suspicion mixer portions local osc circuit, since your 455 signal booms right on through the sets
:RF portion.
:
:I think your in circuit test of the osc coil would have been OK, as my references show it to be capacitively
:solated from being able to make any shunt with any other circuitry.
:Are we considering that the osc grid resistor is OK ? and that your mixer tube is receiving high enough B+
:in its supply circuitry, or it might just react in the like manner of a later set using an 1R5, tube and not oscillate.
:
:
:73's de Edd
:
:
:
:
:
:
:
::I checked the coils for continuity but I did it while still in the circuit. Also the trimmer capacitors....great ideas. It has to be something in that area.
::
::Thanks!
:
:
:
:I no findee 1035 either,but.....
:I do find 6 other True-tone chassis' that use that same tube lineup, for a possible like chassis referencing :
:
:With these notable differences,
:
:The D2621, and D3630 have an extra RF amp tube included in their design, so it shouldn't be them.
:
:The D2663 and D2762 both use VARIABLE INDUCTOR tuning instead of a dual variable tuning condenser.
:
:That leaves the D3619 using a dual variable tuning capacitor AND (1) 35Z5 in the AC power supply portion.
:
:And the D3635 is also using a dual variable tuning capacitor WITH a pair of 35Z5's in its power supply portion.
:
:And you did mention "filter" capacitor, therefore, that would be associated only with the latter two, as all but 1
:of those others were battery only sets.
:I also would suspicion mixer portions local osc circuit, since your 455 signal booms right on through the sets
:RF portion.
:
:I think your in circuit test of the osc coil would have been OK, as my references show it to be capacitively
:solated from being able to make any shunt with any other circuitry.
:Are we considering that the osc grid resistor is OK ? and that your mixer tube is receiving high enough B+
:in its supply circuitry, or it might just react in the like manner of a later set using an 1R5, tube and not oscillate.
:
:
:73's de Edd
:
:
:
:
:
:
:
::I checked the coils for continuity but I did it while still in the circuit. Also the trimmer capacitors....great ideas. It has to be something in that area.
::
::Thanks!