Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Model 60 Rectifier Circuit
#1

Am working on a Mod 60 using schematic #164. Put in new electrolytic caps, and rebuilt the filter condenser bank. Checking the voltage across Cap 46 I see 260vdc, across Cap 45 is 40vdc. Is this correct? The transformer AC volts check okay. Also checking the plate volts of the 6A7 pin 2 to pin6(K) I see nothing should be 250vdc. I don't understand what K means.
Thanks for any help
Bob
#2

Any tube pin marked as "K" generally means cathode, that's often used as a reference point for checking voltage since it's the closest point to ground potential in the circuit.
Regards
Arran
#3

Hi Bob
Not sure what diagram you are using? Can you post a link to it? Typically K stands for cathode in regards to tube connections. You aren't going to find any HV there, look for P would be the plate. That's where the HV should be.
Terry
#4

Read the OP again. He's saying that he's measuring from the plate of the 6A7 (pin 2) to the cathode (K, pin 6), between which should be 250V, but he is seeing no voltage there.

As far as his power supply voltages, I would check the bias resistor (47), and then the field coil on the speaker. No voltage at all to the 6A7 plate could be a shorted capacitor (20) or possibly an open 1st IF coil or resistor (9).
#5

Thank you everyone. These tips are (will be) a great help. Won't be able to get back to the radio for a day or two. I will post what I find.
Bob
#6

Making some progress. Replace Cap 8 and now have around 220 (not 250) volts on the plate of the 6A7. All I get out of the speaker is static whenever I touch the meter to pin 6 and the plate pin2.
I now have 350 vdc across cap 46 and 240 across cap 45. The speaker coil and resister 47 appear to be good. Is the difference between the voltages correct, or should they be the same.
What would be a god next step?
Bob




Users browsing this thread:
[-]
Recent Posts
Philco 42-345 Restoration/Repair
Ok MrFixr55,  I have tried the DeoxIT D5 on the band switch and even though it has relieved the tension I felt when turn...osanders0311 — 11:11 AM
Part numbers to model cross
Is there a reference somewhere where you can punch in Philco part numbers and see what models those parts were used in?Jim Dutridge — 10:17 AM
Philco 42-345 Restoration/Repair
Hi OSanders, Look carefully at the band switch. Turn it slowly and "wiggle" it around the desired band. ...MrFixr55 — 12:33 AM
5U4 vs 5Z4 tubes
I think that RCA and GE introduced metal tubes in the USA in 1936.  I don't know if they were being made by RCA, GE or b...MrFixr55 — 11:20 PM
Philco 42-345 Restoration/Repair
Vlad95, Thank you for the stringing guides and wow there are so manyosanders0311 — 06:01 PM
5U4 vs 5Z4 tubes
A pre war Hallicrafters, and an early one too, very nice! 1936 is pretty early for metal tubes too, which would explain ...Arran — 05:58 PM
Philco 42-345 Restoration/Repair
Thanks Rod, "When you hear the background hiss and no station it usually indicates that the oscillator quit" ...osanders0311 — 05:52 PM
Philco 42-345 Restoration/Repair
RodB :beerchug:Vlad95 — 10:22 AM
Philco 42-345 Restoration/Repair
Vlad, you nailed it. Swiss and German roots.RodB — 09:54 AM
5U4 vs 5Z4 tubes
Well this is a Hallicrafters SX/9 circa 1936. No real issues so far although I dodged a real bullet with a cap that was...bridkarl — 07:59 AM

[-]
Who's Online
There are currently 1840 online users. [Complete List]
» 1 Member(s) | 1839 Guest(s)
Avatar

>