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

philco model 77
#1

hi fellers,i'm having a brain fade tonight,where do i measure b+ in this chassis? and can the last interstage trans be r/c bypassed? pri and sec. are both open,thanks.
#2

philco phan, I believe between the center tap HV secondary and point J on the schematic will give you full B+ available. Center tap to plates for B+ at tubes. B supply not grounded to chassis in this set. PL
#3

The main B+ would be measured between point D and one of the following points: the center tap of the high voltage winding of the power transformer; pin 2 of resistor (26); or pin 2 of the multi-section filter condenser can. Point J carries a lower B+ voltage that has been dropped by the speaker field coil.

If both primary and secondary of interstage transformer (22) are open, then no, one cannot generally convert it to R/C coupling since the secondary is feeding two tubes connected in push-pull. You'll have to replace this transformer with another one.

--
Ron Ramirez
Ferdinand IN
#4

thanks guys,b+ is good,i'll just r/c bypass to one of the 45's to confirm radio is operational until i can find a suitable tranny,phil




Users browsing this thread: 3 Guest(s)
[-]
Recent Posts
1930s Stewart-Warner Tombstone Radio need help identifying model number
UPDATE: I was able to pick up a signal generator on the cheap (amazingly enough) on feebay and I did an IF alignment fol...captainclock1988 — 09:53 AM
Philco 91 Schematic
Hi Rod, The resistor connects to pin 4 and the ungrounded side of block 9. From pin 9 of the RF tube to one side of ...dconant — 09:34 AM
Just got a 49-1613 need to know...everything!
I just found your post. I have this exact same model, and have had it since 1985 when I was 15 years old! I performed a ...MuzzcoVW — 09:11 AM
B&K 1077B no video
Hello Tim, I would if it's a leaky Capacitor So are all 3 of those B- voltages low then ? Sincerely Richardradiorich — 01:55 AM
B&K 1077B no video
I found a schematic and think I have the problem traced down to the minus power supply. I have very low voltages that go...TV MAN — 12:41 AM
RCA 15X
I'd try replacing the bulb first and if that doesn't do it, then change the 35Z5 and see if the problem goes away.NostalgiaRadioTime — 12:28 AM
B&K 1077B no video
Hello Tim, I have that exact unit in my shop too plus a Sencore unit there are times I like one or other !!. Sincerely...radiorich — 11:07 PM
RCA 15X
Everthing goes at once, maybe it's the cold weather, I have had 2 dial strings break and no my little RCA is having dial...Paul Philco322 — 10:26 PM
Philco 91 Schematic
Hi Dan, I can't explain this specific resistor but I have seen the use of a switch to apply B+ voltage to screen gri...RodB — 09:36 PM
6TPZ and 5TPO Radio Help
I suspect it's been repaired before. And I suspect whoever repaired it, wanted to re-use old transistors' pin stubs in o...morzh — 09:24 PM

[-]
Who's Online
There are currently 10489 online users. [Complete List]
» 2 Member(s) | 10487 Guest(s)
AvatarAvatar

>