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

37-660 Alignment Issue
#1

Well I've rewound the OT and it works fine. Began the alignment and all was going fine until the last SW tuning range 2 (2.3-7.4 mc). The first part of this stage you peak at 7 mc by adjusting the oscillator (30B)(no problem) and then you are to go to 2.35mc (closing the tuning cap plates) and peak there (30C) where I don't hear the sig gen signal.

If I set the sig gen to 6 mc the radio dial has to be set to about 6.65 mc to hear the tone (this is after peaking at 7 mc). To me it seems like it is short on capacitance. I note that across 30C (the 2.5 mc osc trim) there is what appears to be a large mica. According to the schematic this is 30x and is a 1150 uufd (I didn't change this one). The parts list does not say it is mica whereas it does state other small ones as mica. I am wondering if this cap might not be mica and could be causing my problem? Looking to you experts for help and suggestions.

http://www.nostalgiaair.org/PagesByModel...013220.pdf
#2

Hello, Marv: The best way to align is to connect a volt meter to the voice coil leads of your speaker and use min sig gen amplitude when adjusting your set.

This prevents your AVC circuit from interfering with your alignment.
#3

If I had to guess (and I do) Icon_wtf you are on the wrong peak. ie if the LO is to be at 6.53MHz when you tune 7Mhz, you have it peaked at 7.47 Mhz on the LO

turn the signal generator level down, and try to find a peak at 7MHz with the trimmer turned in tighter.

I would also assume the 1150 pF cap would be paper, you could try putting 2 .0022uF caps in series (1100pF) and see if the situation improves.

John
Las Vegas, NV USA
#4

Still have problem on range 2. Changed 1150pfd cap, no difference. Close inspection of coils noted that one lead of RF range 2 primary broke off wafer switch. (Probably happend when replacing caps deep within). Soldered lead back on to D3, still cannot align this range correctly.

Before I remove the RF section from chassis again to check this coil closer can someone please confirm that when the radio range lever is in range 2 I should read 12 ohms of the primary between D3 and D6 of the wafer. I read open. Getting to these coils is nearly impossible.

marv




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco Model 38-7: what caps & resistors do fail typically?
Since you stated earlier, you have a console 38-7XX.  They also had a 38-7T (table), and 38-7CS (chairside).  A very nic...GarySP — 01:18 PM
Part numbers to model cross
That I wouldn't know, but sometimes the radio document itself shows one, same as the capacitor cans' etc pinouts.morzh — 12:46 PM
Part numbers to model cross
Thank you morzh, that is exactly what I was looking for. Now , is there some where that shows pinouts for Philco power ...Jim Dutridge — 11:37 AM
Restoration of the Canadian General Electric A-87
Thanks for your help Michael. In fact, this video is only an intermediate result. Later I had to apply another tinting l...RadioSvit — 09:01 AM
Restoration of the Canadian General Electric A-87
Great job on the cabinet. PS. In the US notation, "kenotron" refers to specific type of tubes; we call re...morzh — 08:24 AM
Part numbers to model cross
This document has at least some tables of models and parts used. Example: Choke 32-7572, used in 604 radio. Search f...morzh — 08:19 AM
Restoration of the Canadian General Electric A-87
I also checked all the radio tubes on my Hickok 530 tube tester. The 5Z3 kenotron turned out to be faulty, all the other...RadioSvit — 08:02 AM
Restoration of the Canadian General Electric A-87
Well... While the varnish is drying up, I started repairing the chassis... Of course I started by replacing the pa...RadioSvit — 07:12 AM
Philco Model 38-7: what caps & resistors do fail typically?
Hello Martin, Welcome aboard our little community what great Model 38-7 Sincerely Richardradiorich — 12:30 AM
Philco Model 38-7: what caps & resistors do fail typically?
Welcome to the Phorum Martin. I count about 9 paper caps, the 3 electrolytic caps and 2-Y2 safety caps to replace th...RodB — 09:44 PM

[-]
Who's Online
There are currently no members online.

>