[Griff]

I am a new poster and have a model 89 code 123 that had electrolytics changed about 15 years ago, bakelite blocks rebuilt, and homemade rubber washers placed between chassis and cabinet. It worked for many years, but now has no audio out of the speaker or white noise. I do hear some noise when I touch a screwdriver to any tube top cap except for the first 41 tube after the antenna. I used my multimeter to check the pinouts under the RF coil. Looking at the coil from the bottom with the screw tab to the left and going from left to right (clockwise) pins 1 to 3 are open and pins 2,4 and 5 have continuity leading me to believe this is the secondary coil. Pins 1 and 4 are open. Is pin 1 and 3 the primary and is the primary inside the tube? If so, will it pop out for repair    

[MrFixr55]

Hi Griff,

First off, if you have a dead 89, I will pray for you, mine needed an exorcism!
Second, is that doggie a Weimaraner?

If the RF coil is open, touching the autodyne 1st detector (36) grid cap should get stations. Touching the 75 2nd detector / 1st AF should cause a hum. What bothers me here is that touching a long wire or your finger to the grid cap on the Osc Mixer (1st Detector) should give you stations, especially if you have strong local stations.

Experts, please jump in here in case I get this wrong. Are you talking about the RF transformer that goes between the 44 RF Amp and the 36 (or 77) 1st Detector (Osc / Mixer?) or are you talking about the "oscillator transformer" (The multi winding coil between the 1st Detector and the IF? If the unit has 2 concentric coil forms, then this is the "Oscillator transformer and 1 and 3 are the "tickler" coil, wound over the secondary on the outer form. If this is the RF transformer, then 1 and 3 may be the Primary, also wound over the secondary. Trace the wires. These outer windings are absolutely notorious for opening due to reaction between the coil and the cellulose insulator that it is wound over. There are discussions in the Philco Library about winding these coils. If the 1st Detector Oscillator coil is good, Ron Ramirez and others have written great articles regarding other causes and mods, including changing the cathode resistor to a lower value and the effect of moisture on the tuning cap, padder cap and the coil.

[Steve Davis]

If it is indeed the inner coil of the antenna transformer that is open, what I have done in the past, is use a sewing machine bobbin for a coil form. Your wife may even let you use her sewing machine to wind the coil, if not just use a drill. As you wind, scramble winding as best you can, wind until it looks to be about the same number of turns as the original, the exact number is non real critical.

Steve

[Griff]

Mr. Fixr, Yes, he, Sam, is a weimeraner. My wife named him Sam, and after a few days I wanted to change his name to "Bad" as in "Bad Dog" haha. Really he has been great and is now 10 years old, has quail hunted in the past and is finally calming down. I am somewhat red- faced that part 2 on my parts list, Antenna Transformer 32-1062 may be fine even though I went to the trouble of removing it. I have reinstalled it accordingly after verifying pinouts. I then got my Eico signal generator and hooked the antenna directly to the antenna terminal on the Philco. I get a hum out of the speaker, but not when I just place the sig gens antenna wire close to the terminal. Direct contact is required. I also get a hum when I touch 2nd Det. 1st audio tube 75 and 44 1st IF. Tube 77 Osc 1st Det gives virtually no hum, but the RF 44 tube gives some noise. This set has no 36 tube by the way. I think that means it is a few iterations from the first model. It also has the police band too. Seems to me my issue may be somewhere from the antenna to the 44 IF tube. Again, sorry for the confusion on the antenna transformer.

[MrFixr55]

Hi Griff. Interesting that you get nothing when touching the 77 (a pentode). Yes, this is a bit newer than the original which used a 36 (a tetrode). A 6A7 Pentagrid converter is the best iteration but did not come on these radios.

The fact that you do not get any sound when touching the 77 grid cap makes me think that the "oscillator" coil on the converter transformer is open. This coil has 3 windings. 2 are on the outer core and one is on the inner core. The small outer winding is the oscillator coil and is between the cathode of the 77 and a resistor with parallel cap, the other end being ground. Ohm between the cathode and the connection between the coil, cap and resistor (this will ensure the correct points). There should be a very low resistance, between 1.5 and 5 Ohm. Alternately, with the set out of the chassis but the speaker connected, measure between ground and the 77 cathode. This should be a low voltage. if it is a high voltage, the coil or the resistor is open (more likely the coil) and you will find instructions on rewinding the coil.

Search the Philco Library for "89 coil" and search the Phorum for 89 Oscillator coil or 89 Tickler coil. Ron Ramirez and RadioRoslyn are experts on this issue.

The Autodyne 1st Detector is very cantankerous, particularly in the 89. However, the ones with the 77 are less trouble than the 36. However, follow the advice to bake the coil (and check the insulating enamel on the secondary) before rewinding, and then seal the entire assembly with clear lacquer.

[Griff]

I got my Father in Laws Model 89 code 123 going. Someone on the board suggested the oscillator coil, and that was the fault with an open in the wire. It's operating just fine now after repair. I lost 2 turns of wire in the process which is not critical. THANKS!

[Griff]

Thanks! It was the oscillator coil. I lost 2 turns in the repair, but that is not critical from what I understand. I really appreciate the from all especially Mr. Fixr!

[admin]

Only one thread permitted on the same subject please. Read the Rules.

https://philcoradio.com/phorum/showthread.php?tid=4586

[Radioroslyn]

Griff
You may want to check and see if your set receives stations all the way to the end of the dial 550 to 1500kc. If there is not enough turns on the osc coil feedback winding the osc will conkout before you get to the ends of the dial.

GL