[Jim Dutridge]

A customer brought in a 37-630 for repair and looking at the Riders Vol. 7 they show a total of 10 compensators but there are only 6 physically in the chassis. Am I missing the other 4 or was there a change I'm not aware of? I believe this is the person who posted in the wanted section for a repair shop within 2 hours of Toledo.

[Mondial]

Yes, there should be a total of 10 trimmers underneath the RF subchassis. 4 are in the Osc section closest to the front panel, then 3 in the center RF section and another 3 in the Ant section towards the back.

Which ones are you missing?

[Jim Dutridge]

Missing are the RF compensators for 1500KC and 6.0MC, ANT. compensators for 1500KC and 6.0MC, as well as the entire speaker assembly and shadowmeter assembly.

[Ron Ramirez]

There was a production change in both 37-620 and 37-630 which eliminated some trimmers. Philco issued a Service Bulletin which covered both models.

Perhaps you can get this from Chuck?

[Jim Dutridge]

Thanks Ron, I'll check with Chuck. Another thing, I see that there were 2 different speakers used in this model depending on the cabinet style. Is there any way to determine what the cabinet style is by looking at it? The 2 styles are X and T and the speakers are 36-1262 and 36-1224 respectively.

[Ron Ramirez]

Yes, 37-630X is a console and would use a 10-1/2 inch speaker; the 37-630T is a table model, using an 8 inch speaker.

http://www.philcoradio.com/tech/letters.htm

[Jim Dutridge]

Thanks Ron. I believe this is a console, however, I think finding a speaker for it will be like trying to find a needle in a haystack. Any idea on what the resistance of the field coil would be? Not shown in the riders.

[Ron Ramirez]

The original speaker is H-24, part no. 36-1224. 1140 ohm field coil.

This information and more is available in a free download from the Phorum - look for "Philco Speakers" at:
http://www.philcoradio.com/phorum/showth...hp?tid=215

Actually, you probably won't have a lot of trouble finding a speaker. The majority of 1933-38 Philco sets using 10-1/2 inch H series speakers have 1140 ohm fields. You may have to change the audio output transformer as the one you find may have a push-pull output and you need a single ended output for the 37-630 with a primary impredance of 7100 ohms to match a 1.25 ohm voice coil.

[Jim Dutridge]

Thanks for the information Ron. One more thing if I may, what wattage resistor could be subbed for the field coil if I'm unable to locate a replacement?

[Mondial]

The wattage rating of a substitute resistor may be calculated from either the current drain or the voltage drop across the original field coil.

The service data says that the current rating of the power transformer is about 70 mA, or .07A.

Power = I x I x R or .07 x.07 x 1140 = 5.6 W


Or another way is to take the voltage drop across the original field of about 75 volts and calculate power from it. P = V x V / R or 75 x 75 / 1140 = 5 W

Although the actual dissipation is only about 5 Watts, you want a safety margin, so a 10 to 20 Watt resistor would be recommended.

[Jim Dutridge]

Thanks for the reply Mondial. If I go that route it'll be a challange to find a suitable place to mount that resistor plus I'll probably need to bump up the second filter cap value. I did see the speaker and output transformer on PTOTP's website but I can't contact him until after Friday. Hopefully he still has them.

[Jim Dutridge]

Well I got a speaker from PTOTP but unfortunately its the 10 1/2 inch one for the console. What I need is the 8" for the table top. Anybody got 1 they want to trade?

[Jim Dutridge]

I removed the RF deck on this and it just doesn't look right. Alot of it does not match what the Riders shows. Example, 4 compensators are missing and there is an electrolytic that was installed that doesn't show up anywhere in the schematic or parts list, a 10MFD @ 600V. It was mounted in the empty metal shield on the right of the middle section. Its positive was connected to the police rf transformer #10. WTH do I have here?

[Image: http://i248.photobucket.com/albums/gg187...d03878.jpg]

I should mention that the 16MFD cap #18 is still connected but to a totally different place than what the 10MFD was connected to.

[Ron Ramirez]

I answered this question in post #4 above:

There was a production change in both 37-620 and 37-630 which eliminated some trimmers. Philco issued a Service Bulletin which covered both models.

Perhaps you can get this from Chuck?

You have a 37-630 Code 126. The schematic and parts layout for this version does not match the schematic/parts layout in Rider's. See if Chuck has it.

[Jim Dutridge]

Thanks Ron. I will contact Chuck.