[jjbuzard]

I am a novice, so please bear with me, I just replaced all the tubes in this radio and the main capacitors, ( I was told it worked but the guy that had it pulled out all the tubes out and no one knew why, (tubes were missing, not with radio) he pulled them to check is my opinion as the main caps were bad and all it did was HHHHMMMMM after I put in the new tubes) After replacing these parts it played fine then after about 3 minutes there was a SNAP - and then PSSssHHhhhsssss, smoke rolled out but it kept playing fine, I shut it down pulled the chassis out and looked everything over closley, no burnt looking items, no smoke marks, all resisters look good, all capacitors look good, all new ones installed correctly. So I put it back in and plugged it in and turned it on, played great, played for about 3 hours and all of a sudden silence, I unplugged it and looked and everything seemed fine but I could smell something burnt and a sizzling noise, I pulled the chassis out and and the main transformer was hot, still sizzling and smelled burnt. The transformer is fried, are they difficult to replace (with multiple wires) my plan is to replace all the remaining capacitors, but the snap and pssstt sound and smoke and the fried transformer have me worried. Should I go ahead or should I send it to someone to fix?

Also I noticed the wire on top of the tuner was covered with a crumbling yellow crud and the one end looping through an opening but not touching anything or soldered, whats with this, see picture.

[Ron Ramirez]

Hello and welcome.

Oh boy, did you select a toughie to repair...

First, let's address that wire looped inside one terminal of the tuning capacitor yet not soldered. That wire should be insulated, and the wire should indeed be looped through that hole but not touching that terminal at all. To accomplish this, the insulation should completely cover that end of the wire - no bare wire showing at all on that end.

You can use heat shrink tubing of the appropriate size to insulate the wire if you do not wish to replace the wire.

You say you replaced the "main" capacitors. Did you replace the electrolytic (filter) capacitors? These, if bad, could have caused your set's power transformer to fry. Another cause of a power transformer failure could be the rectifier tube used - an 84/6Z4, I believe (I would have to go check the schematic, and I'm too lazy to do so).

You will have to replace that power transformer. There are so many of these chassis floating around that you won't have any problem coming up with a good used replacement, however.

You will also have to either rewire or resleeve all of the rubber-covered wires inside the chassis. As you have already noticed from the wire on top of your tuning capacitor, this rubber insulation deteriorates with age, crumbles, and falls off. The loss of insulation can cause wires to short together - which can be yet another cause of your power transformer becoming toast.

Good luck. This will not be an easy repair, but will reward you with a pretty decent radio once complete.

[jjbuzard]

I kind of thought that wire should be insulated and just looped through the opening, as it wasn't touching I figured it used to have insulation, BUT wanted to confirm.

I have already replaced all of the rubber coated wire, knew it was bad, FORTUNATELY most of the wire in the chassis is cloth covered, less than 10% is rubber.

The rectifier tube is an 84/6Z4 that Radiodaze told me to use, I relied on them as I didn't have any of the original tubes, this tube is marked Sylvania Made in the USA - no other markings. The other two tube there was a choice on were the 41's they said the Tube Jan CHS 41 - VT-48 was the original style to use in the socket marked 41 on the diagram on the inside of the cabinate. See attached tube diagram picture.

I replaced the electrolytic (filter) capacitors one was a 12 MFD Philco 30-2474-X. single lead, replaced with a C-EA10-160 - 10 MFD@160v Axial-Elec., the other was a double lead - Blue 8 MFD, the other Red 16 MFD Philco 30-2475-X, replaced with 2- C-EA22-450 - 22MFD@450v Axial-Elec Cap.
Is that my error? I should have replaced the double lead (8MFD & 16 MFD) with the 22MFD and 10MFD and the single lead (12MFD) with a 22MFD?
Again these are the ones Radio Daze told me to use, I may have made the mistake of using the 22MFD to replace the 8 MFD, that would be my mistake.

Your thoughts.
Jim B

[Ron Ramirez]

Hi Jim

Answers inline...

I have already replaced all of the rubber coated wire, knew it was bad, FORTUNATELY most of the wire in the chassis is cloth covered, less than 10% is rubber.

Now that is very unusual...and you are VERY lucky! I've never seen one of those chassis that wasn't loaded with rubber-covered wires...unless it was a Canadian model. I have a Canadian version of a 39-25 (39-330AT) that has cloth covered wiring. The USA version is full of rotten rubber. UGH.

The rectifier tube is an 84/6Z4 that Radiodaze told me to use, I relied on them as I didn't have any of the original tubes, this tube is marked Sylvania Made in the USA - no other markings. The other two tube there was a choice on were the 41's they said the Tube Jan CHS 41 - VT-48 was the original style to use in the socket marked 41 on the diagram on the inside of the cabinate. See attached tube diagram picture.

This time I have the schematic in front of me. Yes, the 84/6Z4 is correct for the rectifier tube. The output tubes should both be 41.

I replaced the electrolytic (filter) capacitors one was a 12 MFD Philco 30-2474-X. single lead, replaced with a C-EA10-160 - 10 MFD@160v Axial-Elec., the other was a double lead - Blue 8 MFD, the other Red 16 MFD Philco 30-2475-X, replaced with 2- C-EA22-450 - 22MFD@450v Axial-Elec Cap.
Is that my error? I should have replaced the double lead (8MFD & 16 MFD) with the 22MFD and 10MFD and the single lead (12MFD) with a 22MFD?
Again these are the ones Radio Daze told me to use, I may have made the mistake of using the 22MFD to replace the 8 MFD, that would be my mistake.

Okay, now we're getting somewhere. You say you replaced the input filter capacitor (62), Philco part number 30-2474, with a 10 uF, 160 volt unit. Big mistake! 160 volts is much too low a voltage rating for this capacitor! According to the schematic, 265 volts is being applied across this capacitor when in operation. And, keep in mind that those voltages were measured with 1941 or older vintage test equipment which is not as accurate as today's high impedance multimeters; so that 265 volts is probably more like 280 or 290, given today's more sensitive meters and higher line voltages.

I would bet that this capacitor shorted since it was only rated at 160 volts, and the short took out the power transformer since this is the input filter.

Replace it with a new electrolytic rated at 10 uF, 450 volts.

It will not matter if you replaced electrolytic (27) with 22 uF, although 10 uF would have been a better choice. Replacing the 16 uF (27A) with a 22 uF was the right thing to do. You say the new ones were rated at 450 volts, so all should be OK there.

You will have to replace the power transformer.

Before applying power again, test that 84/6Z4 to make sure it was not harned by the failure of that new 10 uF, 160 volt cap.

Also, be absolutely sure those electrolytics are connected properly! Positive leads to B+, negative leads to B-. In the case of cap (62), the negative lead goes to the left end of the 146 ohm section of resistor (61) as shown on the schematic. This is the multi-section Candohm (resistor with metal folded over it, mounted to the chassis). The positive lead goes to the left end of the field coil (as looking at the schematic) and the cathode of the 84/6Z4 rectifier. This is important! Hook up that electrolytic backwards, and it will go BOOM, and might take out your replacement power transformer. Double-check your work to be sure before applying power.

[Ron Ramirez]

Just another thought. Your 41-296 does not have a 41-295 chassis. The 41-295 chassis is much larger and uses thumbwheel controls instead of knobs.

The 41-296 chassis is the same as the 41-285 and 41-287 chassis.

Be sure you have the correct schematic and service info before proceeding.

[jjbuzard]

How do I test that 84/6Z4 ?

Also, be absolutely sure those electrolytics are connected properly! I was informed the end of the Capacitors with black rubber covers and the groove were the positive ends and the Negative end is marked with an arrow, so those ends were hooked to the 2 red wires and the blue wire, with the negative ends connected to the respective black wires, is that correct? Is wire length important, can it vary a little when replacing, and wire size 16G OK or best to use 18 & 20?

Your 41-296 does not have a 41-295 chassis The Philco site says "This is an interesting set. It uses a 41-285 chassis mounted in a modified 41-295 cabinate." That is where I was confused in my last post, when I ordered I used the 41-285 as reference, not the cabinate reference. Sorry

[Ron Ramirez]

Well, I guess you do not have a tube tester. It would be good for you to find someone that does. Since the radio experienced such a catastrophic failure (i.e. the power transformer burning up), I would not trust that rectifier until it were tested. Chances are it may be OK but it is better to be safe than sorry.

Where do you live? Is there an antique radio club near you? Look here for a listing of clubs:
http://antiqueradios.com/resources/Radio_Clubs/

You might enlist the help of someone in your area to get this set straightened out.

It sounds like you did connect the electrolytics correctly. It's just that 10 uF, 160 VDC cap where a 10uF, 450 VDC cap should have been that probably caused your problem.

Yes, the 41-296 is essentially a 41-295 cabinet; only the front panel hole was cut smaller for the 41-285 chassis, and holes drilled for the control shafts. Then the Tenite escutcheon was added.

Oh, you asked about wire sizes. 20 gauge is plenty sufficient in that 41-285 chassis. Try to keep wire lengths the same as the original. It isn't important in power supply circuits, but in RF and IF circuitry wire length and placement is critical.

[jjbuzard]

Looks like the closest club is 80 miles away, maybe I should just buty another 84/6Z4 to be safe, will replace the suspect capacitor/filter.

Is it difficult to replace the transformer with multiple wires, are they color coded well? If I am reading the schematic correctly, there are 2 white wires from the input/switch, then there is 1 black to the Rect 84 and 1 black to the 84 & filiments, then a green to the 84. a green and a green yellow going to an item marked 61. Willhave to study this closely and try to determine the original coil wire colors, they are faded.

Thanks for your help, I'm sure I will be asking more questions.

[Ron Ramirez]

I think you should contact that club anyway - maybe they have a member, or members, near you?

Any used power transformer from this type Philco will have faded wires, so you will have to be careful in replacing it. Do you have a multimeter? Taking resistance measurements of the various windings will help. (Resistance readings for each winding of the power transformer are written on the schematic.)

[jjbuzard]

Yes I have a Multi Meter and I will look at the schematics, I guess I should buy a good schematic for this radio, the downloaded ones are pretty fuzzy and hard to read.

Radio Daze suggested a Hammond transformer replacement, so that is probabily what I will go with,I will also try that club in Roscoe, Il, my In-Laws lived there til recently.

There used to be several guys here locally that did such work and had parts, but they have all died, and a guy that did all my repairs for many years sold all his tubes, etc and equipment 5 years ago when he retired.

[jjbuzard]

How do you test a capacitor and or a resistor, I seem to remember you can test the resistors in place with a volt/ohm meter, correct? Can the caps be tested with the same equipment in place or do they need to be pulled?

[Ron Ramirez]

For the most part, resistors may be tested in circuit. There are some instances where one end needs to be disconnected, but not always. If not sure, disconnect one end.

Capacitors, assuming your multimeter has a capacitance measurement feature, should be tested out of circuit.

I can tell you now that all of the paper capacitors in that set need to be replaced. They do not survive well over the decades and if not bad now, will go bad shortly after the set is put back into use.

Rule of thumb: Replace ALL paper and electrolytic capacitors. Replace resistors if not within 20% of rated values.

If you are in northern Illinois, you're in luck. The Antique Radio Club of Illinois is a large, well established group and they host one of the oldest, most respected, and best attended swap meets in the country each August - Radiofest. They also hold other meets throughout the year.

http://www.antique-radios.org/

[jjbuzard]

Thanks again, I have already purchsed all the capacitors to replace all of them, plus I am now in process of replaceing the rubber wiring.
Please explain the dfference between paper and electrolytic capacitors. I think paper are all tube shaped, wax coated.

Thanks for the info on the Illinois Radio Club, will call them now.

Maybe my luck is turning, I just spoke to a friend of my Brother-In-Law who just inherited a redio repair shop,it is about 50 miles from here, he said it is full of Philco stuff and Manuals, plus acouple of tube testors, etc, I am going to look at it tomorrow to see what he does have. He doesn't know anything about Radios, etc. So he said come look and see if there is anything I can use.

[jjbuzard]

I guess I am not really of the right temperment to attempt this repair. So I need to consider my options on this project.

It looks like I will have over $400.00 in this radio when I am done..........
I already spent about $91.00 on all new tubes (because they were all missing), new face plate and push buttons came to about another $50.00, new caps and dial cord cost another $17.00, for a total of $158.00, plus $250.00 if I decide to have someone else repair this for me, plus shipping up to $50.00 comes to $458.00. It probabily is not woth that much, so I would probabily be better off to sell the cabinate to somebody and sell the new parts on ebay and forget it.

I tried contacting a local club (80 miles away) but the contact person given didn't respond,

I could probabily buy a nice working radio for 1/2 that cost.

Any thoughts on this?

[jjbuzard]

I am in such a quandry at this point, I have alot of money in this set to just quit, yet money is real tight right now, what to do.

Is it possible to check resistance on the Transformer in circuit? If so the readings on the main transformer are pretty close to the schematic, (schematic #'s in parenthesis) between the green and green on one side is 160 (160) the other is 110 (150).

Between the blacks is 4 (less 1) between the whites in 18 (12)

The field transformer, located next to the main transformer bottom? 300 (1100) this is the biggest difference. Does this tell me any thing? I would assume from this the field transformer is bad also :