[DeckApe]

On that note, I need to replace the dial string on mine. Does anyone have any recommendations as to what size to use? .03 and .04 are readily available, I've seen .026 on Amazon...

[EricS]

After nearly a year, my Philco 40-180 is almost finished. I have replaced all caps, all resistors, and all rubber wire. The rust is gone from the chassis, all of the parts have been cleaned, the transformer has been repainted, I installed a new cloth covered power cord (with a fuse on the hot lead), a reproduction vintage polarized plug, and am just about a day away from a first power up.

So, what is the best way to power up? I have a variac and several volt meters. Can someone walk me through or point me toward a first power up procedure and places to check for voltage references?

Thanks,
Eric

[murf]

I might have a coil for that chassis.
Seemed to me that I have a chassis that I was using for parts.
murf

[murf]

Have a 40-180 that I picked up a while ago.
Have re-capped and got it to play somewhat, but I can't seem to get any volume out of it.
Have checked tubes etc. as well as re-wirinf the wire harness on the loop, but no improvement.
Any idea's?
murf

[morzh]

Murf

The usual.

Checking tubes does not guarantee erformance.
Resistors also affect performance.
And so does alignment.

And as the last resort, check your speaker and related parts.

[EricS]

Well, no luck on first power up. I installed a 1A fast blow fuse and it blew right away when I powered it on. The sticker on the radio says it consumes 60w, so I thought this would be sufficient. Does a typical radio draw more current at power up than steady state?

After the fuse blew, I changed the fuse and put a 100w light bulb in series with the hot leg on the AC cord. When I turn it on this way, the bulb glows brightly and continuously, but the fuse stays intact. If I power it up without the rectifier tube, the bulb stays dark.

How do I differentiate a bad tube from a problem with the power supply transformer? All of this presumes I didn't goof something when recapping and rewiring...

Any good places to start diagnostics?

Thanks,
Eric

[morzh]

Eric

Fuse or not...get thee a variac. I cannot overestimate is usefulness.
No full volage until you are sure of your load.


Now, without going reredaing the whole thing, you have fully recapped it?

1. Remove 84 tube, measure the folament voltage while increasing the input. If using the lightbulb in series withb the input, mesaure the voltage across the input plug and then see if your filament voltage (measure in 84 socket) is (6.3/110)*Vplug. If much less, then start removing tubes. If the condition persists, you have a transformer short or sockets' short.

We'll talk then.

[jerryhawthorne]

Eric, good that your 100w light does not light with the 84 tube. As Mike said, a variac is also very handy but the light will tell you a bit about current draw.
A long post, I would check your two e-caps to make certain the are wired correctly. Item 61 the 12mfd should have it's negative going to the center tap of the high voltage secondary on the power transformer. Item 58, the 16mfd should go to chassis.
Set off, take a resistance measurement from the cathode of the rectifier (+ of the 12mfd) to ground. Negative lead on your meter to ground. Give it a minute to stabilize and report back.
Seems something is putting a load on the power transformer, hence blowing the fuse. The 1 amp fuse should provide enough overhead for the 60 watt radio even on start up which will be a bit higher.
Let us hear back on your resistance measurement and cap checking.

Jerry

[EricS]

Morzh: i have a variac, but am not sure how best to use it in this context. Yes, the entire chassis has been recapped (new resistors, too), with the exception of the bakelite cap block at the AC input. The fuse is after the AC connection to the bakelite block, and since the fuse blows only when the power switch is turned on, I presume the bakelite block is OK. Bear with me a little bit here, I am not sure what you are asking me to do with respect to the rectifier tube. Using this diagram as a reference (http://frank.pocnet.net/sheets/021/8/84.pdf), is the filament voltage the voltage across pins 1 and 5 for the heater? If not, which pins are you referencing?

Using the same pinout image, I get the following voltages on the rectifier socket - tube removed and radio directly plugged into AC outlet:
Pins 1-5: 6.8 vac
Pins 2-4: 258 vac
Pins 3-4: 259 vac
Pins 2-3: 520 vac

Jerry: thank for the confirmation of the e-cap wiring. This was the part I was most unsure of. Polarity is confirmed for both caps. Measuring resistance from rectifier pin 4 (+ of 12 mfd to chassis) reveals 0.6 ohms after a it settles down. Removing the rectifier tube and measuring resistance across all pin combinations reveals resistances of 1 to 10 ohms. How can I tell if I've got a bad tube?

All of these readings are without the speaker and field coil connected. I connected the speaker cord after replacing the fuse and powered it on and the fuse blew again. I think I'll need to buy a few more packages of fuses...

Thanks for your help!
Eric

[OldRestorer]

Mike, All those parts I gave you the last time you were here were 40-180 chassis parts.

Just in case...

Kirk

[morzh]

Eric

good news is, your transformer is fine.
I take it the fuse id not blow with the rest of the tubes in their sockets, with just 84 removed?

Whatever I asked you to do before is no longer needed as you, albeit in a risky manner, tested the transformer and it is fine.

84 needs to be checked for short.
The output of it (across the electrolytics) also needs the short test.

As for the variac, you simply plug your radio in it starting from 0V and see if the voltages behave correctly (like that filament voltage ) as you slowly raise the voltage.



Kirk

good to know, I did not have a chance to look at them yet.

[EricS]

Morzh: i was thinking the transformer is in good shape as well. Yes, the fuse remains intact with the 84 removed and all other tubes in place and the speaker and field coil not connected. What was risky about power up and measurements without the 84 in place?

How do I test the output of the 84, since the fuse blows with this tube installed? Is this where I use the variac? Do I plug the radio into the variac and slowly increase the voltage to see what readings come from the rectifier before the fuse blows?

Eric

[jerryhawthorne]

Eric, your measurement to ground from the positive side of the 12 mfd should be practically infinite with the speaker unplugged and many thousand ohms with the speaker plugged in. You have practically a dead short on the B+ line which you must find. Lucky you have a fuse or the transformer or rectifier would have blown. Do you get the same low resistance from the + of the 12mfd to ground with the rectifier removed?

Jerry

[EricS]

Ugh - sounds like next step of solving the short will be tedious and time consuming... I'll make a copy of my schematic and start crossing things off one by one.

Eric

[morzh]

Eric

no it is not tedious, it is like Jerry said, just take a meter and measure.
You might not necessarily have a short, you might have a shorted 84 tube.