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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Wed 25, 2020 12:19 am 
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Location: Lehighton, PA.
stratozen wrote:
After making the changes with the wrong grounds I connected meter to the plus side of C19a
and the negative side of all caps and shows no voltage.

I'm confused, why do that?

Make sure R25 and CR1 aren't connected to the same side of the On/Off power switch.

Larry

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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Wed 25, 2020 1:38 pm 
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As it stands right now the neg side of cr1 is connected to one side of the on/off switch
R25 is connected to the neg side of C20


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Wed 25, 2020 2:14 pm 
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Which side of the switch is R25 (the end not connected to C20) connected to? Make sure it isn't the same side as CR1. That's the same question I asked above.

Larry

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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Wed 25, 2020 4:01 pm 
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The opposite side of R25 is connected to one side of the ac line which is also connected to the phono ac socket


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Wed 25, 2020 4:27 pm 
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Location: Boston, MA USA
The schematic is absolutely correct. Note carefully the distinction between chassis ground and B-, and inspect your wiring carefully to make sure it conforms exactly. And make sure when you take voltage measurements you connect the (-) lead of your meter to B-, not chassis ground.

When you had the capacitors connected incorrectly it's possible that C20 was destroyed. If it is open there will be no B+. Maybe try replacing it?

-David


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Thu 26, 2020 4:51 pm 
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C20 checks ok
when the grounds were repaired the only component
that checked bad was R25 which was replaced
Wiring has been checked over and over, still can't figure


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Thu 26, 2020 6:50 pm 
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If R25 burned up then anything it’s current passed through is likely to be damaged. This includes C20 and CR1. Use your meter to check the voltage at every part of the circuit to find out where it goes away.

-David


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Thu 26, 2020 7:58 pm 
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Joined: Apr Wed 03, 2013 2:38 pm
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Thanks for all who have helped on this, I won't give up until it works
one quick question came to mind, do all of the plugs gave to be connected
for this to work ie phono audio socket, phono ac socket and speaker socket ???


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Thu 26, 2020 8:03 pm 
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No, on this set the phono motor is in parallel with the amplifier so it doesn't matter if it is connected or not. It's good practice to never run a tube-type amplifier without a speaker or equivalent load resistor connected, but that matters only if the amplifier is working.

-David


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Thu 26, 2020 8:16 pm 
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ok, I had a sp hooked anyway
but ,one more dumb question, the B- could be any one of the caps neg side ???


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Thu 26, 2020 9:09 pm 
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B- includes the cold side of the power switch, the non-banded lead of CR1, pin 5 of the 12AT7, the negative leads of all sections of C19, C190, the green lead of the output transformer, and many other components.

B- does not include either lead of C20.

One thing to bear in mind that trips up a lot of people: Schematics indicating selenium rectifiers used reverse notation of the (+) and (-) leads from those using silicon rectifiers. The graphic is the same, i.e. the arrow lead is the anode and the bar is the cathode. But the convention with silicon rectifiers is to mark the anode (+) while with selenium that would be (-). As long as you follow the graphic when replacing a selenium rectifier with silicon, i.e. the bar (cathode) is the banded lead, you'll be fine.

-David


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Fri 27, 2020 1:32 am 
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Good News David; Through my mistakes and your patience I'm now showing voltage,
All voltage points shown on the schematic at C19a--C19d read 227vdc so 3 of them are off target
R24 resistor reads 5.2K
R23 resistor reads 11.83K


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Fri 27, 2020 4:10 pm 
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Location: Boston, MA USA
Great work! What did you find the problem to be?

The three voltages being the same indicates that the tubes are not drawing current. Are the tubes lit? Check the DC voltage at pin 3 (plate) of the two 50L6 tubes. Check pin 4 (screen grid) of both tubes. Check pin 8 (cathodes of both tubes, tied together). Please report the results.

-David


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Fri 27, 2020 10:42 pm 
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All tubes are operating
pin 3 of both 50l6's is 43v and 45v

pin 4 of both 50l6's both tied together is 32v

pin 8 of 50l6's also tied together checks -0.3v


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Sat 28, 2020 2:53 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Whoa, something's not adding up. You previously reported that the top side of C19a and C19b were both reading 227V. The top side of C19a (40 uF) is connected directly to the output transformer primary center tap (red wire) so the voltage at pin 3 of each 50L6 should be only a few volts lower, 215V per the schematic. 43V and 45V are way wrong.

Likewise, the top side of C19b (20 uF) is connected directly to pin 4 of each 50L6. If the top side of C19b is 227V, so should pin 4 of each 50L6. 32V is way wrong.

First check the wiring carefully to make sure the voltage distribution from the capacitors in the power supply (C19 a & b) to the output transformer and tube pins is correct per the schematic.

Then try this: remove all three tubes, turn on the amplifier, and check that the voltage at C19a is nearly the same as at pin 3 of both 50L6s, and the voltage at C19b is EXACTLY the same as pin 4 of both 50L6s.

-David


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Sat 28, 2020 4:51 pm 
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Joined: Apr Wed 03, 2013 2:38 pm
Posts: 98
Let me back up a bit, when I took those voltages I used the original tie point that included the green wire from the
output trans as the meter neg. Today I used the unbanded end of cr1
and got 227v at all points you listed
I usually take pictures before doing something like this and this time didn't
there was a tie point on C19a - C19d capacitor that included wires that included the green wire from output
theres 5 wires now connected together including, green output, all neg cap wires C19a thru C19d , R23, R2, and R11
I thought I might have made a mistake on the tie point but I don't see it


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Sat 28, 2020 8:08 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4391
Location: Boston, MA USA
There need to be many more connections than that. The unbanded end of CR1 needs to be connected, also R1, R4, C4, C5, the low side of the volume control, R6, C10, R12, C12, C14, R15, the cold side of the power switch, and pin 5 of the 12AT7. All in addition to the green lead of the OT, C19 neg all sections, R23, R2, and R11 that you mentioned. Check that they are all connected.

Then please check that the high (+) side of C19a is connected to the red wire of the OT, and the high side of C19b to pin 4 of the two 50L6s.

If at any time during your troubleshooting you happened to run the 50L6s with voltage on pin 4 but not on pin 3, they are likely to have been destroyed. That's why I asked you to check the voltage on pins 3 and 4 with the tubes removed.

-David


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Sat 28, 2020 8:16 pm 
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Joined: Apr Wed 03, 2013 2:38 pm
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There are more connections, I just named the ones that were connected to the multi cap when I replaced it. I will also check the ones you mentioned which I'm sure they are in place as the solder joints look to be original. will go on with the rest.
thanks again for your ongoing help


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 Post subject: Re: Philco D-1347 Selenium Replacement Problem
PostPosted: Mar Sat 28, 2020 8:19 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4391
Location: Boston, MA USA
You didn't mention the unbanded lead of CR1 or the power switch. Make sure those are connected.

-David


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 Post subject: Re: Philco D-1347 Selen I picked up this ium Replacement Pro
PostPosted: Mar Sat 28, 2020 9:03 pm 
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Joined: Mar Sat 28, 2020 8:59 pm
Posts: 2
I picked up this radio off of our local Buy Nothing group and began the process of restoring it. However, I can’t find any pictures of this exact model online - do you happen to know which one it is?

I’m not a restoration pro so if this radio is super interesting to collectors I plan to sell it and buy a less cool one to play with.


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