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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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19th Jan 2011, 1:27 pm | #41 | |
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Re: Philips B3X85U troubleshooting
Quote:
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19th Jan 2011, 5:25 pm | #42 |
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Re: Philips B3X85U troubleshooting
Alrighty, I just check all the resistor and found 4 of them that don't give me a reading whatsoever they are:
R12 - 4.7 m ohm R15 - 220 K ohm R50 - 4.7 m ohm R56 - 56 ohm Should I change them all? |
19th Jan 2011, 5:46 pm | #43 |
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Re: Philips B3X85U troubleshooting
If by *"no reading" you mean open circuit or infinite resistance, then yes change all four.
* This is what you would see if you had your meter on ohms range with no test leads connected.
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19th Jan 2011, 11:43 pm | #44 |
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Re: Philips B3X85U troubleshooting
I just purchased the resistors and will change them now.
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20th Jan 2011, 4:19 pm | #45 |
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Re: Philips B3X85U troubleshooting
Two of the resistors which I probed on the radio did not give me a reading so I supposed they were bad. They both are 4.7 m ohm. Now that I purchased these two new ones I probed them with my meter and they also don't give me a reading. I don't know if it is because my multimeter (digital) reaches to 2000 k ohms. So I'm thinking maybe I don't need to change them.
On the pic, there is a resistor red, grey, black, silver. If I learned right, it's 28 ohms + -10% Well it is measuring 17.7 k ohms but it does not show up on my schematics. It also has continuity. Last edited by Abraham; 20th Jan 2011 at 4:21 pm. Reason: another notice! |
20th Jan 2011, 4:31 pm | #46 |
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Re: Philips B3X85U troubleshooting
Put both the 4.7M resistors in parallel with one of the ones in the set. If the resistor in the set is OK you should read 4.7M/3 or 1.56M approx.
You'll have to trace the wiring from the 28 ohm resistor to see where it goes to. It's possible it is a replacement with the incorrect value.
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20th Jan 2011, 4:54 pm | #47 |
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Re: Philips B3X85U troubleshooting
Whatever it is/should be, it appears to go to deck. (Ground / The Chassis). The part of the manual that is up here does not show a resistor of that value. Does any other part of the diagram show anything like this?
The point it goes to ground is around the wavechange switch. Look around the IF or Frequency Changer valves. (UF89 and UCH81) Cheers, Steve P.
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20th Jan 2011, 5:18 pm | #48 |
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Re: Philips B3X85U troubleshooting
Here's the manual which has an under chassis layout. I can't see that resistor though.
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21st Jan 2011, 7:19 pm | #49 |
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Re: Philips B3X85U troubleshooting
I changed the resistors and also changed the capacitor but nothing yet, no sound, no static, or hum, nothing whatsoever.
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21st Jan 2011, 7:48 pm | #50 |
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Re: Philips B3X85U troubleshooting
Check wiring and also...
Meter negative to Chassis. Meter to 1000v. Switch on set and wait a minute for the valves to warm up. Go to the smoothing can (big can on the chassis). Both caps go to deck - using the red probe of the meter check for volts (HT) on both capacitors. The resistor to Pin 1 of the UBC81 - Check here and work back to the HT line if there is still zero volts here. Cheers, Steve P.
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21st Jan 2011, 7:50 pm | #51 |
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Re: Philips B3X85U troubleshooting
Try touching the blade a screwdriver on the centre tag of the volume control and see if you hear anything from the speaker.
If nothing, take voltage readings on the EL84 and UBC81 and post the results here. I'm still not sure as to whether or not you have a positive voltage on the grid of the EL84.
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21st Jan 2011, 9:01 pm | #52 |
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Re: Philips B3X85U troubleshooting
That odd resistor I reckon is 18K (brown grey orange) with the colours gone off a bit. Or possibly 18 ohms and really cooked. At any rate, 18 as the significant digits is more likely than 28!
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21st Jan 2011, 9:12 pm | #53 |
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Re: Philips B3X85U troubleshooting
The more I look at the under chassis drawing and the picture in post #45, the more I think that resistor shouldn't be there. It's obviously not original and the unsleeved lead apppears to be twisted back on itself.
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23rd Jan 2011, 5:57 am | #54 |
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Re: Philips B3X85U troubleshooting
Here are the results:
UBC81 Pin 1 - 86v (Anode) 2 - 0v (g1) 3 - 0v (Cathode) 4 - 0v (Heater) 5 - 0v (Heater) 6 - 0v 7 - 0v 8 - 0v 9 - 0v UL84 Pin 1 - 0v 2 - 0v (g1) 3 - 5v (Cathode) 4 - 0v (Heater) 5 - 0v (Heater) 6 - 0v 7 - 113v (Anode) 8 - 113v (Internal Connection) 9 - 102v (g2) Last edited by Station X; 23rd Jan 2011 at 10:55 am. Reason: Electrodes designated. |
23rd Jan 2011, 11:05 am | #55 |
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Re: Philips B3X85U troubleshooting
Some progress. You now have HT on the UBC81.
The voltages on the UL84 are low though. Check that the mains voltage selector is in the correct position to suit your mains voltage. Then check the +, ++ and +++ voltages as shown on the attached extract from the circuit diagram.
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23rd Jan 2011, 11:13 am | #56 |
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Re: Philips B3X85U troubleshooting
A further obsevation. The anode voltage on the UBC81 is high, possibly indicating that it isn't drawing enough current. Check that R15 is the correct value 220K (Red, Red, Yellow). Put one meter lead on each side of R15. What voltage do you see?
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23rd Jan 2011, 12:26 pm | #57 |
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Re: Philips B3X85U troubleshooting
Well as far as I can see if the voltage readings in post 54 are correct, apart from other things being at 0V the heaters are at 0V so it is little wonder nothing is working. Could it be that the meter is not being set to the correct range!
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23rd Jan 2011, 12:32 pm | #58 |
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Re: Philips B3X85U troubleshooting
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23rd Jan 2011, 1:25 pm | #59 |
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Re: Philips B3X85U troubleshooting
Oh dear!. I failed to spot the bling obvious.
However in an earlier post heater voltage was present on the UL34 when checked on an AC range. Also the heaters are in series and as the rectifier is obviously working (HT voltage is present) I think the heaters are in fact lit. I agree that the other voltages are present, but they're low compared to those on the service sheet. That's why I suggested measuring the three HT voltages. Abraham. Are all the valves lit up?
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23rd Jan 2011, 3:18 pm | #60 |
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Re: Philips B3X85U troubleshooting
What is the mains voltage where you are? If it's 110v then the voltages are probably right. If it's 230v then they are probably not.
How is the secondary on the output transformer. You tell us the speaker is OK but have you checked the secondary of the transformer. Disconnect the speaker and put your meter, on the lowest ohms range, across the speaker pins of the output transformer. Here's hoping you get a reading! Cheers, Steve P.
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