Grant PC 999-AC No receive

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astrolab
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Grant PC 999-AC No receive

Post by astrolab »

Hi,
My Grant PC 999-AC have no RX in all modes , ( no green led) .
TX is OK, BF is OK , P.A is good also , if you know this problem, thank you.
73/51
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Admiral
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Re: Grant PC 999-AC No receive

Post by Admiral »

Are the connections in your mic okay?
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Mudslinger
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Re: Grant PC 999-AC No receive

Post by Mudslinger »

Does it receive with the microphone disconnected?

It should do, and if it doesn't there is likely a component gone down somewhere.
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astrolab
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Re: Grant PC 999-AC No receive

Post by astrolab »

Thank you
Microphone is Okay, all capacitors 10 volts are changed , and green led also, by security.
Yes a componant is surely down somewhere :)
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Re: Grant PC 999-AC No receive

Post by zephyr »

Have you changed TR35 the 2SB525C transistor, it's the RX switching transistor.
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Re: Grant PC 999-AC No receive

Post by astrolab »

Good Morning Zephyr,
No, i have changed IC 4 (5218)
Now, TR 35 , 2SB 525 C RX working on AM-FM, but no in SSB :(, led green working fine also :)

Many thanks for your aid.
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Re: Grant PC 999-AC No receive

Post by Mudslinger »

I am pretty sure on of my Grants suffered a similar issue.

I think one of the Diodes in the switching circuit had failed (D12 rings a bell?)
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astrolab
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Re: Grant PC 999-AC No receive

Post by astrolab »

Thanks, anyone know the référence of this diodes (eg D 24) ?
73 Michel
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Re: Grant PC 999-AC No receive

Post by Mudslinger »

Not sure what the number is, but the one that failed in mine looked like this.

http://www.ebay.co.uk/itm/1N34-GERMANIU ... 19ea2c3ea8

Nick Black Spirit might be able to help you furrther as it was he who repaired my radio.
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Re: Grant PC 999-AC No receive

Post by zephyr »

D24 is IS2075K or an IN4148.
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astrolab
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Re: Grant PC 999-AC No receive

Post by astrolab »

Hi,
Now i have no RX on SSB only, green led light OK, but no receive in SSB (LSB/USB) ,TX is ok .
In SSB RX , TR50 is very hot
I think that is switching RX-SSB , but what is components of this circuit ?
Have a nice day :)
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Re: Grant PC 999-AC No receive

Post by cjay »

astrolab wrote:Hi,
Now i have no RX on SSB only, green led light OK, but no receive in SSB (LSB/USB) ,TX is ok .
In SSB RX , TR50 is very hot
I think that is switching RX-SSB , but what is components of this circuit ?
Have a nice day :)
You need to be checking voltages, TR50 is part of the voltage regulator and AM modulation circuit, if it's getting hot then it's dissipating too much power. Check TR47, the 2SB754 and TR47, the 2SA473, they may be leaky or short circuit which would cause TR50 to overheat.
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astrolab
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Re: Grant PC 999-AC No receive

Post by astrolab »

All goods , no short circuit .
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Re: Grant PC 999-AC No receive

Post by zephyr »

TR50 does get very hot it's got a 1w 47ohm resistor going to 0v GND and that also gets hot.
cjay, I think you mean TR47 and 48.
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astrolab
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Re: Grant PC 999-AC No receive

Post by astrolab »

TR 47 TR48 and TR 50 all right. :evil:
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