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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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6th Apr 2021, 7:05 pm | #1 |
Heptode
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Philips P3G38T Stone Dead
Received this today complete with broken dial glass :' (Put a battery in it and got a loud crackle when I adjusted the volume control, but nothing else. So whipped the covers off it and tapped the dreaded AF117's transistors with a screwdriver and it burst into life. MW was working well but nothing on LW. It played for a short while but now it's stone dead, not a crackle. Nothing,
Voltage is reaching the on/off switch. Shorted transistor or capacitor? Cheers, Jay.
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6th Apr 2021, 7:55 pm | #2 |
Banned
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Re: Philips 3G38T Stone Dead
Is that the right model number??
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6th Apr 2021, 7:59 pm | #3 |
Heptode
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Re: Philips 3G38T Stone Dead
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6th Apr 2021, 8:00 pm | #4 |
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Re: Philips 3G38T Stone Dead
Your description of the symptoms suggests the AF117s are knackered. All the usual advice applies. There may also be a problem with the MW/LW wavechange contacts, which usually need a good clean.
Has the volume control crackling stopped as well as everything else? |
6th Apr 2021, 8:09 pm | #5 | |
Heptode
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Re: Philips 3G38T Stone Dead
Quote:
Cheers.
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6th Apr 2021, 8:13 pm | #6 | |
Heptode
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Re: Philips 3G38T Stone Dead
Quote:
Cheers
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6th Apr 2021, 8:36 pm | #7 |
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Re: Philips 3G38T Stone Dead
The OC82D is a pretty run of the mill transistor, and lots of types will replace it, though it does depend on the circuit. In a typical 2 transformer amp design just about any PNP device can be used, including silicon types. Ideal subs would be OC71, OC72, OC81D, OC81, AC126, AC128 but try whatever you have to hand.
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6th Apr 2021, 8:38 pm | #8 | |
Heptode
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Re: Philips 3G38T Stone Dead
Quote:
Cheers jay
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7th Apr 2021, 1:05 pm | #9 |
Heptode
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Re: Philips P3G38T Stone Dead
Well i changed the audio driver for an ACY18 and could hear stations on MW albeit quiet. Tapped the mixer/osc and it burst into life, So gonna swap it out. Infact i might get shot of all the AF117s. Still nothing on LW. Probably a band switch issue.
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7th Apr 2021, 1:21 pm | #10 |
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Re: Philips P3G38T Stone Dead
The ACY18 should be fine, despite being intended as an industrial transistor.
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7th Apr 2021, 1:33 pm | #11 | |
Heptode
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Re: Philips P3G38T Stone Dead
Quote:
Should i leave them or replace them to prevent future problems ?
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7th Apr 2021, 1:46 pm | #12 |
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Re: Philips P3G38T Stone Dead
I would change them all while you have the radio dismantled. Do them one at a time. Any Ge transistor with an ft of 2MHz or better should be OK in a MW/LW radio, and Si types of the BC214/BC558/2N3906 class should be OK too if you have them.
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7th Apr 2021, 1:52 pm | #13 | |
Heptode
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Re: Philips P3G38T Stone Dead
Quote:
Thanks for your input Cheers Jay.
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7th Apr 2021, 7:50 pm | #14 |
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Re: Philips P3G38T Stone Dead
I have a load of unbranded capacitors i was thinking of using to recap the radio. The ESR on them is around 8 ohms. Is this considered high ?
Cheers Jay.
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8th Apr 2021, 6:41 pm | #15 |
Heptode
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Re: Philips P3G38T Stone Dead
Could anybody tell me if the contacts on this band switch should be on the outside or the inside, See pic below. And how do you dismantle it ? As in removing the metal part ?
[img]************************qBZL12r7/IMAG0309.jpg[/img]
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8th Apr 2021, 6:51 pm | #16 |
Nonode
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Re: Philips P3G38T Stone Dead
Hi Jay
I would suggest changing all of those horrible AF117 transistors to those Russian equivalents, and provided the IF's have not been twiddled then you should be OK, from what you say it burst into life when the AF117 transistors were tapped, this would then suggest the driver stage and output stage are OK, I would also check the printed circuit side for any dry joints and even minute breaks in those tracks. Ken |
8th Apr 2021, 7:37 pm | #17 | |
Heptode
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Re: Philips P3G38T Stone Dead
Quote:
Cheers Jay
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8th Apr 2021, 8:23 pm | #18 |
Heptode
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Re: Philips P3G38T Stone Dead
Everything that could go wrong with this radio has gone wrong First up the audio driver fell apart on me, Got that replaced and today i recapped the radio. It was sounding good till i decided to spray the band switch with cleaner as it wasn't receiving on LW.
Now i have misaligned contacts on the band switch and the volume is lower than it should be, And to make things worse the dial cord came off And theres a few dodgy connections that i need to sort out too. But my first job is going to be fixing the band switch. Anybody know how these come apart and where the contacts are meant to be ? On the left of the switch the contacts are on the outside, (Sure thats were they're meant to be) On the right side they're on the inside.. See pic below
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Help!! I've been electrocuted by a glass thing that glows Last edited by Radio Scotland; 8th Apr 2021 at 8:46 pm. |
8th Apr 2021, 8:47 pm | #19 |
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Re: Philips P3G38T Stone Dead
There should be contacts on the outside, in all the switches of a similar type that I've worked on the moving contacts wipe both sides of the fixed contacts.
Lawrence. |
8th Apr 2021, 8:53 pm | #20 | |
Heptode
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Re: Philips P3G38T Stone Dead
Quote:
Jay
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