Pye 1352 0.8uf electrolytic - UK Vintage Radio Repair and Restoration Discussion Forum

poppydog · 30th Aug 2018, 4:42 pm

I have a 0.8uf electrolytic that's bad on a pye 1352 transistor radio, can I use a 1uf cap in its place? Its the audio coupling cap.
regards poppydog

paulsherwin · 30th Aug 2018, 5:19 pm

Yes, you can use 1uF, but 0.8uF is an unusual value so you should double check it.

David G4EBT · 30th Aug 2018, 7:10 pm

C24 - audio coupling cap - (and C23) are shown as 1uF electrolytics. There are no caps on the circuit stated as 0.8uF. Personally, on a set of that age, I'd change all the electrolytics, which will be well past their best even if they're still functioning. If, for example, C28 was to go short circuit, it would plonk a dead short across the battery. Other leaky caps (in the electrical sense) can stress the transistors.

In a dead set, the earphone socket will be suspect and so too could be D2 - the 0A90 detector diode lurking inside the can of T3 - the second IFT. Easy to check that. If you inject am audio tone at the T3 secondary output pin from D2 to the audio stage and hear an audio tone from the speaker, the audio stage is working. If you inject an audio tone at the other T3 secondary pin (the input to D2) but don't hear a tone in the speaker, the diode is suspect.

If you then apply a probe from a signal tracer (ie, small amplifier) to the diode input and hear tunable signals, that confirms that the mixer and IF stages are working, but the diode is dead. (If you do by any chance need an 0A90 but can't find one, other germanium diodes such as 1N34, which are plentiful, will do fine).

Originally the set used a long since obsolete 9V PP7 battery, but the press stud connectors are the same as a PP3 so I guess that's what has been/is being used.

Hope that's of interest and help.

poppydog · 30th Aug 2018, 8:42 pm

Thanks for the replies, I've popped a 1uf in and I have got some music, albeit a little distorted

. The current is a little on the high side as well so I may consider changing all the electrolytics, as the radio is early 60's and so is more than half a century old. Here is a pic of the 0.8uf.

Click image for larger version

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Apologies for the poor picture.

Regards
Poppydog

Boater Sam · 30th Aug 2018, 9:52 pm

Never seen one, how unusual a value. Pye must have had some left over from a government contract!

ricard · 30th Aug 2018, 11:17 pm

I remember seeing electrolytic caps with values starting with 4 and 8 (i.e. 40 µF or 800 µF), predominantly in Philips equipment. I think they were part of the predecessor of the E6 series, in the same way that 10, 25, 50 were the predecessor of the E3 series (10, 22, 47). So, probably something like 10, 15, 25, 40, 50, 80 or something like that.

TonyDuell · 31st Aug 2018, 5:12 am

I remember a Philips 640uF capacitor in one of the EE kits (EE1004?) I wonder what series that fitted in? I suppose there was a sort-of doubling series at one point (1uF, 2uF, 4uF, 8uF, 16uF, 32uF) so it might have been from that.

30th Aug 2018, 4:42 pm	#1
poppydog Banned Join Date: Oct 2015 Location: Cornwall, UK. Posts: 849	Pye 1352 0.8uf electrolytic I have a 0.8uf electrolytic that's bad on a pye 1352 transistor radio, can I use a 1uf cap in its place? Its the audio coupling cap. regards poppydog

30th Aug 2018, 5:19 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: Pye 1352 0.8uf electrolytic Yes, you can use 1uF, but 0.8uF is an unusual value so you should double check it.

30th Aug 2018, 7:10 pm	#3
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,766	Re: Pye 1352 0.8uf electrolytic C24 - audio coupling cap - (and C23) are shown as 1uF electrolytics. There are no caps on the circuit stated as 0.8uF. Personally, on a set of that age, I'd change all the electrolytics, which will be well past their best even if they're still functioning. If, for example, C28 was to go short circuit, it would plonk a dead short across the battery. Other leaky caps (in the electrical sense) can stress the transistors. In a dead set, the earphone socket will be suspect and so too could be D2 - the 0A90 detector diode lurking inside the can of T3 - the second IFT. Easy to check that. If you inject am audio tone at the T3 secondary output pin from D2 to the audio stage and hear an audio tone from the speaker, the audio stage is working. If you inject an audio tone at the other T3 secondary pin (the input to D2) but don't hear a tone in the speaker, the diode is suspect. If you then apply a probe from a signal tracer (ie, small amplifier) to the diode input and hear tunable signals, that confirms that the mixer and IF stages are working, but the diode is dead. (If you do by any chance need an 0A90 but can't find one, other germanium diodes such as 1N34, which are plentiful, will do fine). Originally the set used a long since obsolete 9V PP7 battery, but the press stud connectors are the same as a PP3 so I guess that's what has been/is being used. Hope that's of interest and help. __________________ David. BVWS Member. G-QRP Club member 1339.

30th Aug 2018, 8:42 pm	#4
poppydog Banned Join Date: Oct 2015 Location: Cornwall, UK. Posts: 849	Re: Pye 1352 0.8uf electrolytic Thanks for the replies, I've popped a 1uf in and I have got some music, albeit a little distorted . The current is a little on the high side as well so I may consider changing all the electrolytics, as the radio is early 60's and so is more than half a century old. Here is a pic of the 0.8uf. Apologies for the poor picture. Regards Poppydog

30th Aug 2018, 9:52 pm	#5
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Pye 1352 0.8uf electrolytic Never seen one, how unusual a value. Pye must have had some left over from a government contract!

30th Aug 2018, 11:17 pm	#6
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	Re: Pye 1352 0.8uf electrolytic I remember seeing electrolytic caps with values starting with 4 and 8 (i.e. 40 µF or 800 µF), predominantly in Philips equipment. I think they were part of the predecessor of the E6 series, in the same way that 10, 25, 50 were the predecessor of the E3 series (10, 22, 47). So, probably something like 10, 15, 25, 40, 50, 80 or something like that.

31st Aug 2018, 5:12 am	#7
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,224	Re: Pye 1352 0.8uf electrolytic I remember a Philips 640uF capacitor in one of the EE kits (EE1004?) I wonder what series that fitted in? I suppose there was a sort-of doubling series at one point (1uF, 2uF, 4uF, 8uF, 16uF, 32uF) so it might have been from that.