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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 23rd Apr 2017, 9:18 pm   #1
reeltoreelrob
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Join Date: Nov 2010
Location: Birmingham, West Midlands, UK.
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Default Dynatron FM tuning module

Hi All,
I have a Dynatron SRX26, I have started to have problems with the FM tuning, mostly round the 88 mhz (radio 2) it was very crackly, also in recent times the volume seamed to be a little low (the record player is fine) So in my wisdom I decided to spray the variable capacitor with contact cleaner, now all I get is a static type sound. The same problem this chap had on youtube https://www.youtube.com/watch?v=mOwwr5JCw_E
I am not sure if this is coincidence or what!
I noticed the module has the AF115 on the top board, is this pcb removable from the variable capacitor to be able to replace this transistor?
Any help or guidance would be great.
Thanks in advance.
Rob.
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Old 26th Apr 2017, 8:47 pm   #2
reeltoreelrob
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Default Re: Dynatron FM tuning module

Hi all,
I have managed to remove the pcb from the varicap, just the case of desoldering 4 pins, I have removed the AF115 and replaced with an AF125, although it was a little bit of a fiddle with the pin layout and size being different to the AF115, sure enough the radio burst into life
There is also an AF178 on the board I have a brand new one but are these generally reliable and it is best to let sleeping dog lie or while it is dismantled swap it with the new one.
Thanks
Rob.
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Old 26th Apr 2017, 9:09 pm   #3
ronbryan
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Default Re: Dynatron FM tuning module

I have also found that the TO-12 packaged (i.e. 4 pin TO-5) AF178 transistors are reliable compared to the AF11* series and would leave it alone.

Ron
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