Sort of TEA related (has a voltmeter built in), I posted a pic of my shed radio (a Danish made Sailor 16T) a while ago and someone on here was interested in seeing inside it, well I've finally had enough of the voltmeter under-reading and decided to adjust it.
A quick teardown, this radio uses a lot of those Mullard/Philips AF11x series transistors that have a bad reputation of failing with tin-whisker related shorts, despite this I haven't had any trouble with them yet.
![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1178152)
![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1178148)
![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1178156)
Here is the problem I have, with an external supply set for 9V I get a reading of approx 8V of the built in meter.
![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1178164)
Having a look at the circuit diagram they used a 10kΩ resistor in series with the meter with no provision for adjustment, it's on the power switch (arrowed).
![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1178168)
A decade resistor was used to determine what value could be added in parallel to give a better reading, I came to the conclusion the best compromise was 83kΩ, I used a 120kΩ & 270kΩ in parallel across the original resistor.
![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1178172)
All back together with fresh set of 6 D sized leak-tubes.
![Cheesy :D](https://www.eevblog.com/forum/Smileys/default/xcheesy.gif.pagespeed.ic.KPzuH4J-TG.png)
![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1178176)
David