Farnell L30-2 - UK Vintage Radio Repair and Restoration Discussion Forum

RevGeoff · 29th Feb 2020, 11:55 am

Hello,
I have acquired the above, and the current range does not show an indication, although the voltage is variable, the current limit works and it delivers power to a load.
I suspect VT101 - 2N5294, or VT3 - 2N3053. Comments before I open it up?

short wave · 29th Feb 2020, 1:03 pm

Hi RevGeof,
if the voltage is variable and is present at the O/P the control circuit is ok.
I would suspect the switch(if single meter type) and associated current circuit resistors(across the main current sensing resistor)

RevGeoff · 29th Feb 2020, 3:57 pm

Hi.

I did wonder about the switch. Is the sense resistor R206?

I also forgot to state that the current meter setting pot has no effect.

short wave · 1st Mar 2020, 11:35 am

Yes ��

Wendymott · 1st Mar 2020, 11:58 am

If you have output.. the current sense resistor will be ok..Either the switch or any series resistor FROM the current sense to the meter.

RevGeoff · 5th Mar 2020, 11:19 pm

Success!

I replaced the bridge rectifier, as C1 was getting hot, suggesting it was passing AC. I replaced C1 in case it was damaged. I also replaced the switch. VT101 was OK, but VT3 was intermittent, also replaced. This seems to have cured the problem. Now to soak test it.

Thanks guys!

29th Feb 2020, 11:55 am	#1
RevGeoff Triode Join Date: Feb 2020 Location: Sheffield, South Yorkshire, UK. Posts: 14	Farnell L30-2 Hello, I have acquired the above, and the current range does not show an indication, although the voltage is variable, the current limit works and it delivers power to a load. I suspect VT101 - 2N5294, or VT3 - 2N3053. Comments before I open it up?

29th Feb 2020, 1:03 pm	#2
short wave Pentode Join Date: Mar 2013 Location: Leeds, West Yorkshire, UK. Posts: 246	Re: Farnell L30-2 Hi RevGeof, if the voltage is variable and is present at the O/P the control circuit is ok. I would suspect the switch(if single meter type) and associated current circuit resistors(across the main current sensing resistor)

29th Feb 2020, 3:57 pm	#3
RevGeoff Triode Join Date: Feb 2020 Location: Sheffield, South Yorkshire, UK. Posts: 14	Hi. I did wonder about the switch. Is the sense resistor R206? I also forgot to state that the current meter setting pot has no effect. Last edited by Station X; 1st Mar 2020 at 2:54 am. Reason: Posts merged.

1st Mar 2020, 11:35 am	#4
short wave Pentode Join Date: Mar 2013 Location: Leeds, West Yorkshire, UK. Posts: 246	Re: Farnell L30-2 Yes ��

1st Mar 2020, 11:58 am	#5
Wendymott Octode Join Date: Jun 2013 Location: Huddersfield, West Yorkshire, UK. Posts: 1,795	Re: Farnell L30-2 If you have output.. the current sense resistor will be ok..Either the switch or any series resistor FROM the current sense to the meter. __________________ Should get out more. Regards Wendy G8BZY

5th Mar 2020, 11:19 pm	#6
RevGeoff Triode Join Date: Feb 2020 Location: Sheffield, South Yorkshire, UK. Posts: 14	Re: Farnell L30-2 Success! I replaced the bridge rectifier, as C1 was getting hot, suggesting it was passing AC. I replaced C1 in case it was damaged. I also replaced the switch. VT101 was OK, but VT3 was intermittent, also replaced. This seems to have cured the problem. Now to soak test it. Thanks guys!