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Radio Make and Model: President Lincoln HR2510
PCB Number: Main board PB-111AB
PLL Number: PCB PB 121 AC HCT 58 NY 94V-0
Test gear available: Watt meter, DC AM meter, oscilloscope
Symptoms: No power on FM/AM whatsoever. On SSB the is a very slight noticeable signal on an external reciever. This all seemed to have happened during a mild thunderstorm where a QSO wasn't possible all of a sudden presumably caused by static electricity.

What is working: Receiver and MPU

What has been tried: I received the Lincoln without the final where as the owner thought the culprit might be the final and unsoldered it. Before replacing any transistor I checked if there was any bias but none whatsoever... Maybe the bias diode gave way so I unsoldered the diode and it indeed was defective so it needed to be replaced. After this I tried to get a 50 mA reading between TP4 and TP3 but nothing yet. So I decided to place a brand new MRF477 there were the original was missing and do the test again. At that point I got stuck in finding the reason for this problem... At first my power supply went in a safe mode due to short-circuit . So I got the Volt meter on the two TP's and measured 13,89V between TP4 and TP3...? Is this normal? I don't have to guess what happens when the test pcb is placed back in this condition...

I have to say that I'm confident in making myself sure about the soldering job and checked all solder connections over and over again... I'm not a expert on this but I can do a lot to get a radio working again like many defective radio's before this Lincoln. But in order to avoid making matters worse I really hope that someone could give me a hint where to look for... If I made a stupid mistake or assumption... tell me

I just want to get this radio working again and I know I'm a step away... hopefully....

Any help would be very much appreciated!

Cheers!

John

Hi!

Check C116 (150pf). This one sometimes blows when the radio is "tuned".

73,
Ralf

Hi Ralph!

Thanks for the suggestion! I didn´t have the uppertunity yet to check this capacitor but as internet provides me with some info, this issue was mentioned a couple of times on different sites.

But if it is this capacitor, does it explain the 13,8v between TP4 and TP3?

Thanks!

19WAC495

John

Hi John,

i don't really know, but C116 is one of the most problems in such cases. This can't be a big problem, but a hidden one .

73s, Ralf

Hi Ralph!,

Yesterday I unsoldered C116 after a long search for this tiny component and tested it. (Un)fortunately the condensator passed the test and was soldered back in. I checked the other C115/114 and they worked fine too... Hmzz.. I guess this baby needs a real doctor, only if it was to find this tiny little bug that refused to be found or even fixed...

73's

Breaklight

19WAC495

Hi John,

hmmm...hope that the rig doctor will find the problem. Maybe a small transistor is blown.
Good luck!
73s
Ralf