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Timmus66 · 15th Apr 2019, 1:24 pm

A bit of a development, I started to check the DC voltages as recommended by Ron, all voltages on the A4 board checked out OK with the exception of pin 18, the manual states it should be set at 5.25v, on checking it was at 5.31v (slightly lower with the wire reconnected at 5.29v), so adjusting R3 to bring it to 5.25v I decided to try the set and noticed there was a slight improvement, with that in mind I reduced the voltage in small steps and found that at exactly 5v the unit was perfectly stable when warm (been on for well over an hour now).

Is it possible the 5.25v in the manual could be an error and it should be 5v or could this point to a problem elsewhere?

Tim

15th Apr 2019, 1:24 pm	#8
Timmus66 Triode Join Date: Nov 2017 Location: Essex, UK. Posts: 22	Re: Marconi TF2171 Possible Problem? A bit of a development, I started to check the DC voltages as recommended by Ron, all voltages on the A4 board checked out OK with the exception of pin 18, the manual states it should be set at 5.25v, on checking it was at 5.31v (slightly lower with the wire reconnected at 5.29v), so adjusting R3 to bring it to 5.25v I decided to try the set and noticed there was a slight improvement, with that in mind I reduced the voltage in small steps and found that at exactly 5v the unit was perfectly stable when warm (been on for well over an hour now). Is it possible the 5.25v in the manual could be an error and it should be 5v or could this point to a problem elsewhere? Tim