UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Repair of 1959 WEM Copicat guitar echo unit

sortedradio · 8th Jan 2018, 12:17 am

I would start by checking that you have an anode voltage on pins1 & 6 of the first ECC83 in the schematic. If not check that you have h.t. voltage on the two 100k resistors, these often go open circuit. You don't say whether you have access to a scope to check for a signal on the grids of the valve. You only need this stage to work to get an output from the unit. Other things to check are the resistance of the gain pots, the 1.5k resistor and contacts on the jack sockets. Is the output a length of screened cable with a jack plug, if so buzz it and check it is not shorted?

8th Jan 2018, 12:17 am	#7
sortedradio Heptode Join Date: Jan 2008 Location: Sheffield, South Yorkshire, UK. Posts: 655	Re: Repair of 1959 WEM Copicat guitar echo unit I would start by checking that you have an anode voltage on pins1 & 6 of the first ECC83 in the schematic. If not check that you have h.t. voltage on the two 100k resistors, these often go open circuit. You don't say whether you have access to a scope to check for a signal on the grids of the valve. You only need this stage to work to get an output from the unit. Other things to check are the resistance of the gain pots, the 1.5k resistor and contacts on the jack sockets. Is the output a length of screened cable with a jack plug, if so buzz it and check it is not shorted?