Philips PM 5134 Function Generator - UK Vintage Radio Repair and Restoration Discussion Forum

Mikebee88 · 14th Mar 2019, 10:04 pm

Following the recent discussion on function generators during February 2019, I was prompted to dig out my PM5134 to refresh my experience of its usefulness. On powering up, I straight away noticed a malfunction of the six small red LEDs to the right of the 3.5 digit display. Both the Vpp and Frequency LEDs were lit simultaneously, albeit with reduced brightness. The push switch to toggle between the two changed the 3.5 digit display figures and monitoring a sine wave output on a Â‘scope showed values for frequency and amplitude which matched those shown by the 3.5 digit display. I immediately suspected the Vpp/Freq switch having dirty contacts but how to get some Deoxit into it? There didn't appear to be any obvious entry point - the redundant top side contact legs emerge from the switch housing surrounded by a resin bead. But the lower legs going into the PCB looked more promising. Tipping the instrument front panel down, I applied some of the magic potion using a fine artists brush to the rear end of the switch so that gravity would assist it to flow down and penetrate any available orifice. And hey presto, it worked! One or the other Vpp/Freq LEDs now light in full brightness consistently whilst toggling the switch. Next up is to check out the sweep functions but so far, so good. This is a fine and versatile instrument, the output level and frequency being remarkably stable.

14th Mar 2019, 10:04 pm	#1
Mikebee88 Triode Join Date: Mar 2014 Location: Dunfermline, Scotland, UK. Posts: 23	Philips PM 5134 Function Generator Following the recent discussion on function generators during February 2019, I was prompted to dig out my PM5134 to refresh my experience of its usefulness. On powering up, I straight away noticed a malfunction of the six small red LEDs to the right of the 3.5 digit display. Both the Vpp and Frequency LEDs were lit simultaneously, albeit with reduced brightness. The push switch to toggle between the two changed the 3.5 digit display figures and monitoring a sine wave output on a Â‘scope showed values for frequency and amplitude which matched those shown by the 3.5 digit display. I immediately suspected the Vpp/Freq switch having dirty contacts but how to get some Deoxit into it? There didn't appear to be any obvious entry point - the redundant top side contact legs emerge from the switch housing surrounded by a resin bead. But the lower legs going into the PCB looked more promising. Tipping the instrument front panel down, I applied some of the magic potion using a fine artists brush to the rear end of the switch so that gravity would assist it to flow down and penetrate any available orifice. And hey presto, it worked! One or the other Vpp/Freq LEDs now light in full brightness consistently whilst toggling the switch. Next up is to check out the sweep functions but so far, so good. This is a fine and versatile instrument, the output level and frequency being remarkably stable.