Hi
The following relates to the "Phase 2" Thurlby PL320QMT Three Channel PSU in use as standard on all our work benches at my employer's!
My unit had developed a fault where the middle (is that the "Slave" section?) 30V 2A section bogged out at 130mA and point–blank refused to supply anything above that, and the setup adjustment was useless!
I decided to investigate (grumpy manager on holiday this week!!!!), but nothing obviously amiss came to light, so decided to replace the LM324 (IC7, current control/sense amp), the 4052 analogue switch that selects between the current sense o/p and the front panel current limit control, the electrolytics and Q6 (BC559C) – this restored the full rated 2.2A output, but I can't get the adjustment of VR7, the one to set the PSU for 10mA output with the current front panel control set for 10mA – the pot VR7 doesn't do anything!
Can anyone suggest what I might have done wrong? My employer only had BC557Bs in stock for Q6 – is it important to use the correct BC559C here?
Also, has anyone got the circuit diagram for the 5V 4A board in these? I used the 49 page manual from K04BB and the 5V 4A bit appears to be missing!
Chris Williams
PS!
Nearly all of these units have a Driver board with a W02 bridge rectifier and two 2A pico–fuses in lieu of the four separate 1N4002 diodes given on all the diagrams in the manual – I've not found a revised page detailing this design change – has anyone got info from TTi on it for completeness?