I’ve now dismantled the CHARGE test rig so I can get some space back in my office. Only one task remaining and that is our spare CHARGE controller has a defective AVX capacitor somewhere on the PCB. The controller works fine but across the +5V the resistance is 37 ohms which we can live with on a spare for now, should be around 150 ohms. I’ve tried a new technique but yet to prove it, using this temperature gun.
The gun works fine so in principle a low resistance AVX will get warm/hot so I should be able to detect the faulty capacitor. Problem is that some adjacent TTL chips all get hot under normal operating conditions so could mask a faulty capacitor. One day I’ll revisit this controller and see if I can detect the problem before unsoldering each AVX in turn until I strike lucky.
Harrison X150 Amplifier (Boost Blast):
As mentioned last Saturday I have removed the installed X150 Amp as it looked decidedly tatty (the LCP must be looking pretty good if I’m doing this sort of thing). Here is a photos collection for you to refer to.
The case of the spare X150 has previously been opened but I assume it is
serviceable so will take it to Cosford on Saturday and await we will give it a run. We also have two X300 amplifiers which could be used in an emergency when fixed as they have U/S labels on them. Also, both X150 and X300 amplifiers regularly appear on eBay.
One X300 is interesting as the original innards have been stripped out and two ‘new’ ILP audio amplifier modules (one for each channel) have been fitted; it has unacceptable hum while the other has one channel U/S. I can test once I
get some test leads organised.
We do not have component-level schematic diagrams for these amplifiers yet, only the functional schematics on the lids; perhaps someone out there can locate copies for us.