Exposure Amplifier Repairs
Exposure XXV Integrated Amplifier
This one needed the following components replacing; left channel output transistors, the regulated +\- transistors, zeners and several resistors that had burnt up. The driver transistors ZTX452\552 and the same types in the regulator circuit, worked and sounded fine after, this was after the speaker output was shorted out!
Exposure XX Super Integrated Amplifier
This one had blown many resistors and transistors including the regulators and output transistors; 3 pnp\npn, the ZTX552\452 drivers also the 0.22ohm 3W resistors, 36V Zeners, etc.
Exposure IV Power Amplifier
This wouldn’t energise the on-board relays for some reason. There was no major DC on the outputs, the fuse holders were the problem, they had split and lost connection through the fuses! I replaced all five in the end. The 150µF 10V, capacitors in the relay cct were open circuit. When powered up there was crackling on the left channel, replaced the MPSA06\56 which cured it, they run at 500 deg!