Tuning Up An Fm900 - Philips FM92E Manual

36: Tuning up an FM900:

To tune an FM 900 radio you will need:
• A power meter of some kind ( a VSWR meter into a Dummy load will do)
• Insulated tuning tools to suit VCO slugs. Ceramic works best. Available from Dick Smith
Electronics at around A$8
• Voltmeter 0-20v Analogue is better.
• Signal Generator.
That's the bare minimum required. If you have access to a FM Deviation meter that will be handy.
Undo the screws holding both lids on noting which side they came from.
Identify the Synth/ Controller PCB . It's the larger of the two PCB's and on the side of the radio
opposite the antenna connector. Undo the screws marked with an arrow and hinge the PCB out. Undo
the 4 screws holding the shield over the EPROM (its the larger one).
Earth yourself to the radio with one hand or use a anti-static wrist strap. Carefully remove the EPROM.
Its the chip with a paper label on it, noting its position. If you don't have a IC tool, carefully lever it up
with a screw-diver at each end.
Re-insert the EPROM with your new frequencies
Carefully power up the radio and see if the channel numbers come up on the display. If so good, if not
check the EPROM is in correctly and that it is actually a good EPROM. Sometimes they 'give up' while
being reprogrammed.
Wind the mute to minimum. If the set is 'ticking' the VCO is out of lock.
Undo the screws holding the radio board in and hinge it out.
Find test point 201
Connect your volt meter between TP201 and ground.
Identify the VCO slugs.
Philips FM92E Conversion to 6 Meters: Version 3.9 Page 69