18-09-2023, 09:34 AM
Moved this from elsewhere as its not getting read.
The Murphy B485 is finally working and re-assembled. Not fully home into the Neohide ( thanks for the information ) case, it may need to come out again one day! I have cut the bottom of the case so that it can be pushed out from the bottom.
It did not submit to full working order without an eleventh hour struggle. Replacing C18 had restored reception on Long wave and improved the Medium wave reception, I had become tired of listening to just Gold. Now there were plenty of the remaining stations coming in loud and clear. A quick tweak to the RF trimmers improved the aerial response and put the stations in the correct place on the tuning dial.
I refitted the battery holder pockets on the aluminium bar across the chassis and replaced the loudspeaker. I noted that the loudspeaker is a bit special, 25 Ohm, had not noticed that in the service instructions.
A quick power up before fitting the top and the case halves produced no reception! Tapping and wriggling the battery carrier made no difference so I took it out again and intermittent reception was restored.
The ends of this carrier fits into slots in the chassis sides. One end just touched the sleeved lead of one of the transistors, moving this ever so slightly stopped reception. Not a dry joint but another rusted through transistor lead inside sleeving. These steel wires are really terrible, they break at the slightest touch and rust worse than an Austin 1100.
Extending the remaining lead restored reception once more.
Re-assembled, re-cased and suited, I have declared the radio restored to working order. Hopefully it will stay this way for a reasonable time.
So a radio with many oddities and difficulties for the repairer, terrible access to some components, unusually the sole AF117 transistor is still in good working order!
Replaced 7 electrolytic capacitors, 2 resistors to gain access, 2 AF126 output transistors and rusted leads on 2 other transistors. Phew!
Of course there are no PP1 batteries any more. I use 8 AA cells in 2 battery holders as a replacement.
The Murphy B485 is finally working and re-assembled. Not fully home into the Neohide ( thanks for the information ) case, it may need to come out again one day! I have cut the bottom of the case so that it can be pushed out from the bottom.
It did not submit to full working order without an eleventh hour struggle. Replacing C18 had restored reception on Long wave and improved the Medium wave reception, I had become tired of listening to just Gold. Now there were plenty of the remaining stations coming in loud and clear. A quick tweak to the RF trimmers improved the aerial response and put the stations in the correct place on the tuning dial.
I refitted the battery holder pockets on the aluminium bar across the chassis and replaced the loudspeaker. I noted that the loudspeaker is a bit special, 25 Ohm, had not noticed that in the service instructions.
A quick power up before fitting the top and the case halves produced no reception! Tapping and wriggling the battery carrier made no difference so I took it out again and intermittent reception was restored.
The ends of this carrier fits into slots in the chassis sides. One end just touched the sleeved lead of one of the transistors, moving this ever so slightly stopped reception. Not a dry joint but another rusted through transistor lead inside sleeving. These steel wires are really terrible, they break at the slightest touch and rust worse than an Austin 1100.
Extending the remaining lead restored reception once more.
Re-assembled, re-cased and suited, I have declared the radio restored to working order. Hopefully it will stay this way for a reasonable time.
So a radio with many oddities and difficulties for the repairer, terrible access to some components, unusually the sole AF117 transistor is still in good working order!
Replaced 7 electrolytic capacitors, 2 resistors to gain access, 2 AF126 output transistors and rusted leads on 2 other transistors. Phew!
Of course there are no PP1 batteries any more. I use 8 AA cells in 2 battery holders as a replacement.