Hello all. I have a Marantz PMD222 cassette tape recorder with a front pane=
l VU meter made by Varta. Last week I was demonstrating the use of the reco=
rder to my son and noticed that the VU needle did not move on record or pla=
yback, but it did move around two millimetres when I gently shook the whole=
machine. I thought the moving coil had burned out, and after removing the =
front panel, which involved a lot of physical jerking of the VU meter, I me=
asured the resistance across its terminals with my Fluke12 multimeter. It r=
ead around 400 Ohms and I concluded that the coil was intact. I checked to =
see if anything had changed, but the needle still did not move on playback =
or record. I then realized that the VU meter connections were still in an e=
lectronic circuit and so I disconnected the loom carrying the wires from th=
e VU meter to the 'mother board'. I swapped the Fluke to continuity mode, w=
hich carries a small current, and applied the probes to the terminals of th=
e VU meter. The needle jumped around as if it were possessed. It will now p=
eg to the right, on record, but only goes to -4dB on playback. I'm not sure=
, but it may have always behaved that way. The unresponsive needle problem =
is rectified, but the mystery isn't. I wonder if anyone can tell me why the=
needle moved a small amount when shaken, but required 'cardioversion' to d=
o its job properly? Is it simply a matter of spindle lubrication or somethi=
ng else? Cheers, Greg Winterflood.
|