Wow and flutter may be due to a worn belt.
But more abrupt variations for example while holding a portable cassette player may be due to imperfect battery contacts.
Such was the case while playing around with Sanyo TRC 2500. Even the power LED would dim while holding it.
Yet battery holder contacts looked not bad with no corrosion.
But from experience with very sensitive mic booster preamps such as the Pleiades V6 electron tube battery powered amp, sound that resemble earthquake can be produced by just gently touching around battery holder.
So it was decided to look into it. Battery holder metal contacts were gently streched in the opposite direction of battery pressing. While looking through a magnifying glass it was seen that the second coil of the spring has to touch the first coil when it is compressed by the battery. On one of the battery holders the second coil from the spring was dislodged from the support of the 1st turn. It was out back in place.
Then contacts were cleaned with methylated spirit and cotton buds. Then 1000 fineness wet and dry abrasive paper was gently used. Then methylated spirit again for top cleaningness.
Now Sanyo TRC 2500 plays almost like new.
No comments:
Post a Comment