Featured Post

Beogram 4002: Restoration of DC Motor Video Published - Check It Out!

By popular request (really, I got quite a few emails about this!...;-), I finally completed my Beogram DC motor restoration video! It demon...

Thursday, May 4, 2017

Beogram 4004 (5526): A New Arrival from Canada - First Impressions

A Beogram 4004 (5526) arrived for some TLC from Canada. It arrived very well packaged in double boxes. Thanks for watching our 4002 packing video!:
Even a perfect foam protector for the arms and carriage was cut to size:
Unfortunately, this unit gave me a very hard time when I wanted to take the aluminum panels out. The main panel just did not want to be released from the enclosure! It finally dawned on me that the panel was aligned too far towards the front, as can be seen from the position of the alignment stud that is still underneath the tab that holds it down, even though the wood plinth was all the way out at this point:
It turned out that the back left alignment pin that normally ensures a precise position of the panel was bent forward, preventing the release of the panel. I finally got it out after application of some 'controlled force', which revealed the bent pin:
After that I was able to inspect the inside:
This unit is in pretty good condition, cosmetically and mechanically. It seems all original, a perfect starting point for a restoration. I plugged it in and pressed start. The carriage started moving and the RPM quickly switched from 33 to 45 RPM and then the carriage proceeded all the way to the end of its travel followed by a return to the home position. This behavior is an indication that the carriage position sensor has an issue. Most likely the IR diode is dead. This makes the photo sensor 'think' that the long black stretch on the position ruler is currently passing through, and hence the control circuit switches the unit to 45. After this action nothing happened anymore on the photosensor, and so the carriage kept moving. Other than that the unit seems to be in working condition, i.e. after repairing the diode and doing our standard restoration tasks it should be reliable again.

No comments:

Post a Comment

Comments and suggestions are welcome!