I thought I was finished with this Beogram 4000 turntable after refurbishing its dust cover. However, a new problem emerged. After playing a few records, the tonearm would drop next to the platter as soon as I pressed “ON.” Luckily, the stylus wasn’t damaged (thanks to proper arm height adjustment), but I clearly needed to examine the carriage mechanism’s “17” position switch. This particular switch is the most troublesome of the position switches because it’s the only “break switch.” This means it remains closed until the tonearm reaches the 17cm single record touchdown point, at which point it opens. This section of the circuit diagram illustrates its function:

If the switch is open, the control system assumes the tonearm is at the 17 cm touchdown point and lowers it. Consequently, after pressing “ON” and clearing the SO switch, the carriage immediately stops, and the tonearm descends.

The reliance on the switch tab’s spring force to maintain a closed circuit is a design flaw inherent in this normally closed configuration. The following image shows the switches. The “17” switch lacks a contact terminal across it, meaning its terminal is located beneath the tab, and the spring force presses the tab onto this contact:

While inspecting the position switches, I noticed they appeared clean and free of oxidation. I applied a small amount of DeoxIT D100 and left them as they were. However, I overlooked that someone had previously attempted to “fix” the 17 switch, bending the tab and reducing its spring force. It’s nearly impossible to repair these switches without removing, straightening, and re-soldering the tabs. That’s precisely what I did in this instance. Here’s the bent tab:

The “bulge” near the solder tab and the wide angle between the solder tab and the blade are clear signs of previous tampering. The following image shows the straightened tab:

I re-soldered the tab and tested the turntable again. Everything now operates smoothly. This experience reinforces the importance of thoroughly testing vintage electronics before returning them to their owners. This is Beolove!