UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Latest Acquisition

DMcMahon · 13th Apr 2020, 2:27 pm

Measured the signals at the heads. Same 240V p-p at erase head and 500V p-p at Record head (1,000V into C19 trimmer dropped down to 500).

As before seemed too high. Spec for erase voltage is 70V rms and record bias 155V rms, I must remeasure using my FET VOM.

By Peak to Peak calculation conversion to rms, 240 = 85 and 500 = 177, so my results are somewhat high, but not as high as I had originally assumed.

The heads have good continuity resistance.

I now need to recheck recording & erase to see if they still do not work.

13th Apr 2020, 2:27 pm	#26
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 6,600	Re: Latest Acquisition - Grundig TK 14 Measured the signals at the heads. Same 240V p-p at erase head and 500V p-p at Record head (1,000V into C19 trimmer dropped down to 500). As before seemed too high. Spec for erase voltage is 70V rms and record bias 155V rms, I must remeasure using my FET VOM. By Peak to Peak calculation conversion to rms, 240 = 85 and 500 = 177, so my results are somewhat high, but not as high as I had originally assumed. The heads have good continuity resistance. I now need to recheck recording & erase to see if they still do not work. Attached Thumbnails