by tonymillerus »
Sun Dec 14, 2008 5:13 am
You have just proven that Read-Out and Sense works. The write-up on the site is tailored toward Black & gray box machines, where the write source voltage is indeed about +125 VDC. Since you have the manual, turn to the SCC6 schematic. Notice C3114. This is the Write-In capacitor. Measure the voltage across it, like I asked you to in my last response. it should measure about +300 VDC. If it does not, chances are you have a problem with C3104 or C3105, or with CR3108 or CR3109. Another possibility is that F3102 is blown. If the voltage is good, there could be a problem with the Write-In switch in the SPU (S4206). Check it to make sure that it's not gotten a buildup of carbon on it. Another possibility is the switches in the Selector. The contacts may have gotten dirty or a sludge buildup.
As to the amplifier, you probably have a SAM1 monaural amplifier. A 25 K pot will work. Connect one end to ground (J5104 pin 2), the other end to J5104 pin 4, and the slider to J5104 pin 1. The other two connections are taps for loudness compensation, which don't matter as long as you keep the amplifier at reasonable volume. They only have an affect at low volume.
Cheers,
Tony Miller