Graetz Faehnrich color

[yagosaga]

Hi folks,

one year ago, I got a hybrid color tv set. It was the Graetz Faehnrich 2441.
I remember the good old days when I was 15 years old, in 1975, I saw this set as a new one in the shops. This was the last delta-CRT color tv set with tubes on the chassis, which was sold in Germany.
This set here had a broken CRT (510CKB22) and a broken chassis. The plates of the signal chassis and the deflection chassis were broken. I soldered all broken copper and wire connections. Last week, I had a telephone call. Somebody from the technical university told me that there is a spare CRT on the universities' dump. I fetched it and tested it. It was a Hitachi CRT with 0.8 mA red, 0.7 mA blue and 0.6 mA on the green gun. Together with my son, I disassembled the set, removed the broken CRT and installed the other CRT. After assembling the set and switching on, the screen was total green with no blue. At first, I thought, the CRT is bad. But I have measured it. It was OK. Then I measured the CRT's screen voltage. It was 400 volts for red, but only 100 volts for green and 50 volts for blue. When I turned blue screen voltage to highest level, the crt's screen became dark. I checked the potentiometers for the screen voltage (sometimes they lowered their values), but they are OK. I removed the crt plate and checked the screen voltages without operating the crt. The same effect. The solution I got from the man who told me about the spare crt on the universities dump. He wrote to me that he often had troubles in the past with the switches for the screen voltages for purity adjustments.
In fact, the fault was a small grime trace on the switches with which one can switch off the screen voltages for blue and green. After removing the switches, the set operated well.

http://bs.cyty.com/menschen/e-etzold..._inBetrieb.jpg

Eckhard