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RACAL -DANA 9301A S&H circuit issue

my RMS Voltmeter is in very good condition. However, the S&H circuitry for the input signal obviously does not work.
Can anybody provide help or offer support? If costs are justified I consider to ship it to one of you for repair as my test equipment does not allow to go that deep into details. The manual can be provided.
Thanks and 73.

TonyStark picture

Hello Klaus!

Here you will find a repair description and a wiring diagram for the instrument:

The Sample-Hold circuit is also included. In the article, they dealt with a power supply failure, a failure caused by short-circuited tantalum capacitors. Good luck with the repair, it's a very good instrument.

Regards: Tony



Kari picture

Hello Klaus,
ET hat das Racal-9301 Manual, sonst als Nichtregistrierte kannst auch nur Link eingeben... Woran fehlt es dem-um konkreter zu sein?
LG, Kari


tvdoktor picture

Möchten Sie es reparieren?
Oder jemand anderes reparieren lassen?
Hast du das gelesen? Es ist nützlich. und hier
Dies zum Beispiel auch.
Need for sample
If the input analog voltage of an ADC changes more than ±1/2 LSB/ Least Significant Bit/, then there is a severe chance that the output digital value is an error. For the ADC to produce accurate results, the input analog voltage should be held constant for the duration of the conversion.

As the name suggests, a S/H Circuit samples the input analog signal based on a sampling command and holds the output value at its output until the next sampling command is arrived.