EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: mr ed on December 13, 2024, 07:57:53 pm
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I have a well used afg3022b with a channel 1 error: 2303 : offset error. The service manual is a useless modern no schematic type and the block diagram is geared for the higher end models. (That said I did get both outputs working from the dead state and number 2 is perfectly fine).
Ch 1 works fine up to 40kHz where it seams to roll off down to near zero at 2MHz. The offset actually works fine but has a -50mV offset. That offset is just about at the outside of spec - but cal may be off with the roll off too.
Any ideas on the roll off? Maybe someone has a better block diagram?
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Two identical channels. One has a problem. You couldn't think of better conditions for troubleshooting.
Compare them step by step.
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I know. If it was that easy...but access is very difficult.
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Fixed. Key is to get good access. Pull out power supply and tuck it under the CPU board.
Issue was a hidden SMD fuse in parallel with a 0 ohm resistor between relays. Both more or less open but passing DC to 50kHz.when driving a high Z scope. Not sure why the parallel protection scheme.
As a side note, it's not designed for repair but has an excellent build quality and design with Asian assembly. All Texas Instruments and Burr Brown parts etc.
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Correction: the fuse is in parallel with 10k Ohms, that explains the wierd behavior. Not that the fuse was much use, This is the carnage that was done by someone before I got it. The good side fuse measures 0.265 Ohm which may be around 3/4 Amp. Where is the bloody schematic Tektronix?