Author Topic: Tek AFG3022B repair  (Read 364 times)

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Offline mr edTopic starter

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Tek AFG3022B repair
« on: December 13, 2024, 07:57:53 pm »
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?
 

Offline Harry_22

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Re: Tek AFG3022B repair
« Reply #1 on: December 13, 2024, 09:25:36 pm »
Two identical channels. One has a problem. You couldn't think of better conditions for troubleshooting.
Compare them step by step.
 

Offline mr edTopic starter

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Re: Tek AFG3022B repair
« Reply #2 on: December 13, 2024, 10:55:31 pm »
I know. If it was that easy...but access is very difficult.
 

Offline mr edTopic starter

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Re: Tek AFG3022B repair
« Reply #3 on: December 15, 2024, 10:50:04 am »
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.
 

Offline mr edTopic starter

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Re: Tek AFG3022B repair
« Reply #4 on: December 15, 2024, 06:57:44 pm »
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?
 


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