Dear fellow members, I recently received a AWA distortion meter F2423A, serial number 255 which has some problems. On the web the only service manual available is for serial numbers 586 and higher. And there clearly was an update in schematics, so I am stuck. i hope someone can help me out on this issue.
F242A.
Have you identified where your meter differs during fault-finding, and that is the reason for trying to find the first rev manual and schematics?
I would have thought that first-in fault finding would be possible with that available schematic and manual.
I luckily have a F240 - a lot simpler beast.
It's also lucky that nowadays a simple probe, soundcard and PC can provide most of the fault-finding tools for your meter (very low distortion signal generation and spectrum analyser with a noise floor below the F242.
Have you identified where your meter differs during fault-finding, and that is the reason for trying to find the first rev manual and schematics?
I would have thought that first-in fault finding would be possible with that available schematic and manual.
I luckily have a F240 - a lot simpler beast.
It's also lucky that nowadays a simple probe, soundcard and PC can provide most of the fault-finding tools for your meter (very low distortion signal generation and spectrum analyser with a noise floor below the F242.
hello trobbins, I guess about 15-20% of the schematics differ, checking actual component placing against the downloaded manual parts listing. The voltmeter function works, but in distortion measurement mode you get a lot of relay switching and then Out of range LED lights up even without an input signal. The beast is in good condition otherwise and it seems a pity to scrap it, anyway I like restoring all kinds of electronics. Concerning sound cards, etc., I am an Apple addict so that is not the road to take....
Are the IC's in sockets?
Are you able to identify if the schematic differences are mainly related to a particular functional block or two?
Are the power supply rails before or after the 7812/7912 showing glitching down from what could be faulty parts when certain functions or settings are switched on?
Yes it's a quandary what to do when there is no full schematic, or IC's are soldered in, and you have to fault find new and complex equipment - it can take lots of concentration to just to work out where to start checking/confirming sections of circuitry are or are not working correctly.
Yes, starting a thread at eevblog was well worth it, although it will get 'buried' in a day or two - lots of activity on that sub-forum!
Are you able to identify if the schematic differences are mainly related to a particular functional block or two?
Are the power supply rails before or after the 7812/7912 showing glitching down from what could be faulty parts when certain functions or settings are switched on?
Yes it's a quandary what to do when there is no full schematic, or IC's are soldered in, and you have to fault find new and complex equipment - it can take lots of concentration to just to work out where to start checking/confirming sections of circuitry are or are not working correctly.
Yes, starting a thread at eevblog was well worth it, although it will get 'buried' in a day or two - lots of activity on that sub-forum!
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no, no sockets at all. Power supplies are ok. I checked the IC parts list against the pcb and not very positive result; 6 ic's not in my unit and 7 ic numbers are a different part! Also R and C numbers differ sometimes.
Clearly they redesigned some parts of the beast and kept other parts identical with same numbering.
EEVblog got no results, I even tried AWA company, now doing other things but they don't have any archive from the good old days left, it seems.
What doesn't help is that everything is on one huge pcb, slightly smaller than the cabinet.
I am afraid I will have to give it up as a total loss.....
Clearly they redesigned some parts of the beast and kept other parts identical with same numbering.
EEVblog got no results, I even tried AWA company, now doing other things but they don't have any archive from the good old days left, it seems.
What doesn't help is that everything is on one huge pcb, slightly smaller than the cabinet.
I am afraid I will have to give it up as a total loss.....
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