How stable are the power supplies?
> Date: Fri, 7 Dec 2012 22:56:40 +0000 > From: [email protected] > To: [email protected] > Subject: Re: [volt-nuts] Solartron 7150plus - Chasing AC gremlins > > There aren't any electrolytics in the AC signal path. > > Cooling the AD637 causes the displayed voltage to drift but doesn't > clear the calibration error. Power cycling the unit will allow AC > calibration to complete. None of the other parts on the "suspect list" > have any effect. > > I've resoldered everything in that path - from the Coto relays through > to the amplifier and RMS-DC converter. No luck - it's still misbehaving. > The readout on the 0.2V setting has dropped 200 counts (0.00200) in the > space of a few minutes. It's reporting "GOOD" for calibration, but I > expect that'll change when it warms up. > > There's a Philips 100V / 2.2uF metallised polyester capacitor (C17) > connected between pins 8 and 9 of the AD637 and a second one filtering > the output via a 27k series resistor. > > I'm starting to think I'm getting a bit out of my depth... in any case > this is going to have to wait until tomorrow night as I have a to-do > list a mile long and precious few hours left to finish it off! > > It looks like most of the circuit sections are linked with passive > components and can be isolated by desoldering one or two leads. Signal > injection and tracing is next on my "try that!" list. > > Thanks, > Phil. > > > On 07/12/12 18:59, m k wrote: > > > > How about a leaky electrolytic? look for dried out ones, give the cans a > > quick spin, if it actually rotates it has leaked and dried out. > > > >> Date: Fri, 7 Dec 2012 09:48:13 -0800 > >> To: [email protected] > >> From: [email protected] > >> Subject: Re: [volt-nuts] Solartron 7150plus - Chasing AC gremlins > >> > >> I would first look at the electromechanical aspects. Are there any > >> relays or connectors in the signal path? Next would be any device > >> sockets - they can be exercised by rocking the parts a little. Next > >> would be to inspect carefully for bad solder joints, corrosion, and > >> signs of physical damage. Then consider the actual electronic components. > >> > >> Ed > >> > >> > >> _______________________________________________ > >> volt-nuts mailing list -- [email protected] > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > >> and follow the instructions there. > > > > _______________________________________________ > > volt-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > > > > -- > Phil. > [email protected] > http://www.philpem.me.uk/ > > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
