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Old 10th Apr 2018, 7:03 am   #2
Diabolical Artificer
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Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,637
Default Re: Telequipment/Tektronix D75 No trace on Power Up.

"am I going about it the right way??" I'm no expert but I'd say yes. One thing I've learned in my short time mucking about with electronics is "Thou shalt check voltages" and the other is break a big complex circuit into little bits.

Another tip here ont forum is to attach a schematic of said device or bit of device to help folk help you with your enquiry. the only one I found that didn't charge money had picture's of lasses in bikini's and playing poker, so I didn't bother. They might be nice young ladies, who're not after the £10 I have in the bank, but still.

That aside, sounds like something is pulling the 105v line down, there's two ways of finding the fault, that I know of - use a DMM across the rails to check resistance, anything under 100 ohm's is suspicious, around 10 ohms or less = fault. Second is using a lamp limiter or similar to keep the brake on current drawn, power up and have a feel and smell to try and trace said fault. Were trying to avoid the stinky smoke stage if poss. Obviously checking out the schematic should give clues like series pass transitors, zener diodes used as shunt regulators etc.

Andy.
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