Re: Trying to bring back a AA501
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Watch out! The CD and 74 pinouts are different. You don't what to hack up your circuit board.
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Also, be advised, when troubleshooting IC's in general having the schematic of the device gives understanding of how inputs and outputs work. For example a tri-state output could be "off" and not "open." A CMOS input is high impedance so you don't know if the input stage is blown unless a clamp diode is shorted. The ultimate is to try the truth table, a lot of work on complex parts. Parts substitution can't be beat for getting results. I always buy two or more when in that situation. eBay to the rescue - Item #372418190226 Arden
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From: Eric Sent: Sunday, January 05, 2020 6:51 AM To: TekScopes@groups.io Subject: Re: [TekScopes] Trying to bring back a AA501 I did find out that the AA501 does need the VCC of 15V so the HC series logic is out for sure. I am going to order some of the direct replacement parts as there is a supply house that has then mouser and digikey were out. Texas Instrument cross reference says a CD40175BE is a comparable part as well. I have also confirmed the fault as with this IC out of circuit the 501 says 100+% distortion on all frequencies also one of the outputs is open when i check it with my small curve tracer. On this one pin 14 is dead. On 1/5/2020 1:08 AM, KeepIt SimpleStupid via Groups.Io wrote: My GOTO place has it: http://www.utsource.net/sch/MM74C175N
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