Re: Trying to bring back a AA501
Watch out! The CD and 74 pinouts are different. You don't what to hack up your circuit board.toggle quoted messageShow quoted text
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
Sent: Sunday, January 05, 2020 6:51 AM
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