240260280 Posted July 14, 2019 Author Share #13 Posted July 14, 2019 Good news! It was the op-amp Hitachi FA-6007T that died. I'm not sure if there are any other Hitachi radios using this early bird? FYI a quick and dirty test of the audio section is to simply touch pin 1 and the radio should hum. 1 Link to comment Share on other sites More sharing options...
HS30-H Posted July 14, 2019 Share #14 Posted July 14, 2019 7 hours ago, 240260280 said: I thought this was yours: https://www.gtr.co.uk/forum/236658-1969-nissan-s20-twin-cam-engine-rebuild.html ? Yes but what's the connection with zclub.net? From here: 8 hours ago, 240260280 said: btw your UK website is great. It often comes up in searches... They are two - completely unconnected - clubs and forums. Link to comment Share on other sites More sharing options...
240260280 Posted July 14, 2019 Author Share #15 Posted July 14, 2019 My error. Excellent sites and content none the less. Alan your genius comes to light on the GTR site! Nice stuff! 1 Link to comment Share on other sites More sharing options...
240260280 Posted July 16, 2019 Author Share #16 Posted July 16, 2019 (edited) Just ordered an opamp to repair the radio. All is good. Old (Pin 1 is on left side above. There is a raised line on the left edge) New Edited July 17, 2019 by 240260280 1 Link to comment Share on other sites More sharing options...
Captain Obvious Posted July 17, 2019 Share #17 Posted July 17, 2019 15 hours ago, 240260280 said: Pin 1 is on right left side Uhhhh.... That might make sense to someone, but I'm not one of them. Out of curiosity, do you have a datasheet for that part? Link to comment Share on other sites More sharing options...
240260280 Posted July 17, 2019 Author Share #18 Posted July 17, 2019 Sorry. I corrected entry but left the wrong right in. <<< makes sense right? Fixed now. Sorry. No I do not have data sheet. I would love to see it too I think the IC is more than just an op-amp as it feeds back to the auto tuning circuit. See Pin 7's output below. I will guess that the op-amp function can be substituted with a compatible op-amp but you will loose the auto tuning without developing the associated circuitry to trigger an amplitude lock on a signal or maybe it is a mute while tuning control? Link to comment Share on other sites More sharing options...
Captain Obvious Posted July 17, 2019 Share #19 Posted July 17, 2019 13 minutes ago, 240260280 said: the wrong right in. <<< makes sense right? Yup! I Got it! Haha!! So not that it really matters, but that's an AF (Audio Frequency) amp, not an op-amp. Good luck with the repairs. I paid my way through a couple years of college fixing audio-visual equipment. One of the things I learned is that 95% of all failures are blown output stages. Even if the problem does not appear to be a blown output, it might be anyway. 1 Link to comment Share on other sites More sharing options...
240260280 Posted July 17, 2019 Author Share #20 Posted July 17, 2019 I bravely swapped bad unit's output stage to working unit and it continued working. I put working units output stage in bad radio an no change. I then moved good AF SIP to bad radio and it worked... risky but easy. I did verify all voltages in power transistors were the same before swapping so low risk in the end. 1 Link to comment Share on other sites More sharing options...
240260280 Posted July 17, 2019 Author Share #21 Posted July 17, 2019 @Captain Obvious attached below is schematic with details of FA6004 audo amp in 1972 portable Hitachi radio. Same 8pin SIP module. It may be similar in some ways. The best I can do. FA6004 Details.pdf 1 Link to comment Share on other sites More sharing options...
Captain Obvious Posted July 18, 2019 Share #22 Posted July 18, 2019 Cool. Neat find. based on the pin numbers and similar use in the schematics, I would concur that there are a lot of similarities. Good luck with the repair. Sounds like you're almost done! Link to comment Share on other sites More sharing options...
Jeff Berk
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