Nakamichi SR-4A Tuner and display are dead; please help - diyAudio
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Old 31st January 2012, 06:16 PM   #1
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Default Nakamichi SR-4A Tuner and display are dead; please help

Just for fun I aquired a Nakamichi SR-4A receiver. I own quite a few Nakamichi cassette decks, but no other Nakamici device. Coming across this receiver, I thought it would be a nice gadget to play with...
It works just fine in all mods, from Phono (both MC and MM), to tape. The only things which are not working are the Tuner, the Display and anything related to this one. The remote control does not work either.
I assume it has to do with the power going to the tuner and display where the remote sensor is too.
I checked all fuses and they are all fine. Since I was not able to locate a service manual, I have nu schematics; that would be a step in the right direction but if any one experienced the same issue, please share.
Thanks
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Old 31st January 2012, 07:09 PM   #2
Jebem is offline Jebem  Portugal
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This site has got service manuals, but it requires you to register first.
Download the Nakamichi SR-4 service manual for free - Hifi Manuals
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Old 4th March 2015, 06:49 PM   #3
hewo is offline hewo  United States
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Default SR-4A orange power LED indication

Can some one please guide troubleshoot steps to restore operability ?
orange power light indicated but no display and no relay clicks on power up.
downloaded service manual above but manual is SR-4 not SR-4A
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Old 5th March 2015, 12:21 AM   #4
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Quote:
Originally Posted by hewo View Post
Can some one please guide troubleshoot steps to restore operability ?
orange power light indicated but no display and no relay clicks on power up.
downloaded service manual above but manual is SR-4 not SR-4A
Easy.
open unit.
test to find faults.
repair faults.
close unit.

Anything else you'd like explained ?

Or, My favorite.
if your unable to perform basic tests, safely, then take to someone that can...
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Old 5th March 2015, 12:22 AM   #5
rayma is online now rayma  United States
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Quote:
Originally Posted by Old'n'Cranky View Post
Easy.
open unit.
test to find faults.
repair faults.
close unit.

Anything else you'd like explained ?

Or, My favorite.
if your unable to perform basic tests, safely, then take to someone that can...
Wow, you really are cranky.
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Old 5th March 2015, 03:46 AM   #6
hewo is offline hewo  United States
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Default easy SR-4A

Orange light indicates fault.
it is difficult upsidedown power board measuring proper dc feeding voltages, toroid and power board upsidedown dismantled, key voltages threesome 5.6, 10 (12), 30 dc.
Orig discovery 2amp fuse open and power board sponge underside leaking energy out of system. Replcd 2amp pigtail fuse, zd403, q403 and q402. (Zener6.8, c945, d1406)
Yet persists orange power light.
Checked bridges okay out of circuit (three).
Gotta save this amp cause rare.
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Old 5th March 2015, 09:30 AM   #7
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Originally Posted by rayma View Post
Wow, you really are cranky.
You forgot the old bit.
Old And Cranky
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Old 5th March 2015, 10:25 AM   #8
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I would check the power supply for rails missing particularly the display supply that is common with the tuner supply. The 4A is electrically similar to the Canada Only 4.
Keep a clear head and be methodic.
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Old 6th March 2015, 03:05 PM   #9
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Quote:
Originally Posted by hewo View Post
Can some one please guide troubleshoot steps to restore operability ?
orange power light indicated but no display and no relay clicks on power up.
downloaded service manual above but manual is SR-4 not SR-4A
I had the same problem on a SR-4E, fixed it by replacing Q404 and D414. Used a KSA733 and a 1N4002. (also replaced Q405 while I had it dismantled, but it was probably not needed.)
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Old 6th March 2015, 03:27 PM   #10
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By the way, orange light means standby.

Constant flashing green means it's in protection.
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