Sharp SG400E - UK Vintage Radio Repair and Restoration Discussion Forum

unralan · 15th Mar 2020, 4:14 pm

Hi there, does anyone have a user manual for Sharp SG400E, If found the service manual by searching on this thread (sharp sg-400h which is the same), but no luck with the actual user manual.

It has a fault I'm trying to fix, when it's turned on the turntable starts spinning, you can't put the tone arm to the record, it just moves back to the tone arm rest. Like it thinks its at the end of the record. Also while spinning the turntable, the mechanism keeps making a clicking sound. I thought maybe there is a broken cam or missing spring, but comparing it to the exploded view in the service manual, everything appears to be there is there are no obvious broken parts. I've checked both top and bottom. The only thing I did notice is underneath there is a micro switch, I guess to turn off the motor when the tone arm is at rest, the parts don't move to any position that would ever contact the switch.

When I turn the middle pin clockwise by hand, I can see the large cog on the right never disengages, here are two pictures of top and bottom.

****************/0sPt5FL
****************/594nRGH

Any ideas what the issue might be will be appreciated, thanks.

ben · 15th Mar 2020, 8:23 pm

I would be looking at how the arm is coupled to the linkages to the end of disc trip pawl. Removing /disconnecting the deck from the music centre and observing what moves when you swing the arm towards the disc centre would give a good idea. It sounds like something is pushing the trip pawl way too early.

I had one case where there was a sort of collar on the arm pivot, on deck underside , which had split and gave similar symptoms.

unralan · 16th Mar 2020, 12:51 am

Thanks Ben, I double checked the exploded view from the service manual and it seems the part on the underneath of the tone arm that moves is not orientated correctly. I'll reposition tomorrow and hopefully get it working.

unralan · 16th Mar 2020, 10:48 pm

Hey Ben It's working now

My guess is someone forced the tone arm way too far, over the centre. Then the rod from the tone arm that descends to the underneath lost its grip from the bolts that connect the mechanism underneath. I loosened the bolts and reorientated the part on the bottom that hits the micro switch, and after a few adjustments it's working perfectly

Thanks.

unralan · 1st Jul 2020, 7:12 pm

Hi there everyone, had an issue with the tone arm on the Sharp SG-400E and thanks to this forum I was able to fix it. It was working fine for a couple of months but unfortunately there is no audio output any more. It was working fine one night, the next morning no sound

I have the service manual for the SG-400H, it's exactly the same inside as the manual. I've started off by checking the voltages from the main power/amplifier board F0498AF. All appears to be OK, capacitors appear to be OK but only checked with in circuit ESR, not out of circuit. I was thinking maybe the main power transistor but then decided to test the input audio to the power/amplifier board. I could not detect any signal on my oscilloscope. It looks like a time consuming job to remove the other circuit boards but I'm willing to give it a try. As there is no audio output from record, tape or radio does anyone have any suggestions where to start. I thought maybe the preamp , which i think is IC-201 and IC-202?

Service manual is here https://freeservicemanuals.info/en/s.../SHARP/SG400H/

Thanks for any help

15th Mar 2020, 4:14 pm	#1
unralan Diode Join Date: Mar 2020 Location: Newcastle upon Tyne, Tyne and Wear, UK. Posts: 4	Sharp SG400E Hi there, does anyone have a user manual for Sharp SG400E, If found the service manual by searching on this thread (sharp sg-400h which is the same), but no luck with the actual user manual. It has a fault I'm trying to fix, when it's turned on the turntable starts spinning, you can't put the tone arm to the record, it just moves back to the tone arm rest. Like it thinks its at the end of the record. Also while spinning the turntable, the mechanism keeps making a clicking sound. I thought maybe there is a broken cam or missing spring, but comparing it to the exploded view in the service manual, everything appears to be there is there are no obvious broken parts. I've checked both top and bottom. The only thing I did notice is underneath there is a micro switch, I guess to turn off the motor when the tone arm is at rest, the parts don't move to any position that would ever contact the switch. When I turn the middle pin clockwise by hand, I can see the large cog on the right never disengages, here are two pictures of top and bottom. **************/0sPt5FL **************/594nRGH Any ideas what the issue might be will be appreciated, thanks.

15th Mar 2020, 8:23 pm	#2
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: Sharp SG400E I would be looking at how the arm is coupled to the linkages to the end of disc trip pawl. Removing /disconnecting the deck from the music centre and observing what moves when you swing the arm towards the disc centre would give a good idea. It sounds like something is pushing the trip pawl way too early. I had one case where there was a sort of collar on the arm pivot, on deck underside , which had split and gave similar symptoms. __________________ Regards, Ben.

16th Mar 2020, 12:51 am	#3
unralan Diode Join Date: Mar 2020 Location: Newcastle upon Tyne, Tyne and Wear, UK. Posts: 4	Re: Sharp SG400E Thanks Ben, I double checked the exploded view from the service manual and it seems the part on the underneath of the tone arm that moves is not orientated correctly. I'll reposition tomorrow and hopefully get it working.

16th Mar 2020, 10:48 pm	#4
unralan Diode Join Date: Mar 2020 Location: Newcastle upon Tyne, Tyne and Wear, UK. Posts: 4	Re: Sharp SG400E Hey Ben It's working now My guess is someone forced the tone arm way too far, over the centre. Then the rod from the tone arm that descends to the underneath lost its grip from the bolts that connect the mechanism underneath. I loosened the bolts and reorientated the part on the bottom that hits the micro switch, and after a few adjustments it's working perfectly Thanks.

1st Jul 2020, 7:12 pm	#5
unralan Diode Join Date: Mar 2020 Location: Newcastle upon Tyne, Tyne and Wear, UK. Posts: 4	Sharp SG-400E No audio output. Hi there everyone, had an issue with the tone arm on the Sharp SG-400E and thanks to this forum I was able to fix it. It was working fine for a couple of months but unfortunately there is no audio output any more. It was working fine one night, the next morning no sound I have the service manual for the SG-400H, it's exactly the same inside as the manual. I've started off by checking the voltages from the main power/amplifier board F0498AF. All appears to be OK, capacitors appear to be OK but only checked with in circuit ESR, not out of circuit. I was thinking maybe the main power transistor but then decided to test the input audio to the power/amplifier board. I could not detect any signal on my oscilloscope. It looks like a time consuming job to remove the other circuit boards but I'm willing to give it a try. As there is no audio output from record, tape or radio does anyone have any suggestions where to start. I thought maybe the preamp , which i think is IC-201 and IC-202? Service manual is here https://freeservicemanuals.info/en/s.../SHARP/SG400H/ Thanks for any help