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Old 15th May 2018, 6:01 am   #1
macmich
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Default LA 16 Diode

Hi
I have to replace two diodes in a Hitachi music centre SDT-7660, I cannot find a schematic to download and the marking on the diodes is LA 16. I have searched the net for information on this diode without success and I am hoping someone could point me in the right direction.
I have gone through and changed the belts to the turntable and cassette player and cleaned the unit through. When I went to power up the cassette player it had no power, when I connected the 12-volt bench power to it everything worked fine and with a bit of searching, I found the burnt out diodes and I presume these are the cause for loss of power to the cassette player on the unit.
Thanks
Paul
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Old 15th May 2018, 11:30 am   #2
Refugee
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Default Re: LA 16 Diode

They will most likely be ordinary rectifier diodes such as 1N4002 (small) or 1N5402 (large).
Higher voltages will work if you have got them in your stash.
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Old 15th May 2018, 7:27 pm   #3
Marconi_MPT4
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Default Re: LA 16 Diode

Suspect they are the standard, difficult to get, 16V zener diodes commonly employed in late 1970's Hitachi audio. Some fail due to overheating and if short circuit I would also check associated series feed resistor going low value. Physically, from memory, they were possibly of glass/ceramic bead construction.

Cheers
Rich
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Old 15th May 2018, 7:57 pm   #4
ms660
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Default Re: LA 16 Diode

The SDT 7680 might use 16 volt Zeners, not sure what, if anything the circuit has in common with the SDT 7660, SDT 7680 manual's available on Elektrotanya.
(I think)

Lawrence.

Last edited by ms660; 15th May 2018 at 8:07 pm. Reason: correction
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Old 16th May 2018, 1:13 am   #5
macmich
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Default Re: LA 16 Diode

Hi.

I downloaded the 7680 service manual and it is not close to the 7660.

Cheers.
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Old 16th May 2018, 10:34 am   #6
ukcol
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Default Re: LA 16 Diode

I suspect your diode is a Hitachi AU01-16 and the markings are possible a short form type number. The AU01-16 is a 16 volt zener rated at 2.5 watts (see attached data sheet).

Can you post a picture of the board with the diodes on?
Attached Files
File Type: pdf Hitachi AU01 zener.pdf (70.6 KB, 35 views)
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Old 16th May 2018, 10:42 am   #7
ms660
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Default Re: LA 16 Diode

The SDT 7680 I referred to earlier uses them.

Lawrence.
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