Replacement for a Sanyo A1221 4-pin. Transistor? - UK Vintage Radio Repair and Restoration Discussion Forum

collisr · 21st Apr 2021, 2:33 pm

Hello!

As a relative novice, I am attempting to overhaul an early 70s Shibaden S610 VTR. I have a working machine as a reference (good), but no service manual (bad)

After re-capping the Demodulator board (which had several way out of spec elcos), my next challenge is to fix the lack of flow from Tape RF in -> CVBS out.

There are no traditional ICs on the board but looks like a component labelled "IC1" has failed.

It is a Sanyo A1221 4-pin semiconductor component which I have never come across before. Can anyone advise what this thing is and - hopefully - a modern replacement?

Cobaltblue · 21st Apr 2021, 2:46 pm

Looks like its one of these.

https://www.digchip.com/datasheets/p...LA1221-pdf.php

Cheers

Mike T

paulsherwin · 21st Apr 2021, 2:46 pm

It appears to be an FM detector chip.

https://www.ebay.co.uk/itm/LA1221-A1...-/282053719406

It looks to be quite simple, so you may be able to lash something up using discrete components.

collisr · 21st Apr 2021, 3:14 pm

Thanks guys. I did see the US-based ebay listing for NOS, but was hoping someone with more knowledge than me would be know of a modern equivalent to replace it with. An FM detector makes sense, this is the first component after the Tape RF input, but the next component down has no signal detected on a scope.

G6ONEDave · 21st Apr 2021, 4:16 pm

According to my 1999 Jaeger Elektronik book that A1221 is actually an LA1221 and is classed as a linear IC for FM intermediate frequency use. Unfortunately the book does not list an alternative.

Dave

DMcMahon · 21st Apr 2021, 5:30 pm

Fairly obvious maybe but make sure that the DC supply (VCC) is getting to pin 2 wrt (with respect to) the ground pin 4 as per the data sheet in Mike's Post.

Some ICs can have low pin count and physically look like typical transistor body shape wise.

David

21st Apr 2021, 2:33 pm	#1
collisr Pentode Join Date: Oct 2016 Location: Ware, Herts, UK Posts: 171	Replacement for a Sanyo A1221 4-pin. Transistor? Hello! As a relative novice, I am attempting to overhaul an early 70s Shibaden S610 VTR. I have a working machine as a reference (good), but no service manual (bad) After re-capping the Demodulator board (which had several way out of spec elcos), my next challenge is to fix the lack of flow from Tape RF in -> CVBS out. There are no traditional ICs on the board but looks like a component labelled "IC1" has failed. It is a Sanyo A1221 4-pin semiconductor component which I have never come across before. Can anyone advise what this thing is and - hopefully - a modern replacement? Attached Thumbnails Last edited by collisr; 21st Apr 2021 at 2:38 pm.

21st Apr 2021, 2:46 pm	#2
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,866	Re: Replacement for a Sanyo A1221 4-pin. Transistor? Looks like its one of these. https://www.digchip.com/datasheets/p...LA1221-pdf.php Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

21st Apr 2021, 2:46 pm	#3
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: Replacement for a Sanyo A1221 4-pin. Transistor? It appears to be an FM detector chip. https://www.ebay.co.uk/itm/LA1221-A1...-/282053719406 It looks to be quite simple, so you may be able to lash something up using discrete components.

21st Apr 2021, 3:14 pm	#4
collisr Pentode Join Date: Oct 2016 Location: Ware, Herts, UK Posts: 171	Re: Replacement for a Sanyo A1221 4-pin. Transistor? Thanks guys. I did see the US-based ebay listing for NOS, but was hoping someone with more knowledge than me would be know of a modern equivalent to replace it with. An FM detector makes sense, this is the first component after the Tape RF input, but the next component down has no signal detected on a scope.

21st Apr 2021, 4:16 pm	#5
G6ONEDave Octode Join Date: Dec 2019 Location: Owston Ferry, North Lincolnshire, UK. Posts: 1,701	Re: Replacement for a Sanyo A1221 4-pin. Transistor? According to my 1999 Jaeger Elektronik book that A1221 is actually an LA1221 and is classed as a linear IC for FM intermediate frequency use. Unfortunately the book does not list an alternative. Dave __________________ Quote "All is hyperthetical, until it isn't!" (President Laura Roslin, Battlestar Galactica)

21st Apr 2021, 5:30 pm	#6
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 6,603	Re: Replacement for a Sanyo A1221 4-pin. Transistor? Fairly obvious maybe but make sure that the DC supply (VCC) is getting to pin 2 wrt (with respect to) the ground pin 4 as per the data sheet in Mike's Post. Some ICs can have low pin count and physically look like typical transistor body shape wise. David