Looking for a replacement for L405 from a Sony STR-6060FW. This is a 19KHz tuned transformer with center tapped primary and secondary that feeds the diode frequency doubler. This type of stereo demux is so common I would expect these transformers to be ubiquitous, but my searches so far have come up empty.
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You can se why the MC1310 was such a game changer.
A stable 19 kHz transformer was probably a ferrite pot core in those days and expensive
A stable 19 kHz transformer was probably a ferrite pot core in those days and expensive
It may be a Toko product : I suggest that you contact the owner of
info@gekade.com: TOKO coils and chokes
It was EMEA representative for toko and keep a stock
info@gekade.com: TOKO coils and chokes
It was EMEA representative for toko and keep a stock
Hi Ylli,
I have the same receiver with the same problem, I think my stereo light is not working. I traced it to the same transformer as you.
My question is did you ever find a new transformer?
Thanks
I have the same receiver with the same problem, I think my stereo light is not working. I traced it to the same transformer as you.
My question is did you ever find a new transformer?
Thanks
What would be making those xfmrs fail? They seem to be in a low voltage low current sort of a circuit.
I'm not sure all I know is I spent 3-4 hours tracing a dimly lit stereo lamp that wouldn't respond when a strong signal was obtained.
I have never come across a bad transformer in that type of circuit before either, that's why it took me so long to figure it out.
The unit was brought to me for a recap and I changed all the lamps which were out, before discovering the problem.
What I did notice was someone tried to repair it before and had the two wires from the stereo-mono switch backwards so I'm thinking they must have removed the board at one point.
I have never come across a bad transformer in that type of circuit before either, that's why it took me so long to figure it out.
The unit was brought to me for a recap and I changed all the lamps which were out, before discovering the problem.
What I did notice was someone tried to repair it before and had the two wires from the stereo-mono switch backwards so I'm thinking they must have removed the board at one point.
OR, this is DIY audio. The multiplex board is a stand alone board. You can still get the Motorola MC1310P
PLL decoder IC (works better than the frequency doubler). Design a new board to replace the old one. No
complex alignment and just 1 pot to set the center frequency of the internal oscillator.
Stereo decoder circuit using MC1310P
The worst you would need to add (only maybe) an input opamp to get the input level to 1 VRMS and maybe
an output opamp to boost the output level. 2 ICs and maybe a couple dozen passives and you're good to go.
If you're intent on "restoring" the unit this would not fill the bill but if the goal is to listen to FM stereo, this
would be fine.
G²
Agreed with the MC1310P replacement board. You don't even know whether the transformer's primary is a CT one or just tapped somewhere in order to match impedances. The secondary supposedly is CT indeed.
Best regards!
Best regards!
Now I'm really confused,
The guy that brought this unit (which used to be his dads) has another one that was not working so he brought me the decoder board from it and..........Same problem with the lamp Err, but now the stereo-mono switch seems to work. But the sound is now weak on the left side in FM stereo, in mono it switches back and sounds normal as far as sound level on both sides.
He will probably never listen to FM but he said he wanted it fully restored, CRAP.
I may have to put the decoder chip in, but I haven't given up on it yet I like a challenge.
I can send pics of the schematic if anyone wants to help, I can explain voltages. All the transistors on both boards check good I even replaced the two in the lamp circuit (old board) just to make sure, I also recapped it as far as electrolytics go.
The guy that brought this unit (which used to be his dads) has another one that was not working so he brought me the decoder board from it and..........Same problem with the lamp Err, but now the stereo-mono switch seems to work. But the sound is now weak on the left side in FM stereo, in mono it switches back and sounds normal as far as sound level on both sides.
He will probably never listen to FM but he said he wanted it fully restored, CRAP.
I may have to put the decoder chip in, but I haven't given up on it yet I like a challenge.
I can send pics of the schematic if anyone wants to help, I can explain voltages. All the transistors on both boards check good I even replaced the two in the lamp circuit (old board) just to make sure, I also recapped it as far as electrolytics go.
RF transformers rarely "burn out" or otherwise break.
The only likely disaster is a ham-fisted attempt to tune it cracking the tuning slug
The only likely disaster is a ham-fisted attempt to tune it cracking the tuning slug
I realize this is an old thread, but I'd like to propose another reason why these transformers fail... the adhesive they used for the caps is corrosive (based upon the green crud on the resistor legs ONLY by the .0047 uF caps that also happen to be right by the transformers). It's highly unlikely that every 6060 that has the stereo issue (many of them do) had a ham-fisted repair. It's more likely IMO that these wires are corroding and failing, they are very thin. I can't think of another reason why an otherwise relatively stable component like that would fail in so many examples of this receiver.