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 Post subject: Carver TX-11
PostPosted: Jan Thu 31, 2019 2:29 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1450
Location: Hartford, KY
Not the TX-11a or b but the TX-11. I have searched all over the internet but can not find much info on this tuner. I have been given one to look at as it does not produce any sound, hiss or crackle. I need a schematic for this unit. Hi Fi Engine has a little but most is on the TX 11a and b. This is an FM only tuner. Its been some time since I have seen the insides of any tuner but is anyone familiar with this unit? I may need to try AudioKarma but thought I would try hear first.


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 Post subject: Re: Carver TX-11
PostPosted: Jan Thu 31, 2019 2:49 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 18544
Location: Albuquerque, NM 87123
I would first look at the power supply voltages. Carvers of various models didn't have the best PS designs and they used under-sized heat sinks.


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 Post subject: Re: Carver TX-11
PostPosted: Jan Thu 31, 2019 9:50 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1450
Location: Hartford, KY
Thanks for your response Johnnysan. Do you have any idea what the power supply voltages are supposed to be? I am assuming +12 and -12 and that's what I get from one transformer. Yes it has two, it looks like one feeds the main board and and second one feeds the multipath board as they call it. I have 11.97 volts on one lead and 11.98 volts on the other lead to the main power board, however the second power supply shows a higher voltage if memory serves. I plan to recheck the voltages again as I noticed several caps were running warm to the touch. Main thing I have done to to visually inspect the boards for issues that might can be seen. I have studied the boards my just reading the circuit board and it's various notations and figuring out some common sense type things but will continue on to see what I can find. I also have found voltage readings for many of the chips on the board. Again thanks for the response.

LLOYD


Last edited by Spivey on Feb Fri 01, 2019 1:41 am, edited 1 time in total.

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 Post subject: Re: Carver TX-11
PostPosted: Jan Thu 31, 2019 10:01 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 18544
Location: Albuquerque, NM 87123
If the power supply voltages seem close then I would check the audio op-amps; make sure they have - and + power going to them. Are the schematics for the A and B versions close enough to use?


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 Post subject: Re: Carver TX-11
PostPosted: Jan Thu 31, 2019 11:01 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1450
Location: Hartford, KY
They appear so but its hard to follow. It just takes a little longer to figure out.


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 Post subject: Re: Carver TX-11
PostPosted: Mar Thu 07, 2019 6:44 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1450
Location: Hartford, KY
Still looking for a schematic for this thing. I am curious should there be a 5 volt supply somewhere? The only place I haven't taken a part so far is the front display board. That comes next.


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 Post subject: Re: Carver TX-11
PostPosted: Mar Thu 07, 2019 7:36 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 18544
Location: Albuquerque, NM 87123
Does it have station presets? If so then it probably has a 5 volt rail; there will be a capacitor near the microprocessor that should be about .047 farad or so. 5.5 volt rating.


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 Post subject: Re: Carver TX-11
PostPosted: Mar Thu 07, 2019 11:13 pm 
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Joined: Jan Tue 31, 2012 1:55 am
Posts: 9488
Location: Mountains of Mourne. Ireland.
A 30-page service manual for Carver TX-11 can be purchased here.
http://www.stereomanuals.com/man/rep/carver/index.htm

CRVTX11-SM


Greg.


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 Post subject: Re: Carver TX-11
PostPosted: Apr Tue 30, 2019 3:21 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1450
Location: Hartford, KY
OK, a quick update on this unit. There is a lot going on circuit wise with this receiver but here is where I am. This Carver has an LA 3381 STEREO DECODER in it and I have a question about finding a data sheet that shows me the pin outs of this chip and which are input or outputs. Google only gives a data sheet in Japanese I believe and is of no help. There use to be I thought, data books that listed all popular chips of the day and what went on inside, this would have been in the mid 80's I think. My question is with the chip right now is that all pin voltages listed on the schematic is within a half volt or less volt however we have discovered that pin 12 of the chip has 15 volts on it when the schematic says it should be 1.4 volts. Right wrong, schematic has no voltage readings on this section. Am I thinking correctly that this chip may have a problem? Just trying to keep my thought processes correct. I certainly would hate to go chasing my tail.


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