'Vintage' Toshiba portable no sound: searching for IC TA7176AP
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Location: Albany, WA
Member since 20 January 2012
Member #: 1068
Postcount: 25
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My vintage Toshiba "portable" C-1815 has lost sound and I've verified that the TA7176AP chip is dead. Apparently this IC cross-references to AN241, CA3065, HA1125, KA2101, LA1365, LA3065, MC1358, ULC2168 and ECG712.
The set is in nice condition and has a decent picture and If a few $ gets it going again it will be worth the effort so if anyone has a suitable IC please let me know price and postage to 6330 WA.
I couldn't find a schematic online for this model either, so if anyone can help with that it would be greatly appreciated also.
TIA for any help.
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Location: Hobart, TAS
Member since 31 July 2016
Member #: 1959
Postcount: 544
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I think from memory these are the output chips that have little wing heat sinks in the middle.
Will have a look tomorrow for you, I'd be surprised if I didn't have one or its equivalent.
I think even HMV used these in their c211 colour sets.
Just edited my post, may be wrong might have been in the sound detector, not the winged output chips. Anyway should have one.
JJ
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Location: Albany, WA
Member since 20 January 2012
Member #: 1068
Postcount: 25
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No wing on this particular chip it's a straight 14 pin dip. Yes it's a TV IF detector/amp sound chip
Cheers.
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Location: Sydney, NSW
Member since 28 January 2011
Member #: 823
Postcount: 6686
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Location: Hobart, TAS
Member since 31 July 2016
Member #: 1959
Postcount: 544
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Have had a look, but unfortunately no.
Lots with similar numbers.
WES Components Sydney have them for a few dollars, and I notice EBay has a lot at various ridiculous prices.
JJ
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Location: Albany, WA
Member since 20 January 2012
Member #: 1068
Postcount: 25
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WES looks like the go, thanks guys for your help - appreciated.
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Location: Albany, WA
Member since 20 January 2012
Member #: 1068
Postcount: 25
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Well I found some on Aliexpress, Under $3 for five, including postage.
Expectations are low but for $3... worth a punt. I'm in no hurry to repair it.
I'll post an update if and when when they arrive, if they are the real deal, recovered or new and if they work or not.
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Location: Hill Top, NSW
Member since 18 September 2015
Member #: 1801
Postcount: 2012
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Just remember the chip probably blew up for a reason, so check nearby electrolytics.
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Location: Belrose, NSW
Member since 31 December 2015
Member #: 1844
Postcount: 2369
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Could have been CRT flashover, most likely cause. Not much you can do about that.
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Location: Albany, WA
Member since 20 January 2012
Member #: 1068
Postcount: 25
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I have already replaced the electrolytics in the audio circuitry already as a precaution and I'll replace the main filters too I think.
I'll see how it goes beyond that.
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Location: Belrose, NSW
Member since 31 December 2015
Member #: 1844
Postcount: 2369
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The original large can electros in that TV are probably better quality than any replacements you might use.I wouldn't bother.
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Location: Albany, WA
Member since 20 January 2012
Member #: 1068
Postcount: 25
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I removed a few of the caps and tested them. Capacitance and ESR seemed bang on so they went back in. I'll assume all the others are OK.
Another problem I have now found is that the kids say they can hear an irritating high pitched sound when it's on. I did a check and it's the 15kHz... which of course the more mature members of the family can't hear. Sigh...
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Administrator
Location: Naremburn, NSW
Member since 15 November 2005
Member #: 1
Postcount: 7300
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All CRT televisions and monitors emit a resonating noise, I assume from the tripler or its associated circuitry. I can hear it loud and clear despite partial deafness. Though if it is louder than usual, it may mean something is under stress.
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A valve a day keeps the transistor away...
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Location: Sydney, NSW
Member since 28 January 2011
Member #: 823
Postcount: 6686
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Flyback noise presumably. I can't hear it that well these days either, but I gave my analogue TV away to a worthy cause a while ago.
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Location: Hill Top, NSW
Member since 18 September 2015
Member #: 1801
Postcount: 2012
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I used to be able to hear that whistle from TVs, but now with the tinnitus, the noise is there all the time, together with many other noises.
In my younger days I was able to hear it in the street, as I walked past houses with the TV turned on. Not any more.
The noise, I believe, is emitted by the line output transformer, and perhaps the picture tube and yoke too. It was absolutely deafening close to the back of a TV.
I only have one CRT TV left to annoy me, plus some CRT computer monitors which run at a higher (inaudible) frequency.
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