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Chip Amps Amplifiers based on integrated circuits

Technics SUV4X  runs cool!
Technics SUV4X  runs cool!
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Old 7th June 2017, 10:45 AM   #21
SVI2004A is offline SVI2004A  New Zealand
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Location: Feeding eels in a stream near you
Technics SUV4X  runs cool!
I once tried a blue led on one of my safety operation... stayed there a week... was much brighter than any other in the system.

What speakers do you prefer - though a V4X makes them all sound great....
ATM I am using the Technics Honeycomb disc ones SB-6 SB-X500 SB-X700
Enjoy B&W on them too... A surprise is the Sony XG900AV speakers...
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I remember when amps were amps & speakers were nervous!
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Old 7th June 2017, 11:07 AM   #22
ssi is offline ssi  United Kingdom
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Hi

I am using a pair if B&W Dm601S2's but also have a pair of later (cheaper) sony APM's with 3 drivers (floorstander) but my wife will only let me get them down from the loft occasionally.

Do you think I would have done some permanent damage to the amp by plugging in the ribbon cable the wrong way? I switched it off with in seconds of the relay clicking on and off (two or three times max) which is what the blinking safety operation light would have been doing! I suppose the higher voltage blew the safety operation led

I turned it on again this morning and it was quiet for a few second but came back to normal.


Will check it out again when I get home from work. Really quite annoyed with myself for making such a dumb mistake. Any "health checks" I can do to assess any potential damage?

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Old 7th June 2017, 11:37 AM   #23
SVI2004A is offline SVI2004A  New Zealand
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The fact it's still working is very good.... the icq controller and led drive array has survived...

I'd check dc offset - have amp on for 10 mins - volume at 0 -no speakers connected, check for DC voltage at speaker outputs use 200mv dc mode on meter. (maybe adapt a small run of wire to lock into speaker terminals) if all is healthy you'd see less than 5mV (mine all range from 0mV to +/- 2mV. - bias is automatic in these sets (no adjustment)

Another thing to look at is the 2 Gold Caps 2.5V 3.3F (these are memory caps for the input selector) if these fail, it'll always revert to Tuner input
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Old 7th June 2017, 12:01 PM   #24
ssi is offline ssi  United Kingdom
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Hi

When I had a look this morning bias was 15 - 17mv on left and 5-7mv on the right - pretty much what it was when I got it. Besides changing the IC which controls bias is there anything else I could do / check to get these values down?
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Old 7th June 2017, 01:00 PM   #25
SVI2004A is offline SVI2004A  New Zealand
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It's not bias... it's AN7062 (more precisely the differential pairs of input transistors) only cure is a new AN7062 - they're nearly all fakes now. But those readings are still ok. (I had one once that was -112mV, which was fixed by fitting new 7062)
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Old 7th June 2017, 04:29 PM   #26
ssi is offline ssi  United Kingdom
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Hi, AN7062 in the unit is fake - from your earlier description - has an m on it. Is it worth spending 20 on a replacement from a reputable uk seller?
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Old 7th June 2017, 05:29 PM   #27
SVI2004A is offline SVI2004A  New Zealand
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Technics SUV4X  runs cool!
It may be a late run genuine... the fakes I come across just died on power up.

Looks like eBay is riddled with them....

I'd just leave it be for now.... maybe one may surface.

In the mean time I recommend you get familiar with desoldering braid (get decent stuff) it will stop train wrecks pulling chips and transistors
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Old 7th June 2017, 06:55 PM   #28
ssi is offline ssi  United Kingdom
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Hi. I have an suv2x and replaced the "New Class A" bulbs tonight without a hitch using a solder sucker and then brade. I only attempted to remove and solder in a component about 2 weeks ago for the first time - replaced a relay and was very proud of myself! I was quite scared to even have a go at first.

Thank you for your suppport and encouragement.
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Old 7th June 2017, 07:11 PM   #29
SVI2004A is offline SVI2004A  New Zealand
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Technics SUV4X  runs cool!
Nice going...

Braid is best for chips and things with lots of pins

https://www.youtube.com/watch?v=cfKTnKeRZYw

Did this ages ago, you can see a power ic pulled without any pin damage.... even after a number of drinks
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Old 7th June 2017, 07:21 PM   #30
ssi is offline ssi  United Kingdom
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Saw the video - very stable after a few beers! Thanks
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