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Chip Amps Amplifiers based on integrated circuits

Technics SUV4X  runs cool!
Technics SUV4X  runs cool!
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Old 30th June 2017, 11:28 AM   #41
SVI2004A is offline SVI2004A  New Zealand
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Technics SUV4X  runs cool!
I have never re capped a V4X yet... unlike a lot of amps, there aren't a lot of caps in this amp only 3 in signal path (2 of them on tone board)

There is a 4th cap on phono board.

- I am somewhat a recap skeptic- lost count of how many times I've read on forums how an amp quit working after a so called re cap... but it's no big job to change the few caps in path.
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Old 12th July 2017, 08:28 AM   #42
ssi is offline ssi  United Kingdom
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Hi

Which cap is in the signal path on the v4x that is not on the tone or phono board? Is it the 2200uf cap?

Thanks
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Old 12th July 2017, 08:51 AM   #43
SVI2004A is offline SVI2004A  New Zealand
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Technics SUV4X  runs cool!
C501 Lch and C502 Rch- 50V 3.3uF
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Old 12th July 2017, 11:06 AM   #44
ssi is offline ssi  United Kingdom
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Thanks
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Old 14th July 2017, 08:23 AM   #45
ssi is offline ssi  United Kingdom
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Hi, replaced the C501 Lch and C502 Rch- 50V 3.3uF on my SUV4x without issue. Getting good at using the braid for desoldering now thanks SVI2004. I have improved my technique by using a larger and hotter tip which flows the solder easily through the braid and allows the braid to absorb the solder. The tip I was using before was too small.

The amp sounds a bit sharper but it could just be my imagination! I want my little change to be an improvement!

Another thing.

Do you think it is worth reapplying thermal paste to the SVI2004 chip as these amps are 30 + years old now or would it cause more problems than it is worth disturbing things unnecessarily?

Any thoughts....?

Last edited by ssi; 14th July 2017 at 08:27 AM.
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Old 14th July 2017, 10:41 AM   #46
SVI2004A is offline SVI2004A  New Zealand
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Technics SUV4X  runs cool!
Hiya

No point pulling power ic... I never pull chips out unless necessary. The compound from factory is fine and only needs changing on installation of power ic.

I've never recapped a V4X (except the memory gold caps - done a heap)

Main thing is you're getting the good sound

Most of my V4X amps the power ic has never been touched/resoldered... mostly I resolder q501-4 dry joints and the occasional relay
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Old 14th July 2017, 11:25 AM   #47
ssi is offline ssi  United Kingdom
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Thanks - good advice

I just replaced those 2 small caps to develop my skills further.
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Old 7th November 2017, 03:31 PM   #48
ssi is offline ssi  United Kingdom
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Hi all

Not used my SUV4x for a bit and got it out recently. Left channel sometimes drops out completely at lower volumes but comes back on if you turn it up. Often happens if cold but has happened after a few hours of use as well. Tried the usual like checking solder joints on the main board including the relay and also the volume control. Not checked the input selector module yet or balance control or speaker selection. Any advice or pointers would be appreciated. Sounds great when working.

Thanks
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Old 11th November 2017, 09:47 AM   #49
ssi is offline ssi  United Kingdom
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Hi all

Found the error. Soldering on main board for the speaker terminals. Reflowed solder and all good. Amp worked fine on headphones which led me to suspect error with speaker terminals.

Best Wishes
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Old 11th November 2017, 11:56 AM   #50
ssi is offline ssi  United Kingdom
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New problem. At about 33% volume with a heavy bass thump the amp may be clips and goes silent momentarily (not relay) and then resumes. It is too loud for normal listening anyway at this level but just testing it!. There is no distortion prior to the "clipping". Could it be the main power caps?

Thanks

Last edited by ssi; 11th November 2017 at 12:04 PM.
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