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Chip Amps Amplifiers based on integrated circuits

Technics SUV4X  runs cool!
Technics SUV4X  runs cool!
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Old 18th May 2017, 07:36 PM   #1
ssi is offline ssi  United Kingdom
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Default Technics SUV4X runs cool!

Hi all

I purchased a Technics SUV4X and it tunrs out to be a German market model (220v) but seems to run ok in the UK 230/240v roughly. It has a slightly different circuit board (4 copper coils near speaker terminals) and no voltage selector. Unlike my UK market model it runs cool unless you turn up the volume a lot. Why would this be? Replaced SVI2004 perhaps? A small IC chip with a heat sink does get hot and so does the speaker relay which I replaced.

Please note I am very much an amatuer but am willing to have a go and learn.

Best Wishes

SSI

Last edited by ssi; 20th May 2017 at 05:45 AM.
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Old 21st May 2017, 03:30 AM   #2
sgrossklass is offline sgrossklass  Germany
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Measuring the rail voltages may be worth a shot here. I'd expect they'd be a fair bit lower in a unit destined for 4 ohm territory, even at slightly higher mains voltage, which may explain the difference.
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Old 21st May 2017, 05:30 AM   #3
ssi is offline ssi  United Kingdom
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Hi

Thanks for replying. How do I measure the rail voltage with a multimeter and what voltage am I looking for? The amp has a switch at the back to switch between higher and lower ohm speakers. I have it on 8 - 16 ohms as my B&602's are rated at 8 ohms.

In terms of sound quality the unit sounds great and has worked for hours without issue (only had it a couple of weeks), after replacing the relay.

Do you foresee any serious issues with continuing to run the amp?

Best Wishes
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Old 21st May 2017, 07:22 AM   #4
Mooly is offline Mooly  United Kingdom
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Technics SUV4X  runs cool!
Quote:
Please note I am very much an amatuer but am willing to have a go and learn.
With the very greatest of respect, it could be very easy for you to cause damage. One slip of a meter lead, a wrong range when measuring......

I would suggest you try and locate a full service manual for both variants and initially compare the circuit details. The manuals should show the supply voltages the amplifier runs on and it should also be possible to determine the current the output stage draws (I'm assume its manually adjustable although it may not be). That would be a good guide to the expected heat generation that will be produced.

Also, the relay 'getting hot' doesn't sound normal. If you replaced that part then be sure that the replacement is of similar voltage rating and also of similar coil resistance.
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Old 30th May 2017, 06:10 PM   #5
SVI2004A is offline SVI2004A  New Zealand
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Technics SUV4X  runs cool!
Shouldn't be any issue...

Send a pic of the inside... I can spot a replaced power ic all the way here from Australia

The EGA model got extra chokes on input and outputs... must have had some reg....

Also hold amp sideways a bit power supply down (this will ensure that the coolant liquid will be behind power ic)

Then make sure it's level as these amps do not like having no fluid behind ic
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Old 30th May 2017, 07:54 PM   #6
ssi is offline ssi  United Kingdom
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Hi, will post a picture after the weekend svi2004a. Also picking up a faulty suv4x at the weekend with a flashing safety operation light. I have the replacement transistors that you have suggested in previous posts. I would appreciate it if you could give me a fault finding checklist if you have time. I love the sound of these amps. Best wishes ssi
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Old 31st May 2017, 12:47 AM   #7
SVI2004A is offline SVI2004A  New Zealand
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Technics SUV4X  runs cool!
Sure thing.... check for voltage at R523 (Lch) and R524 (Rch) located near relay...
These should be 0vdc... if voltage present check voltage on Collector of Q501 (Lch) or 502 (Rch) (should be +1.8v).

I quite agree... the V4X has definitely a magic to it.
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Old 2nd June 2017, 07:45 PM   #8
ssi is offline ssi  United Kingdom
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Hi SVI2004A

Here are two pictures of the suv4x chip. Hope you can ID that it is genuine! Let me know if you need further evidence.

Incidentally picked up a Technics SUV505 with intermittent safety operation - recovered if you wiggled the board a bit. There was a sparky sounds as well! Turned out to be one of the pins on the input selector. Reflowed the solder and all appears to be well over the past hour.

Best Wishes ssi
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File Type: jpg IMG_20170602_202114492.jpg (330.6 KB, 202 views)
File Type: jpg IMG_20170602_202103193.jpg (295.4 KB, 198 views)
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Old 2nd June 2017, 10:04 PM   #9
SVI2004A is offline SVI2004A  New Zealand
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Technics SUV4X  runs cool!
Genuine chip... does not look to have been ever removed....

1st pcb run too - see how the last pin is labeled 17.... (SVI is 16 pin)
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Old 3rd June 2017, 08:30 AM   #10
ssi is offline ssi  United Kingdom
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Hi

Picked up the broken SUV4 x . Appears to work and no safety operation. 0 volts on the resisitors that you suggested. However DC is around 15mv on left channel and 5mv on the right. Is this a problem?

Thanks
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