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kevvywevvywoo

Member Since 19 May 2006
Offline Last Active Feb 19 2013 03:29 PM

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Group Members
Active Posts 110
Profile Views 760
Member Title Power User
Age 38 years old
Birthday February 4, 1975
Gender
Male
Location
United Kingdom

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Website URL http://www.k-edwards.co.uk

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Topics I've Started

MA5000VZ soft start problem

05 February 2013 - 03:49 PM

I have another odd one here, a repair that came in for one fault but is displaying another.

While testing, I found the amplifier was not soft-starting on ChB (I found out by lifting each main transformer fuse).

I found the 5R thermistor blown and scorched. I replaced it and checked the pwm pulses on the opto-triac were ok. When I switched on, the amp soft-started properly and didn't trip any breakers.

However, occasionally, maybe one in 10 starts, the soft start triac operates in half-wave. This causes excessive current at startup until the relay closes, a loud buzzing from the transformer, and a strobing desk lamp. The amp works fine apart from that.

I have changed the triac, snubber capacitor, checked the snubber resistor and scoped the pwm waveform, all ok.

Any ideas?

<_<

MA5000VZ fans running fast

28 January 2013 - 11:08 AM

I have another interesting one here. MA5000VZ. The fans run flat-out fast at switch-on when cold. Channel 1 does not work and has the IOC bright and ODEP on. I've checked the thermal trip in the transformer. There's no diagnostic lights on internally. Output modules test ok. ODEP -/+ voltages are fine, temp IC sensor volts is fine.

Ch2 also has a small fault, though i don't think its related. The soft-start precharge doesn't work. The amp powers up and when the soft-start time has run out the main relay comes in, dimming the lights and sometimes blowing the breaker because the capacitors are empty.

Any clues?!

MA5000VZ strange fault

10 January 2013 - 03:01 PM

Hi, got an MA5000VZ (internally same as 5002 late model) with a fault. It shows IOC (bright led) on Ch1 on switch on. The ODEP light comes on fine at the same time as the good channel. The output is muted. I've swapped the output modules over, fault is still on Ch1.

Voltage checks show normal ODEP voltages and temperature. There's no DC offset at power up, bias is all zeroes suggesting the drive has been removed. The mains relay is in, there's power on the DC caps +/- balanced. If VZ-Auto is switched in, the VZ goes straight into high voltage mode. In lock low, it locks into low fine.

Volt checks around the IOC warnings show the LED is being brought on by the 'ES1' line. Checks on the error amp show it is driving hard to +14V. I've swapped the error amp.

I'm wondering where to probe next?

XTi4000 switches itself off

10 January 2013 - 02:52 PM

Got an XTi here that will randomly turn itself off. I assume the SMPSU is being commanded off due to an intermittent detected fault such as DC/LF etc. The question is, might there be a way to find out the cause of the trip? Once the power goes off, live fault tracing is impossible..and when the power's on, it all works ok! The amp might be idling a few hours when it decides to power down.

XTi service bulletins

22 December 2012 - 10:18 AM

Hello, does anyone have an up-to-date copy of these? Thanks :mellow: