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pioneer hi-fi problem, please help!

 
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PostPosted: Thu Jan 03, 2013 8:16 pm    Post subject: pioneer hi-fi problem, please help! Reply with quote

Hello,

I am learning to repair electronics as my hobby, but unfortunately, I am now stuck with a problem and would really appreciate if someone could help.

I am trying to repair a Pioneer X-HM20 DAB Hi-Fi system where when I plug it in, the relay switch on primary part of PSU keeps clicking.

It clicks to connect, waits for about half a second, then clicks off and immediately clicks to connect again hence I can't manage to even bring it to standby mode. I think I need to also mention that it clicks as soon as I turn the power on at the socket unlike my other equipment which seems to charge up first before switching on, but perhaps it is by design. I bypassed the relay and the system still doesn't come on, the timer light keeps flashing.

On the output connections, there are 5V and 8V DC which read near same voltage, but there are two 12V connections which read 14.5V and 28V. The 28V drops down to 18V when connected to main PCB and the above mentioned 5V also drops to 4.6V. The others stay the same.

Can anyone help please?

Thanks.
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Guest






PostPosted: Sat Feb 09, 2013 2:48 pm    Post subject: Reply with quote

Hi. Just found out that it is not actually the power supply that is faulty. Swapped it for another one from a working stereo and still it does the same. Tha fault is somewhere on the main PCB. Will look into it further.
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PostPosted: Fri Mar 22, 2013 9:10 am    Post subject: It's working Reply with quote

Just for info, remove the battery inside remote control unit and start X-HM20
by using the touch in front of device and not with remote control unit.
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mondu1fv
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PostPosted: Thu Jan 25, 2018 4:49 am    Post subject: bad part in main board Reply with quote

I just replace a bad output cap on the Ipod power supply located on the main board, not on the power supply board. It is a switching regulator and I found a bad looking output on this suppy using my old but trusty scope. The wafevorm looks as if the filter cap is not connected. I replaced the old cap (probably dried out) and the output became clean. this voltage along with other important supply voltages, is monitored by the CPU and anything other than DC will trigger a fault condition and the the whole thing shuts down and the red standby LED blinks. I just bought my XHM30 from a surplus shop and found the fault when I tested it at home. It has the same schematic as the X-HM20 but uses a slightly higher power IC, the STA350BW -Mon DU1FV
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Guest





PostPosted: Sat Apr 11, 2020 2:45 am    Post subject: Pioneer X-HM30DAb timer LED flashing Reply with quote

Folks, I have just repaired such a unit. The problem was found to be a 4,700 microfarad power supply capacitor that goes leaky under voltage which blows fuse #404. I noticed it was slightly bulging at the top compared to the other capacitors.
I couldn't get a circuit but also traced the circuitry around the relay that connects the mains to the main transformer and found a problematic 7550-1 I.C. which I replaced with a 78L05. The circuitry associated with this regulator gets controlled from elsewhere and disconnects the mains if something is detected as wrong.
Hope this helps someone.
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thepuppiespie



Joined: 05 Jun 2021
Posts: 2

PostPosted: Wed Jun 23, 2021 10:03 am    Post subject: repair electronics Reply with quote

This section concerns one of my recent hobbies - Electronics. I never had the chance to study and learn about the marvellous world of electronics because at school, college and university, I dedicated my time to Chemistry, Biology and Medical Lab Science. However in late 1996, I had the oppurtunity to take a course in electronics as a part time (during the evenings) and hence learn about electronics. The course was aimed for repair and servicing of electronic devices. namely Radio and TVs.


I showed a lot of interess in this new hobby and eventually, after finishing the 4-year course, I began to service and repair electronic items. I only have about 3 years experience (1999 - 2002) but I am very proud of this work so far, as I almost fixed every item that I accepted to repair. I take every repair job as a chellenge, rather than a source of money income. Most of my hobbies had the element of 'challenge' in them, but I never found satisfaction as of repairing items. Also every repaired job is important, as the more you repair the more you gain experience and the better you achieve.


I plan to make many categories in this Electronics section, but for the time being I have time to put the following 3 sections shown below. (click on the title link or button).
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tymzwoho



Joined: 05 Sep 2021
Posts: 1

PostPosted: Sun Sep 05, 2021 12:47 pm    Post subject: Reply with quote

Hi....I have an old pioneer SA-5300 which I got about a year ago. Just recently its become very crackly in one speaker. I've switched the speakers to see if it was a speaker problem and its definately a problem with the amp. It crackles at the same volume regardless of the volume....and regardless of the input Ive selected (eg. tuner, aux, phono). I really wanna fix it....but I'm a complete novice with electronics.

Any idea of what it may be and how I'd go about fixing it. It's an old amp so Im assuming its not worth taking it to a repair guy....it only cost me $50 in the 1st place.

It sounds so good so I wanna do all I can to keep it. Any ideas would be very much appreciated!
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