Tip: JVC DR-MH30SEK PSU repair
Posted: Thu Jan 11, 2007 10:12 pm
I had to repair my PSU after 18 months use. As this was not a simple task (i.e. it wasn't a fuse) here is my experience, hopefully it will help others!
ONLY DO THIS IF YOU ARE A COMPETENT ENGINEER otherwise you could die. I don't want know if you do kill yourself, you have been warned.
It all started with distorted sound, no other symptoms. I unplugged and moved the unit to my bench but when I powered it up there was a sound like frying chips along with a horrible smell of burning
The main switching chip (the one on the big heatsink) had exploded, a resistor or two had disappeared along with some PCB track.
Why did JVC use 1mm square SMD resistors in a PSU when they didn't exactly need to save space?
Anyway, I ordered the following from RS
127925 100uF 400v
144223 680R 0.25W
2942849 R27 2.5W
2244218 1000uF 16v
2244331 22uF 50v
3150827 27uF 50v
1918132 220uF 10v
4490996 1500uF 16v
5261569 680uF 25v
2671727 47R 0.5W fusible
144318 3K9 0.125W
151798 100R 2.5W
148253 5K1 0.25W
And the STR-G6653 from Grandata
Then set about replacing lots of components. I used 1500uF to replace the 1200uF's, the only tricky parts were as follows:
5K1 which replaced R5304 and 5305, remove both SMD's and the wire link
and solder the lead of the 5K1 in to replace the link and the other end of this resistor to pin 1 of IC5301 on the track side.
R5107 I had to solder one end to pin 5 of IC5101 and the other end to R5108
I had to use a short length of wire from R5108 to pin 2 of IC5101
R5106 had changed value to around 182K, I drilled two holes to allow me to solder this resistor in place of the SMD
I had to drill new holes for C5003's replacement
C5103 had dropped it's value to about 10uF
I checked the opto using a couple of 270R resistors, two LED's and a 5v supply on a breadboard, it was ok. I checked all the diodes, transistors, rectifier, resistors.
When all this was done I was surprised to find the PSU worked and the sound fault had gone
ONLY DO THIS IF YOU ARE A COMPETENT ENGINEER otherwise you could die. I don't want know if you do kill yourself, you have been warned.
It all started with distorted sound, no other symptoms. I unplugged and moved the unit to my bench but when I powered it up there was a sound like frying chips along with a horrible smell of burning
The main switching chip (the one on the big heatsink) had exploded, a resistor or two had disappeared along with some PCB track.
Why did JVC use 1mm square SMD resistors in a PSU when they didn't exactly need to save space?
Anyway, I ordered the following from RS
127925 100uF 400v
144223 680R 0.25W
2942849 R27 2.5W
2244218 1000uF 16v
2244331 22uF 50v
3150827 27uF 50v
1918132 220uF 10v
4490996 1500uF 16v
5261569 680uF 25v
2671727 47R 0.5W fusible
144318 3K9 0.125W
151798 100R 2.5W
148253 5K1 0.25W
And the STR-G6653 from Grandata
Then set about replacing lots of components. I used 1500uF to replace the 1200uF's, the only tricky parts were as follows:
5K1 which replaced R5304 and 5305, remove both SMD's and the wire link
and solder the lead of the 5K1 in to replace the link and the other end of this resistor to pin 1 of IC5301 on the track side.
R5107 I had to solder one end to pin 5 of IC5101 and the other end to R5108
I had to use a short length of wire from R5108 to pin 2 of IC5101
R5106 had changed value to around 182K, I drilled two holes to allow me to solder this resistor in place of the SMD
I had to drill new holes for C5003's replacement
C5103 had dropped it's value to about 10uF
I checked the opto using a couple of 270R resistors, two LED's and a 5v supply on a breadboard, it was ok. I checked all the diodes, transistors, rectifier, resistors.
When all this was done I was surprised to find the PSU worked and the sound fault had gone