Sony EV-S550E MA2820 Regulator - UK Vintage Radio Repair and Restoration Discussion Forum

Cobaltblue · 7th Oct 2020, 5:41 pm

Last night (rather late) I picked up this Sony Video 8 unit.

Thanks Roger it was a pleasure to meet you and you packed it up beautifully.

Having got the lid off it was clear that the switching regulator MA2820 had gone to meet it's maker.

I have not come across this particular device before.

There are plenty for sale but I suspect it would be a much faked chip so can anyone point me to a reliable source of this part.

I have checked the parts around the chip and so far all is well although I will probably change a few Capacitors

Cheers

Mike T

Cobaltblue · 8th Oct 2020, 12:19 pm

Got the bestie out it's less than 1 ohm between pins 2, 3 and 4 I have cleaned it all up ready for replacement to be fitted.
My usual sources didn't have one so I have taken a bit of a chance on a Chinese source I will do some testing prior to installation.

Cheers

Mike T

Cobaltblue · 8th Oct 2020, 2:35 pm

Lunch time I thought I would have a check of all the passive parts whilst the IC is out.

Depressingly I found a mess under one of the caps and it had actually overheated the tracks and pcb.

I have scraped out most of the mess but when I repair it once the parts have arrived I will probably have to drill out this bit of pcb as its carbonised to quite a depth.

It actually burnt of the link JW3

I am wondering if this is what caused the primary side failure, its the -5V supply.

The diode reads OK as does the following regulator no shorts.

Not much more to be done till new parts arrive

Cheers

Mike T

Cobaltblue · 1st Nov 2020, 11:49 am

The MA2820's arrived on a slow boat

As they were very cheap I half expected them to be just blobs of plastic on the wires.

Cold test shows diodes and transistors where I expect so next test is at high volts!

That going to be a few days away as all that stuff is in Poole

If it survives high volts next thing is try it in circuit.

Cheers

Mike T

murphyv310 · 1st Nov 2020, 1:24 pm

Hi Mike.
The chip should have a mask number as well as the device type number. If the number is different you might find the lire of the new chip is short. These power supplies were known to have leaky caps and mess up the print. In the end we were fitting 125c caps in them. Check to see if there were any service bulletins on the power supply, I don't remember if there was but may have been after I left Sony.

7th Oct 2020, 5:41 pm	#1
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,864	Sony EV-S550E MA2820 Regulator Last night (rather late) I picked up this Sony Video 8 unit. Thanks Roger it was a pleasure to meet you and you packed it up beautifully. Having got the lid off it was clear that the switching regulator MA2820 had gone to meet it's maker. I have not come across this particular device before. There are plenty for sale but I suspect it would be a much faked chip so can anyone point me to a reliable source of this part. I have checked the parts around the chip and so far all is well although I will probably change a few Capacitors Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

8th Oct 2020, 12:19 pm	#2
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,864	Re: Sony EV-S550E MA2820 Regulator Got the bestie out it's less than 1 ohm between pins 2, 3 and 4 I have cleaned it all up ready for replacement to be fitted. My usual sources didn't have one so I have taken a bit of a chance on a Chinese source I will do some testing prior to installation. Cheers Mike T Attached Thumbnails __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

8th Oct 2020, 2:35 pm	#3
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,864	Re: Sony EV-S550E MA2820 Regulator Lunch time I thought I would have a check of all the passive parts whilst the IC is out. Depressingly I found a mess under one of the caps and it had actually overheated the tracks and pcb. I have scraped out most of the mess but when I repair it once the parts have arrived I will probably have to drill out this bit of pcb as its carbonised to quite a depth. It actually burnt of the link JW3 I am wondering if this is what caused the primary side failure, its the -5V supply. The diode reads OK as does the following regulator no shorts. Not much more to be done till new parts arrive Cheers Mike T Attached Thumbnails __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

1st Nov 2020, 11:49 am	#4
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,864	Re: Sony EV-S550E MA2820 Regulator The MA2820's arrived on a slow boat As they were very cheap I half expected them to be just blobs of plastic on the wires. Cold test shows diodes and transistors where I expect so next test is at high volts! That going to be a few days away as all that stuff is in Poole If it survives high volts next thing is try it in circuit. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk Last edited by Cobaltblue; 1st Nov 2020 at 11:50 am. Reason: spelling

1st Nov 2020, 1:24 pm	#5
murphyv310 Dekatron Join Date: Sep 2006 Location: Kilmarnock, Ayrshire, UK. Posts: 5,422	Re: Sony EV-S550E MA2820 Regulator Hi Mike. The chip should have a mask number as well as the device type number. If the number is different you might find the lire of the new chip is short. These power supplies were known to have leaky caps and mess up the print. In the end we were fitting 125c caps in them. Check to see if there were any service bulletins on the power supply, I don't remember if there was but may have been after I left Sony. __________________ Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member