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Obsolete MV5152 LED. Information sought regarding replacement.

Isobarik

Isobarik

pfm Member
Hi to all
In another thread entitled Smoking Revox.
The left Recording Led blew when I engaged record mode. The right LED was not effected.
The MV5152 is now obsolete. I've searched the net for information and found this https://www.mouser.co.uk/ProductDet...=sGAEpiMZZMtmwHDZQCdlqWHn8Tgk4u25nXSM4qBItSk=

I am not familiar with LEDs, in fact only replaced one and that was in my Naim 42.5. Changed the red one to a green one.
Anyone give me guidance on a suitable replacement.
I was told any LED would do but I doubt the advice given was correct. So best to ask on here.
Regards
Ray
 
Any LED will do yes. Are you sure it's blown? Quite unlikely to be... remove from board and check using diode check range on DMM. You should see about 1.8V with a feint glow one way round and open circuit the other way.
 
Arkless Electronics said:
Any LED will do yes. Are you sure it's blown? Quite unlikely to be... remove from board and check using diode check range on DMM. You should see about 1.8V with a feint glow one way round and open circuit the other way.
Click to expand...
Hi Jez
Yes it's definitely blown. It turned brown and emitted smoke!:D
Cheers Jez. Thanks for the information.
 
Isobarik said:
Hi Jez
Yes it's definitely blown. It turned brown and emitted smoke!:D
Cheers Jez. Thanks for the information.
Click to expand...

WOW I've never known that happen before in over 40 years almost daily experience with electronics! They almost always have a current limiting resistor in line which means this couldn't happen.... Be very careful as there is a very good chance the LED was blown by another fault!
 
Hi Jez
That's what i'm afraid of.
When I switch to record on the right channel I can here a relay switch in circuit, but when I switch to record on the left channel I hear no sound emitting from the other relay. So the relay could be the problem.
This machine hasn't been used for quite a long time and what with all that nicotine it's a wonder it's still working at all:(
Regards
Ray
 
The driver shorting just makes the LED stay on or off. Neither will blow the led.
This looks more like a power supply has gone crazy or there is a wiring short.
 
davidsrsb said:
The driver shorting just makes the LED stay on or off. Neither will blow the led.
This looks more like a power supply has gone crazy or there is a wiring short.
Click to expand...

Not if there is a current source for the LED in the driver rather than a simple resistor and the current source has failed short.... entirely the reason why I said possibly a faulty driver IC!
It does seem a virtually impossible fault though yes....
 
Arkless Electronics said:
Not if there is a current source for the LED in the driver rather than a simple resistor and the current source has failed short.... entirely the reason why I said possibly a faulty driver IC!
It does seem a virtually impossible fault though yes....
Click to expand...
Hi Jez
Your probably right saying the cause of the LED blowing was probably caused by a faulty driver.
The problem is,which one?
The boards want investigating, the only problem is, I haven't got the necessary test gear to do the job.
Everything was working OK until I pressed the record button then whoosh smoke appeared from the now defunct LED.

Regards
Ray
 
davidsrsb said:
A shorted current limit resistor would do this
Click to expand...
Hi David. Where would I find the current limit resistor? any idea?
There is the Logic Board,Oscillator board,Input Amp Board,Recording Amplifier Board.
I really haven't a clue but always willing to learn This manual is what i'm trying to fathom out what's wrong. I'm using this manual for guidance. https://elektrotanya.com/studer_revox_b77_mk2_sm.pdf/download.html
Thank you so much for your input David.
Cheers, Ray
 
Arkless Electronics said:
Impossible other than solder having been splashed across the resistor maybe.
Click to expand...

Hi Jez
No soldering done by me on any of the boards except for the power supply caps. No solder splashes! Very easy access to the components!
It could have happened when the Rifa PME M 0.1uf exploded behind the voltage selector panel causing a surge, but wouldn't the fuses on the power supply board blow?
Cheers, Ray
 
Its on the Oscillator diagram Page 7/51. The LED is used in series with a 330ohm resistor and the relay, so its failure will stop the relay operating. As the LED does have to pass a current to energise the relay its possible that the failure is just 'old age'. I would try simply replacing the LED with a modern equivalent, the only problem might be the higher efficiency of a new one
being much brighter. Any LED the correct colour that's happy passing 30 mA (the spec of the original) or more should be fine.
The cost of the LED is so low it's worth trying a simple replacement before digging too deep.
Good Luck, and please let us know how you get on.
 
ralphfcooke said:
Its on the Oscillator diagram Page 7/51. The LED is used in series with a 330ohm resistor and the relay, so its failure will stop the relay operating. As the LED does have to pass a current to energise the relay its possible that the failure is just 'old age'. I would try simply replacing the LED with a modern equivalent, the only problem might be the higher efficiency of a new one
being much brighter. Any LED the correct colour that's happy passing 30 mA (the spec of the original) or more should be fine.
The cost of the LED is so low it's worth trying a simple replacement before digging too deep.
Good Luck, and please let us know how you get on.
Click to expand...

Brilliant! Thank you Ralph. So much information!

I have been toying with the idea of taking the panel off and inspecting the actual blown LED to see what other damage has been done.
Honestly I was looking at the said Led and the resistors surrounding it on the schematic last night.....I thought! no! don't be silly it couldn't be as simple as that? there must be something more serious that's causing the problem.
I'll check it out on Monday as I need a break from the B77,been on it for well over a week!
Yes Ralph i'll keep you posted. Fingers crossed!:)
Regards
Ray
 
ralphfcooke said:
Its on the Oscillator diagram Page 7/51. The LED is used in series with a 330ohm resistor and the relay, so its failure will stop the relay operating. As the LED does have to pass a current to energise the relay its possible that the failure is just 'old age'. I would try simply replacing the LED with a modern equivalent, the only problem might be the higher efficiency of a new one
being much brighter. Any LED the correct colour that's happy passing 30 mA (the spec of the original) or more should be fine.
The cost of the LED is so low it's worth trying a simple replacement before digging too deep.
Good Luck, and please let us know how you get on.
Click to expand...
And if the new LED is too bright it should be simple to tame it with another resistor.
 
If the relay coil current passes through the LED, the only way to reduce brightness is to add a resistor across the LED.
Forward voltage drop across an orange LED is about 1.6V, so 100R would bypass 16mA from the LED
 
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