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Luxman Diode ID Help

lifer70

lifer70

What?
Subscriber
Trying to find replacement diodes for my Luxman R1070 and having problems identifying the originals. Not a lot of info in the SM. Somewhere I read they are zener diodes but schematic just looks like a regular diode.

20160612_142744.jpg

The SM says they are S3V40/TD0106 but the ones I took out say SV394. The SV394 must be obsolete as I can not find any info on that code.

D203 to 206 in the schematic below.

Any help would be greatly appreciated.
Monte

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Those are standard power supply diodes. The ones you have are rated at 3.5A @ 600V. You can put in any rectifier diode that is at least that rating, or higher.

Why are you replacing them?
Are the ones you have shorted or open??
 
Using the part number that Roobarb and Custard gave us, you can google that and see that Digikey has em in stock and will send them to you free shipping if you send them a check for the parts (add tax it is cheap and they came back to a friend for tax on a purchase here in PA).
 
Or just Google "4A 600V diode" (without quotes) and see what comes up from suppliers you know.
 
Thanks for the suggestions from all.

Tom B
I was going to replace them after first testing. Later realized I was using the wrong setting on my Fluke. Retested and believe they are OK and w/in tolerance. I will still order a set to be safe.

The R-1070 is my first total recap. It has taken way to long to get it back together. Always something (grand-kids, family repair emergencies, etc.) more important to do that prevents 4 hours of total concentration. I have many photos to help me though.

Hopefully this will be my last parts order and will get this beast back together.

Thanks again for the help! AK is the best!
Monte
 
The Luxman had all but one of the output transistors blown.

I am replacing all the capacitors and transistors except for the small transistors in the picture. Should I remove and test these transistors or just order new ones and replace?
Thanks,
Monte
20160613_205827.jpg
 
lifer70 said:
Thanks for the suggestions from all.

Tom B
I was going to replace them after first testing. Later realized I was using the wrong setting on my Fluke. Retested and believe they are OK and w/in tolerance. I will still order a set to be safe.

The R-1070 is my first total recap. It has taken way to long to get it back together. Always something (grand-kids, family repair emergencies, etc.) more important to do that prevents 4 hours of total concentration. I have many photos to help me though.

Hopefully this will be my last parts order and will get this beast back together.

Thanks again for the help! AK is the best!
Monte
Click to expand...
Monte,
Power supply diodes such at these are not like capacitors that can get leaky, drift out of tolerance, of develop high internal series resistance. Power supply diodes like this are either good, or bad. If they are bad, they usually short, and blow fuses.
As I repair and or restore units, I usually limit the items I replace to defective parts, questionable parts, parts right at, or drifting out of tolerance, and parts that are known to become an issue going forward.
I never replace power supply diodes unless they are bad.
I know that most people use modern multimeters. I uses modern digital meters for voltage, current, and sometimes resistance readings. But I also have a vintage Triplett 630 analog multimeter for checking diodes and transistor junctions. using the "RX1" scale results in a midscale deflection (around 5 ohms) on forward bias, and no deflection on reverse bias using the "RX1000" scale
 
As for thos small transistors, I would check them out before replacing them. You may need to remove them from the circuit to make sure they are OK and not leaky, shorted or open. Hopefully they will be OK because dual transistors such as this are hard to find. Due to bad outputs in both channels, you will need to check all diodes (if any) transistors, and small value resistors in both channels of the driver and output stage to make sure they are OK. Also check bias pots to make sure they aren't burnt open. Finally, make sure to use a dim bulb tester as you first attempt to power on after repairs. Do not plug unit into direct AC until it successfully passes the dim bulb test
 
Tom, great advice. I will check all the power transistors and resistors on that and the other boards. Nice tip on the bias pots and I have my DBT waiting.
Thanks for sharing your knowledge.
Monte
 
In my opinion, there's far too much 'over restoring' carried out by people who come to the sport from non-electronics background, but hyped up by the hobby - I get that. One of the problems is that forums are loaded with mega restoration/rebuild tales (and always, how A-mazing the difference is afterwards) and eventually the need to replace things such as perfectly good diodes and transistors becomes common place - de rigueur. It's just not necessary! keep restoration to changing components that either are on the blink or very likely to be on the blink. I don't even change electrolytics 'as a matter of course', I first listen to and evaluate the general performance of the receiver for some time, live with it, understand it, and if all is well, leave well alone unless you are aware of a component that is widely known to be suspect or 'dangerous' if it fails. Of course, cleaning switches, pots and the like, that's fine and needed in pretty much all cases. But in general, common sense and restraint, that's what's needed. Oh, and a knowledge of electronics helps too. I am not knocking the enthusiasm of those new to vintage electronics and their desire to improve the performance of their finds, but this whole subject of rebuilding needs to be put into perspective I feel.
 
Steve, I agree with your way of thinking and that's what i generally do when fixing equipment. The initial problem was blown fuses and no output. Started with the rectifier circuit and have worked my way through the receiver. Found the output transistors were bad and checked resistors and caps on that board. Didn't find anything way out of line except for some caps. Figured that I was in deep enough that I should replace the rest of the caps.

Also, I am trying to improve my repair status from dangerous to mildly incompetent.

If I had my druthers, I would have liked to start with a working unit and go board by board with testing between boards. That method would tell me if replacing components really make a difference.

Thanks for your input,
Monte
 
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