Hello,
I'm restoring an older Marantz amp and I would like to replace the leaky 1N60 germanium diodes.
As used in this application, can they be replaced with a Schottky diode?
The diodes are H714-H717.
H718-H719 are M8513 A-O. I'd replace those as well.
I'm having some issues with the amp and I am doing a complete recap. Also I'm replacing some resistors so I'd replace the diodes as well while I'm in there. It's pretty hard to remove those boards so I'd like to do it once for a long time.
So, for this application, what would work best instead of 1N60 and M8513?
I'm restoring an older Marantz amp and I would like to replace the leaky 1N60 germanium diodes.
As used in this application, can they be replaced with a Schottky diode?
The diodes are H714-H717.
H718-H719 are M8513 A-O. I'd replace those as well.
I'm having some issues with the amp and I am doing a complete recap. Also I'm replacing some resistors so I'd replace the diodes as well while I'm in there. It's pretty hard to remove those boards so I'd like to do it once for a long time.
So, for this application, what would work best instead of 1N60 and M8513?
Attachments
Those are germanium diodes, so you should replace with the same, IMO, to get the correct forward drop. Those appear to be in the protection circuitry. 1N34A should be a good substitute. Lots of ebay sellers with those, and some have NOS.
I'd go for 1N60 from ebay but I don't have time really. tomorrow I get all the parts for the amp and during weekend I plan on getting up early and start replacing parts. I want to finish as fast as possible. Ebay would delay my project for about 3 weeks.
I have access to BAT41 diodes today if they would be a good substitute.
I have access to BAT41 diodes today if they would be a good substitute.
I guess you'll just have to find out. The circuit wasn't designed with Shottky's so who knows. How leaky are the germaniums? It's absolutely normal to have some leakage in those.
I'm asking someone who can understand the implications of replacing those with silicon. Haven't measured them yet, but they usually are. And I plan on not going inside in the near future. And if those fail, they take out the transistors as well. And don't want that.
I'm doing it for good measure.
I'm doing it for good measure.
H714-717 are current steering diodes for the SOA protection. They prevent the positive limiter from being activated on the negative half cycle (and vice versa). Any low capacitance fast diode will work there. The only reverse voltage they ever see is generated across the emitter resistors during high currents, so leakage and breakdown voltage aren't concerns. Hence, the germaniums. But Shottkys or even 4148's will work. Chances are they'll never go bad unless you've burnt up the output stage and taken collateral damage.
H718-719 are part of the bias stack. You need silicon diodes with a very close forward voltage to the originals (i.e., something of the same current rating) to get the bias adjustment in range and with the proper tempco. Again, I would replace these if the output stage was ever fried, but leave them alone otherwise.
H718-719 are part of the bias stack. You need silicon diodes with a very close forward voltage to the originals (i.e., something of the same current rating) to get the bias adjustment in range and with the proper tempco. Again, I would replace these if the output stage was ever fried, but leave them alone otherwise.
M8513 seem to be 0.65V with 50mA so I guess any small signal would do. Like 1n4148. But I'll leave them alone I guess.
What type are H005/006? VDxxxx stabistor diodes enjoy a reputation for sometimes going intermittent....
Those are the weird SV-3A diodes. Can't find them anywhere. People usually replace those with 3x1n4148 in series. They are thermo-coupled to the output transistors heatsink
The Schottky BAT46 is a good replacement for the germanium 1N60. In the crystal radio world, they have similar characteristics
Digikey P/N 497-3768-1-ND 47 cents for 1, 35.2 cents for 10
Mouser P/N 78-BAT46 43 cents for one, 29.1 cents for 10.
-Steve
Digikey P/N 497-3768-1-ND 47 cents for 1, 35.2 cents for 10
Mouser P/N 78-BAT46 43 cents for one, 29.1 cents for 10.
-Steve