Uncommon Old Diode found in Japanese SS Hifi: RW06 Any Info?

[rjb5191]

Hi there,

My Denon PMA 830 has a bunch of these diodes and I'm trying to find some info on them. Does anybody know anything about them? My guess is its's a general purpose 1A 200V but I don't know for sure. Nominal voltage drop at 5 mA is about .635 V on healthy versions. This amp uses large bias currents in class A and has a Class A and B switching scheme so I want to make sure any replacements I use won't cause more issues. I have uploaded a photo.

 

[sajti]

SOD57 general purpose 1-2A/200V rectifier - e.g.Vishay BYW52

 

[rjb5191]

Yes, I've seen these and I do agree, they look the similar . Maybe they are of a similar heritage, but my example is from a Japanese integrated amp from the 1970's.

 

[sajti]

Checking the service manual, this diode is connected parallel with the relay coils, against negative voltage spikes. So even some small current types, like 1N4148 will fit.

 

[rjb5191]

It's also in the power amp in many sections. This is the are of concern. They seem to be a critical part of the biasing scheme but my knowledge is limited in deciphering what is actually going on there.

 

[sajti]

That application is the overcurrent protection (D14,16,18,20). Small current switching only. Bias network (D10, D12) use STV-2H diodes only.

 

[audiofan]

I remember these general pupose similar to 1N4002

 

[BSST]

D10 and D12 are forward biased and heavily bypassed by C40, so speed is not an issue. Often these two diodes are thermally attached to the output heatsinks, so package might be a consideration in that case. Otherwise, any Si diode should be OK.

 

[Nelson Pass]

Yes, it's not likely to be any exotic Silicon diode technology.

 

[rjb5191]

That application is the overcurrent protection (D14,16,18,20). Small current switching only. Bias network (D10, D12) use STV-2H diodes only.

Thank you, this helpful in understanding what is going on in the circuit.

 

[rjb5191]

I remember these general pupose similar to 1N4002

Thank you, this is what I was thinking and that the 1N4xxx series will be the most reasonable solution.

 

[rjb5191]

D10 and D12 are forward biased and heavily bypassed by C40, so speed is not an issue. Often these two diodes are thermally attached to the output heatsinks, so package might be a consideration in that case. Otherwise, any Si diode should be OK.

Thank you, these are not the diodes of concern, but that is also helpful information. Thankfully these hard to find STV-2H diodes seem to be OK.

 

[rjb5191]

Yes, it's not likely to be any exotic Silicon diode technology.

Thank you, and that's a relief. It always causes a bit of anxiety when you come across a part with narry a datasheet to be found and essentially no other information.