Marantz 2265 Power board - Diode replacement

[anti-doom]

I am rebuilding power supply board for Marantz 2265 receivers. Diodes WZ-071 (7V 1w) and diode WZ-140 (14V 1w) need to be replaced. Can I use 1N4148 diode to substitute for those diodes? Thanks.

 

[Goldie99]

Both of those are Zener diodes, so the short answer is no - if they need to be replaced, then you'd need to use equivalent Zener diodes. The 1N4148 is a standard small signal diode, completely wrong for those locations.

I haven't checked, but if the designations you listed above (7V 1W, and 14V 1W) are correct, then those would be the corresponding Zener voltages & power ratings that you need to match, but I'd suggest to just search the AK forums for WZ-071 & WZ-140, someone is sure to have been there before....

 

[avionic]

The WZ series are 500mw. 1 watt would be BZ series
http://www.datasheetarchive.com/pdf...d67db38534819e96c433af9b43&type=M&query=wz140

https://www.digikey.com/product-detail/en/nexperia-usa-inc/NZX7V5A133/1727-6164-1-ND/2762659
https://www.digikey.com/product-detail/en/nexperia-usa-inc/NZX14C133/1727-2236-1-ND/5395514

 

[avionic]

Diodes WZ-071 (7V 1w) and diode WZ-140 (14V 1w) need to be replaced. Can I use 1N4148 diode to substitute for those diodes? Thanks.

As goldie has previously stated....No way

 

[anti-doom]

Thanks a lot. I am going to order exact replacement from Digikey now. Thanks.

 

[llwhtt]

That's what's nice about many Japanese Zener diodes, the Wattage and Voltage are right there in the part number, just have to put a decimal point where ever it makes the most sense. And as Avionic said W is 1/2W and B is 1W.

 

[6taafondo]

Installing 1W versions would provide increased power margin. Most likely wouldn't blow anymore. Nothing else would be altered by this switch.

 

[avionic]

Installing 1W versions would provide increased power margin. Most likely wouldn't blow anymore. Nothing else would be altered by this switch.

Kinda slim pickens for the required voltages unless you use a SMT diode.Besides that the OEM 500mw diode probably lasted over 30 years.If there even bad now.

 

[anti-doom]

Can I replace Zener diode WZ-071 (7V 1W) with Zener diode WZ-120 (12V 1W)? Thanks

 

[mbz]

Can I replace Zener diode WZ-071 (7V 1W) with Zener diode WZ-120 (12V 1W)?

Generally a bad idea.

Maybe think of a zener as a simple voltage regulator. It clamps the voltage
to the required value, any excess voltage causes the zener to conduct. The
voltage is then reduced by increased current flow through resistors.

I'm guessing that you are talking about H809, answer no, use 7v or as close
as you can get, eg, 6.8V and 7.5V both available at mouser.

 

[mbz]

You've been previously advised that 500mW is fine, these guys know what they are talking about.

 

[6taafondo]

You've been previously advised that 500mW is fine, these guys know what they are talking about.

Did you make the numbers about load on these 2 zener diodes? Well, I did. 0.35W and 0.31W. This does not sound like a huge margin regarding maximum power dissipation to me.

There's no difference in price between 1/2,1 or 5W diodes... having said this, TEHO.

 

[mbz]

Maybe I got the search wrong at Mouser, however the only close 1W items I saw were 6.8V or 7.5V
while for 500mW they had closer items, 7.01V(???). I'd prefer the closer fit than the unnecessary
watts. Now you will tell me that Digikey (or whoever) has truckloads of 1W 7V zeners.

 

[6taafondo]

Maybe I got the search wrong at Mouser, however the only close 1W items I saw were 6.8V or 7.5V
while for 500mW they had closer items, 7.01V(???). I'd prefer the closer fit than the unnecessary
watts. Now you will tell me that Digikey (or whoever) has truckloads of 1W 7V zeners.

The schematics show that the 7V zener diode is part of a adjustable power supply. Considering this, and that this ps output voltage is 35V, it makes no difference installing a 6.8, 7, or 7.5V diode; with either one you will be able to adjust the ps output voltage to that specified.
Regarding the 14V one, you will also notice that voltage on H804's emiter can't be 14V as seems it was not considered the expected B-E voltage drop. 13.5V would be expected if the zener diode cut exactly at 14V. Here, you can install a 15V diode (standard value) without much impact over output voltage value stated.