Electronics > Repair

Looking to cross-reference replacement power supply diodes

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WildcatMatt92:
I have a few old Mitsubishi VCRs that I'd like to get working.  They are notorious for power supply issues -- half of them have caps that have leaked over the diodes which appear to be pretty cooked also.

The service manual identifies these types (now with links to datasheets I could find):

* RM 1B
* EM 1Z
* EM01Z
* HZ30-2
* 1SS252The first three at least appear to be Sanken part numbers which appear to be hard to track down.  I think the first one is 800ma/800v (which seems difficult to match) and the next two are both 1a/200v (which seems pretty common).

I've added the diagram from the service manual and two views of the supply itself as attachments (I've already removed the caps on the one).

Can anyone help identify substitutions for currently available part numbers I could plug into DigiKey, Mouser, or eBay for replacements?

james_s:
Well you don't need to match the current or voltage, you just need diodes that are rated at least as high for both. What matters more is speed, assuming this is a SMPS most of the diodes are likely to be much faster than jellybean stuff like the 1N4007. If you can find datasheets for them that would make it a lot easier to suggest replacements. Otherwise it would be helpful to know how they are used in the circuit.

fzabkar:
It would help to see the service manual ...

amyk:
The first 3 appear to be general-purpose mains rectifier diodes. I'd try 1N4007 for all 3.

HZ30-2 is a 30V 0.5W 3% zener. BZX55B30 seems suitable.

1SS252 is a 90V 130mA fast diode and someone previously suggested a 1N4148 for replacement: https://www.eevblog.com/forum/repair/repair-denon-amp-stuck-for-diodes/

WildcatMatt92:

--- Quote from: james_s on December 03, 2022, 03:38:46 am ---Well you don't need to match the current or voltage, you just need diodes that are rated at least as high for both. What matters more is speed, assuming this is a SMPS most of the diodes are likely to be much faster than jellybean stuff like the 1N4007.
--- End quote ---

That's helpful to know, thanks!


--- Quote from: james_s on December 03, 2022, 03:38:46 am ---If you can find datasheets for them that would make it a lot easier to suggest replacements. Otherwise it would be helpful to know how they are used in the circuit.
--- End quote ---

I've updated the post to include links I could find, and to the relevant section of the service manual.

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