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Old 8th November 2014, 11:51 PM   #1
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Default Diode identification

These diodes were in a modified Dynaco 70 tube amp (to replace the tube rectifier). I've googled the numbers on the diodes but haven't come up with anything I can use.
Does anybody recognize them? They are quite large compared to the UF4007 I was going to replace them with. I'm new to electronics, but I am wonderign why they have a plastic housing?

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Old 9th November 2014, 07:51 AM   #2
Elvee is offline Elvee  Belgium
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Vrm:6kV Io:300mA Vf:7.2V@100mA

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Old 9th November 2014, 09:38 AM   #3
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The original rectifier (5U3 etc) has a forward voltage drop of some 35V or so. A UF4007/1N4007 has a forward voltage drop of just 0.7Volt.
Do you think it wise to possibly exceed the HT maximum voltage across smoothing capacitors etc? Check the warm up/off load HT before running for any length of time!
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Old 9th November 2014, 09:53 AM   #4
JMFahey is offline JMFahey  Argentina
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^^^^^^^^^ check that.

Looks like a typical "audiophile Mod" to me, where a functionally correct (and originally specified) part is replaced by some "exotic" , in the futile attempt of somehow "improving sound".

Here they used a 6kV diode pack (there's not even 1 kV around there so 1kV 1N4007 is fine), it has only 300mA capacity instead of humble 1N4007 1A , the problem is not so much the average current but the initial capacitor peak charging current, there's also whay Jon points out: +V will be higher than designed ... will filter caps stand that? (although maybe they also used 6kV caps )

Oh well .
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Old 10th November 2014, 03:33 AM   #5
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Thanks for identifying them. I didn't realize they were such high voltage but lower amperage.

The amp is using 525v filter caps, so I think I will be ok.

Thanks again
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