82E13 card zener diodes

[oyanliz]

Hi all,

I suspect there is a faulty zener diode  (D21) in one of my 82E13  VCA card.
I am thinking to buy a bunch of zener diodes as spare for the future repairs. Do you have any recomendation of wich diodes are the best replacement? (see attached capture)
Does someone have a BOM of diodes for general use in channel cards, master section cards...?

For the other hand, after recapped an repchipped (op-amps replaced) the 82E13 cards, I realized that a few of them have less output signal than the rest. I did not do the calibration with these cards (still), but all of them have the factory sticker onto the trimmers and they all have simillar output signal, except a few of them. Is there any componnet in the card that can influence on this? (I would like know to know before doing the calibration of those cards)

Thanks to all in advance.

Best regards.

Oihan

[waltzingbear]

the general purpose of those diodes is to protect various other parts of the circuit from over-voltage.

THe physical size will tell you the wattage of the original parts, can't imagine they are over 1W.  THe voltages are clearly marked on the schematic you posted, 1V4 = 1.4 volts

Cheers
Alan

[oyanliz]

Hi Alan,

thanks for answering. I bought some diodes yesterday, all the values are clear in each component and on the schematics. But I was not sure if there is any difference between the quality of diodes and if is important to use a speciffic brand for these purposes. I understund that any good quality zener diode could be used for replacing. Am I right?

Regarding to the 82E13 cards that have lower output signal... does someone have any idea of why happens this?

Thanks again.

Oihan

[waltzingbear]

any real product should be good. So buy from a reputable distributor, not ebay. There are counterfeit parts for everything these days. Zeners are not made of unobtainium like some things, no use taking a chance.

Cheers
Alan

[oyanliz]

Hi,

Any reference of 1v4 diodes? mouser, farnell... they do not sell this 1.4v value zener diodes.

Thanks in advance.

Oihan

[waltzingbear]

in one instance you need two 1.4V zeners in series, a 1V and a 1.8V give the same result. Zeners like that are additive.

at the other instance, a 1.4 plus a 3.3V, it sets an upper limit on the control voltage, not a critical value. You should be able to go ahead and use the 1.8V here with no negative affects.

Cheers
Alan

[amillar]

These were a pain to get hold of even when the 4Ks were new. But you can make them out of two 1N4148 diodes in series for each 1.5V "zener" - that's actually what they are! (The circuit diagram for the 13 card even says this: "2 silicon diodes per pack"). So D23 to D25 become six 1N4148s in series.

Wattage needed is tiny!

For the 3.3V zeners BZX55C types would be fine. They're readily available.

That all said I'd be surprised if any of these are faulty, but it's always possible.

Cheers,

Andy

[oyanliz]

Thank you so much Andy!

Best regards.

Oihan