1
\$\begingroup\$

The diode on my AVR popped. I believe it is a flyback diode, but it has no marking. I could not find the schematic or datasheet for my Denon AVR-X3300W board. I am trying to find a source for the part but I have no idea what to look for. The relay (JZC-42F) is a 24 V 6 pin relay. What about the polarity. Since the relay doesn’t have polarity, how would I place the diode? Can I use a bidirectional diode?

The diode is very small, less than 3 mm in length.

the unmarked diode

this is the zoom out version

The yellow arrow shows the diode location between the relay.

\$\endgroup\$
8
  • \$\begingroup\$ Welcome! Can you please zoom out a bit? What is it connected to? \$\endgroup\$
    – winny
    Commented Nov 19 at 7:43
  • \$\begingroup\$ it is placed between a 24v relay. it is on the speaker output section. \$\endgroup\$
    – fikri najmi
    Commented Nov 19 at 8:26
  • \$\begingroup\$ Check the datasheet for the relay to tell for sure, but most probably just a flyback diode as you say. Try to trace out the circuit around the relay or find a service manual for it. \$\endgroup\$
    – winny
    Commented Nov 19 at 8:28
  • \$\begingroup\$ if i know the relay used? will i be able to know what kind of diode to use? the relay used is marked as jzc-42f. \$\endgroup\$
    – fikri najmi
    Commented Nov 19 at 8:31
  • 1
    \$\begingroup\$ >And how about the polarity. since the relay doesn’t have polarity, how would I place the diode? Can I use a bidirectional diode? Does such a diode exist? The whole point of a diode is that it's unidirectional. Unless you mean a Zener, but I don't think it's a Zener. In any case I would assume the polarity is going to be opposite the relays triggering voltage, otherwise when the relay is "switched on" the current will go through the diode itself and not the relay. You can use a multimeter to find which way the current flows into the relay to switch it. \$\endgroup\$
    – QuickishFM
    Commented Nov 19 at 9:21

1 Answer 1

Reset to default
2
\$\begingroup\$

The JZC-42F relay coil is DC voltage, from 5 to 48 VDC, so polarity needs to be check. Probably these relays are used to switch loudspeakers, and one point of all the coils are joined to + 24 V or to 0 V. Check with multimeter which ones are connected together, and track if it is to a bulk capacitor (+ terminal) or to - terminal (0 V).

In www.hifiengine.com you can find Denon AVR X3200W service manual, probably very similar. In this case the common terminal is +24 V, and the other terminal is connected to 0 V through open collector transistor. See detail at the left, the diode used 1SS355 (search a equivalent, it is not a critical component), and how it is connected:

enter image description here

\$\endgroup\$
6
  • \$\begingroup\$ Thank You. Is it safe to introduce power to the board without the diode. The problem with my avr is the speaker making crackling, static sound intermittently. the speakers and cables are fine. Is it possible that dirty relay contact cause that? \$\endgroup\$
    – fikri najmi
    Commented Nov 19 at 10:57
  • \$\begingroup\$ @fikri najmi : it is not safe for the transistor, when switching off it will get a voltage peak. Check polarity and connect a standard diode like 1N4148 or 1N400x . If only that speaker fails could be the relay, if all speakers are erratic, maybe the +24 V is the faulty. \$\endgroup\$
    – Bravale
    Commented Nov 19 at 11:34
  • \$\begingroup\$ all the speakers failed. how to solve the +24v issue? \$\endgroup\$
    – fikri najmi
    Commented Nov 19 at 11:36
  • \$\begingroup\$ hi again. i have tried what you suggested me to do but i am unable to track the polarity. so i just put a diode blindly. a fuse blew up so i turn the diode the other way round and changed the fuse. again, the same fuse blew. i have checked other components, everything seems fine. i took a risk and put a bigger fuse. i am surprised it seems ok but i only dare to let it stay on for about 5 seconds. what could be the problem \$\endgroup\$
    – fikri najmi
    Commented Nov 28 at 12:47
  • \$\begingroup\$ Maybe the original fuse is "slow" and can handle the inrush current, and you are using a "fast" fuse and burns in the inrush. If not confident, connect a bulb (incandescent type) of about 60 W in serial with the device, that way the current will be limited. \$\endgroup\$
    – Bravale
    Commented Dec 1 at 9:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.