On this PCB Z5 and Z6 look the same but Z5 is broken. From what I can tell there is a 3.0 and 9 H printed on them. This is from early '90s Honda Accord radiator fan timer.
Hello,
Thank you for contacting the Technical Forum. Well this appears to look like a diode. Unfortunately I am unable to find any information on the part marking. I am sorry. I would not like to guess. I tried to see if there was a symbol on the part to see if I recognized it. I could not. Sorry.
“Z” on the silkscreen tends to indicate a zener diode and it’s obviously a through-hole part, suggesting that this pot of parts may hold a winner.
Identifying the voltage rating would be the harder part; there are 3V zeners, there are 30V zeners, and what’s pictured may very well be neither. If the markings are the same on both, they’re likely the same part; carefully removing the one that’s not brokenated and measuring it’s reverse breakdown voltage could be a path to finding a workable replacement. Other parts may have been less visibly damaged in/by/during the failure event though, so replacing that one part may not offer a fix.
Thank you so much for your reply. Sorry it’s taken me awhile to get back. I removed this from the board and found a large “T” and “ZNA” (no quotes) that was not visible until it was removed. Another question that comes to mind after you mentioned other components that could have been damaged as a result of this one, is this something normal that happens to a component like this or is this something that was physically broken?
I can’t seem to locate any info about this but, I seem to recall there was brand of transient voltage suppressor diodes (TVS) last century that used “ZNA” in their name or designators.
A TVS will often fail broken open after a surge far larger than the circuit designer anticipated has been absorbed.
