What electronic component likely failed here?

[Muse]

I'm a user of a digital timer to turn on/off an A/V receiver. I've gone through 3 of them. The first was a daily timer, the 2nd a 7-day timer (8 on/off pairs) whose buttons stopped working reliably. The 3rd is another 7-day timer (8 on/off pairs), and it seems to work AOK except that when "On" it stopped supplying AC current. What inner component likely failed? It's a Hydrofarm TM01715D 7-Day Digital Program Timer I bought off of Amazon. I just bought a GE 15154 (Jasco, 29 on/off pairs) off Amazon to replace it. I've thought of buying a Z-Wave dongle to do the same thing. Presumably it would be a lot easier to program (would do so with a computer), and I suppose I would have fairly unlimited On/Off combinations, but it's an expensive solution (probably around $150).

 

[aigomorla]

the rapid on and off the power at the outlet end could of fryed the caps im guessing.

I was always told... pulling it from the plug is not the same as the off switch, which a timer does.

Also that timer i believe would have a hard time handling the rush amperage of the amp, unless its a weak amp.

 

[PottedMeat]

"On" it stopped supplying AC current.

the relay contacts probably crapped out - or bad solder joints on the relay

 

[Cerb]

No idea exactly what failed, but that doesn't look like it's really made for 15A (15A peak, maybe?). Also, there are a lot of failures in reviews of all of these units. If it can't handle the turn-on current, relay joints would be fairly likely. Or, the battery.

The Honeywell units seems to have good reviews, and I can't complain about anything I've used made by them...but, they are wall plates.

 

[Muse]

I did take it apart a couple of weeks ago but couldn't see anything that looked amiss. The caps didn't look bulged or anything. I guess the relay, whereever it is, could be the problem. I probably couldn't see that. I put it back together. It worked OK a couple of years turning on and off on the average of once a day pretty much. The draw was always that AV receiver, which draws around 80 watts, at least in general, maybe it spikes when first connected to power. I'm actually surprised that the receiver always retains it settings. I believe the manual said that it's internal battery for maintaining memory when not supplied power would only last a couple of years. I've been doing this with it for over ten years, no problem. It's a Kenwood VR-6070.

 

[bryanl]

If the buttons respond properly and the LCD appears to indicate normal activity, then I would suspect the relay or the circuitry that drives its coil. Otherwise there could be bad solder joints. I doubt capacitors would fail so soon in a product like this, where they aren't involve in high power, but Chinese manufacturers have constantly amazed me.

Honeywell used to be a respected name for all its products, but now the company often licenses its brand to other companies and has absolutely nothing to do with their design, manufacture, or warranty, as customers who bought Honeywell LCD monitors can attest.

 

[Muse]

If the buttons respond properly and the LCD appears to indicate normal activity, then I would suspect the relay or the circuitry that drives its coil. Otherwise there could be bad solder joints. I doubt capacitors would fail so soon in a product like this, where they aren't involve in high power, but Chinese manufacturers have constantly amazed me.

Honeywell used to be a respected name for all its products, but now the company often licenses its brand to other companies and has absolutely nothing to do with their design, manufacture, or warranty, as customers who bought Honeywell LCD monitors can attest.

Yes, everything seems completely normal except that there's no power supplied when "On" and the LED that indicates an "On" condition (not "On" in the LCD display, that does say "On" in accordance with proper button presses) does not illuminate.

 

[bryanl]

Yes, everything seems completely normal except that there's no power supplied when "On" and the LED that indicates an "On" condition (not "On" in the LCD display, that does say "On" in accordance with proper button presses) does not illuminate.

Everything working except the relay and the power indicator LED indicates the damage is in the relay driver circuit, which could mean the microprocessor has a blown output (not repairable) or a transistor it drives has blown (cheap and easy repair) due to high voltage back EMF from the relay coil. When that happens, the protective diode across the coil or transistor usually fails as well. Adding a 400V, 1A diode across the relay coil typically prevents this. It's possible the relay uses an AC coil running at 120VAC, in which case it may be driven by a triac that cannot be protected with a simple diode but instead needs a MOV or pair of back to back zener diodes in series.