Yamaha home theatre receiver - won't power up

Any activity at all ? Standby LED ? Powers for a moment and then shuts down immediately ? Yammy AV amps are very complex, and not for the faint hearted, but if it is *totally* dead rather than not coming or staying out of standby, you might stand a better chance with it.

Arfa

Does the unit have a small standy power transformer?. If so, isolate and check for an open primary. Jango

Totally dead, no LED, no nothing. As Jango suggested I'll look for a small standby transformer - I was thinking it must be something like that to power the logic for the controls on the front while it's off.

Thanks Arfa, give my regards to Terry - I might come and see you about a tasty motor sometime.

Cheers,

MK.

You're welcome, and your kind regards have been passed to Terry ...( ! ) Jango's suggestion is a good one, and exactly what I would have said. He too is an experienced engineer. If the worst comes to the worst, I have access to Yammy service info. Mail me off-group if you get to the point of needing it, and I'll see what I can do for you.

Arfa

Thanks for the endorsement Arfa :), what are you busy with these days?. Well, Matthew, how's the progress on the RX-V520 going?. I try my best to post final results on a successfully completed job here so people may refer to it later. Jango

Hi Jango

Same old same old. Still pitting my wits against recalcitrant hifi's, DVDs, DVDRs, PVRs, group amps and the plethora of other nonsense and rubbish that the poor old public have inflicted on them as the latest "must have". Guess you're probably about the same. We are also working on an updated version of the three-changer video, and perhaps a couple of others like the Pan

Arfa

Bit hectic here, probably have to wait until next weekend! But I will definitely post my outcome.

Cheers, MK.

In one of the more awesome pieces of long-distance diagnosis I have known, it turns out the small standby power transformer has an open primary!

Now - my problem is to find out what to replace it with. It runs on

XW608 AO TAM M 0118

It's only got one primary and one secondary as far as I can see.

I have a schematic for the RX-V420, which is a slightly less powerful version with the same features (this one is RX-V520), and the transformer is on the schematic. It's component T161, listed as an "XW608" for the Australian model in the parts list on the right. Seems like the same components are used in this part of both models.

The schematic shows "AC 12.8" as the voltage measurement across the secondary.

I am a bit naive in these things but I am assuming

(a) that 12.8 is VRMS, and (b) that a 240V AC transformer with a 12.8V RMS output, of similar physical size, would be a good replacement (I can't see a power rating and I assume it would be small given that it probably only runs the standby switch, IR receiver and a relay).

How critical is the voltage likely to be? It looks like there is some kind of regulatory circuitry downstream. I can supply that part of the schematic if it would help.

Thank you SO MUCH for your incredible suggestion.

Cheers,

Matthew.

Ah well, didn't work. It was a classic case of finding what I set out to look for - I had been using the continuity beeper on my multimeter to see if the primary and secondary were open or not - turns out the primary WAS OK but its resistance was slightly higher than my meter will beep for. So that wasn't the fault after all. I've given up and will pass it back to my mate in the hope he can take it to someone who actually knows what he/she is doing.

Thanks to everyone who helped.

Cheers,

Matthew.