Sony receiver STR-DE545 Protection fault?

[Spacedye69]

This receiver cuts sound and goes into "protection" error. It will cool down and work for a little while, then cut out again. Anyone got any quick checks before I get in too deep? I'm assuming transistor in the output or maybe some bad caps, but if anyone knows any specifics about Sony receivers, I would like the help.

[Logistics]

Re: Sony receiver STR-DE545 Protection fault?

Did you just recently start using this? Perhaps you're using speakers which require a lower impedance than the amp wants to drive. If you haven't even checked for bad caps, yet then why are you posting?

[kc8adu]

Re: Sony receiver STR-DE545 Protection fault?

iirc the last ones i had were bad solder joints or blown stk's

[Maxxarcade]

Re: Sony receiver STR-DE545 Protection fault?

I have that receiver in my home theater, and I have to try pretty hard to make it kick out. I've kept it fan cooled since it was new. Using it to drive Cerwin Vegas (LS-12, LS-6C, LS-5).

One thing I noticed is that if you use 4 ohm speakers (on even one output) by mistake, it will cut out very easy. If I remember right, there is also a 4 ohm/8 ohm switch on the back, but that is only for when you are using it in 2 channel mode.

What speakers are you using?

Also the output of this receiver is discrete transistors if I recall. I've never had to take it out of the rack for repair

[Spacedye69]

Re: Sony receiver STR-DE545 Protection fault?

Its a customer unit. He is using it with the same setup as when he bought it.

About a third of the solder joints are crap, which I'll resolder, but I think I found the problem.

What use to be r736 is now a chunk of charcol. It is inline with q727, which seems to be a high gain transistor. Also inline is an Elna cap which reads about 8 ohms ESR.

Anyone have prints or a manual? I hate to have to BUY one!

q727 p/n seems to read C1841 AEOIE. Mouser will cross over the C1841 to an NTE p/n, but is an obsolete part.

[Maxxarcade]

Re: Sony receiver STR-DE545 Protection fault?

I'll look for prints when I get a minute, since I'd like a set myself. If none can be found, I could probably open mine up and give you the value of the resistor.

EDIT: Datasheetcatalog.com has a datasheet for the 2SC1841. Check it out and see if that's the one.

Eserviceinfo.com appears to have the service manual, but the site is down ATM,

[Spacedye69]

Re: Sony receiver STR-DE545 Protection fault?

Thats the right transistor. eservice only has part1 of a 2 part rar file for the DE545.

[Maxxarcade]

Re: Sony receiver STR-DE545 Protection fault?

They should both be there somewhere... Sometimes the site is hard to navigate. Right now I can't even get it to load Hopefully it will be back up soon.

[Spacedye69]

Re: Sony receiver STR-DE545 Protection fault?

I'm a dork! Mulipart was listed on the download page!

[Maxxarcade]

Re: Sony receiver STR-DE545 Protection fault?

Sweet, I just got a copy myself in case mine ever quits. Though I've probably got less than 300 hours on mine so far

[ivtec]

Re: Sony receiver STR-DE545 Protection fault?

Max i also have a strde475 and also goes in protect as soon i turn power on,but mine did run good before except the tuner,that made hum noise and did not lock in the stations,till i replaced all the caps electrolytics on the smoked area and tested for ESR and they were dead dry so i replaced them all, and put the receiver together and power up, for my surprise i smelled some burning and it went in PROTECT mode and i opened up again and inspected and tested all the caps that i replaced all i could come up with was IC690 a C1815 just next to the IC702 UPC2581 that was short so i replaced and didn't see anything burned so powered up and nothing just PROTECT, and i rechecked the IC C1815 and it was good this time, so I'm stuck in protect,i suspect ic 501 but i 'll be darn if i spend any money on this besides i have another Str de 335.if you come up with some solution let me know.