Yamaha HTR-5920 cracked schottky diode

[Uranium-235]

So I was replacing some bad caps on this receivers main amp and a glass schottky was inside the goop by one cap and cracked when I removed it. I already got some good idea from another member but I don't know if there is anything else I need to know. Here a direct link to posts and pictures


https://www.badcaps.net/forum/showth...24&page=38#756

if anyone has a schematic to this board, that would be fantastic

thanks

[Uranium-235]

Re: Yamaha HTR-5920 cracked schottky diode

found service manual. D938. References Q654. Also had a diode list but not sure which one it is.

now i'm not sure its a schottky, maybe Zeiner

[petehall347]

Re: Yamaha HTR-5920 cracked schottky diode

1SS133
it is written next to it on schematic .

http://uk.farnell.com/rohm/1ss133t-7...rfnonsku=false

[Uranium-235]

Re: Yamaha HTR-5920 cracked schottky diode

I thought that area would be text searchable, shows what I know. Thanks for the info, you're a life saver

ugh shit, I am not finding a replacement at mouser my closest supply. How much margin is there for error on this one? can I just surpass the maximum surges to the nearest high value? voltage too?

[petehall347]

Re: Yamaha HTR-5920 cracked schottky diode

1N4148 or something like it should work .

[rhomanski]

Re: Yamaha HTR-5920 cracked schottky diode

I usually keep about 50 1N4148's around the house.

[Uranium-235]

Re: Yamaha HTR-5920 cracked schottky diode

its been answered before but I would like a second opinion, do you think the forward voltage difference of 200mV should be ok?

also, do you think the stuff covering the diode was there to prevent the cap from heating up too much? I mean, it has a 175C tolerance, putting it next to a 105C cap, was it for this purpose.

funny ive dealt so much with caps on mboards and tvs but when it comes to pretty much every other component i'm pretty much in the dark (except maybe resistors)

[rhomanski]

Re: Yamaha HTR-5920 cracked schottky diode

Should be fine. That's such a small difference.

[Uranium-235]

Re: Yamaha HTR-5920 cracked schottky diode

well I got them (diode, all 4 caps)

and, nope. The original problem was just a 60hz hum

now the initial power relay clicks, and as soon as the main amp relay clicks it turns off

[petehall347]

Re: Yamaha HTR-5920 cracked schottky diode

are you running it direct on mains power ? not that it should do this even on limited power .
any speaker loads ? if so try without .

[Uranium-235]

Re: Yamaha HTR-5920 cracked schottky diode

I'm...not sure what you're talking about.

speakers, yeah, I disconnected them , one at a time to see if it made any difference, nope

[petehall347]

Re: Yamaha HTR-5920 cracked schottky diode

try both disconnected

[budm]

Re: Yamaha HTR-5920 cracked schottky diode

well I got them (diode, all 4 caps)

and, nope. The original problem was just a 60hz hum

now the initial power relay clicks, and as soon as the main amp relay clicks it turns off

So the main power relay RY91 drops out when the speaker relays (RY61~64) comes on?

[Uranium-235]

Re: Yamaha HTR-5920 cracked schottky diode

it sounds that way

[Uranium-235]

Re: Yamaha HTR-5920 cracked schottky diode

video (turn your sound up, kind of soft)

[redwire]

Re: Yamaha HTR-5920 cracked schottky diode

It powers up, after a delay, relay clicks and it powers off?

The MCU has made an executive decision, lol. If this is what is happening, I'll guess... two things.

The MCU has a mega power supply monitoring line PROTE_PS pin 5 BN82 to CN96. It's a summation of a bunch of PSU voltages. This signal gets renamed PRV and is a monitor for +5V, +12V, -12V and the amp's rails +50V, -50V.
I estimate that line should be 2.5VDC if all PSU rails are OK. If you can watch it with a multimeter. Guessing the MCU turns things off if there is trouble seen there.

It might be nightmare in the muting circuit you were in, with D938 (by IC98).
Did you have a failed STK402? Maybe unmuting the power amps causes one channel to have a DC shift and trip the protect line at Q559/Q558.
I don't know what this receiver does if a power amp problem trips PROTECT.
Most stay on and display PROT or something, instead of powering down.

[Uranium-235]

Re: Yamaha HTR-5920 cracked schottky diode

normally it clicks once the second you turn the power button. Display turns on and displays the volume or input for a second, and the second click turns on the speakers.

I don't think the second relay is clicking on, the sound is the first relay clicking on and off

I don't think my relays are failed. The unit was working just fine with the exception of 60hz buzz that I were believed from the bad caps on the main vrm (C960, C933(which wasn't bloated, but I replaced it just in case)). And two more next to them

[redwire]

Re: Yamaha HTR-5920 cracked schottky diode

If something works worse after I replace parts, I check my soldering, connectors etc. in case I did something "extra"

I would measure the power supply voltages and see if they are good, and then the 6 power amp output voltages to check if a channel has DC offset and it's in protect mode. R564-R570 are one place to measure voltages.

[Uranium-235]

Re: Yamaha HTR-5920 cracked schottky diode

Already checked it. Indeed I did break some traces right around many of the joints, but I scraped the insulation off the trace and flowed the solder to the trace. I then check the nearby joints with the meter to make sure its connecting, all seem fine.

[rhomanski]

Re: Yamaha HTR-5920 cracked schottky diode

I've never owned a Yamaha, but I have read a lot of people griping about their crappy soldering. You probably flexed the board and made the bad solder worse. You could just reflow everything you can around the relays.