Yamaha RX-V350 , BD3816K1

Watch out for this one folks, just warning you'll because i got fooled. Symptom: No input selction or audio. All you hear is click click when you crank the volume control.

The BD3816K1 is mounted on a vertical pcb which plugs into 2 connectors on the main board. 1 connector supplies + and - DC along with data, clk, mute etc, the other connector has 5 channel audio outputs to main board. A few 8 pin smd op amps lie in the ics periphery.The vertical board has pcb mounted rca sockets for various audio inputs. I measured supplies, looked at data and clock on my scope and everything checked out fine. Two transistors in a TO92 package had "K429 A1266" and "K435 C3198" printed on them. I wrongly assume they're FETs and do an in circuit check for a shorted gate-drain, find none and move ahead. So i invested 25$ in a new BD3816K1 and replaced the old one. Naturally i'm shocked and desperate when i power up the set and find the same symptom. I've already quoted estimate and an anxious knot in my stomach has me thinking "oh god what if another ic which isn't available locally is the actual culprit , i'm doomed." I slip into depression , curse the woes of this trade , and decide to give it a last attempt before resigning myself to accepting another loss.I look up datasheets for 2sk429 and i find the package doesnt match, turns out the damn thing's a 2SA1266 with an open BE junction. The other being a 2SC3198, the K no.s printed on top in both cases. Seems like some leakage from another device connected to the cd input on board (it left a nasty scar near the rca socket)( i'll bet a philips....say what?) took out both the transistors. They are in series with + and - supplies. What is this transistor coding system that starts with K ?, have never seen it before. Jango

Reply to
jango2
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So the A1266 fixed it? The "K" stands for KSA1266 as opposed to 2SA1266. Korean counterparts, usually but maybe not always interchangeable with the Japanese.

I've been looking through the service manual for the RX-V350 (US version anyway...)

Cannot find the transistors you reference.

Mark Z.

Reply to
Mark D. Zacharias

Yes, replaced both A1266 and C3198, both had open B-E junctions.Problem solved!. I think their part designatory numbers were Q451 and Q452 on the pcb. So let me get this right, K429 is supposed to be KSA1266? How weird. Jango

Reply to
jango2

NO! The K249 would be a 2SK249 FET, I would assume. I was only talking about the bipolar TO-220 plastic tab ones with the "K" mark at the top.

Mark Z.

Reply to
Mark D. Zacharias

Firstly, there are just 2 TO92 transistors on the board. Secondly the numbers printed on them read; K429 A1266 Just like that, K429 above A1266. I'm thinking here this might be another one of their ploys to con us, and then they'd shoot off a bulletin to the glorious authorised service centre family informing them of the mysterious double printing. Remember my pioneer trap switch post?.

Reply to
jango2

"I've been looking through the service manual for the RX-V350 (US version anyway...) Cannot find the transistors you reference"

The unit i had was made in China. Did you locate Q451, 452 on the schematic? Jango

Reply to
jango2

Yeah, I meant the Yamaha U, C model intended for the American market. They're all made in China.

I probably should have passed on commenting about the markings on your transistors - I'm not looking at them after all. I was just relating my experience with Korean counterparts, and assumed your Yamaha used them, which would have been pretty common.

Re: Q451 and Q452, in my schematic they are signal transistors used as + and - 7 volt regulators. Physically near IC451. They transistor types in my schem are 2SA1015 and 2SC1815.

I had glanced at them before but hadn't looked too closely because they weren't the larger type regulators that yours seems to have, and for some reason the "Edit - Find" function of Adobe 7 isn't picking up the schematic locators on this one.

Mark Z.

Reply to
Mark D. Zacharias

Yup - this is the one that got me. The old 2SA1266 is a plastic - tab TO-220 type. Sorry for the mix-up.

Mark Z.

Reply to
Mark D. Zacharias

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