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Louie
Louie, Technician
Category: Home Theater-Stereo
Satisfied Customers: 12682
Experience:  Have been in the business 25+ yrs., down to component level.
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Have two 377 Yamaha receivers. While checking the good

Customer Question

Have two 377 Yamaha receivers. While checking the good receiver, it powered off. Now both will not power. The fuse in the transformer is good. The primary transformer is hot. Secondary has 15 v, 5 v, and 3 v. Believe is good. Have reset.
JA: What's the make/model of your device? How old is it?
Customer: 2 years, Yamaha 377
JA: How long has this been going on? What troubleshooting have you tried?
Customer: Read what I have written? Please!
JA: Anything else you want the instrument expert to know before I connect you?
Customer: They must know Yamaha and their "Protection" circuits.
Submitted: 3 months ago.
Category: Home Theater-Stereo
Customer: replied 3 months ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call.
Customer: replied 3 months ago.
Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 3 months ago.
My phone number is(###) ###-####
Customer: replied 3 months ago.
OrderID: 17746433-373, can I check back about 9:00 AM Sunday AM EDT? I have a family emergency now. Thanks. I appreciate.
Expert:  Louie replied 3 months ago.

Hi and welcome to JustAnswer, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.

Expert:  Louie replied 3 months ago.

Initially, let's try and review the basics. Proposed preliminary checks (if have not been done):

  • • check for the consistency of the standby voltage +9.27V at the emitter of Q1503 at the OPERATION (3) board;
  • • ACDET voltage +7.62V at the cathodes of D1508 and D1509;
  • • when attempting to turn On, PWR_RY voltage +2.97V at resistor R1501;
  • • and +0.5V at the collector of Q1501.
Customer: replied 3 months ago.
Will make the checks to the extent I understand and can find the connectors after church. Sorry about being late responding. I will log back on in about two hours. Thanks
Expert:  Louie replied 3 months ago.

I understand and yes please; an update when conveniently able.

Customer: replied 3 months ago.
Use metal frame as the common/neutral?
Customer: replied 3 months ago.
All three connections with the Pos lead read prox 12.v DC to the metal case(Ground/Neutral). I guess the power is totally off due to protection circuits?????
Customer: replied 3 months ago.
I only removed the top and two side plates. I can't see any components labeled: I see the label for
Q1501 and am not comfortable removing the board to get to components below. Don't see another I/C other than 1503 on the top of this board. Will be away from the PC for an hour. Thanks!
Expert:  Louie replied 3 months ago.

Apologies for delays, Internet down and back but sluggish.

There are four (4) reasons why the auto-protect would kick in:

  • high temperature (unlikely);
  • speaker/wires shorted (least likely);
  • output transistors have failed (likely);
  • low or missing secondary voltage(s) (most likely).

The last may be caused by a failed 3-terminal regulator and/or even a cold solder/loose connection or leaked capacitor.

And yes; metal chassis as common DC ground for the secondary voltages. From the main transformer, the voltages are:

  • 31.63;
  • 8.26;
  • 9.15; and
  • 5.61.

From these, the power supply circuit produces:

  • +5.85V @ output of IC133;
  • +9.16V @ D1308;
  • -12V @ output of IC137;
  • +12V @ output of IC136;
  • +5.85V @ output of IC133;
  • +3.3V @ output of IC131;
  • among others.
Customer: replied 3 months ago.
I will check power supply voltages at 8:00 AM Monday and send. Thanks very much.
Expert:  Louie replied 3 months ago.

No prob;...later then.

Customer: replied 3 months ago.
Will try to send a movie which I hope is not too large and is informative. Too larger. Now, see three still pix.
1. Zero volts to transformer primary. Note: The volts are when secondary cables are connected, and when not connected.
2. When is NOT connected to Transformer the volts leaving the pwr control unit is 120 volts.
3. Shows two (two lead) 120 volt sockets. Left is main power cord. Right is 120volt from power control board (guessing).
My guess is there is a sensor and a electronic relay/disconnect that kills the power to the transformer when the "Protection Circuit/s" have been activated. WOW! Felipe and I will now check the other 377 unit and expect to find the same results. Stay tuned! Thanks for patience.
Customer: replied 3 months ago.
sir, the other 377 behaves exactly the same. The two secondary plugs from the Transformer to the boards did not influence the voltage test above. Both units, no doubt, have the same issue/s. Many thanks!In attempting to confirm the voltages from your charts, none could be confirmed. Actually, we could not find about half the components. How do we get the Power Control Circuit ???? (Guess-name) to pass power to the Transformer primary?
Expert:  Louie replied 3 months ago.

That black block is a relay (RY151). It does the actual switching of the main transformer. This relay is powerd by the +9.27V at the emitter of Q1503. It is triggered on by the presence of PWR_RY voltage +2.97V at resistor R1501. This PWR_RY voltage +2.97V is an output of the CPU when it receives an input to turn on the RX-V377.

The CPU also processes other sensors' outputs; i.e. if it has to kick-in auto-protect mode by halting the output of PWR_RY voltage +2.97V. These sensors monitor:

  • temperature;
  • speaker/wire condition;
  • if the output transistors are good;
  • if voltages are present and correct.

Thus failure/fault on any of the above and auto-protect mode kicks in, CPU stops the +2.97V, Q1503 turns off, relay turns off, no 120V to main transformer.

Customer: replied 3 months ago.
Louie, what can be done to isolate the issue. I could not find/identify PWR_RY and R1503. I assume the voltage would be good on Q1503 if the power supply was connected. While testing the speakers and all other items have been disconnected. What suggestions at this point?
Expert:  Louie replied 3 months ago.

Please post back with clear pictures of all the circuit boards. Click HERE.

These pictures would then serve as common references.

Customer: replied 2 months ago.
Pix 7355 is overview of boards from top. 57 is Power supply. 58 - board locations and connections. 59 Top Board connected (close up is later). (More pix on next transmission)
Customer: replied 2 months ago.
60 Loose connection was to verify power when disconnected. No doubt protection disconnects when connected. 61 AC in is black and AC to unit is the grey/red (Loose). 63 is view of busy low power stuff. 67 Speaker board. Remainder is attempt to provide close-up of boards. Hope this is helpful and will be able to send all the pix.
Expert:  Louie replied 2 months ago.

Appreciate the pictures.

May we step back to the basic(s); "...The fuse in the transformer is good. The primary transformer is hot...." but have you checked fuse F1501?

When attempting to turn on, can you hear/feel a click from relay RY151?

Customer: replied 2 months ago.
May we step back to the basic(s); "...The fuse in the transformer is good. The primary transformer is hot...." but have you checked fuse F1501?)
(When attempting to turn on, can you hear/feel a click from relay RY151?) "No click"
"Is F1501 electrically located between the power cord and 110v plug CB155?" "If so, It appears to be good as we have 110v on CB155 when the plug is removed, or the wire disconnected". " NO power when the circuit is connected. " "Bet we are close to the culprit?" "I will be out of town the remainder of the day". Have a great day. Thanks!
Expert:  Louie replied 2 months ago.

I understand and later then when conveniently able.

I would make use of the time to further review the Service Manual and schematic diagrams.

Customer: replied 2 months ago.
Fuse F1501 has continuity. Relay RY151 clicks with 7v (Relay is 9v.). Next? Thanks for your patience.
Expert:  Louie replied 2 months ago.

Why is the brown wire cut please?

Customer: replied 2 months ago.
I assume the Amp does not have to be connected to the speakers to turn on? I hope I have not caused much work by having the speakers disconnected.
Expert:  Louie replied 2 months ago.

As long as the volume control is set to minimum, no further damage when testing without speakers connected.

Have you spliced back the brown wire?+

Customer: replied 2 months ago.
the brown wire is secure and attached as originally wired.
Expert:  Louie replied 2 months ago.

Reconfirm:

  • • check for the consistency of the standby voltage +9.27V at the emitter of Q1503 at the OPERATION (3) board;
  • • ACDET voltage +7.62V at the cathodes of D1508 and D1509;
  • • when attempting to turn On, PWR_RY voltage +2.97V at resistor R1501;
  • • and +0.5V at the collector of Q1501.

Please carefully access the OPERATION (2) board. Attempt to turn on the Yamaha and determine the presence and consistency of:

  • +5.85V @ output of IC133;
  • +9.16V @ D1308;
  • -12V @ output of IC137;
  • +12V @ output of IC136;
  • +5.85V @ output of IC133;
  • +3.3V @ output of IC131;

A friendly reminder: voltage measurements by its very nature requires that the unit be plugged in and turned on. It is therefore LIVE! Please exercise due care and caution.

Customer: replied 2 months ago.
Please provide a link or otherwise, provide information to make identification of the emitter and other leads to IC's and other components involved here. My EE degree from U of Tenn was back in 1957 and I took their first transistor course. I have spent limited time in this arena since, but enjoy. Regards
Expert:  Louie replied 2 months ago.

Please click on the linked HERE of each part below for their specification/data sheet:

  • HERE for Q1503 / 2SA1708;
  • HERE for D1508 and D1509;
  • HERE for Q1501 / KTC3198.
  • HERE for IC133/KIA7805;
  • HERE for D1308;
  • HERE for IC137/KIA7912PI;
  • HERE for IC136/KIA7812PI;
  • HERE for IC133/KIA7805API;
  • HERE for IC131/NJM2388F33.

These specification/data sheets are in Portable Document Format (PDF) file and can be viewed in most web browser. Right click on the link to "Save as", click on the link to open the file and/or click on the Download button to download the file. It would require Adobe Acrobat Reader or equivalent for this purpose.

Customer: replied 2 months ago.
When (HERE for Q1503 / 2SA1708) are open'd I see a PDF for both, but can find only Q1503 on the boards?
When opening (HERE for D1508 and D1509;) I see ONLY a PDF for KDS160.
I am confused. Please provide additional detail. I am sorry for my lack of understanding. Again, I appreciate your patience and expertise.
Expert:  Louie replied 2 months ago.

Q1503 is the part designation on the board. 2SA1708 is the real Part Number.

Part Number KDS160 is used both for D1508 and for D1509.

Customer: replied 2 months ago.
Brown wire is connected and secure via red wire nut. Travelling today and will test voltage as requested soon. Confirm the unit will turn on with no speakers connected? Volume is turned to minimum. Thanks and Good morning!
Expert:  Louie replied 2 months ago.

It is safe to test the unit with no speakers connected but with volume down. It would only fully turn on if auto-protect mode is not kicking in.

Customer: replied 2 months ago.
Sorry, I have a project consuming all my time for another week. I did Bid on a duplicate unit on ebay and hope to have that in a week. With a working unit, perhaps I can assist more in identifying the culprit in the two current units. With two repaired, I would have a spare. In the meantime, I hope to measure the voltages as recommended the weekend of Aug 20th. Thanks for your support and patience.
Expert:  Louie replied 2 months ago.

I understand.

And yes please; when conveniently able.

Customer: replied 1 month ago.
Got the 3rd unit from ebay. See:
https://vod.ebay.com/vod/FetchOrderDetails?sspagename=STRK%3AMESO%3AVPS&itemid=142442894560&transid=1435392834004
or,
Yamaha RX-V377 5.1 Channel AV Receiver #29waO
Item price $91.89 FREE SHIPPING
Quantity 1
Item number 142442894560The unit test perfectly in all respects. My helper is placing on workbench beside the other two. I want to be so very careful checking. I had #2 shipped from my FL home where it had worked fine for a year. Five minutes on the workbench and it was dead and I have no idea if I did it, or the housekeeper who disconnected it in FL. Will report back. Love any suggestions.
Expert:  Louie replied 1 month ago.

Hi again and appreciate the update.

Strongly consider passive tests; i.e. not powered / not plugged in.

Use alligator clips with wires similar to the items shown HERE. Join/connect ALL common grounds (metal/chassis) of the three (3) RX-V377 to the black probe of the multi-meter.

Choose any (test) point. Get an Ω reading of say of the cathodes of D1508 and D1509 of the third/new RX-V377. This is now our reference/template.

Then move to the the cathodes of D1508 and D1509 of the second/Florida unit. Read Ω compare.

And then to the first RX-V377.

Repeat for any/all test points.

Customer: replied 1 month ago.
Very helpful. I should have thought of that as I am very familiar with probes and grounds. I am not current on micro components and their lead assignments. Did not get to spend much time on the unit this morning. Watched an entire movie while listening to #3 last night -- flawless!! Thanks.
Expert:  Louie replied 1 month ago.

Great!

Glad that the above test method may serve your purpose.

Customer: replied 1 month ago.
BINGO! Now, number two is working fine. WOW! Since the parts are so hard to identify and my time has been limited, I took some risk and changed cards. I can send Pix.The Card containing the HMDI connections was changed to fix the issue with Unit 2. Likewise, the Card for #2 caused #3 Amp to remain dead. The card in question has Label: YF985 and ZJ58150, and ZJ99580. A box is checked indicating the label ZJ58150 is applicable.The serial number to #2 is: T390644VX.
I will test the same board from #1 (Inoperative) on #3. Can this board be reset? Will the entire board with hundred's of components have to be replace? Can the board be replaced? I found another unit on Ebay for $80 including shipping. I am tempted to buy it as this unit serves my small theater in TN and at Boca well. With this storm, I may not need one in Boca for some time. My place is a prime target?
I logged on to Yamaha service and hope to hear back from them next week.
Customer: replied 1 month ago.
The 4th card was the one in question. Changing the power supply and two related cards did not help. Thanks and have a great weekend. Sorry to keep this open so long.
Expert:  Louie replied 1 month ago.

Appreciate the update.

And good to hear that the issue with the second/Florida unit has been resolved, congratulations.

...Be Safe!

Customer: replied 1 month ago.
The HDMI card in unit 1 checked bad. Looks like I need two HDMI cards. I think I have found an eBay vendor for those. Price was $35. Will recheck this morning. Thanks! Any suggestions for repairing the cards?
Expert:  Louie replied 1 month ago.

Please post back with clear pictures of the "...two HDMI cards..." Click HERE.

These pictures would then serve as common references.

Customer: replied 1 month ago.
Three pix of card for Unit #1. The card for Unit 2 (Bad) and the Original Card for Unit 3 (Determined good and works in Unit 2 and Unit 3). I have the good card installed in Unit 2 in the Theater currently. If needed, I could remove and supply pix. I could detect no difference between the good and bad.I had no luck finding a card on Ebay this AM. I doubt that Yamaha Service will be of help. Suggestions appreciated. Regards, jim
Expert:  Louie replied 1 month ago.

Two (2) potential approaches:

  • reflow - use a soldering / hot air station to reflow all the solder joints;
  • recap - change all the electrolytic capacitors.

Both of the above are 'shotgun/blind' method; i.e. no identified culprit hence suspect all.

Customer: replied 1 month ago.
Will you favor me by searching for a replacement card?As to the two recent suggestions, there are just too many connections to manually solder and I am not familiar with an efficient method to re-solder dozen's of connections. Ordering and replacing all the capacitors would take considerable time and I never see a capacitor failure without visible signs of overheating.I just replaced all components in Unit 1 and using HDMI Board 3, the unit is perfect. Clearly, I need to repair/replace two HDMI Cards. I would like to accomplish this for $20 to $40 each. Any suggestions for a source would be appreciated. Thanks
Expert:  Louie replied 1 month ago.

I will try to run a search for replacement Digital/HDMI boards within that price range.

Expert:  Louie replied 1 month ago.

Hi again,

Unfortunately, no readily available replacement boards in my search; sorry.

Customer: replied 1 month ago.
I left an email/report with Yamaha on Friday, but no answer. I will try again now. Thanks
Expert:  Louie replied 1 month ago.

I realize that the above information may perhaps be not what was expected. Unfortunately, there is no quick-n-easy fix and neither is there a workaround. Our last bet would be with Yamaha; sorry for having to be the bearer of bad news.

Expert:  Louie replied 1 month ago.

Hi again,

Is further information/assistance still needed with this?

Customer: replied 1 month ago.
I appreciate your patience and support. Please hang in with me while I dialog with Yamaha. I received a message last evening claiming they had emailed me. I will challenge that today. Thanks,
Customer: replied 1 month ago.
Too, I will take comparison resistance measurements between components of the good card and that of the defective cards. Likewise, will measure voltage. Any suggestions? Thanks.
Expert:  Louie replied 1 month ago.

May I suggest passive tests first; i.e. alligator clips to the boards for ground connection to the multi-meter black probe.

And then the red probe to a test point on the good board, then to the bad board.

Check for Ω readings.

Expert:  Louie replied 13 days ago.

Hi again,

Expert:  Louie replied 13 days ago.

Any update(s) ?