Yamaha HTR-5660 troubleshooting/repair

[dochenry]

Hello! First post here lol

I have a Yamaha HTR-5660 that's been working for years. About a month ago all the sudden it stopped decoding Dolby, so I was thinking it needed a new Dolby board/dac. Then a day later everything just stopped. No audio, then it just stopped working all together.

I have a myriad of tools for working on electronics. I have a pretty good background in computers and automotive diagnosis and repair...but not anything like this lol so im looking for some advice on how to start going about diagnosing, repairing, and places to get parts or maybe a rebuild kit if possible (if thats a thing for something like this).

Any help would be greatly appreciated!

 

[mbz]

Apologies, don't have much time.
First up, download the service manual from hifiengine or...
In the early chapters will be a description on how to envoke diagnostic mode, typically a 3 key sequence while powering on.
Read the diagnostic information, eg, PS XXX:nnn.

The 2 most common protection issues mean that either the amp does not respond to power on or the amp powers up for 2-3 seconds before shutting down. What is your case? Common faults are failed regulators or caps in the power supply, this is a reasonably easy fix, other faults are not so easy.

 

[dochenry]

Awesome! I'll do that right away when I get home. At this point it doesn't power on at all.

 

[mbz]

To enter diagnostic mode your need to press the STANDBY/ON key while pressing "8CH INPUT"
and "STEREO", ie, hold down 8CH Input and STEREO then hit the standby/on key.


Expect the following messages,
I PROTECT

The other possible protection messages are,

PS PROTECT: nnn, amp shuts down 1 second after power ON
DC PRT, amp shuts down 3 seconds after power ON
TMP PRT: nnn, amp shuts down 1 second after power ON

Post the full message you receive.

There was an old fault in such units where it would not "wake up" from STBY mode.
Problem was a failed 22nF cap in the standby power circuit. Would expect that problem
was resolved long ago. Will try and confirm.

 

[dochenry]

Hello, I did what you said, and the receiver didn't respond at all. I held down the two buttons, pressed the standby/on key and no "click" of the amp turning on, and the screen didn't turn on or say anything.

 

[mbz]

the receiver didn't respond at all. I held down the two buttons, pressed the standby/on key and no "click" of the amp turning on, and the screen didn't turn on or say anything.

That may be good news, it may indicate a problem in the "standby power supply" (subtrans board in older units) probably that 22nf cap. I had a quick look but could not locate, may have been replaced by a 10nF in newer models. Will try and find some time today to look further.

 

[dochenry]

Well that would be nice if it was that simple. I'm in no big hurry, I already replaced the receiver...I'm just trying to get this one going and use it to learn how to service these things. Ultimately it will end up going to a friend.

I picked up the service manual, so I'll do some looking through that and see what I can find out.

 

[mbz]

Service manual shows 2 fuses on the Power(2) PCB, F701(Switched outlet), F702(main).
Good house keeping to check them. Note no fuse for the standby power.

On the Power(2) board (the one with the small transformer), check connector CB701 S12 pin
for +12...+13.6Vdc, simply plug the unit in and switch on at mains outlet if equipped, that should provide
standby power to the mcu.

Then check Vdc at the PRY pin by hitting the standby/ON key, looking for a brief blip of about +0.8Vdc

Test CB605 +5M pin for +5Vdc standby power supply, this is on the Function(4) board (with the mcu)

 

[dochenry]

Checked the fuse's, both are good.

CB701 pin S12 showed 2-3mV

Couldn't get a blip on the PRY pin

CB605 showed no Vdc at Pin +5M

I just used one of the main screws holding down the AMP as ground. Is there a better place to ground in these situations?

 

[mbz]

I just used one of the main screws holding down the AMP as ground. Is there a better place to ground in these situations?

Chassis connection/screw should be fine. You could try any black speaker connector/post, I assume it's a common GND.

CB701 pin S12 showed 2-3mV

Couldn't get a blip on the PRY pin

CB605 showed no Vdc at Pin +5M

Points to the standby power, no 5Vdc to microprocessor. Could be the infamous 22nF cap, I had a look but couldn't find it, will try again.

I'm just trying to get this one going and use it to learn how to service these things.

Great that you have a learn attitude however the AVR's are very complex and might be frustrating. Suggest find a vintage amp and tinker with that. NAD's are a good starting place, eg, 3020, 3140, 3150. A Sansui AU-505 or AU-555A would be better (as would "any" vintage Sansui), also Luxman SQ505X. Maybe decide what type of sound you like and get the corresponding unit. The Yamaha CA-1000 is something of a personal favourite however a PITA to work on.

 

[mbz]

The area of interest (Power Relay Circuit) is on page 92 of the manual, power plug is shown at co-ordinates G2.
With no volts on CB701 S12 points back to Q702 which is controlled by R702,3, D702,3 and ...

Would be nice to measure Q702 b/c/e voltages to GND. If you have minnigrabbers then great but don't probe transistor
legs, one slip... instead probe connected parts, ie, D701 cathode = Q702emitter. D707cath = Q702c, R702 for the base.
Wanting to see Q702c at +13.6Vdc, Q702b at +13Vdc and Q702e at about +12.5Vdc (this is S12 so know it's 0V)

If Q702c and b voltages are ok then Q702 has failed. Otherwise need to look at D702,4,7 (diode test) and zener D703.
Hopefully T701 is ok.

 

[dochenry]

The area of interest (Power Relay Circuit) is on page 92 of the manual, power plug is shown at co-ordinates G2.
With no volts on CB701 S12 points back to Q702 which is controlled by R702,3, D702,3 and ...

Would be nice to measure Q702 b/c/e voltages to GND. If you have minnigrabbers then great but don't probe transistor
legs, one slip... instead probe connected parts, ie, D701 cathode = Q702emitter. D707cath = Q702c, R702 for the base.
Wanting to see Q702c at +13.6Vdc, Q702b at +13Vdc and Q702e at about +12.5Vdc (this is S12 so know it's 0V)

If Q702c and b voltages are ok then Q702 has failed. Otherwise need to look at D702,4,7 (diode test) and zener D703.
Hopefully T701 is ok.

Sounds good, I'll see about some mini grabbers and tackle that tomorrow. Thanks