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Old 23rd Jan 2024, 7:48 pm   #1
hugocarmo
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Default Sanyo VHR-D4710G VCR no sound.

Hi again guys.
Today I have a problem with this Sanyo VCR.
I bought it online, It worked sometimes.
I recap the Power supply and it started working fine.
Image is perfect and all digital effects too.
All of a sudden it stopped outputting sound. I checked for dried solders an all boards and soldered when needed, no fix.
I have no sound on playback, on tuner, or aux in.
On symptom I noticed is when it was working fine, the HI-FI led was on when I power up the VCR, now is OFF, A-B leds are on but when I put a tape they go off.
On one of the sound processing boards (has two) there´s a relay, I remember that when it was fine, when I power the vcr on, I hear the relay switching but now it doesn´t.
I´m struggling to find what is causing the problem. If it´s an IC, I think It´s garbade dispite the image still great.
I bought the service manual, wich I attach in my post.
I hope once again someone can help me fixing this VCR.

Service manual
https://drive.google.com/file/d/1TRE...ew?usp=sharing

Thank You all.

Hugo do Carmo.
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Old 25th Jan 2024, 11:04 pm   #2
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Default Re: Sanyo VHR-D4710G VCR no sound.

How have you connected this to your TV? I mention this because it would help narrow things down to check if you hear sound via the RF/antenna output, or the SCART/RCA output.
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Old 26th Jan 2024, 12:25 pm   #3
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Default Re: Sanyo VHR-D4710G VCR no sound.

Quote:
Originally Posted by ben View Post
How have you connected this to your TV? I mention this because it would help narrow things down to check if you hear sound via the RF/antenna output, or the SCART/RCA output.
Hi ben.
Yes I made all the tests connected to my TV, and tried headphones too.

Thank You.
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Old 26th Jan 2024, 9:21 pm   #4
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Default Re: Sanyo VHR-D4710G VCR no sound.

Perhaps when you were working on it, a solder splash bridged some pcb traces on a board, it could have moved into a position where a signal is shorted to ground. Some kind of signal tracer is needed here to ascertain where it is getting lost.

Measure the voltage on the coil of the relay.

Try feeding audio into the line in, do the VU meters react? If so, try recording, then play on a different VCR. It would be a bit unusual if both record AND playback were affected - that would point to an IC or its supply voltage.
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Old 1st Feb 2024, 10:48 pm   #5
hugocarmo
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Default Re: Sanyo VHR-D4710G VCR no sound.

Quote:
Originally Posted by ben View Post
Perhaps when you were working on it, a solder splash bridged some pcb traces on a board, it could have moved into a position where a signal is shorted to ground. Some kind of signal tracer is needed here to ascertain where it is getting lost.

Measure the voltage on the coil of the relay.

Try feeding audio into the line in, do the VU meters react? If so, try recording, then play on a different VCR. It would be a bit unusual if both record AND playback were affected - that would point to an IC or its supply voltage.
I Ben.
Did all You told me.
No react on the VU, line in, tv channels or play mode.
No voltages on the coil.

Thank You.
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Old 16th Feb 2024, 11:27 am   #6
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Default Re: Sanyo VHR-D4710G VCR no sound.

Good morning.

I have some updates.
I took appart the psu from the vcr and measured voltages on the sockets and compared them with the ones on the service manual and some of them seem different.
I´ll post the picture.

Thank You!
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Old 17th Feb 2024, 12:48 pm   #7
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Default Re: Sanyo VHR-D4710G VCR no sound.

Switched output voltages won't be there using it out of circuit. The psu gets a control voltage from the cpu when switched out of standby. The -21v is because your meter was set to DC volts instead of AC volts. Hope that helps.

Dave
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Old 19th Feb 2024, 3:07 pm   #8
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Default Re: Sanyo VHR-D4710G VCR no sound.

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Originally Posted by G6ONEDave View Post
Switched output voltages won't be there using it out of circuit. The psu gets a control voltage from the cpu when switched out of standby. The -21v is because your meter was set to DC volts instead of AC volts. Hope that helps.

Dave
Hi Dave.
Thank You for your answer.
In deed it´s AC that should have on that points, I have my multimeter in auto-mode and it displays that voltages in DC, I putted in manual AC mode and the voltages are fluctuating from 8v, to 1V then 0v, and repeats.

Thank You.
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Old 19th Feb 2024, 3:54 pm   #9
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Default Re: Sanyo VHR-D4710G VCR no sound.

CN512 pin 7 appears to be the psu switch on control connection. This looks like a negative control to make the supply switch on. You could try taking that pin to 0v when the supply is out of the machine, hopefully that should give all the missing switched line voltages.

Don't run the psu off load for any longer than needed to check voltages, as the psu might not be happy running off load and you don't want to damage it.

The AC voltages are possibly fluctuating due to the psu being in standby mode. It could also be due to them not being true sinusoidal waveforms and are confusing your test meter.

Dave
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Old 19th Feb 2024, 5:08 pm   #10
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Default Re: Sanyo VHR-D4710G VCR no sound.

Quote:
Originally Posted by G6ONEDave View Post
CN512 pin 7 appears to be the psu switch on control connection. This looks like a negative control to make the supply switch on. You could try taking that pin to 0v when the supply is out of the machine, hopefully that should give all the missing switched line voltages.

Don't run the psu off load for any longer than needed to check voltages, as the psu might not be happy running off load and you don't want to damage it.

The AC voltages are possibly fluctuating due to the psu being in standby mode. It could also be due to them not being true sinusoidal waveforms and are confusing your test meter.

Dave
Hi again Dave.
You´re right!
So my PSU have all the correct values.
My problem is another as I can see.
I´m giving this restore project as finish because it must be some IC that is damaged.

Thank You all for your help!!

Best regards,

Hugo.
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Old 19th Feb 2024, 6:03 pm   #11
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Default Re: Sanyo VHR-D4710G VCR no sound.

So at least you now know that the psu is OK, or at least as far as you can tell. That is good and helps to eliminate it from the problem.

Do you have access to an oscilloscope by any chance? It will make the search for a missing signal easier.

Since several audio functions appear to be missing, it is reasonable to think that there must be something common to all of them. The psu has been ruled out, so there must be something common in the audio circuitry. It could still be a missing supply voltage but perhaps due to a fusible resistor or filter choke in the actual audio section. It will require a study of the circuit diagram to advise further. Don't give up just yet though.

Dave
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Old 19th Feb 2024, 6:33 pm   #12
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Default Re: Sanyo VHR-D4710G VCR no sound.

Further checks to make. Audio pcb AD-1 board CN229 should have a +12v and a +5v going to it. Likewise AD-2 CN210 should also have both +12v and +5v. This appears to be the input supply voltage to each pcb.

Also check out what the function of the IR sound remote adaptor is and if it's in mute mode or switched on when it should be off. With it being IR it could be controlled by the handset, got to be worth checking?

Dave
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Old 20th Feb 2024, 7:27 pm   #13
hugocarmo
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Default Re: Sanyo VHR-D4710G VCR no sound.

Quote:
Originally Posted by G6ONEDave View Post
So at least you now know that the psu is OK, or at least as far as you can tell. That is good and helps to eliminate it from the problem.

Do you have access to an oscilloscope by any chance? It will make the search for a missing signal easier.

Since several audio functions appear to be missing, it is reasonable to think that there must be something common to all of them. The psu has been ruled out, so there must be something common in the audio circuitry. It could still be a missing supply voltage but perhaps due to a fusible resistor or filter choke in the actual audio section. It will require a study of the circuit diagram to advise further. Don't give up just yet though.

Dave
Hi again Dave.
I don´t have an osciloscope.

Quote:
Originally Posted by G6ONEDave View Post
Further checks to make. Audio pcb AD-1 board CN229 should have a +12v and a +5v going to it. Likewise AD-2 CN210 should also have both +12v and +5v. This appears to be the input supply voltage to each pcb.

Also check out what the function of the IR sound remote adaptor is and if it's in mute mode or switched on when it should be off. With it being IR it could be controlled by the handset, got to be worth checking?

Dave
I just made the checks You told me.
In AD-1 pcb I don´t have any of the voltages that were supposed to be.
In AD-2 pcb I have 12v on pin 1 and 5v on pin 3, they are correct.
I´m still waiting for the remote control, I don´t have it yet. I´ve disconnected the ir sound emitter module from the board just in case.
The vcr was working fine, just one day I turned it on and no sound.
When I power on the vcr before it stopped to have sound, the HI-FI led o the front panel lit, now it doesn´t too.

Thank You again Dave.
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Old 21st Feb 2024, 11:51 am   #14
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Default Re: Sanyo VHR-D4710G VCR no sound.

All 3 of those audio boards have audio going in and coming out, as such removing one will disconnect the signal. I would try to find out why there is no supply to the AD-1 pcb and also if the IR sound remote board has power to it.

I would need to have another look at the circuit re the IR board to find where the supplies come from, likewise AD-1 board.

Dave
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Old 21st Feb 2024, 12:34 pm   #15
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Default Re: Sanyo VHR-D4710G VCR no sound.

I've just had a look in my service manual and have found that the sound IR board, actually is there to transmit stereo audio to the remote control handset. The remote control handset has a headphone amplifier and h/phone jack socket. An interesting check would be to see if there is any audio to the h/phones, once you obtain the remote control.

From looking at the overall wiring diagram (A). AD-1 pcb appears to get it's supplies via AD-2 pcb from CN205 pins 1 & 2, also CN204 pin 2. Cn205 pin 2 is there when in playback mode. These supplies need confirming as to where the break is.

Dave
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Old 21st Feb 2024, 12:40 pm   #16
hugocarmo
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Default Re: Sanyo VHR-D4710G VCR no sound.

Quote:
Originally Posted by G6ONEDave View Post
I've just had a look in my service manual and have found that the sound IR board, actually is there to transmit stereo audio to the remote control handset. The remote control handset has a headphone amplifier and h/phone jack socket. An interesting check would be to see if there is any audio to the h/phones, once you obtain the remote control.

From looking at the overall wiring diagram (A). AD-1 pcb appears to get it's supplies via AD-2 pcb from CN205 pins 1 & 2, also CN204 pin 2. Cn205 pin 2 is there when in playback mode. These supplies need confirming as to where the break is.

Dave
Thank You again Dave.
I´ll try if I can check where is the break.
I disconnected the IR board only yesterday, just to try without it connected.
I think that I will not have any sound even from the remote headphones because the VU meters are inactive in playback, or sound AUX IN, or even in tv channels.

Regards,

Hugo.
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