Sony TC-WR770/870

Hello Darryl and welcome to EP.

Sorry that no one has responded before now. Do you have a schematic?

Chris

 

Please post them.

Chris

 

Sorry, not with my old eyes. Even when I enlarge them they're just a blur.

Perhaps a skilled member with younger eyes will chime in here.

Chris

 

Questionable skill and no younger eyes here.
It'd help if maybe you could make a larger pic of the power supply section schematic?
Also, unless you see some heat damage with your referenced resistors, I'd be looking more at the capacitors
as posing a potential problem here.

 

Sounds like good advice from someone with questionable skills. I think you've graduated to skilled level.

Chris

 

Maybe after another 46 years on the workbench, I'll move-up another peg to semi-skilled.

 

With any luck we'll get a larger photo with the area in question circled. With 46 years to play with I think the chances are good.

Chris

 

Sir Darryl . . . . . . .

Of your page 1 photo submitted . . . . 4th schematic page down.

I was reading the schematic fine from A18---26 down to M18---26 and
then you had just chopped off N-O-P 18 thru 26 where the vital info was
located.

Looking within the relevant portion that I can see . . . .
As per any R700----702----703---- fuses? they would have to be low value
fusible resistors and the R700 . . .etc series that I do see
are being up in the 1K regions . . .therefore they are not being fusibles.
There ARE F701 and F702 . . .1.6 A fuses.
Do you have your + and - 7.5 vdc supplies and the + 5vdc supply ?


Can you hit me with a conversation/message feature on this site to
exchange E-mail addee's and I can extract and process the relevant
schematic info to post ?

73's de Edd

 

Nuts. 73's de Edd must have a microfiche reader to have seen that.

 

Sir Daryl . . . . .

Referencing to the simplified schematic at the very top, first . . . . . considering that you do not have a blown R704 fusible resistor . . . . . what supply voltages do you now have ? Finding those supply points on full schematic 2.
OR confirm if you have AC output voltages at the transformer SECONDARY windings.

Aside . . . .
Ω test . . . . . testing Ω Ω Ω . . . . . . 1...Ω 2...Ω 3 . . .Ω ...testing.

REFERENCE SCHEMATIC SNIPPET OF POWER SUPPLY . . . .



73's de Edd
.....

 

Sir Daryl . . . . .

WHERE? . . . . .you . . . .g o o o o o o o o o o o o o o ?

latest update is that this deck now has no power lol its lifeless and i need it to work again any help appreciated.

If that is the case, then take ohmmeter and test across the AC cords plug to see if you are reading tens of ohms resistance of the transformers primary winding.

IF SO . . . . . . . . .

Those are being fusible resistors that will that blow open circuit, in case of excessive .overload.
R704 at the top is a given, in its wired installation.
The lower R700 or R703's options are being incorporated in accordance to different -11,-12 or -13 board versions

Starting all over again . . . . .

Why don't you start by using a DVM and connect its black ground lead to the central ground buss that crosses the unit .
THEN power up and check with DC metering to see if you find the bottom left corners MINUS 28 VDC supply being present.
Then move up to check for the presence of the +5 and +11 VDC supplies..
Then, move to the extreme right of the board and check for presence of the +7.5 VDC supply at the top left corner and then check the bottom right corner to see if the MINUS 7.5 VDC is present..

Clue us in on what supply is missing . . . and we can then proceed.
Sort of expecting your +5 and / or / + 11VDC to be missing.
If that is the case . . .switch metering to AC mode and check for the presence of the ~15 VAC across power transformer terminals #11-13. Then stay on one lead and move one probe to #12 to see if it is reading ~ 1/2 the previous voltage being read.


73's de Edd
.....