Another Yamaha

[No1baggiesfan]

Re: Another Yamaha

I hope it does fix it, I can't really see anything else that would cause the problem.

I hope so too lol 👍🏼

https://uk.rs-online.com/mobile/amp/...ators/6869748/
Min order is 10 but free shipping, mouser wanted £5 to ship 1, crazy.

[No1baggiesfan]

Re: Another Yamaha

Installed new 7912, still no joy ��
PS value still fluctuating but not as bad: 129-135/129
Still getting ps prt 135 h error
Still no standby led

[R_J]

Re: Another Yamaha

So what is the voltage on the 7912 now? If it is still low there must be something loading it down. or it could be the cap (C1088) on its output is bad.
-12 volts supplies VIDEO (10) board, unplug CB383 and see if the -12v comes up.
-12 also supplies one side of the relays on (page 141)
The -12 also goes to the op amp ic's on (page 137) and elswhere

[No1baggiesfan]

Re: Another Yamaha

Wife's taxi, lol, I will have a look in the next hour, ty R_J

[R_J]

Re: Another Yamaha

O.k.You DO need that -12volts, so it might be a pain to trace the fault , but it is starting to look like a bad op amp ic?
After closer inspection that -12 goes to quite a few places

[No1baggiesfan]

Re: Another Yamaha

Weired, I now have 8-10v on the chassis with just the negative lead on it, getting 0v on the new 7912

[No1baggiesfan]

Re: Another Yamaha

Getting
0.9v 0.6 and -0.02v off the new 7912

[R_J]

Re: Another Yamaha

Thats strange? what are the voltages on the input. It was an all plastic 7912 correct?

[No1baggiesfan]

Re: Another Yamaha

0.6v on input
0.9 across c1088
All plastic L7912cp

Old and new in picture

[R_J]

Re: Another Yamaha

If you only get .6v on the input, R1238 must have gone open. It could be due to excessive load on the -12 volt line.

[No1baggiesfan]

Re: Another Yamaha

R1238 reading 9.9 ohms
20.9v on both sides

Shouldn't it be 0.22ohm ?

[R_J]

Re: Another Yamaha

20.9v on both side of the resistor tells me you ripped the trace replacing the regulator.
R1238 is 10Ω Wher did you come up with .22Ω ????
Please look at the schematic the resistor connects DIRECTLY to the INPUT of the regulator.
If you have 20.9 volts on one side of a piece of wire and 0 on the other side, where would you look for the problem.

[No1baggiesfan]

Re: Another Yamaha

Dry joint on regulator :/
I now have -12v -18v 0v on regulator

-18v and -19.7v on resistor

[R_J]

Re: Another Yamaha

So you now have 7.8 volts on the ground terminal???? I have know idea what you are doing.

[No1baggiesfan]

Re: Another Yamaha

Autocorrect on iPhone, sorry

[R_J]

Re: Another Yamaha

ok, so NOW you have -12 volts on its output. Does the amp now work?

[No1baggiesfan]

Re: Another Yamaha

I hadn't tried

Ok, reset amp, powered up and it stayed on

I guess now we reassemble it and hook up some speakers

[No1baggiesfan]

Re: Another Yamaha

Still no stand by led ?
Ps now showing 80/129

[R_J]

Re: Another Yamaha

Ok, reset amp, powered up and it stayed on

so the amp stays on but the diagnostic still shows an error
p1-2
Ps 80/129
Did you do the S3 factory reset?

[No1baggiesfan]

Re: Another Yamaha

It's not a 'protect' error, it's the reading from the hidden menu
Amp is hooked up and working so far though