OK. NOW WITH THE AMP OFF read the resistance from pin3 to pin8 please.

Between 3 and 8 is giving Overlimit on my meter

 

Read the resistance between pin8 and pin9 with the amp OFF and between pin3 and pin7 please.

 

Read the resistance between pin8 and pin9 with the amp OFF and between pin3 and pin7 please.

Pin8 and pin9: bouncing around alot, but in the range of Mohm and Kohm, so very high. Seemed to settle on 0.36Mohm

Pin3 and pin7: gives about 1.2 ohm, which is about the same as when I short my meter leads, so I would say it's closer to 0 ohm

 

Can you get voltage readings on all the other pins?

 

Now I suspect resistor R510 a 180K between pin8 and pin9.
Do you see any bad solder connections on those pins and components?
Do you have a resistor to jump across pin8 and 9 to test with?

Solder looks okay around R510, and is reading at the right resistance

What kind of resistor would I want to be jumping with? I can salvage one from some boards I bought home from work to practice soldering on

 

Forget the resistor for now can you check voltages on all the other pins please.

 

Forget the resistor for now can you check voltages on all the other pins please.

1: 0.67v
2: 0
3: 0
4: 0
5: -0.8
6: 42
7: 0
8: 42
9: 3.16

 

I think you mean 42 millivolt on pin 8 but no matter the problem is that 0.67 volt on pin 1 it should be appx -0.8 volt.
Short pin1 to pin 3 and to see if the relay comes on.

 

I think you mean 42 millivolt on pin 8 but no matter the problem is that 0.67 volt on pin 1 it should be appx -0.8 volt.
Short pin1 to pin 3 and to see if the relay comes on.

Yep just double checked pin 8 and it is mV.

Shorting pin1 to pin3 starts the relay, I also found that shorting pin6 to pin7 does too (found incidentally)

Edit: let me try again, had my pin order the wrong way around. (Fixed now)

 

Yep just double checked pin 8 and it is mV.

Shorting pin1 to pin3 doesn't start the relay, but shorting pin3 to pin4 does

What? Pin 3 and 4 should be connected together according to the schematic.
Check solder connections again or possible break on the pc board traces.

 

What? Pin 3 and 4 should be connected together according to the schematic.
Check solder connections again or possible break on the pc board traces.

My mistake sorry, I meant 6 and 7

 

That makes sense but shorting pin1 to 3 doesn't work?

 

That makes sense but shorting pin1 to 3 doesn't work?

It does, sorry for the confusion.

 

OK then the problem might be associated with Q501 and Q502.
Can you get voltage measurements on all leads of those transistors?

 

OK then the problem might be associated with Q501 and Q502.
Can you get voltage measurements on all leads of those transistors?

Okay so Q501 has: B: -0.69 C: -1.5 E: -0.69

And Q502 has B: -1.5 C: -6.67 E: -6.67

Or perhaps positive numbers, unsure on meter leads way-aroundness when testing to chassis / GND

 

Okay so Q501 has: B: -0.69 C: -1.5 E: -0.69

And Q502 has B: -1.5 C: -6.67 E: -6.67

Or perhaps positive numbers, unsure on meter leads way-aroundness when testing to chassis / GND

Those readings don't match the schematic especially on Q502.
See what the voltage reads on both sides of diode D501. Make sure the polarity of the meter leads is correct.

 

Those readings don't match the schematic especially on Q502.
See what the voltage reads on both sides of diode D501. Make sure the polarity of the meter leads is correct.

It's reading 0.67V ac on the anode and 0.97V ac on the cathode side
Edit: I'm learning now that my multimeter has a diode mode, let me figure this out

 

Should read minus DC volts on the anode side.
Can you do a diode check on both D501 and D503?

 

It's reading 0.67V ac on the anode and 0.97V ac on the cathode side
Edit: I'm learning now that my multimeter has a diode mode, let me figure this out

I think the diode is open edit:shorted?
Using diode mode on multimeter and Getting 0.7 voltage across with black lead on anode and red lead on cathode and 0.45 with leads the other way around.
so it is passing current both ways?

 

Should read minus DC volts on the anode side.
Can you do a diode check on both D501 and D503?

D503 is 0.61 anode to cathode and OL cathode to anode