In the google chrome browser, the input field for biography in the profile settings of this forum is about 2400pixels wide haven't checked other browsers, I do enough of that for work

I'm in Brisbane

Edit: clarification

 

Photos of console board attached.

A much higher quality photo of the front is here, too large to attach in this forum. I roughly stitched two closer photos together. I'm doing the best I can with an iPhone

I'm starting a schematic, working from the power board connector, as I wait for any suggestions here.

Some component pins aren't soldered properly through both sides of the board, although it at least looks like the business side of each joint is soldered ok. I'll fix them all of course, and I have done some of them already ... I'm bringing my soldering skills back to what they used to be before I do the IC pins. Don't want to cook any of them.

You'll also notice some marks and scratches and what may look like stray solder in some places. I've checked all of those and found just surface scratches and flux-type substance, which can look like solder in the photo.

I may have to get a magnifying glass and check out some of the spots though, including the mass of surface mount resistors near S13 and S9 on the back. I'll wait for suggestions first though while I begin the schematic.

 

What ICs are U2, U3, and V3? What transistors are Q3-Q8?

Can you get a shot of that part of the board in higher resolution? (U3 to connector horizontally, and whatever fits vertically)

 

U2: HD74HC02P
U3: HD74HC14P
V3: 74HC595N

Q3 - Q8: D882P by NEC.

Hi-res shot available tomorrow morning. Should have done that this morning

edit: Haha. I had the pin numbers on the connector to the motor board reversed. check out the motor board schematic and you'll see why I got confused when I followed what I THOUGHT was pin 5 through a high wattage resistor to the input of a voltage regulator ... I was following pin 6 ...

Removed incorrect info from post, updated original photos and corrected HD74HC02P; it was wrong.

 

Are the transistors 2SD882P Rather than D882P?

 

Are the transistors 2SD882P Rather than D882P?

Nope, they just have this on them:

NEC
D882 P
M 1Y

 

Console board schematic enable signal is done as much as I can do it without some input from here.

I'm going by these datasheets, I'm hoping that they are correct:

U2 - HD74HC02P
U3 - HD74HC14P

I also hope that I got all of the connections right; the tracks to pins 2 and 3 of U2 run underneath the chip itself so I had to confirm by continuity.

No idea what the chip with all the pins is, it's got some semi-translucent goop on top of it. If I got hold of a magnifying glass I may be able to identify it, but I wouldn't have a hope of being able to do anything with it solder-wise.

I'll measure and post all voltages and verify ground connections next and wait for feedback.

 

Tested all I can while standing by. I'm unsure whether I have ID'd the chips correctly ... I always thought inverters (U3) were supposed to be unidirectional? The numbers printed on them are correct anyway.

Test results. I'm sure some of these are unnecessary, but it doesn't hurt anyone to provide as much info as possible.

All voltages are DC and referenced to board ground. Vcc is at 5V for both chips and grounds check good. See the attached schematic for reference, test points are labeled:

1:
4.97V all times

2:
15V all times

3:
0.0V at idle
0.10V at run (I measured 0.17 yesterday)

4:
0.0V at idle
0.34V at run

5:
0.0V at idle
0.34V at run

6:
3.49V at idle
4.62V at run

7:
4.7V when safety key is removed
0.0V all other times

8:
0.0V when safety key is removed
4.7V all other times

9:
0.0V when safety key is removed
3.7V all other times

I'll wait for advice of course, but it looks to me like I've run into the brain chip (of course the fault may be at one of its inputs, but hmmm). If I have ID'd U2 properly, then either input to the NOR gate being high will cause its output to be low, so test 6 always being (somewhat) high will stop the enable signal to the motor control board.

I'll sit tight for advice.

 

That 66 pin chip is probably a 64 pin chip. Each side has 16 pins. Most likely it's a microcontroller. If the console board lights up and the LED displays work it's probably okay. I'd look elsewhere.

 

Processor is output is responding with a high output at run command initiation

I need to know where else Pin 3 of U2 goes, I cannot make out, pin 3 will be connected to another out put of NOR Chip.

Check to what of these pins, 4, 10, 13 of U2 is connected to pin 3 of U2. This is where the problem lies.

I'll explain what I see. I has assumed these from ur voltage measurements.
The safety key is responding as point 9 at μC is changing, but in order for point 8 of U3 inverter to change input of inverter should change, from measurement this shows it is true.

Referring to your findings
test point 7 wire is LOW for safety deactivated. Makes pin 3 of U2 low.
test point 6 wire should be low for the out put to activate supply driver opto.
But, for the NOR output to go high both input shud be low, pin 3 is working, but not pin 2 which is run command terminal of μC's voltage transition levels

Pin 2 (U2) Levels are wrong. at idle it should high. i.e > 3V or so.
to run the thread that pin should go active low, text point 6 should be closed to 0V for the NOR to respond.

From ur measurements the point 6 voltages does not change much. The μC pin should be forced to ground level for the thread to run, if μC does not pull the point 6 to ground level NOR will not respond.

There are few faults that this could be, I'll lay out for u all.

one fault could be that μC control pin which pulls the gate input low could be open. the output drive is open, in this case. for Idle it will float or will be pulled by an external pullup resistor. but for an active state it won't pull to ground or a fault is preventing it from going to 0V.

second is that gate input pin is shorted to a high level.

So, for the tread to respond point 6 shud switch.

Here is a test. connect the tread and power up.

Deactivate safety to run, hit run. If Motor does not run then short pin 2 of U2 to ground, If gate is U2 is OK, the motor shud start. But for this condition to meet pin 3 of U2 shud be close to 0V.
If these conditions are met and the tread runs then there is an issue at the processor or the connection in between of processor and the NOR IC

If it did not run. then measure the out put, i.e pin1 of U2, it should be close to 5V in run mode. If not, U2 is faulty. If 5V is there then the connection from pin 1 of U2 to lower PCB is faulty.

{ed}
By the way, I admire ur determination. Your keenness is the reason this is progressing fast.

 

Check to what of these pins, 4, 10, 13 of U2 is connected to pin 3 of U2.

I find continuity between pins 3 and 12. Any track on the board that does this must be underneath the chip, so I can't verify it visually unless I unsolder the chip.

short pin 2 of U2 to ground

Did this, with the following results:

Point 7: 0V
Point 6: 0V (it's grounded)
Point 5: 4.7V all times
Point 4: 4.7V all times
Point 3: 1.3V all times
Motor did not run.

Back to the motor control board and your earlier tests:

Next put DMM is DC volt mode, connect black probe to C4 Negative. Red probe to terminal point 6 of console board.

U shud measure around 20VDC.

17V.

Leave the black probe connected
Now connect RED probe to positive side of C4 .
U shud measure 5V.

5V.

Now connect RED probe to Base of Q5, and switch on the tread from console as an operator is ready to tread. Once the console is on, u shud measure 0.6V at the base of Q5.

0.72V all times.

Measure pin of opto PC817, U6. U shud get 5V when tread is off, & around 1.1V when tread is in running mode.

Pin 1 of PC817: 1.1V all times.

Pin 2 of opto or emitter of Q5. U shud measure 5 V when tread is standby and 0.6V or below when tread is running.

Pin 2 of PC817: 0.02V all times.

Previously, LED1 on the motor board would light up faintly. Now it's not lighting at all. Voltage across large filter cap C12 is 238VDC at run.

 

What the heck happened....ur measurements have changed now..
Did you do anything...if not..try assembling the tread. Double check the connections and try again.. post back

 

Did this, with the following results:

Point 7: 0V
Point 6: 0V (it's grounded)
Point 5: 4.7V all times
Point 4: 4.7V all times
Point 3: 1.3V all times
Motor did not run.
0.72V all times.
Pin 1 of PC817: 1.1V all times.
Pin 2 of PC817: 0.02V all times.
Previously, LED1 on the motor board would light up faintly. Now it's not lighting at all. Voltage across large filter cap C12 is 238VDC at run.

From this..u are telling me that console is switching on the supply. And it is tru when you measured DC voltage at the filter cap.....

Ques? is why the motor is not running when you clearly stated that previously shorting the opto, forcing the SCR to fire caused the Motor to run.

You are doing something wrong now.

 

What the heck happened

Yeah I've been asking myself that question. I am 100% absolutely positive that I got the part number of U2 right, the pins right, all connections are as they should be, literally everything. I double checked, but now I'm going to triple check.

I'm not surprised that the previously failed tests show good now, it makes sense. The drive signal is getting to the base of Q5 now as it should, which grounds pin 2 of the U6 opto and turns it on. What I am surprised about is the rest of the circuit going dead.

Is it possible that by grounding pin 2 of U2 in the console board (which pulls down the 5V line from the processor) has impaired the processor's ability to send another signal (like the speed signal) properly? Mind, I don't know how that is sent, but the speed is adjustable at the console so that signal has to get to the motor somehow (I know how PWM works, I'm only talking about the control signal). If that is true, then theoretically breaking the circuit between pin 2 and the processor and then grounding pin 2 would work ... not as a fix of course, but as a test.

Anyway, that's partly conjecture and mostly a question to you. Now that I'm this far in, I wouldn't mind learning how the processor actually controls all of that.

I'm going to do nothing else but remove that ground link from pin 2, and see if the machine returns to the same condition as when we started. I'll let you know what happens. Of course I'm not game to fire the SCR again, so I can't verify that something in the drive circuit hasn't blown in the meantime.

After that, a thought is to manually ground pin 2 of the U6 PC817 opto on the motor board to switch it on, just like we just did with the NOR gate ... but I ain't gonna do that unless I'm asked to

 

Is it possible that by grounding pin 2 of U2 in the console board (which pulls down the 5V line from the processor) has impaired the processor's ability to send another signal (like the speed signal) properly? Mind, I don't know how that is sent, but the speed is adjustable at the console so that signal has to get to the motor somehow (I know how PWM works, I'm only talking about the control signal).

Yeah, that would do it. Pin 2 should have been an input pin on the IC 74xx02 NOR IC pin 2, is that tied directly to the main power bus? Not pin2 of the connector... Did anything get very warm?

please clarify

 

Pin 2 should have been an input pin on the IC 74xx02 NOR IC pin 2, is that tied directly to the main power bus?

No, if the chip info is correct it wouldn't be because it has to be at or near 0V to make the NOR gate fire.

That said, it might have been wise to check for a short if possible before grounding the pin ... if the processor has an internal short, it could have made things worse

Did anything get very warm?

Nope.

Anyway, after removing that ground link, the machine seems to be back to the state it was in at the start of the thread. LED1 on the motor board is again glowing faintly when power is on, and voltage across the cap is now 230VDC at run time. All previous tests result in the original voltages.

Standing by

 

The cap is charged I think....

When you first shorted the opto out put or something before, the PWM and speed worked fine ......
Try checking that again and post back the results

 

Try checking that again

Works fine. All operations are normal ... except heart rate display doesn't go over 105, weird. Hadn't checked that before

 

What, exactly, are you jumping to make it work? The SCR or the opto output or something else?

When you are going to put an input at 0V, use a resistor to test first, something around 500 ohms, that should be enough to not damage anything, and still bring the input low in most cases. If the resistor gets warm, something is wrong.

 

What, exactly, are you jumping to make it work?

NOTE: bad practice, don't do this ... but, I'm bridging the TLP561G opto outputs that drive the SCR. This (without the voltage drop) simulates the opto switching on, which is the end result, among other things, of the enable signal that we were working on back in the console board.