C64 cassette motor signal issue

protek

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Finally got a chance to try my Tapuino out. I wonder if my settings are correct? I can browse and select a .tap file and it appears to start loading as the spinner spins and there is loading text but the percentage number doesn't grow and the C64 doesn't seem to find the program. The screen just stays blank.
Anything to try?
 

sweetlilmre

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Sounds like the motor detect line is not working. Does the display show a lower case 'm'? If so, then the Arduino is not getting the motor signal. Check wiring and the opto coupler
 

protek

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Sounds like the motor detect line is not working. Does the display show a lower case 'm'? If so, then the Arduino is not getting the motor signal. Check wiring and the opto coupler

Yes, it does show 'm'. The optocoupler I have is 4N36 as my local store didn't have the 4N35. The 4N36 is pin compatible with 4N35. Could that be the issue?

Also I don't seem to be able to update the firmware as I'm getting avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x30 in the Arduino. I've checked that the board, processor and port are correct.

- - - Updated - - -

The upload now works. It was a case of bad USB cable.

- - - Updated - - -

Think I found the problem. I tried with a datassette. The C64 isn't giving motor signal. :(
 

sweetlilmre

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@protek are you using JiffyDos by any chance?

Edit: you need to check the fuse in your machine as well. Seems this often happens with a blown fuse. Be sure to test the PSU as well...
 
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protek

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No JiffyDos in this one, just normal Basic prompt. The fuse seems ok visually and gives continuity with multimeter, when removed. Tried with two PSUs. Can the PSU be measured straight from the plug?
 

sweetlilmre

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You can measure the PSU at the plug side. It would also be good to measure after the switch on the C64 as this can cause issues (corrodes and causes massive resistance and voltage drop).
The two closest together pins on the PSU should be the 5V DC line, you should read over 5V. The other two will be the 9V AC line (remember to set your meter to AC :)).
Test the 5V line on the Datasette edge connector as well (this is a way to see if the switch is causing issues: if it registers much less than the PSU 5V line there is a problem).

The Motor line power is provided by the 9V AC supply so there may be other factors at work. I hope its not the CIA.
Do you have any way of testing sound? The 9V line also provides power to the SID.

-(e)
 

protek

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Ok, Tapuino tested working. Dug out my breadbin. It loads games fine with two of the three tested PSUs. The one that came with the C64 C won't even give a picture with the breadbin even though it does with the C. Tapuino won't get motor signal from breadbin either with the C's PSU.

Motor doesn't get signal on the C with any of the tested PSUs. A capacitor issue perhaps? I'll try and change also the fuse just in case.

No sound on the C model. Does it turn the odds in favor of the 9V instead of the CIA? I have a junker C128 motherboard, from which I can take the CIA.

About measuring the plug, the 5V is pretty obvious but do I measure the 9VAC from both 9VAC pins and not one 9VAC and ground? My intuition tells to measure from both 9VAC pins.
 
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sweetlilmre

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Brave man... that bad PSU could have done nasty things to your breadbin! :) luckily not.

So the PSU isn't good. Please test and report back, it might help to know what it is supplying.
If fuse has continuity then it seems that is not the issue, but it doesn't hurt to swap and test.

If there is no sound and no motor, then there is a problem with the 9V supply. I'll have a look and see what I can learn about this issue.
-(e)
 

protek

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Voltages measured. Both good PSUs gave 10,9 VAC and the bad one only 1,3 VAC. All three gave around 5,1 V.

- - - Updated - - -

Did a bit of sanity check on the sound. I am getting sound on the C with a good PSU. That pretty much rules out the fuse.
 

c64new

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Ok, Tapuino tested working. Dug out my breadbin. It loads games fine with two of the three tested PSUs. The one that came with the C64 C won't even give a picture with the breadbin even though it does with the C. Tapuino won't get motor signal from breadbin either with the C's PSU.
Motor doesn't get signal on the C with any of the tested PSUs. A capacitor issue perhaps? I'll try and change also the fuse just in case.
No sound on the C model. Does it turn the odds in favor of the 9V instead of the CIA? I have a junker C128 motherboard, from which I can take the CIA.
About measuring the plug, the 5V is pretty obvious but do I measure the 9VAC from both 9VAC pins and not one 9VAC and ground? My intuition tells to measure from both 9VAC pins.

The voltmeter should be placed between the two pins of 9VAC no load (NOT connected to c64!). You should not measure between 1 Pin 9VAC and the ground, because they are two separate transformer windings-coils (5VDC and 9VAC).
Only in case of the Commodore SX64, one wire of the 9VAC it is connected to ground (user port).
It should also be measured between the cathode and anode of the zener diode CR2 and you detect 7.5V.
Usually it burns the power-transistors Q3 as has already said 'sweetlilmre'.
In other cases, unfortunately, may also be the microprocessor 6510 or the CIA 6522 that directly control signals to 'motor' and 'read/write'
 
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protek

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I took a closer look at the service manual. I have an E board, which has slightly simpler schematic. Unregulated 9 V comes to Q1, which then is connected to pin C3 of the cassette port. Q1 looks like a power transistor or regulator. So I probably should measure voltages from the collector of Q1, if I'm not getting any voltage from the cassette port, right? Is it already rectified to DC at that point?
 

sweetlilmre

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Yes I think that should be 9V DC unregulated.
Check that you are getting 9V at that point, then you can see if the transistors are OK, remembering that the motor is only switched on when the SENSE is active which IIRC is LOW, i.e. SENSE shorted to GND.
(also please check that, this is from memory and seems to tie in with the code)

I would have a look at what is happening at:

  1. the 9V point
  2. the base of Q2 when SENSE is LOW
  3. the base of Q1 when SENSE is LOW

-(e)

EDIT: you should be able to set SENSE by connecting the datasette and pressing play / FF or RW
 
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c64new

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... probably, the correct schematic for 'protek' is this:

C64_-crop.jpg
 

protek

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... probably, the correct schematic for 'protek' is this:

View attachment 88512

Not exactly that schematic but the implementation is the same.

Going to try it out tonight. I have a logic pen, so I can test the state of the CPU pin controlling the motor signal with it.
 

protek

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Quick update. The CPU pin controlling the motor goes from low to high, when sense is low, so I suppose we can rule the CPU out. The collector of Q1 gets 12 V. Still need to check the bases of Q1 and Q2.

- - - Updated - - -

I measured voltage from the cassette port, when sense was low. The motor pin was giving 6,1 volts. I then dug out another datasette with edge connectorand plugged that in to the C64C. It was spinning.

Therefore, the C64C is working all right. It's the cassette port adapter of the 1531. Although I'm not sure what the problem is. The continuities in the adapter are ok. The 1531 won't spin in neither of the C64s. Tapuino will spin on the breadbin but not the C. Finally, the other datasette spins on the C.

Is this weird or what?
 

sweetlilmre

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That is indeed weird... Tho great news that the C64C is OK! What Tapuino build do you have? Can you measure voltages when it is plugged in and trace them?
 

protek

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The board revision is 1.4 and the software build is from yesterday. The Tapuino board card edge connector comes to mind to measure voltage for motor. I take at least the motor signal is passed through to it?
 
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sweetlilmre

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It is, but measure at the source as well. Also measure at the output of the opto (should be inverted i.e. low when motor is high etc.)
 
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