HP 65 Card reader task

[jftman]

I have tinkered with adjusting the leaf springs on these so equipped. I located 4 relative pads 14,9,8, and 7 are their traces where a multimeter can check for continuity and open circuit.
I would tighten slightly the silver screw to lift the spring endwise contact.
Putting in a card and looking for continuity says the pads are connected to the full plate with position 14 as a reference.

I have expected readings but the motor still does not start? The motor runs good with a battery applied between the motor terminals. Good motor.

Of note however is that the 0.00 display does NOT blink at all when a card is pushed up into the roller. I just hear a little ‘pink’ sound that could be the leaf spring spring doing it’s thing. The sound is once in and once when the card is retracted.

I hope there are other tests I can perform.

Can someOne fill in more traces to investigate?
The 4 I measured are the motor activation 9, read and write 8,7 and 14 center which is the plate. Not sure more exactly what it does.
But there is another pad not leading to the lower PCB for testing as I am doing.

I have other working HP 65's to swap boards. I would like guidance as to what may be done to trigger the motor......Regards James. Pics attached

[teenix]

There is some info in my Classic Notes pdf download.

If you adjust the leaf springs make sure they are sitting up the same amount or one could operate out of sequence and give errors.

The large hybrid chip on the CPU board controls the card reader. If you have a working 65 then try swapping the CPU boards between the two calculators and test both. It will quickly eliminate any problems if the board is the cause of the fault.

If the fault persists with the swapped board and original faulty reader, then it is hopefully a connection problem. Check the pins connecting the small card reader board for corrosion, and any wiring attached from the motor and battery.

If this checks out ok, then the sense chip may be faulty. You can only test this by substituting a good sense board or swapping the IC with a good one.

While fiddling with the disassembled calculator you may damage the connecting wiring at the top of the circuit board near the displays. Page 48 of the above notes has a picture showing what can happen.

cheers

Tony

cheers

Tony

[jftman]

I will certainly try swapping the CPU bottom boards.
I hope that the large chip you mention can be eliminated as the reason why the motor does not respond when a card is pushed in lifting the MTR leaf spring ball.

My working readers happily wind up the motor with the card inserted BUT not in contact with the pinch roller and ORing combo. It tells me something will start the motor, even while the ORings do not quite grab the card.

The HP 67 in question is silent, and I test a good connection between pins 14, the plate and 9 the MTR leaf spring. Juice is not heading from the CPU all the way to the motor?

I will switch boards, and post again.

[jftman]

Swapped.
Both boards work in the known working card reader.
Neither board works in the troubled card reader.
So, the CPU boards can be eliminated.

I suppose I could now jump to swapping the two boards that have the leaf springs?
Although as previously tested the MTR leaf at trace 9 seems to close OK. From reading this puts ground into the MTR circuit, and removes the High VOLTAGE, right?

If the multimeter test isn’t as much concerned with timing put only open and continuity, I should try something else besides swapping the leaf switch boards at this time. Correct?

[teenix]

There is card switching info in the previous mentioned Classic Notes on page 28.

With no power applied and the CPU board removed, and for a non-protected card,

pin 9 should be at GND when a card is inserted just before it hits the drive wheel. This starts the motor
Normally, the MTR pin on the sense chip (pin 17) will be pulled low by the Hybrid chip. This turns the motor ON. HI turns the motor OFF.
pin 7 and 8 should be open


pushing the card in a bit further,
pin 9 still GND
pin 8 should be at GND - non write protect detect
pin 7 open


pushing the card in a bit further,
pin 9 still GND
pin 8 still GND
pin 7 at GND - starts read/write process

cheers

Tony

[jftman]

Ok. I will run the multimeter sequence with the CPU removed. Counting from the right and going left I will pick up pin 9,8,7.

I want my ground reference to be picked up, say at the Keyboard bridge where the black wires are? Or which pin among the row at the bottom?
************UPDATE
Quick tested twice, all shows as you say. And when card retracted, all return to open, infinite Ohms.
Just adding that, pin 14, is ground ALL the time. But that one is neither a part of timing.
I only use it because of the physical layOut of the leaf springs and plate.

I can move the card a good distance, say 3/16th of an inch and pick up the ground on pin MTE number 9 on the keyboard slab.
That is how I know the motor if it was to turn on the card would not necessarily be pulled through.
MOTOR is silent at this stage of testing.Poopy.

I used the trace at the top of the bridge CPU where the black wires at in the middle, side by side.

ThankYou for All Tony.

[teenix]

pin 14 is a GND connection

with the CPU board in and powered on in RUN mode, maybe with jumper leads to the battery terminals, -ve towards the top, measure the voltage on pin 17 of the sense chip. It should be around 6V.

If you push a card in to the drive wheel, this voltage should drop to zero.

If it does, make sure pins 16 and 18 have around 3.8V.

GND pin on the sense chip is pin 7.

pin 11 should be GND for a card read

pin 1 to the motor +ve should be around 2.5V

cheers

Tony

[jftman]

I will try a rubber band around the battery in place. But I do have a bench variable voltage unit as part of a watch analyzer.
To insure good voltage which the readings correlate what should I dial in?
I will observe polarity with the connections, negative on top terminal.

My sense says these voltages will make current flow to the motor if they measure correctly.
I do wish to learn how to measure current, but I do not know how to hook up the device in series, without disconnecting a component or wire.

But I would like to test the current draw when the motor is operating.

So all the test points are on the sense chip?

[teenix]

The rubber band and battery is probably the safest, but from a power supply, set it to 3.75 volts.

The motor should draw about 180mA. If you have a variable output power supply with a current meter, you should see the change when the motor is running.

If you have a multimeter with current reading capability, then just connect it in series with the power supply +ve output. Meter positive to supply positive, meter negative to hp-65 bottom +ve terminal and power supply -ve to hp-65 top -ve terminal.

All the pins I mentioned are on the sense chip, be careful not to short any pins with the probe.

There is an indent at the centre top of the chip. pin 1 is directly to the left, down to pin 10, across right to pin 11 and up to pin 20.

http://www.hpcc.org had circuit diagrams by Tony Duell, but I can't access the page.

cheers

Tony

[AndiGer]

Are you sure the motor isn‘t mechanically blocked?
The worm gear is inside the little bearing opposite of the motor?
Andi

[jftman]

Here is what I found.

I applied 5.3-5.5v with my supply.
With power on, in run mode grd-p17 is shy, it hovers around what the power supply shows after switching the calc. on. About 4.20 volts.

The two pins 16 and 18 w/respect to ground are that same 4.20 ish volts.
When I put the card into position to trip the motor leaf, I INDEED see p17 drop to 5mv, so that is what should happen if I am doing this right.

P1 sits with 0.00 volts, both with card in and no card. Bad……….
BUT I do not see a ground continuity on p11, it is open to infinity!

I test for ground on the rail, where the black wires go into the plug and card reader motor, with p7 on the sense chip, GOOD.

BUT, using either p7 or my rail, to p11 , reading open on each reference!
This is the same wether or not the card is in position for MTR and if I push it in to close the other two leaf contacts.

Maybe this is why the voltage on p17 is not greater than the pins 18 and 16 with no card in place?
Do I need to look for a lifted ground, or a broken ground to p11 on the sense chip?
This is pretty interesting, what do you suggest?

[jftman]

(01-27-2024 07:03 AM)AndiGer Wrote:  Are you sure the motor isn‘t mechanically blocked?
The worm gear is inside the little bearing opposite of the motor?
Andi

Yes, not needing to be manually coaxed because I tested it ahead with a battery across the motor wires, but with one off to isolate the sense chip.
I don’t know if that is totally necessary, I only used a 1.5v battery that is kind of weak now.

It looks like, the testing with a volt meter there are issues of low voltage and a missing ground. Tony can respond. I followed his guidance!

[teenix]

I would limit the battery voltage to no more than 4V in case something gets damaged.

The attached image is a copy of Tony Duell's circuit for the HP-65 sense board.

The contacts at right are the pins connecting the sense board to the CPU board.

I marked the voltages when a card should be reading with motor active.

cheers

Tony

[jftman]

Ok.
I can set it at 4v, and repeat. But after I turn the calculator on, the output drop alot, Vss

You gave me instructions that p17 should have 6v, greater than Vss? But the diagram shows p19 reads 6v. And p17 is not labeled.

So, if I set the 4 volts is that going to be AFTER the on switch is on?
I can guess that the chip is an amplifier as denoted, is this why 6v appears in the diagram, if the Vss is less than 6v?

I do not see six ish volts on p17 during the first test. With a reiteration what show my reading be on p17?
Mainly, I should switch the calculator on, and dial up 4 volts, then test?

That is essentially what it seems I did. When tge calculator was on and I was making readings the bench showed about 4.2 volts.
With calculator OFF the jumpers had 5.25 ish potential available.

[jftman]

(01-27-2024 07:49 AM)teenix Wrote:  I would limit the battery voltage to no more than 4V in case something gets damaged.

The attached image is a copy of Tony Duell's circuit for the HP-65 sense board.

The contacts at right are the pins connecting the sense board to the CPU board.

I marked the voltages when a card should be reading with motor active.

cheers

Tony

My experience shows no voltage on p1 hence the motor can't run.
Under operation during the test, p11 does not move from open in continuity mode.
(Or should I leave the volts meter in Vdc and read 0volts, NOT ohms to ground? On p11……
Sorryy…!

[teenix]

Sorry, I missed adding the voltage on pin 17, see below.

The power supply voltage is probably dropping a bit because it may not be able to supply the calculators operating current, especially if it drops when the motor is trying to turn on. Most power supplies should be able to cope though.

Anyway, assuming the calculator is just turned on in run mode, (these voltages may vary a bit),

Pin 17 [MOTOR CONTROL] should be 6V.
Pin 1 [MOTOR VOLT] should be 0V.
Pin 11 [WE] can be either 6V or 0V it doesn't matter.
Pin 16 and 18 should be the battery voltage
The rest of the voltages should be as marked.

As soon as you push a card in with the Run/Prgm switch in the Run position (card read):

Pin 17 [MOTOR CONTROL] should fall to 0V. <<<<Make sure this drops to 0V
Pin 1 [MOTOR VOLT] should rise to 2.4V.
Pin 11 [WE] should be 0V for a read operation
Pin 16 and 18 should be the battery voltage
The rest of the voltages should be as marked.

Hybrid IC
pin 1 same as [WE] voltage
pin 5 same as [MOTOR CONTROL] <<<<Make sure this happens

If the [MOTOR CONTROL] does not drop to 0V check the voltage on pin 9 of the connector at the bottom of the calculator. It is the same connection, and it should also drop to 0V. If it does not, the hybrid and sense IC's are not seeing the card switch activating.

cheers

Tony

[jftman]

Ok.
How does 6v appear in these places?
Given that Vss and Vbs are less than 6v?

In my case regarding the drop when the card has triggered the mtr pin 17,
It drops to 4-5 MV so, not zero but is functioning correctly? Should I be good in that area?

My power supply is designed for Quartz watch current and voltage measurements. There are several current draw and base lines when the watch is in operation

If I connect the Supply and then turn on the calculator, I see a voltage drop but there is the capacity for me to raise the applied voltage up over 4 volts, say 4.25-4.50.

When I do the readings on the sense chip, I don’t see 6v anywhere only the Vbs supplied, and it will drop as required when a card goes in.

But sadly there is 0 volts on pin 1.

Are there any desoldering points to isolate the chip that allow more trouble shooting for the 2.5 volts on pin 1? Perhaps the four red and black on the pcb, but leave the head wires untouched.

To swap out the entire board of course all these would be desoldered. I was trying to reason a way to remove a fault by separating the circuit, to look for restored normal conditions. Like a short, that may exist PAST the sense chip, or a ground that isn’t supposed to be there. (I am a retired telephone company repairman, HA).

[teenix]

(01-27-2024 07:51 PM)jftman Wrote:  Ok.
How does 6v appear in these places?
Given that Vss and Vbs are less than 6v?

The switch mode power supply generates different voltages to run the calculator, somewhere around +6V, +8V and -12V.

Quote:In my case regarding the drop when the card has triggered the mtr pin 17,
It drops to 4-5 MV so, not zero but is functioning correctly? Should I be good in that area?

The voltage won't be exactly zero, but close.

Quote:My power supply is designed for Quartz watch current and voltage measurements. There are several current draw and base lines when the watch is in operation

Maybe it is better to run the calculator from a charged battery, perhaps taped in position. This will supply the proper voltage and current for the calculator operation.

Quote:When I do the readings on the sense chip, I don’t see 6v anywhere only the Vbs supplied, and it will drop as required when a card goes in.

I was incorrect with the 6V logic HI signal. These are the voltages measured on the sense board connector just after switch on.

VSS 6.3
RA 3.6 - varies reading a card
RB 3.6 - varies reading a card
WE 0.13 - LO = Read, HI = Write
(Unused pin) 1.27
WB 3.6 - varies writing a card
WA 3.6 - varies writing a card
BATT 3.6
MOTOR 3.6 - HI = Motor OFF, LO = Motor ON
GND

So
3.6V will be HI logic
0.13 will be LO logic

Quote:Are there any desoldering points to isolate the chip that allow more trouble shooting for the 2.5 volts on pin 1? Perhaps the four red and black on the pcb, but leave the head wires untouched.

You could disconnect the motor red wire and see if it changes when a card is in.

Quote:To swap out the entire board of course all these would be desoldered. I was trying to reason a way to remove a fault by separating the circuit, to look for restored normal conditions. Like a short, that may exist PAST the sense chip, or a ground that isn’t supposed to be there.

Apart from disconnecting the motor lead, the listed voltages should be there for a given card operation. If they are then I would suspect the sense chip, given that you said the motor is working. If there is a discrepancy then it might be an open circuit between the CPU board and the sense chip, most likely at the sense board connector.

Quote:(I am a retired telephone company repairman, HA).

Funnily enough I worked as an install technician for the phone company here back in the 70's and 80's. It was a good job back then :-)

cheers

Tony

[jftman]

Ha, yes good job. I retired in 2012. Copper being abandoned by transitions to fiber to the ‘curb’. Meaning any dispatch to change over, required Drop wire removal and new fiber core ‘drop wires’ installed. Plus the network interface, all new install. Mainly my job was maintenance splicer, to fix anything in the network that was not from the customer’s terminal or in towards the house. So, bucket truck work, and manhole work.

Is it a good idea to update the drawing you attached earlier?
I gather pin 17 is not measured to be 6v but 3.6, Hi?
ThankYou!

[teenix]

(01-27-2024 11:28 PM)jftman Wrote:  Is it a good idea to update the drawing you attached earlier?
I gather pin 17 is not measured to be 6v but 3.6, Hi?
ThankYou!

I added a note about voltages.

That should be the case.

cheers

Tony