QY6-0067 diagnosis

[Ink stained Fingers]

I'm not sure what you want to acheive - so I wish you some fun

 

[Emulator]

Anyway here are some images of the bits of a QY6-0076, not yours but may be similar.

 

[The Hat]

@sneezer2, If soaking in a dish of Windex doesn’t improve the nozzles then it is safe to say that black side of your print head is lost for good and Friggin around with it may do further damage, so unless your prepared to use the other colours for black text, then its game over.

The age of a print head has no bearing on how long they last, they can go for years or they can go bang in a day, but if you persist with trying to fix it, you may in fact damage the logic board and you won’t know that till you install another print head.
Quit while you’re a head...

 

[sneezer2]

Well, what I want to achieve is pretty simple (and clear, at least to me). I would like to get a working printer out of it.
I understand there will be some expense and some difficulty. Besides, the desired result may not occur and I am
prepared to junk the machine if I have to.

In particular though, it looks like changing the print head will be necessary. I am cognizant of the many posts I have seen
here warning of the possibility that a logic board may be damaged or a new print head may be damaged by an already
bad board. I respect those warnings but observe that none of them seems to involve any effort to find out if a logic
board may actually be bad or why or how that may be indicated. In my latest posts I am saying that maybe a look at the
board outputs could disclose what it is actually doing and thereby reduce the chances of destroying a new printhead.

I really don't know where the idea has come from that I am trying to fix the back side of any printhead. I have not said
or done any such thing. In fact, the only thing I have done to the printhead is to soak it and don't expect to physically do
any more to it. However, I am trying to understand something about what is in there and how that affects circuits
external to it. Even a very vague idea of what is actually on those parts and how they are interacting could help to
show what can be done in there and what cannot.

What I have tried to say in my last post is that IF the outputs of the logic board can be reached and IF the machine can
be made to operate at the same time, then a look at those points with a logic probe MIGHT reveal whether any of them is
dead or presenting voltages that would ruin a new printhead. If that ells me anything then I would feel much more
comfortable about burning a hundred on a new head.

 

[Ink stained Fingers]

o.k., fine - go ahead; I think I'm reading that you have a circuit diagram. Please be aware that there are not just logic voltages but a higher voltage of 24-28 Volt as I remember, that's the voltage which is switched in the decode/driver chip onto the resistor elements in the nozzles with short pulses, and this voltage should be on some contacts on the logic board as well.

 

[sneezer2]

@InkStainedFingers
Thanks again. Very useful information. No I do not have a circuit diagram but I am used to working on all kinds of
strange equipment without one. It doesn't always work out but sometimes its worth a try. Actually though, I do
remember having a service manual for (I think) an ip4000) that had a block diagram showing the overall logic.
Probably still similar in the mp610. I wonder where that is?

Einstein called them "thought experiments". I don't claim to be any Einstein and in fact fall far short.
He also said anyone can do them.

So here's what I'm getting at. If, by using whatever fragmentary information is available, one can deduce something
about what is going on inside a part, then one may be able to say something about how it should appear from the
outside (voltages, lights, dots on a paper, etc.). If that appearance does not accord with the deduction, then either
the thesis is incorrect or the part is bad. Take your pick. You may replace the part, even having less info than you
could establish later in the game. Sometimes necessary. Or you can revise the thesis and try again.

@InkStainedFingers - again
Ah, yes! Other voltages. Need to be careful. If, as you suggest, 24-28 volt pulses are being switched in the
decoder chip, that would make things much more difficult. It would also be a very odd custom chip, not
belonging to any of the normal logic families (CMOS, TTL). It should not be too hard to determine that
those voltages are or are not in there. Where they go and how they are used is another matter.
Thanks for the tip!

 

[Ink stained Fingers]

it is a custom chip but not odd, some logic signals drive some power voltages/currents for the nozzle resistors. That's CMOS since a long time.

 

[sneezer2]

Glad you know that. I'm out of touch for a long time on that sort of thing.
You are saying, I think that the logic inputs to such a chip could be standard logic level,
say 5V or less, while the voltages/currents being switched are higher, say 24V.
Do I have that right?
Do you have a nomenclature of some kind so that I can look this up to understand it
better, say a particular type of CMOS or whatever they call it? I did look on Digikey
casually to see if I could find something like that but didn't see any.

Guess I won't go in looking for that. We already know that some of these voltages/currents
are not being switched. If I can find the logic voltages driving these ones (or all) that
suggests a couple of things:
1) The logic board is OK since it is putting out what it should.
2) The decoder, or something between the logic board and the decoder is not OK.
3) There will have to be a 24V supply through the ribbon cables. That might be easy enough to find
by way of confirmation.

All taken with a large dose of uncertainty.

 

[stratman]

All taken with a large dose of uncertainty.

I applaud your voyage into the unknown and enjoy reading this thread. There have been a handful experienced folks who ventured where you are going. One guy out of Russia seemed adept but haven't seen him on the forum for some time. Too bad. The two of you would probably have a good conversation.

Boldly going where few have dared to tread.

 

[PeterBJ]

The CMOS logic circuits in a Canon Pixma printer do not operate at 5V but at 3.3 V. You can read more about the voltage levels in an MP610 in this thread, and notice the link to the iP4200 service manual in this post. The iP4200 service manual has an appendix with some technical info about the signals and pinouts of the logic board and the print head and more. The print head and logic board are different from those used in the MP610, but you will get an idea about what signals are involved in the control of a print head.