Re: Another IC I Can't Identify
On 2018-Nov-11, at 2:04 PM, Rob Jarratt wrote: >> -Original Message- >> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Brent >> Hilpert via cctalk >> Sent: 11 November 2018 21:50 >> To: General Discussion: On-Topic and Off-Topic Posts >> >> Subject: Re: Another IC I Can't Identify >> >> On 2018-Nov-11, at 1:32 PM, Rob Jarratt wrote: >>>> -Original Message- >>>> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of >>>> Brent Hilpert via cctalk >>>> >>>> On 2018-Nov-11, at 11:52 AM, Rob Jarratt via cctalk wrote: >>>>> Thanks for all the replies. If that is indeed what it is, then I >>>>> still >>> have not >>>> been able to find the source of one of the signals that seems to be >>> causing >>>> the Reset, every pin I have found so far is an input, I have not >>>> found it connected to the output of anything yet :-( >>>> >>>> >>>> Have you tried the reverse? : follow an origin that you know should >>>> be controlling reset, such as the power-on indication from the PS, >>>> and see if >>> you >>>> can trace it to the CPU.= >>> >>> I have already found that source and it all looks OK. I think I have >>> identified another input to a NOR gate that is high and causing the >>> reset, but I can't find where it comes from. >>> >> >> Perhaps I'm not clear on what you're saying, I was taking you as meaning > you >> hadn't found a source driving the reset line. >> While you've found a PWR-OK signal and it looks good, have you found how >> it connects to the reset line? >> >> Reset-line arrangements on small machines aren't usually that complicated. >> (Usually the power-on signal source is a series RC combination (often with >> additional discretes such as diodes) between a power-bus and ground). >> >> Perhaps put up an image of the schematic you have so far. > > I have posted an image here: > https://rjarratt.files.wordpress.com/2018/11/system-board.png > > At the far right you will see a "To F11 Reset", my understanding is that > this is active High. I have determined that the D input on E141 is always > high. The CLR input on E141 is periodically set, thus causing a pulsing high > output on E141, leading to a pulsing Reset on the F11 chipset. Well that (the circuit, as much as is presented) is quite bizarre. There's not a lot to make sense of from what's shown. If it's really that complex then the question is why? What is all that complexity intended to do, for the sake of reset? Without understanding the intention you're stuck tracing your presumed faulty signal back hoping (luck) that you encounter a fault along the way. But it may be that the pulsing is not itself a fault, but an intended (perhaps looped-back) consequence of some more-distant condition (ala the watchdog timers others were mentioning earlier). Aside from continuing as you have been and hoping that you luck out, I'd be looking at options such as: - RE the whole thing and analyse it in entirety to figure out the intended reset operation. - Find the docs on the CPU and see if they could provide some explanation as to the intention, based on the CPU reset functionality. - Examine the schematics of other machines using the same CPU (as others have mentioned) to see if they have similar complexity around reset. - Double/triple check to ensure you haven't gone astray in the tracing. A note regarding E141, the 7474 (and following 74174) are edge-triggered, not transparent, and will require activity on the CLK input to produce a pulsing output (if PRE is fixed high), activity on the CLR input is not alone sufficient.
RE: Another IC I Can't Identify
> -Original Message- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Brent > Hilpert via cctalk > Sent: 11 November 2018 21:50 > To: General Discussion: On-Topic and Off-Topic Posts > > Subject: Re: Another IC I Can't Identify > > On 2018-Nov-11, at 1:32 PM, Rob Jarratt wrote: > >> -Original Message- > >> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of > >> Brent Hilpert via cctalk > >> > >> On 2018-Nov-11, at 11:52 AM, Rob Jarratt via cctalk wrote: > >>> Thanks for all the replies. If that is indeed what it is, then I > >>> still > > have not > >> been able to find the source of one of the signals that seems to be > > causing > >> the Reset, every pin I have found so far is an input, I have not > >> found it connected to the output of anything yet :-( > >> > >> > >> Have you tried the reverse? : follow an origin that you know should > >> be controlling reset, such as the power-on indication from the PS, > >> and see if > > you > >> can trace it to the CPU.= > > > > I have already found that source and it all looks OK. I think I have > > identified another input to a NOR gate that is high and causing the > > reset, but I can't find where it comes from. > > > > Perhaps I'm not clear on what you're saying, I was taking you as meaning you > hadn't found a source driving the reset line. > While you've found a PWR-OK signal and it looks good, have you found how > it connects to the reset line? > > Reset-line arrangements on small machines aren't usually that complicated. > (Usually the power-on signal source is a series RC combination (often with > additional discretes such as diodes) between a power-bus and ground). > > Perhaps put up an image of the schematic you have so far. I have posted an image here: https://rjarratt.files.wordpress.com/2018/11/system-board.png At the far right you will see a "To F11 Reset", my understanding is that this is active High. I have determined that the D input on E141 is always high. The CLR input on E141 is periodically set, thus causing a pulsing high output on E141, leading to a pulsing Reset on the F11 chipset. Thanks Rob
Re: Another IC I Can't Identify
On 2018-Nov-11, at 1:32 PM, Rob Jarratt wrote: >> -Original Message- >> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Brent >> Hilpert via cctalk >> >> On 2018-Nov-11, at 11:52 AM, Rob Jarratt via cctalk wrote: >>> Thanks for all the replies. If that is indeed what it is, then I still > have not >> been able to find the source of one of the signals that seems to be > causing >> the Reset, every pin I have found so far is an input, I have not found it >> connected to the output of anything yet :-( >> >> >> Have you tried the reverse? : follow an origin that you know should be >> controlling reset, such as the power-on indication from the PS, and see if > you >> can trace it to the CPU.= > > I have already found that source and it all looks OK. I think I have > identified another input to a NOR gate that is high and causing the reset, > but I can't find where it comes from. > Perhaps I'm not clear on what you're saying, I was taking you as meaning you hadn't found a source driving the reset line. While you've found a PWR-OK signal and it looks good, have you found how it connects to the reset line? Reset-line arrangements on small machines aren't usually that complicated. (Usually the power-on signal source is a series RC combination (often with additional discretes such as diodes) between a power-bus and ground). Perhaps put up an image of the schematic you have so far.
RE: Another IC I Can't Identify
> -Original Message- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Brent > Hilpert via cctalk > Sent: 11 November 2018 20:07 > To: General Discussion: On-Topic and Off-Topic Posts > > Subject: Re: Another IC I Can't Identify > > On 2018-Nov-11, at 11:52 AM, Rob Jarratt via cctalk wrote: > > Thanks for all the replies. If that is indeed what it is, then I still have not > been able to find the source of one of the signals that seems to be causing > the Reset, every pin I have found so far is an input, I have not found it > connected to the output of anything yet :-( > > > Have you tried the reverse? : follow an origin that you know should be > controlling reset, such as the power-on indication from the PS, and see if you > can trace it to the CPU.= I have already found that source and it all looks OK. I think I have identified another input to a NOR gate that is high and causing the reset, but I can't find where it comes from. Regards Rob
Re: Another IC I Can't Identify
On 2018-Nov-11, at 11:52 AM, Rob Jarratt via cctalk wrote: > Thanks for all the replies. If that is indeed what it is, then I still have > not been able to find the source of one of the signals that seems to be > causing the Reset, every pin I have found so far is an input, I have not > found it connected to the output of anything yet :-( Have you tried the reverse? : follow an origin that you know should be controlling reset, such as the power-on indication from the PS, and see if you can trace it to the CPU.
RE: Another IC I Can't Identify
> -Original Message- > From: Tony Duell [mailto:ard.p850...@gmail.com] > Sent: 11 November 2018 18:41 > To: r...@jarratt.me.uk; Jarratt RMA ; General > Discussion: On-Topic and Off-Topic Posts > Subject: Re: Another IC I Can't Identify > > On Sun, Nov 11, 2018 at 6:32 PM Rob Jarratt via cctalk > wrote: > > > > I am still working on the causes of a Reset on my Pro 350. One 8-pin > > DIP chip that I have traced to is marked as follows: > > > > > > > > 9643TC-B1 > > > > F 8313 > > > > KOREA > > > > > > > > It is very close to the F-11 chips at the bottom left and marked E135 > > in this picture > > https://rjarratt.files.wordpress.com/2018/10/system-board-labelled.jpg > > How about a Fairchild 9643TC dual TTL-MOS level shifter? > > I found a datasheet with Google. The pinout seems to be : > 1 : Input A > 2 : Enable Input > 3 : Input B > 4 : Ground > 5 : Output B > 6 : Vcc2 (Output stage Vcc) > 7 : Output A > 8 : Vcc1 (Input stage Vcc, normally +5V) > Thanks for all the replies. If that is indeed what it is, then I still have not been able to find the source of one of the signals that seems to be causing the Reset, every pin I have found so far is an input, I have not found it connected to the output of anything yet :-( Regards Rob
Re: Another IC I Can't Identify
> 9643TC-B1 http://bitsavers.trailing-edge.com/components/fairchild/_dataBooks/1978_Fairchild_Full_Line_Condensed_Catalog.pdf pdf p.219 Dual TTL to CCD/MOS Drvr Pinout? http://ic72.com/pdf_file/d/161010.pdf
Re: Another IC I Can't Identify
On Sun, Nov 11, 2018 at 6:32 PM Rob Jarratt via cctalk wrote: > > I am still working on the causes of a Reset on my Pro 350. One 8-pin DIP > chip that I have traced to is marked as follows: > > > > 9643TC-B1 > > F 8313 > > KOREA > > > > It is very close to the F-11 chips at the bottom left and marked E135 in > this picture > https://rjarratt.files.wordpress.com/2018/10/system-board-labelled.jpg How about a Fairchild 9643TC dual TTL-MOS level shifter? I found a datasheet with Google. The pinout seems to be : 1 : Input A 2 : Enable Input 3 : Input B 4 : Ground 5 : Output B 6 : Vcc2 (Output stage Vcc) 7 : Output A 8 : Vcc1 (Input stage Vcc, normally +5V) -tony
Another IC I Can't Identify
I am still working on the causes of a Reset on my Pro 350. One 8-pin DIP chip that I have traced to is marked as follows: 9643TC-B1 F 8313 KOREA It is very close to the F-11 chips at the bottom left and marked E135 in this picture https://rjarratt.files.wordpress.com/2018/10/system-board-labelled.jpg Can anyone tell me what this is? Thanks Rob
