Dropcheck Posted May 12, 2015 Author Share Posted May 12, 2015 On the right side of the switch above, either color could be FDC WP/ pin at pull up resistor R24 and this resistor also remains connected to the FDC WP/ pin throughout. Again the trace from that junction to the drive connector is cut with the other color wire making the cut trace restored when this side of the switch is closed. In the open position, this effectively removes the drive's WP/ sensor and it can no longer bring the signal down to write protect the system. There's only one cut and that is the IP jumper on the main board. Could CSS have forced the sensor to go high on the drive itself? Quote Link to comment Share on other sites More sharing options...
1050 Posted May 13, 2015 Share Posted May 13, 2015 In post #22 what I describe relates to just a DPDT switch depicted and not concerning a module let alone a CSS module. Just for those tying to understand my first crude attempt at how it could be done. There's only one cut and that is the IP jumper on the main board. Could CSS have forced the sensor to go high on the drive itself? What you suggest is quite probable, I would think it might be a bit hard on the WP/ photo transistor unless it's limited in current on the drive and that's very likely but we can't know that for a fact until we prove it somehow. Brute force high with 5+ for WP/ line could be yes via some logic within the module. It may well be that the grey wire to drive itself method is needed so as to allow the drive's on board controller to take the forced high WP/ seriously. What I describe in #22 would allow only the FDC on the XF551 board to think there is a notch, but the drive itself has better information. And NOT allow data to reach the specified head for example. The grey wire method as implemented convinces both complicated ICs to believe there is a notch. NANDed MO input to the module could be used to turn on the WP/ signal ONLY when needed within the module. Using a dumb switch to override the drive's WP/ sensor 24/7 prolly not a good idea. Might let some of that magic smoke out eventually. Is your switch depicted wrong in post #24 and/or is the brown wire going to both the FDC IP/ (pin 24) and the module? Larry has it as center pin of just one side of the switch and your diagram shows it much different. That and your switch seems to have six terminals but does only one simple function on/off. I guess that's actually two questions needing answers here. Quote Link to comment Share on other sites More sharing options...
Dropcheck Posted May 13, 2015 Author Share Posted May 13, 2015 One of the problems we are having is that we don't know if colors of the wires on the switch relate in anyway to the colors of the wires connecting to the board. I suspect at least some of them do. But which? Once we can agree on what is happening in the module and on the board, then we can square the switch wiring. Leaving that problem for last I decided to tackle what the wires coming to the board might do. I think I have accounted for all the wires. Whether this is what is happening is another story. Take a look and see if I am making sense. 1050: On your question on current going directly to the WP sensor on the drive itself I don't know. That is definitely a question. If anyone has the mod and can measure current at the grey connection on the drive itself with the switch in normal and 1050 mode, with a flippy in on side A/1 and then again with a flippy in on side B/2. Be careful not to short the drive or harm yourself in the process. I've updated my schematic as so: 1 Quote Link to comment Share on other sites More sharing options...
Dropcheck Posted May 17, 2015 Author Share Posted May 17, 2015 1050 any comments? Larry can you measure current at the grey connection on the drive itself? Quote Link to comment Share on other sites More sharing options...
+Larry Posted May 17, 2015 Share Posted May 17, 2015 Can I do it with a DVM? And if yes, what is the drive supposed to be doing when I measure it (if it matters)? Have to see if I have docs for this -- think I do. -Larry Quote Link to comment Share on other sites More sharing options...
Dropcheck Posted May 17, 2015 Author Share Posted May 17, 2015 Can I do it with a DVM? And if yes, what is the drive supposed to be doing when I measure it (if it matters)? Have to see if I have docs for this -- think I do. -Larry We are trying to find out how the module is affecting the write protect circuitry. So we need to measure the voltage and amperage where the grey wire from the module connects to the write protect sensor on the drive mech. Yes, you can use a DVM. Use clips if you can, so you aren't physically in the circuit and can manipulate the computer operation too. I think it best to measure voltage first. Voltage in 1050 mode with a write enabled disk. Try to write to a flipped disk Voltage in 1050 mode with a write protected disk. Try to write to a flipped disk Is there a change in voltage between a standby state and when the drive is commanded to write? On most DVMs you will need to move the red lead to the amperage socket. You should be measuring DC at a maxium of 1 A. Probably will be less. Be careful, no shaky hands here. DC Current in 1050 mode with a write enabled disk. Try to write to a flipped disk. DC Current in 1050 mode with a write protected disk. Try to write to a flipped disk Quote Link to comment Share on other sites More sharing options...
+Larry Posted May 17, 2015 Share Posted May 17, 2015 Ok I'll give it a try, but it won't be real quick. I've got some other things going on now and it is back all put away. -Larry Quote Link to comment Share on other sites More sharing options...
1050 Posted May 18, 2015 Share Posted May 18, 2015 Busy here too sorry. No problem with new version of layout to deal with expressed issues before this - only pressing issue is unreadable numbers/letters at such small scale sometimes and it's usually the one item I wanted to read the label of too. I barely recognized the divide by 12 chip. Was thinking I'll try to measure a PC drive WP/ sensor and possibly attempt to override it with cautious resistor to 5+, but again busy and don't know when. Quote Link to comment Share on other sites More sharing options...
Dropcheck Posted May 18, 2015 Author Share Posted May 18, 2015 I've changed the font and hiked the resolution on the schematic. See if that is better. Sorry. Quote Link to comment Share on other sites More sharing options...
+Larry Posted May 20, 2015 Share Posted May 20, 2015 OK, I've got the Enhancer drive out again and open to the wiring. The gray wire goes to a small pcb & device that looks to be above the WP sensor location. It is connected on the same pad as an orange wire that is part of the 551 drive wiring (not from the Enhancer). If I measure it here, it will be measured with the orange lead. Is that what you want done? -Larry Quote Link to comment Share on other sites More sharing options...
Dropcheck Posted May 20, 2015 Author Share Posted May 20, 2015 OK, I've got the Enhancer drive out again and open to the wiring. The gray wire goes to a small pcb & device that looks to be above the WP sensor location. It is connected on the same pad as an orange wire that is part of the 551 drive wiring (not from the Enhancer). If I measure it here, it will be measured with the orange lead. Is that what you want done? -Larry Yes sir. Quote Link to comment Share on other sites More sharing options...
+Larry Posted May 20, 2015 Share Posted May 20, 2015 I'm not sure that I have a good ground point. Any suggestions? As-is, grounded to the chassis of the mechanism, I get 1.5 - 2.0 VDC if the WP sensor is blocked. If the WP sensor is open, I get 0 VDC in 551 mode. In 1050 mode, it is 0 VDC either open or blocked. Writing dos to the disk produces the same results. My amperage choices are 200 ma or 10 adc. I show 0 ma (with a flashing "-" on the 10 a scale in either mode. -Larry We are trying to find out how the module is affecting the write protect circuitry. So we need to measure the voltage and amperage where the grey wire from the module connects to the write protect sensor on the drive mech. Yes, you can use a DVM. Use clips if you can, so you aren't physically in the circuit and can manipulate the computer operation too. I think it best to measure voltage first. Voltage in 1050 mode with a write enabled disk. Try to write to a flipped disk Voltage in 1050 mode with a write protected disk. Try to write to a flipped disk Is there a change in voltage between a standby state and when the drive is commanded to write? On most DVMs you will need to move the red lead to the amperage socket. You should be measuring DC at a maxium of 1 A. Probably will be less. Be careful, no shaky hands here. DC Current in 1050 mode with a write enabled disk. Try to write to a flipped disk. DC Current in 1050 mode with a write protected disk. Try to write to a flipped disk Quote Link to comment Share on other sites More sharing options...
Dropcheck Posted May 20, 2015 Author Share Posted May 20, 2015 (edited) I'm not sure that I have a good ground point. Any suggestions? As-is, grounded to the chassis of the mechanism, I get 1.5 - 2.0 VDC if the WP sensor is blocked. If the WP sensor is open, I get 0 VDC in 551 mode. In 1050 mode, it is 0 VDC either open or blocked. Writing dos to the disk produces the same results. My amperage choices are 200 ma or 10 adc. I show 0 ma (with a flashing "-" on the 10 a scale in either mode. -Larry So when in 1050 mode the write protect sensor appears to be forced to ground regardless. That's interesting. But a low on FDC 1772 pin 25 according to the data sheet prevents writing. Were you writing to the backside of an unnotched disk? Edited May 20, 2015 by Dropcheck Quote Link to comment Share on other sites More sharing options...
+Larry Posted May 21, 2015 Share Posted May 21, 2015 Yes. Quote Link to comment Share on other sites More sharing options...
Dropcheck Posted May 21, 2015 Author Share Posted May 21, 2015 Yes. Thanks Larry! Time to revisit my schematic. Something isn't adding up. Quote Link to comment Share on other sites More sharing options...
Dropcheck Posted May 21, 2015 Author Share Posted May 21, 2015 (edited) Larry Before you put up the drive again can you take a few ohm measurements? Of course no power applied. From the write protect sensor on the drive to each of the pins on the Enhancer switch. When in 1050 mode do you get a short on any of them? Edited May 21, 2015 by Dropcheck Quote Link to comment Share on other sites More sharing options...
+Larry Posted May 21, 2015 Share Posted May 21, 2015 Presume you mean to check continuity. WP shows continuity with the orange/blue wire (lower right). The black wire (upper left) shows about 5 ohms resistance. No others. -Larry Quote Link to comment Share on other sites More sharing options...
1050 Posted May 21, 2015 Share Posted May 21, 2015 I did some testing on a PC. The green wire was found to be ground and the orange wire with no disk inserted read .7 volts which tells me the photo transistor being illuminated is shunting to ground all the current coming down the orange wire to it. Base/emitter junction results in .7 volts. When blocked by a disk the voltage rose to only 2.15 volts which tells me they are not pushing very much current to begin with. I am looking for my resistor substitution device and not having that was going to cut the orange wire and place my ampmeter in line to see what current is there normally. Will do one or the other eventually and would like to do both. Have not done any disk writing attempts yet, was stuck on finding my resistor sub device, but will attempt to format a new un-notched disk in MS-DOS eventually and report what resistance and/or current was required to override the WP/ sensor of the drive. Larry, you were aware that in order to measure amperage you have to at least unsolder one wire and have the current flow thru the meter? The grey wire would be of most interest for this test, it would be reconnected to one lead of the meter while the other meter lead goes back to where the grey wire came from. Set the meter for 200ma scale for most accurate reading since 10 amp scale will probably show zero when we are hoping for something in the 10ma range. Then turn on the meter, then turn on the drive and commence taking readings with various disk but especially formatting the back side of a flippy that has only one notch. Positive or negative reading is possible depending on which color of lead is attached to the grey wire but either are equally valid. Red lead to grey wire should get a positive reading unless it's made in china and then all bets are off. If you are not too comfortable with all this, give me a few days and I'll pooch mine as I am quite comfortable doing exactly this sort of thing. I also have replacement parts on hand, if they are needed. Measuring voltage should be also be done on a scale within close range of expected results, mine is set to 20 VDC so point 7 showed handily and even repeatedly showed exactly 2.15 three times in a row when blocking the photo transistor. Once I was showing .7 volts with no negative sign, I then moved the black test lead from the green wire to the frame of the drive and got .7 volts again showing that the frame was ground as well as the green wire. It would be nice to know how many milliamps are flowing in the grey wire. Quote Link to comment Share on other sites More sharing options...
+Larry Posted May 21, 2015 Share Posted May 21, 2015 I did some testing on a PC. The green wire was found to be ground and the orange wire with no disk inserted read .7 volts which tells me the photo transistor being illuminated is shunting to ground all the current coming down the orange wire to it. Base/emitter junction results in .7 volts. When blocked by a disk the voltage rose to only 2.15 volts which tells me they are not pushing very much current to begin with. I am looking for my resistor substitution device and not having that was going to cut the orange wire and place my ampmeter in line to see what current is there normally. Will do one or the other eventually and would like to do both. Have not done any disk writing attempts yet, was stuck on finding my resistor sub device, but will attempt to format a new un-notched disk in MS-DOS eventually and report what resistance and/or current was required to override the WP/ sensor of the drive. Larry, you were aware that in order to measure amperage you have to at least unsolder one wire and have the current flow thru the meter? The grey wire would be of most interest for this test, it would be reconnected to one lead of the meter while the other meter lead goes back to where the grey wire came from. Set the meter for 200ma scale for most accurate reading since 10 amp scale will probably show zero when we are hoping for something in the 10ma range. Then turn on the meter, then turn on the drive and commence taking readings with various disk but especially formatting the back side of a flippy that has only one notch. Positive or negative reading is possible depending on which color of lead is attached to the grey wire but either are equally valid. Red lead to grey wire should get a positive reading unless it's made in china and then all bets are off. If you are not too comfortable with all this, give me a few days and I'll pooch mine as I am quite comfortable doing exactly this sort of thing. I also have replacement parts on hand, if they are needed. Measuring voltage should be also be done on a scale within close range of expected results, mine is set to 20 VDC so point 7 showed handily and even repeatedly showed exactly 2.15 three times in a row when blocking the photo transistor. Once I was showing .7 volts with no negative sign, I then moved the black test lead from the green wire to the frame of the drive and got .7 volts again showing that the frame was ground as well as the green wire. It would be nice to know how many milliamps are flowing in the grey wire. "Larry, you were aware..." Nope, I just clamped on the ground and measured at the pad of the orange + gray wire as if I were measuring voltage. (I've never tried to measure current flow before.) Thinking more about it, yes, that makes perfect sense. But no, I don't think that I want to desolder this sensor. It's not broke... I could desolder at the switch if that will be helpful. I'd like to replace this unusual (stub) switch, anyway. I used both ranges and got zero on both (but that may mean nothing in light of your info). -Larry Quote Link to comment Share on other sites More sharing options...
1050 Posted May 21, 2015 Share Posted May 21, 2015 Yes, measuring at the other end of the grey wire works too, please proceed carefully. Quote Link to comment Share on other sites More sharing options...
+Larry Posted May 22, 2015 Share Posted May 22, 2015 OK, new and better info... In 551 mode, the current in the gray wire is zero when writing/formatting. In 1050 mode, the current is .12 - .13 ma. (It is set on the 20 ma scale.) This current is there all the time, even if the drive is inactive. And of course, I learned something, so it was a good exercise. -Larry Quote Link to comment Share on other sites More sharing options...
Dropcheck Posted May 22, 2015 Author Share Posted May 22, 2015 OK, new and better info... In 551 mode, the current in the gray wire is zero when writing/formatting. In 1050 mode, the current is .12 - .13 ma. (It is set on the 20 ma scale.) This current is there all the time, even if the drive is inactive. And of course, I learned something, so it was a good exercise. -Larry Now that makes more sense. Thanks Larry. CSS is indeed forcing the WP sensor high. Almost like it is tighed to +5V without any logic involved. Not sure why they would need the MO signal then. Hmmm..... Quote Link to comment Share on other sites More sharing options...
1050 Posted May 22, 2015 Share Posted May 22, 2015 Larry, do you happen to have two DVMs? Use one for the current meter as in last test setup and then re-measure voltage with 2nd meter on the orange wire with current flowing in the other meter as double confirmation of measured state desired. Your previous post #37 indicating 0 volts there is inconsistent with how the facts should be. I just threw it away thinking your ground wire for meter fell off and was not noticed, but now we should have confirmation that indeed 0 plus twoish is still zero - I thought that math teacher didn't know what she was talking about cuz zero be just that awesome. /sillyness off - You should always see at least .7 volts there. From there it goes up, but to exactly where when fed current from the module is the real question that begs an answer. Find it and I can trust your readings at that point. I'll still make my own here and report that when that happens. Also .13ma? 13ma is more what we should be having from a logic gate output going to ground. At 20 ma setting which you didn't have before (10 A or 200ma were your stated selections), your decimal point should NOT be visible at all or completely to the right most position. On 10 A scale a reading of .13 would be 130ma, the 13ma we are looking for would be .013 on that scale. On 200ma scale it should read 13. and on 20ma scale it should read 13. again, yet you report .13, so need even more better still I'm left thinking. On my meter if you want to use 10 A scale you need to move the red meter cable to a new hole - otherwise it stays in the same hole used for all other measurements, you happen to move that wire? All bets off then. NEVER set one of these meters to 2000u or 200u settings unless you want to burn out that part of your meter cause it's so easy to do and murphy is very obliging in this regard. Should really be selecting ranges with one meter lead unplugged from meter as a firm rule at all times, but I get lazy. Rolling the dial around while meter is connected is murphy's favorite game. I have a box for those 'parts' meters and the count grows. Don't ever feel bad about getting the wrong reading when using a DVM - this is exactly WHY analog meters are still so popular, no one gets away without being bamboozled when reading a DVM. Every time I turn mine off I think 'I should get an analog meter'. Same thought when I turn it on too. 1 Quote Link to comment Share on other sites More sharing options...
Mathy Posted May 22, 2015 Share Posted May 22, 2015 Hello 1050 I always learn that you shouldn't use two DVMs simultaneously. Sincerely Mathy Quote Link to comment Share on other sites More sharing options...
+Larry Posted May 23, 2015 Share Posted May 23, 2015 OK, I got out my bigger, bulkier, but better meter. But I still get "00.12" on the ma scale. It is what it is. The probe is in the regular position -- not the 10a position. With both meters attached -- orange wire (on the switch -- not the orange mech wire attached to the photo sensor) with the ma reading still the same, I still get 0.0 VDC. Now, if you mean the orange wire attached to the photo sensor, while booting, I get 1.94 VDC that is with both meters attached. That is the same as I measured on the gray wire attached at the same point. -Larry Quote Link to comment Share on other sites More sharing options...
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