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Lynx 1 on/off issue


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#1 ewokmic OFFLINE  

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Posted Mon May 12, 2014 2:47 PM

Hey guys - looking for some expert help.

Got a Lynx 1 in super duper condition cosmetically. Nice and clean inside. Won't switch on. Tested the power to audio ground trick and 'ta-da' we have lift-off!

Bought a 3055E from eBay and replaced Q11. No change....

If I run a bit of wire between the 3055E big leg and the last small leg it starts working, but the chip heats up. No matter what I do the on/off buttons have no effect. The circuitry is all clean - had a careful look with a magnifying glass and can't find any breaks etc. I actually got two of the chips so tried the other just to see if the first was broken. Nothing. Any ideas guys? Trying my best but a bit of an amateur here!

Its annoying because the screen/sound/casing all great. I wan't to play Crystal Mines again...

#2 Stephen Moss OFFLINE  

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Posted Tue May 13, 2014 1:30 AM

There is a latching circuit that is used to keep the lynx in its on/off states when the On/Off power buttons are pressed, if this is not operating correctly then noting else has a chance so if you have a DVM try checking the following DC voltages...

 

U6 (4069) Pins 13, 12, 11 and 10.

With the Lynx off I would expect to see approximately 5V, 0V, 0V & 5V respectively, once the on button is pressed I would expect those voltages to be reversed

 

Across R84 (or R64 not clear on schematic, 100K connect to the Gate and Source pins of Q11), with the Lynx off I would expect this to be 0V, once the On button is pressed I would expect to see approximately 5V.



#3 ewokmic OFFLINE  

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Posted Tue May 13, 2014 4:44 PM

Hi Stephen - thanks for the detailed reply. Unfortunatly I'm not massively clued up on checking voltages but will do my best - I do have a test meter.

U6 found. I'm not sure where to place the 2nd meter prod(? dont laugh :-) ) so sticking with one end on + power and the other on the pin it seems the full 9v of battery (well, just under) is going through some of the pins. Not sure what counts as pin 1 because the board printing is the opposite way around as the chip number. Going with the board printing (so starting very top left, speaker below) 1, 2, 5, 6, 8, 11 and 12 all allow full voltage to pass through. Pretty tricky holding the on button ehilst re-checking but no differenc was made with that held down.

R84/R64 could this perhaps be the R842 - its right next to Q11. 0V coming through this (very small piece stamped 104) with or without the on button pressed.

Thats all I have for tonight! thanks again.

#4 Stephen Moss OFFLINE  

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Posted Wed May 14, 2014 1:55 AM

When measuring the voltage at a point like the pin of an IC the probe connected to the V/R or V/ohms symbol (which looks a bit like a horseshoe) terminal of your meter should go to that point and the probe connected to the COM terminal should go to 0V which look like should be found at TP16. 

 

When measuring the voltage across something such as R84 then you place one probe on each end of the component.

 

IC pin identification:-

usually there is either a small semi-circular cut out in the middle of one end or a small circular indent in one corner of the top side of the IC, this would the "top" end of the IC. If the IC is a DIL package (as U16 is) pin 1 is always the top one to the left of this and pins are numbered sequentially in a anticlockwise direction as an additional aid to orientation the power pins are normally located at the top tight (+V) and botton left (0V)

 

R84 could be R842, if you look on the schematics at http://atariage.com/...l?SystemID=LYNX  it definitely looks like R84 but the 104 marking on R842  would make it the correct value.

 

Yes measuring something while pressing a control is difficult if you do not have a third hand to help.

It looks like power for U16 comes via the ROM Cart although I can't see how it gets there, I assume that means a game Cart so make sure one is inserted when testing and also test that U16 has power on Pin 14 (top right)   



#5 ewokmic OFFLINE  

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Posted Wed May 14, 2014 6:31 AM

Thanks so much Stephen I will test again tonight. Just noticed your profile image is from the Number 1 rock 'n' roll band in the land :thumbsup:

 

Here's a photo of U6 I took last night (iPhone + magnifying glass!) - Pin 1 is bottom right?

 

e0plcx.jpg


Edited by ewokmic, Wed May 14, 2014 6:36 AM.


#6 ewokmic OFFLINE  

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Posted Wed May 14, 2014 3:55 PM

right - managed to get past some of my amateur issues and worked out IC pins etc. Batteries are currently outputting 8.56v. Finally realised that you don't have to hold the on button, you just have to press it and then press off to make the change (pretty oblivious but not so much when your fiddling with 1mm pins and trying to hold three things at once!).

Anyway, when switched ON (obviously the machine shows no visible reaction or we wouldn't be here) the pins read:
10 0.1v
11 7.79v
12 8.56v
13 0.1v

Pressing OFF did switch this round so 10 and 13 had power and the others did. Checked a few times. Voltage did vary very slightly.

So that sounds good I think.

I rechecked R842 but getting nothing through that ON or OFF. closer to the problem?

I can't find U16 but have a cart in so probably not the problem there as it does boot the game if I bypass Q11 as noted previously.

#7 Stephen Moss OFFLINE  

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Posted Thu May 15, 2014 1:53 AM

U16 was a typing error, I meant U6.

If the latch is working you only have to press and release the buttons as in normal usage, I said to hold the power button in because if the latch was not working you would need to do that to try and force it into a stable state while making measurements. 

I prefer my avatar version of the logo to that they use for the Beer, slightly disappointed with the frantic 4 gig in April but it was nice to see them play and hear some classic tunes in full.

 

Back to the problem in hand, hopefully we are a little closer to the problem, you have to eliminate things one stage at a time. From the readings you have taken it looks like the On/Off power latch is working. 

The output of the latch (U6 Pin 10) goes through R79 (10K, (103)) into the remaining inverter gates of U6 so with the unit in the on state I would expect the following voltages...

 

Pin 1 = 0V

Pin 2 & 3 = 8V

Pin 4, 5 & 9  = 0V

Pin 6 & 8 = 8V

 

and as with the latch these voltages should be swapped when in the off state.


Edited by Stephen Moss, Thu May 15, 2014 1:55 AM.


#8 ewokmic OFFLINE  

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Posted Fri May 16, 2014 5:02 AM

Thanks Stephen - I won't have a chance to check until Sunday so will get back with findings then!

 

I didn't hear any reviews of the Frantic Four gig this year but I went to the Hammersmith one on the Friday last year and thought it was fantastic. The crowd were really up for it too! First time I had seen the original line-up.



#9 ewokmic OFFLINE  

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Posted Sun May 18, 2014 11:49 AM

With one end of the probe on R79 (tried both ends and it's the same each side) and the other probe on U6 as per your list each pin gives the expected reading you listed - problem is its like that when on, off or even if holding on or off. The voltages do not swap!

#10 Stephen Moss OFFLINE  

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Posted Mon May 19, 2014 2:04 AM

Can you clarify the last post, you seem to be saying the voltages on U6 pins 1 - 9 (excluding 7) are as I listed them in my previous post...

 

Pin 1 = 0V

Pin 2 & 3 = 8V

Pin 4, 5 & 9  = 0V

Pin 6 & 8 = 8V

 

and do not change, the fact that the voltages are not switching is clearly wrong, we just have to figure out what is causing it. However, as the voltages above are for the On state I would expect the problem to be not turning off (if those voltages are correct) where as you said the problem is it does not turn on!

 

Consequently your last post was a little confusing, to clarify you should have been measuring voltage between ground (0V, i.e. TP16 or pin 7 of U6) and the pins mentioned as you were doing with the latch voltages previously. Could you please double check the voltages for me, if the latch is still working then when the Lynx is in its Off state I would expect the voltages on U6 (4069) to be approximately...

 

Pin 10 = 8V

Pin 1 = 8V

Pin 2 & 3 = 0V

Pin 4, 5 & 9  = 8V

Pin 6 & 8 = 0V

 

When the Lynx is in its on state I would expect those voltages to be reversed as follows...

 

Pin 10 = 0V

Pin 1 = 0V

Pin 2 & 3 = 8V

Pin 4, 5 & 9  = 0V

Pin 6 & 8 = 8V

 

  



#11 ewokmic OFFLINE  

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Posted Mon May 19, 2014 2:25 PM

Off:
Pin 10 = 8.5V
Pin 1 = 8.5V
Pin 2 & 3 = 0V
Pin 4, 5 & 9  = 8.5V
Pin 6 & 8 = 0V

On:
Pin 10 = 0.1V
Pin 1 = 0V
Pin 2 & 3 = 8.5V
Pin 4, 5 & 9  = 0V
Pin 6 & 8 = 8.5V

10, 11, 12 and 13 do change, as detailed before, but all the others (not counting 7) do not change.



#12 Stephen Moss OFFLINE  

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Posted Tue May 20, 2014 1:46 AM

Not sure why you are saying that the voltage on pins 10 - 13 do change and the others do not when the voltages you have just listed clearly show that the voltages on pins 1 - 6, 8 and 9 do change as expected.

 

The output of Pins 6 & 8 drive the gate of Q11 (MDT3055E) which in turn should power on the Lynx. With the Lynx in its on state (U6, pins 6 & 8 = 8.5V)...

1) Do you get 8.5V at the gate of Q11 (not sure which pin that is as data sheet does not indicate) / one end of R84 (possibly R842)?

2) If you have a suitable piece of wire available connect one end to TP16 (or pin 7 of U6) and the other end to L6, does the Lynx turn on with the wire at one or both ends of L6?  



#13 ewokmic OFFLINE  

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Posted Tue May 20, 2014 1:06 PM

Sorry Stephen I made that list late and was half asleep. Details noted as OFF above are correct for both on and off - only 10, 11, 12 and 13 change. ignore the ON numbers - copy paste error (apart from pin 10).

Progress:

1 - pin 6 or 8 connected to Q11 only shows voltage through what I assume is the wrong end. this doesn't change when switching on or off.

Using pin 5 (which I assume now is what basically pin 6 would be doing if on worked) and checking with the R842 leg of Q11 actually switches the machine on and, get this, it stays on when I remove the prods. Touching pin 5 and Q11 again switches it off. This is the same no matter if you have pressed on or off switches on the front.

2 - L6 seems to be the headphones ground and yes it switches it on the console for the duration you hold the wire on it. No difference again whether you have pre pressed on or off.

Noticed if you bridge pins 5 and 6 it also switches on.

Thanks again for the mega patient help!

#14 Stephen Moss OFFLINE  

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Posted Wed May 21, 2014 2:30 AM

Not quite sure what to make of #1 as I am not sure what you mean by "wrong end".

I would expect connecting pin 5 to the Gate side of R842  (R842 goes to both the Gate and Source legs of Q11) to turn the Lynx on but for the Lynx to turn of when that connection is removed and not on re-application, although shorting Pin 5 pin 6 may have put the inverter gate in an odd state keeping it on. 

 

In regard to #2 due to the misleading voltages you posted this test basically bypassed the power switching area of the circuit thus confirming that the problem was in this part of the circuit and the rest of the lynx was operating correctly. 

 

I suspected this when I posted Monday but just needed to be sure as it is not easy working by remote and relying on information from people who have no electronics background as understandably miscommunication and errors can occur. I think the problem is one of the following...

1) Open Circuit (No connection) between pin 10 of U6 and R79

2) Open Circuit (No connection) between pin 1 of U6 and R79

3) Open Circuit R79

 

Remove the batteries and external power unit, then adjust your meter to the 20K setting on the Resistance (Ohms) range. Next place one meter probe on each end of R79 to measure its resistance, R79 is a 10K (103), 5% resistor and so you should get a reading of between roughly 9.50 and 10.50 if it is ok or just a 1 on the left of the display (assuming a digital meter) which means it is open circuit and needs replacing.

 

If R79 appears to be ok then placing one probe of you meter on R79 and the other to pin 1 of U6, then pin 10 of U6 you see see a reading of either...

a ) approximately 0.00, if there is a direct connection (good)

b ) 1 on the left of the display if there is no connection (bad).

c ) the same value as the resistance for R79 - move the probe to the other end of R79 and you should get a result that matches either a or b

 



#15 ewokmic OFFLINE  

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Posted Mon May 26, 2014 9:10 AM

Hi Stephen. By 'wrong end' of Q11 I meant the end that didn't go to R842. Sorry I'm not too clear.

 

Right, so R79, no batteries, 20k setting. Withe the probes not touching anything the meter reads 1.The probes on either end show 1.24 or 1.28 when swapped around but this changes slightly - 1.25/1.27 when I tried a couple of minutes later.

 

R79 to U6 Pin 1 = 0.00 north end, 1.28 south end (of R79)

R79 to U6 Pin 10 = 1.24 north end, 0.00 south end



#16 Stephen Moss OFFLINE  

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Posted Wed May 28, 2014 2:30 AM

Well from those reading I would conclude that there is not an open circuit although the reading for R79 is a bit odd if it is 10K (marked with 103, assuming it is surface mount). However, if R79 is 10R (printed missing the top edge so look like K on the schematic) then I would expect it to be marked 100 (or 10R) in which case the reading is too high.

 

Incase the reading for R79 is cause by a problem with one of the surrounding components could you set your meter to the 2K resistance range and measure the resistance...

between TP15 and Pin 1 of U6 and

the resistance of D12 (I think as the schematic is not clear, it will probably be close to R56 & Q13)

 



#17 ewokmic OFFLINE  

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Posted Thu Jun 5, 2014 12:37 PM

Hi Stephen. Sorry for the delay!

R79 has 103 printed on it like you expected.

2000 Ohms set on the reader - TP15 to Pin 1 U6 reads 327
D12 I simply cant find. D10, D11 sure, but not D11. D14 is the closest D to R56 and Q13.

#18 Stephen Moss OFFLINE  

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Posted Mon Jun 9, 2014 1:48 AM

I was hoping that the reading would be more helpful than that however, I am still of the opinion that R79 is the problem therefore if it was my Lynx I personally would remover R79 and measure its value out of circuit (20K range on meter) it should read in the region of 9.5 to 10.5 if it is OK

While R79 is removed you might want to check the resistance between pins 1 and 7 of U6 (2K range on meter) just in case it is internally shorted to ground. Without taking my Lynx 2 apart for reference I am not certain what values you will find although in general I would say that a value equal to or less than 0.1 is bad and over 1.0 is good.

#19 ewokmic OFFLINE  

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Posted Sun Jul 6, 2014 11:31 AM

Hi Stephen - R79 is giving me 10.08 while on the circuit but I'm unable to get it off the board without damaging the area and possibly other bits too - at least not with the tools I have. Its tiny and in a busy area.

 

Sorry for the late reply, I've been away for a while. I think I'm probably wasting your time now.. might be time to throw in the towel.



#20 GTretro87 OFFLINE  

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Posted Wed May 20, 2015 10:48 PM

Why in the frick did you guys give up on this as I'm having the same proble, with a new 3055 MOSFET at that!

Except my problem is on a lynx 2

#21 Stephen Moss OFFLINE  

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Posted Thu May 21, 2015 2:15 AM

What stage are you at?
If the On/Off latch of U6 is working correctly and providing the on/off signal to the 3055 then check ...
120 Ohm resistor R56 (Lynx 1)/R74 (Lynx 2)
4.3V Zenner Diode D12(?, Lynx 1)/ D13 (Lynx 3) which should read open circuit one way and 800-1200 Ohms the other.
100uH Inductor L6 (Lynx 1)/L15 (Lynx 2) which should have a low resistance measurement if it is ok, and a high resistance if it has burnt out (would also be discoloured and probably smell quite a bit).

#22 GTretro87 OFFLINE  

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Posted Thu May 21, 2015 4:22 AM

Well I've provided my Lynx II with a regulator mod by removing D13 and Q8 which I think both affect R74. So I'm not sure if that will cause the power not to work - but apparently it's not supposed to affect power on/off

But I will check L6 ASAP and keep this thread updated.

I wonder if it's the actual U6 IC

#23 GTretro87 OFFLINE  

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Posted Thu May 21, 2015 10:23 AM

I forgot to check the L15 inductor this morning.. but I did record this on U6..

 

 

I believe this would be pin 1 - photo.JPG

 

 

And if so, here's what I recorded with the system on and off - but without the ribbon cable connected and/or the power on button pressed. All i did was hold batteries in place and jumped the system on with battery ground to headphone ground..   

 

 

 

System OFF                 System ON

 

  1 - 0v (11.6mv)               1 - 0v (15.8mv)

  2 - 4.97v                         2 - 4.97v

  3 - 4.97v                         3 - 4.97v

  4 - 0v (11.6mv)               4 - 0v (16.3mv)

  5 - 0v (11.5mv)               5 - 0v (17mv)

  6 - 0v (3.0mv)                 6 - 4.74-4.94 v

  7 - 0v (11.5mv)               7 - 0v (17.4mv)

  8 - 0v (0.5mv)                 8 - 4.96v

  9 - 0v (1.5mv)                 9 - 0v (15.8mv)

10 - 4.96v                       10 - 0v (15.4mv)

11 - 0v (1.1mv)               11 - 4.92v

12 - 0v (0.3mv)               12 - 4.97v

13 - 4.91v                        13 - 0v (15.6mv)

14 - 4.97v                        14 - 4.97v

 

 

 

 

 

 

 

Q12 On (Looking at the MOSFET with the legs pointing upwards)

 

Base - 3.80v

Leg left - 15.7mv

Leg right - 4.96v

 

 

Q12 Off

 

Base - 4.98v

Leg left - 1.3mv

Leg right - 0.2mv

 

 

 

R74 - I forgot if the system was on or off, but both sides also read 4.97v

 

 

 

 

Besides L15, is there anything else I have to check? Also, for the MOSFET, is there something I should be reading with that??

 



#24 GTretro87 OFFLINE  

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Posted Thu May 21, 2015 4:16 PM

Well I figured out the problem. It was indefinitely the flex circuit.

Once I popped a new one in the system booted up with the power button!

I guess with the Lynx 2, the method is Q12 MOSFET change, then flex circuit..

#25 Stephen Moss OFFLINE  

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Posted Fri May 22, 2015 1:11 AM

I guess with the Lynx 2, the method is Q12 MOSFET change, then flex circuit..

Glad you got it working. I really need to take my Lynx apart and have a good look at it, in the meantime if there is more than one flex circuit which one did you change?
 
 

And if so, here's what I recorded with the system on and off - but without the ribbon cable connected and/or the power on button pressed. All i did was hold batteries in place and jumped the system on with battery ground to headphone ground..

Those measurements did not look right, for a start you should not have the same voltage going into and coming out of an inverter gate but then as the Lynx was not in one piece and you bodged the On condition instead of measuring it having pressed the power switch they are relatively meaningless as the circuit is no longer trying to operate in the way it was designed due to you bypassing the entire power circuit.




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