XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

Cruise Control rebuild

 
  #41  
Old 05-05-2019, 12:00 AM
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Both Transistor legs are as follows
Centre pin B
Outside pin C
Other outside pin E

ZTX650
Red Probe to B and Black Probe to E about 0.6V - 0.75V
Red Probe to B and Black Probe to C about 0.6V - 0.75V
Swapping Probes so Black to B should give no reading or open circuit - correct open circuit 0V
C to E one way will read 0.6V and open circuit the other way - average was 0.25V BOTH ways (high was 0.29 and low 0.21)This was on both diodes

ZTX750
Exactly the same but the probes are swapped, so Black Probe to B and Red Probe to E will give 0.6V etc.Same as above - both read the same.I have no idea which as which.- I read them from underneath the circuit board just in case that makes a difference



Are these the diodes?

Tested the 6 soldering joints.
 
  #42  
Old 05-05-2019, 04:51 AM
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No the 2 on the bottom left of the PCB shown here, The flat ones not the 1/2 round ones They will have ZTX650 and ZTX750 printed on them



Are these the diodes?
 
  #43  
Old 05-06-2019, 02:26 AM
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Thanks - lets try again...

Both Transistor legs are as follows
Centre pin B
Outside pin C
Other outside pin E

ZTX650
Red Probe to B and Black Probe to E 0.6v
Red Probe to B and Black Probe to C about 0.6v
Swapping Probes so Black to B should give no reading or open circuit Correct NO voltage
C to E one way will read 0.6V and open circuit the other way Correct

ZTX750
Exactly the same but the probes are swapped, so Black Probe to B and Red Probe to E will give 0.6V etc.

Black Probe to B and Red Probe to E 0.003v
Black Probe to B and Red Probe to C about 1.47v
Swapping Probes so Red to B should give no reading or open circuit 0.6V one way and 0.003v
C to E one way will read 0.6V and open circuit the other way 0.6v one way and 1.06v


 
  #44  
Old 05-06-2019, 05:30 AM
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The ZTX750 is bad and will need to be replaced. While you are at it test the diodes circled in red, they should test the same as the transistors 0.6V one way and open circuit the other. Post the voltages for each diode so I can see what they are.

 
  #45  
Old 05-07-2019, 01:38 AM
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Hi Warren,

See below picture for results, thanks.
 
  #46  
Old 05-07-2019, 06:42 AM
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Ok they are good. get another ZTX750 and hopefully that will fix your problem.

To replace the transistor cut the legs off, makes it easier to de-solder. Put solder on the iron tip before you put the tip to the work then pull the legs out with pliers.

When you install the new one make sure it goes in the correct way.
 
  #47  
Old 05-07-2019, 09:43 AM
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Excellent Warren, will report back soon.
thanks & cheers
 
  #48  
Old 05-08-2019, 03:12 AM
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Hi Warren... could not purchase in NZ ... obsolete.
Ordered 10 from China for $9 delivered, hope they are ok.

Searched Ebay and even the ones from Germany looked the same, so why pay an extra $10 for 2?
3 weeks until delivery.

cheers
 
  #49  
Old 05-08-2019, 03:44 PM
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Sorry I should have said RS Components have ZTX753 for $1.55 each, but the Chinese ones will work.
 
  #50  
Old 05-11-2019, 06:37 PM
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I tried RS components but their website said obsolete.
Just waiting now....
 
 
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