Secret Service
Data East, 1988Hello,
I have a secret service pinball machine and I am getting a strange reading on the power supply for the alphanumeric display.
The voltages I see for the display are the following:
+102.8 vdc
- 122.9 vdc
+ 4.94 vdc
The negative voltage for the display seems really high. I have verified the components in the circuit for the negative voltage and they all test normal.
Anyone ever had this issue?
Are those readings with the display attached or not?
If so, then that -122 is high.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info
Quoted from ChrisHibler:Are those readings with the display attached or not?
If so, then that -122 is high.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info
it reads 122 with and without the display attached
desoldered the mds60 and ordered parts from GPE.
will update what changes this makes.
still no idea why the mds60 was there
Your power supply origins from a Laser War (001)..... I have seen these power supplies more often with an MDS transistor installed. Beware of the ECB pinning of the MJE transistor iso the EBC of the MDS transistor. Check the 100V zenerdiodes too (measure the voltage over the zeners!)....somebody has been working there before. You can replace them by 91V zenerdiodes to make your displays last longer.
/\/\arco
Quoted from MarAlb:Your power supply origins from a Laser War (001)..... I have seen these power supplies more often with an MDS transistor installed. Beware of the ECB pinning of the MJE transistor iso the EBC of the MDS transistor. Check the 100V zenerdiodes too (measure the voltage over the zeners!)....somebody has been working there before. You can replace them by 91V zenerdiodes to make your displays last longer.
/\/\arco
tested everything else and its all normal. the zener diodes are 4763a so someone swapped them already.
the only thing which doesn't test correctly is the mds60. so hopefully when I put the MJE in the voltages drops to the correct level.
thanks,
Quoted from thepita007:Check the 100V zenerdiodes too (measure the voltage over the zeners!)
Measure as suggested - if you have 91V zeners, then you should read 91V across the diode.
Quoted from minnesota13:Measure as suggested - if you have 91V zeners, then you should read 91V across the diode.
I am seeing 99.8v and -105.6v on the zener diodes
If the zeners are good. Overvoltage in these circuits tends to come from the main transistor even if it shows proper power off diode check voltage drops.
As other has mentioned, be careful with replacement transistors, i have used some where you have to bend the legs around to get the right pinout.
Where are you guys getting these transistors from? I need to stock up. Anyone ever use a can style transistor here with a star heatsink, like a bally hv transistor???
Quoted from thepita007:I am seeing 99.8v and -105.6v on the zener diodes
That seems to be ok. Zeners can be a bit of from time to time.
Quoted from barakandl:Anyone ever use a can style transistor here with a star heatsink, like a bally hv transistor???
In stead of the MDS transistor i used a 2N5416 metal can transistor a few times succesfully, of course with a heatsink.
Quoted from G-P-E:If you want originals --> MDS60 = CEN-U60.
Since Central Semi is no longer talking to me -- you can try to get them from Mouser.
I actually just ordered a MJE15035 from your site which is what the schematic shows. I know I will have to bend the pins but is there any downside to using this part instead?
Quoted from thepita007:but is there any downside to using this part instead?
None at all. It's just a beefier version.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charte.net/chibler/Pinball/index.htm
http://www.PinWik.com - The Place to go for Pinball Repair Info
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