Last action hero pinball LED help

[CoCkNeY-NuTjOb]

Hi everyone,

Ive been shopping my LAH, play field has been all done now and ive fully LED'ed the play field however there is a bank of lights at the back where the roll overs are under the plastic shields, these bank of lights are really dim... Well some times there just bearly on and sometimes there a bit brighter?? I understand there can be LED ghosting but every other lights are super bright? what could be the problem with just these light? I have multi metered a light that is bright and it was measuring 5v but the ones that are dim are measuring 1v? Ive checked and cleanned the sockets for those light and there fine? I changed all those LEDs incase there was a dodgy one but still the same?

Many thanks

 

[drhex]

Usually the driver transistor or its predriver. Are incandescent lamps dim as well?

 

[CoCkNeY-NuTjOb]

I have no incandescent lamps apart from the flashers, sorry im a bit of a noob but where is the driver transistor and predriver? And how do i test?

 

[CoCkNeY-NuTjOb]

Is it this area?

 

[CoCkNeY-NuTjOb]

Ra7 and Ra8 are very warm, and slightly discolored could this be the problem even tho all other lights are bright?

 

[CoCkNeY-NuTjOb]

Plus another strange thing with these bank of leds is when i preform a lamp test these light dont go out?

 

[drhex]

That is a sure fire sign the respective transistor is shot. What measuring devices do you have? Most multimeters can measure diodes/transistors. You can compare the drivers and see if any are different. First thing to do is establishing which row or column is broken. Look at the lamp map in the manual and establish what is common for the non working lamps. Single lamp test will also show this. Swap the associated driver. Can you solder?

 

[CoCkNeY-NuTjOb]

That is a sure fire sign the respective transistor is shot. What measuring devices do you have? Most multimeters can measure diodes/transistors. You can compare the drivers and see if any are different. First thing to do is establishing which row or column is broken. Look at the lamp map in the manual and establish what is common for the non working lamps. Single lamp test will also show this. Swap the associated driver. Can you solder?

I have a multi meter, and i can solder no problem, ive looked at the lamp matrix and im a bit confused tbf this the matrix and where the effected lights are... But ive just noticed the leds under the crane plastic and under the ramp plastic top left are affected also, i lifted the play field all these leds are connected via a soild violet wire, these other lights are not listed on the matrix where the shield ones are?

 

[CoCkNeY-NuTjOb]

Plus this is whats confusing me on the lamp matrix the other lights in that column are not affected just the first few??

 

[CoCkNeY-NuTjOb]

Hang on think i have got myself confused here i dont think the ones i have circled on that matrix are the ones in question tbf as there are yellow shield inserts on the playfield my fualt, i will have to find the lamps on the matrix

 

[CoCkNeY-NuTjOb]

Right so these aren't on the lamp matrix maybe part of general lighting the only mention to these lights in the manual are for the part numbers and some are not even listed please see pic

 

[CoCkNeY-NuTjOb]

And on the schematics is vio 3

 

[CoCkNeY-NuTjOb]

Cant seem to locate which transistor does GI lamps??

 

[drhex]

Ok, so all the controlled lamps work and you lost a GI string?
Now GI originates on the power board’s upper right corner and then goes to the PPB’s upper left corner where you’ll find the fuses for it. Now both plugs and fuse holders like to burn up on these boards, if they haven’t been replaced it may be time to do so. You’ll need the right crimp tool, trifurcon pins, housings and the male strips. Can all be ordered at RS.

 

[drhex]

Two of the GI strings go via a relay on the power board, that may be broken, too.

 

[CoCkNeY-NuTjOb]

Hi thank you for all the replys,
Yes all control lamps work no problem just the GI lamps on the violet wire are dim there working but dimmer than the rest of the GI lamps, i have had a quick look at the connectors which i will double check tomorrow i believe one connector is a bit discolored so i will swap that one out might have to send you a picture so you can tell me what type of connector it is so i can order the right one lol, the relay triggers but i will check for cold joints see if there is any? Fuses are all good

 

[drhex]

See if the fuse holders still grip the fuses alright. They age and get brittle. Also, even if the plugs and pins are good (and it sounds like they aren’t) sucking the solder out and putting in new solder in is a good idea.
These plugs are Molex KK156 in .156’’ pitch. Always replace both pins and plugs and use Trifurcon terminals which grab the pin from three sides instead of one. Also, use the proper crimp tool, there is a cheap Molex one and a really expensive proper one. Also, some third parties offer fitting crimpers.

 

[CoCkNeY-NuTjOb]

See if the fuse holders still grip the fuses alright. They age and get brittle. Also, even if the plugs and pins are good (and it sounds like they aren’t) sucking the solder out and putting in new solder in is a good idea.
These plugs are Molex KK156 in .156’’ pitch. Always replace both pins and plugs and use Trifurcon terminals which grab the pin from three sides instead of one. Also, use the proper crimp tool, there is a cheap Molex one and a really expensive proper one. Also, some third parties offer fitting crimpers.

Thank you very much for the reply i will have a look at this later on today and see if i can sort it

 

[CoCkNeY-NuTjOb]

Right yup you were right j5 connector is burnt out when i wiggle the connector the lights go bright and dim, ive ordered what you suggested, so i will get that fixed, many thanks mate for the help, much appreciated!