Ok - HELP! I shorted out something in my lamp matrix, fooling around with a loose socket and light bulb for Marilyn, of course, the game was on and the socket touched some other metal and that's all it took to screw something up.

It looks like the whole column 4 in the lamp matrix is screwed up all the characters plus a few others. When I turn off the machine, Drac and Gorbie, along with the Ride Again light stay lit and then slowly fade out. I also noticed that the Santa light lights up at the start of the game and just stays on. It looks like those character lights are not blinking the way they should in attract mode.

I am stooopid with the electronics end. How do I find what is fried? Could it be the diodes that are attached to the lamp sockets?

I'm hoping there is no damage to the board - it looks like 1J6 controls this column.

I have a meter but don't know how to use it. Maybe someone can help walk me through this. I'm soooo bummed, I refurbished this Taxi and now caused a problem - I need to fix this before holidays and friends/family visit.

Thanks for your help ahead of time.........

-Urgh, Nate-

I'm up for it - I think!!! Light socket is "fixed" although I think it'll need to be replaced, I think the BULB in the damn thing was acting up as well (LED of course, when will I learn just to stick with regulars?).

Oh, I will also mention that if anyone lives near me (Baltimore - county), I'd be happy to pay to have someone troubleshoot/fix for me.

-Nate

Thanks boscokid, I'll take a look. Offer is still good for someone to come to my place and fix it................

Well, from reading about the lamp matrix, it looks like I have some burned out TIP transistors. Anyone in Baltimore County good at board soldering?? That's something I haven't done yet............I say I have bad transistors because the same row is turned on constantly, and very bright - so they are obviously betting the entire voltage and not being switched on/off so that they blink.

*Sigh* I'm so stoopid!

Simplykind and Kporter - thanks for the support. I actually have soldered and done repairs (I brought Taxi back to life....before injuring her!!!) and it is a rewarding feeling - but I am worried about messing up the board. I would think the TIPs are fairly easy to replace?.................I will be ordering the parts.

Do you have JohnWartJr info? You can message me. Thanks.

-Nate

kporter that's nice to know, I'm fairly agile with repairs, I just worry about soldering those small round contacts out of the board - I know older boards this happens often.

I have a meter, will test them this week (when I figure out what to do!), gotta learn to use it sometime! Thanks for the recommendations also.

-Nate

fish1975 and bosco - ooookay, you guys convinced me, fish, that is the type of instruction I need - I will get a solder sucker and see what happens - of course, carving out a niche of time to DO this damn repair is something else.......

I also need to ask how to use the MMeter when checking the circuits - I will shoot a photo of my particular meter and someone can point out the settings - sorry, but thanks, you are making me feel a little better - I was soooo depressed about this but it seems fixable!!

-Nate

Herg - I have not yet, I am going to get some alligator clips to test with. From the behavior of the bulbs I am assuming at this point. It happened last night - now I'm at work........ I was hoping maybe it was the diodes - could that be possible that they were fried - could the transistors be ok? (That would be great!) I know, we won't know until I test the damn things - I hear ya!!

I think the socket that was worked loose contacted the metal of the Marilyn pops which is directly beneath it.......I located the column that appears to be affected and the corresponding row on the schematic (pat on back!!!).

-Nate

Yes, I'm leaning to having someone else do it - I just don't wannt f*&# up something else in the process - but I think I can do this type of thing, I need to practice on a dead board.................I've had some offers of help - I will keep you posted - I WILL do the troubleshooting to isolate what needs fixing though.

Thanks everyone!

Nate

Okay, here's an update:

I used my Multi-meter to test the diodes on the sockets, black on the banded side and red on the opposite side. Readings were good at around .5 volts. This is my first time doing this, it seemed like sometimes I couldn't get a reading at all, even when I replaced one of the diodes with a new one after getting a "null" reading on that one in particular??? I might be doing something wrong?.....I guess easiest thing is to replace all diodes that I can't get a reading and just assume they are fried.

I did the test Boskokid pointed me to on the repair website while in the "all lamps on" test mode: on 1J7 location, all the pins touched with my diode (unbanded side) lit my light socket and made it blink -BUT pin 4 (counting from the right to left at 1J7) made the light sooooper bright and blinking, so I think that is the associated transistor that needs replacing - I am guessing that the "full force" of wattage is getting to that light since it's so bright.

On 1J6, all the 8 pins lit the bulb normally and made it blink when I touched each 1J6 pin with the banded side of the diode, so it looks like there is not a problem with that lamp row, only the column?

Can the multi-meter measure the current on the individual TIP transistors?

In the manual the column suspect is 4, which is the lamps for all characters (Pinbot, Drac, Marilyn, Santa, Gorbie, Ride Again, Passengers Carried, and the Lock arrow on the right of the pf). There's a small Q80 on that column heading written-in in the manual matrix table so that is the corresponding transistor location, correct? There are also a range of numbers from 25 to 32 written next to each lamp name (Pinbot, etc.) in the manual not sure what that number is.

Looking at the game in play mode, it looks like all those lamps are brighter than they should be an pretty much ON all the time with a slight dimming where it should be blinking.

Hope this helps, would like to get this thing fixed. My CPU board has been repaired before from what looks like acid damage, a lot of the trace work has been "polished through" and looks silvery - up to now though I haven't had any problems with the game.

Thanks again for comments/help -

Nate

boscokid and herg, yes, that was a typo, - It is Q60, I am using a Taxi manual/schematic. I think it is the transistor, I will attempt the below tonight, but I have a question (see below):

"You should be able to work backwards from there, comparing identical points such as the output of R86 (that feeds Q60) with the output of R87 or R85 (identical circuits) - if those readings are all the same then you have proven Q60 is bad."

Question:What setting should I use on the Multi-meter for this test? And where does red/black lead go? Thanks, as you can see, I am learning as I go along - appreciate the input. I see that on the schematic, so I know where we are on the board - thanks.

Back to not getting any readings on some diodes, is it possible they are blown out? As I said, I got readings on some and not others, this is my first use of my multi-meter out-of-the-box new so could I be doing something wrong testing the diodes? I am putting the black probe on the banded side metal and the red side on the opposite side metal.

-Nate

Boscokid, thanks for the "hand holding" - I will trace that tonight with the probe and see what I get - hopefully it is only that isolated Q60!!!

Herg, thanks for the added input on the diodes - the bulbs were out of the ones tested, I think I'll hold off on any diodes until I get the transistor(s) replaced.

Best,

Nate

Ok, I tested the heat resistors R82-89 using the multi-meter set to DC, Volts - I used auto-range because I couldn't figure out how to make the range 20 - touched the right side (my right as I'm looking at the mounted board in the backbox I'm assuming......)with red and grounded the black on a corner screw.

If my meter is correct, it looks like all the resistors are fine, each showing 15 volts (I never did get 14).

Sooo, I'm guessing that only Q60 needs replacing.

Does this sound right?

Thanks boscokid, I can check the pins on 1J7, almost surely, that fourth pin will be putting out much more voltage. I'm assuming I measure the same way as I did the resistors? (DC, ground black, touch red to pin - game in attract mode......).

-Nate

Yep, that will tell me. I will check tonight.

I dunno about soldering on the board, I know that there are small metal discs around the actual CPU board that can sometimes get heated loose and cause contact problems. This happened to me on the small lamp board that sits beneath the spin-out ramp when I removed a bad light socket - although I wasn't too concerned about that becuase I replaced that lamp board with an LED strip.

Someone mentioned cutting the legs off of the old one, and for a temporary solution, just solder the new resistor legs onto the old ones that are already soldered onto the board - is this ok to do for a few weeks fix until after the holidays??

-N

Okaaaay, still messing with this problem, but hopefully closer.

I had a Pinsider resolder a new TIP at Q60 after bringing him the board. Glad I did because one of those tiny metal rings around where the TIP's legs are inserted lifted off when removing the old legs - sooo, he had to connect that leg directly to a trace - that's exactly what I thought would happen as this is an old board.......

Anyway, put the board back in last night, replaced the bulbs in the offending sockets (all Taxi characters) and........they still didn't light DOH! Why Youuuuuuu! Ok, it was late and I didn't do too much after that, I DID squeeze the diode from the bulbs not lighting and I got a VERY dim light coming from the bulb - so that is telling me that the diode is probably no good - correct assumption?

I have one new diode, so I will try replacing one this evening and see what happens. I also noticed some sockets are wonky, so will be replacing them as well.

Nate

There are two lights on that green board not working, (Carry Passengers and one of the "20k" squares in that green row above the characters) I haven't re-flowed that yet, but plan to - I assume you mean that ring where the socket screws, clamps down on? I did try making sure the metal leads on that screw-in socket were clean/pulled-out for good contact.

Blackbeard, Oh, I gotcha - thanks. Will try that.

Ok, someone mentioned maybe these sockets are not grounded properly?? I can't understand why all-of-a-sudden the bulbs are not working after I replaced the TIP on the board?

Anyway, they said to try running a clip from the ground braid to the socket, if it lights then it's a grounding problem. Either that or low voltage..........

I haven't done anything more with this, but will be looking at it tonight.

I'm done. I had that TIP replaced, I don't think it was done correctly because now all the lights don't come on at all. I ran that test again with the alligator clips, and now that Pin #4 doesn't light the bulb at all.............

Also, now my pop bumpers don't work at all.

I really would like someone to come to my house (Baltimore, MD 21234) and repair Taxi. If anyone can do this, PM me and let's set up a time.

-Nate

BoscoKid, I'm pretty sure the TIP is not soldered in correctly, I am getting absolutely no reading now when I test the pins with the light-bulb at pin 4 as I had before. I have called a local guy to come look at this for me - but naturally, he is very busy until after Christmas....

We did check the TIP and got the same readings as the other ones after the new one was installed, I really think that is the problem.

As I mentioned, now my pops (all of them!) are out (unrelated I know)............I did check the fuses, they look okay. Oh, also a wire came out of the socket connect for the PinBot drop targets (they are so brittle)!!! I feel like this thing is falling apart as I work on it - like a Laurel and Hardy short!!!

I tried metering the TIP's last night with board in machine, from what I could read (some legs I couldn't get to) the readings all checked out, I really think its the solder job! Just my luck.........

Urg.

KingDaddy, yes, I checked the fuses, as I said I pretty much isolated the bad transistor, once that was swapped out, now I get no power to that column at all.

Here's a pic I happened to have of the board - the board is back into my machine, so I will have to pull it again to get better photos, you can see where something was done to the board because the traces in that very area are sanded down.........I know this isn't a very good photo - just a "fill-in."

I tested those resistors also, all tested ok.

Board.jpg

Someone mentioned this:

Did you check the conicity from the legs of Q60? This may help to see if
when Q60 was shorted out, it also took out the Q59 Pre-Driver transistor
(2N6427) and possibly the U53 (7408) Quad Gate. On your manual's schematic
page 70, follow the path to the left from Q60. You will see it leads to Q59
and then to pin 6 on U53. If there is good conicity from the three legs of
Q60, and column 4 is still out, then Q59 and possibly U53 have been blown.

I will check this too.