Hello,

I re-enter a topic to merge 2 questions I had inputted, for which no solution was found.

On my Jokerz!, the vertical ramp of 8 lamps indicating the jackpot amount on the backbox insert does not work (see picture). All lamps are dark while playing and in "all lamp test" mode.

I came to the conclusion that the strobe 8 of the lamp matrix has a malfunction. I connected a #555 bulb on a socket directly (with a diode between the lamp and the pin) between 1J7 - 9 (strobe 8 ) and every pin of 1j6 (rows), the bulb never went ´on'. Also measuring the voltage on 1J7-9 gives 0, where other pins on 1J7 show positive voltage.

I found no anomaly when checking Q52, Q51 with the DMM, setting "diode" and none with the continuity. I replaced Q52 anyway by a TIP42C, in case of, but no effect.

Then, I went upstream to the IC U52 (TTL 7408) and checked the inputs and outputs with a logic probe and DMM. This IC contains 4 "AND" gates (the one with pins 8,9,10 is the one which drives strobe 8 via the transistors).
On UC52, the 2 input signals for all gates are consistent (high for blanking, and pulse for the second input). The outputs are similar except the one that I am interested in, i.e pin 8 gives a result different from the output of the 3 other gates. With the DMM, it gives 0,72Vdc whereas the others show 0,32 Vdc.
For a complete comparison, I made the check on my Cyclone which has a similar set of lamps for strobe 8. The voltage check of U52 pin 8 on the Cyclone gives the same value as the other outputs, i.e. 0,32Vdc, hence not the same value as the U52 pin 8 on the Jokerz!

Finally, and I am back to the JokerZ!, the output lug of Q52 shows no voltage as the 7 other transistors commanding strobes 1 to 7 do.

Hope to be complete in my description, I am wondering how to find the part in default.

Your help is welcome, thank you

Thanks in advance

fronton lampes.JPG

Which resistor are you refering to ? For my understanding in english: by resistor network, you mean the single component having 10 resistors, here SR17 ?

sorry, I don't know how to measure a single resistance on a resistor network ?!

I measure 4.15 kohm for each resistance of sr17 and 2.2 for sr16. Strange for sr17, the spec says 4,7 kohms. But no inconsistency among values

Yes ... I can anyway replace Q51 by a new one and see what happens, now I guess there are not many options as the différences are noticeable between UC52 and the connector 1J7. I will not bother the helping members for weeks On the one hand, you learn a lot, on the other hand you spend time spinning around ... mix of pleasure and frustration. That is life. I will come back with the results

Yeah, yoooohoooo! Ca marche !!
I replace the sand wore wound resistor and Q51 and it works perfect now.

Great time, many thanks for the support. Wine for dinner tonight !