Dec 102015
 

I have this Tatsujin PCB in my collection :

Tatsujin_PCB

Some days ago I wanted to play it on my Astro City so, before rotating vertically the monitor, I tested the board on a supergun.Game was running absolutely fine but I noticed some wavy lines on screen as it was some kind of interference/noise:

I remembered I had same issue on some boards in the past and fault was due an electrolityc capacitor with increased ESR (the role of a capacitor is to block the DC filtering the AC ).So, with my ESR meter I went to test in-circuit the electrolytic capacitors and I came across a 470uF 16V one @C1 (the one that filters the +12V for the audio amplifier) with a high ESR :

bad_470uF16V@C1

You can see from ESR chart that a typical value for a 470Uf 16V electrolytic capacitor should be 0.2 Ohm while I measured 33 Ohm.So I desoldered and measured it out-of-circuit having confirm it was really bad (53 Ohm measured):

470uF16V@C1_out_or_circuit

With a good capacitor fitted no more wavy lines and finally I could enjoy this cool shoot ’em up on my Astro City.

 Posted by at 2:24 pm

  4 Responses to “Tatsujin repair log”

  1. Is that a Bob Parker ESR Meter? Looks like a neat bit of kit. I have the Atlas ESR70, not sure how that compares but I think I prefer yours with the handy chart.

  2. Got a similar issue on a Saint Dragon Bootleg board. Fortunately these are easy to fix.
    Great tool that ESR meter !