Hello Everyone, I hope someone can offer testing advice please on A-16917
I have three DCS boards, two fully working and one which produces No Bongs at startup and no real sounds, just the occasional pop when I switch on and what I refer to as a squiggle sound when I switch off – and that’s it.
It does not declare Sound Board Interface Error, the machine boots clean and plays well,
the board is good looking and clean, with no signs of any previous repairs.
Note, I get No Bongs whether Game chips from the U2 position are loaded or removed.
I have replaced C20, C21, C52, C32 & C41 (as I had stock of those)
There are a couple of other can caps that could be done, but I reflowed C10 & C15 some pins on U20 and 1 pin on the ribbon connector.
I found help online regarding voltage tests at a few components on the board and went ahead.
The test points (8 different component legs) referred in a few posts, ALL compare well between the boards, suggesting that the No Bongs board has good voltage at these critical locations.
With zero sound, I feel sure I am looking for a short – or break in the early part of the circuit.
I did a quick IC leg value comparison under Diode test on U16,U17,U18,U19,U20,U29.
All compare favourably between the 3 boards (Pos to ground, then Neg probe of each leg produced values that appeared to match well)
If I am wrong and there is not a shorted component or broken trace which is preventing any sound, and the fault lies with a chip, then I would like to prove it first with my Logic probe, but I don’t know where to look i.e. which leg on which IC might be critical to the problem.
I may have come across something which hints at an issue.
I happened to voltage test some legs on the first game chip at U2 and finally found a difference between the boards.
U2 Pin 1 (top left) has approx 5v present on all 3 boards, but only the working boards have voltages (around 0.016v) present on the bottom right pins (17, 18 & 19).
The No Bongs board has zero voltage on the pins in that area.
I do not have the schematics for this board so cannot determine which components should be delivering to those legs.
Help on that would be appreciated thank you.
I have three DCS boards, two fully working and one which produces No Bongs at startup and no real sounds, just the occasional pop when I switch on and what I refer to as a squiggle sound when I switch off – and that’s it.
It does not declare Sound Board Interface Error, the machine boots clean and plays well,
the board is good looking and clean, with no signs of any previous repairs.
Note, I get No Bongs whether Game chips from the U2 position are loaded or removed.
I have replaced C20, C21, C52, C32 & C41 (as I had stock of those)
There are a couple of other can caps that could be done, but I reflowed C10 & C15 some pins on U20 and 1 pin on the ribbon connector.
I found help online regarding voltage tests at a few components on the board and went ahead.
The test points (8 different component legs) referred in a few posts, ALL compare well between the boards, suggesting that the No Bongs board has good voltage at these critical locations.
With zero sound, I feel sure I am looking for a short – or break in the early part of the circuit.
I did a quick IC leg value comparison under Diode test on U16,U17,U18,U19,U20,U29.
All compare favourably between the 3 boards (Pos to ground, then Neg probe of each leg produced values that appeared to match well)
If I am wrong and there is not a shorted component or broken trace which is preventing any sound, and the fault lies with a chip, then I would like to prove it first with my Logic probe, but I don’t know where to look i.e. which leg on which IC might be critical to the problem.
I may have come across something which hints at an issue.
I happened to voltage test some legs on the first game chip at U2 and finally found a difference between the boards.
U2 Pin 1 (top left) has approx 5v present on all 3 boards, but only the working boards have voltages (around 0.016v) present on the bottom right pins (17, 18 & 19).
The No Bongs board has zero voltage on the pins in that area.
I do not have the schematics for this board so cannot determine which components should be delivering to those legs.
Help on that would be appreciated thank you.