Rainbow Islands repair log #5

 PCB Repair Logs, Repair Logs  Comments Off on Rainbow Islands repair log #5
Dec 212014
 

Another Rainbow Islands on the bench, this one from my friend “Mikidaffy1983”:

Rainbow_PCB

 

Board was in excellent state but when powered on all I got was a screen of wavy lines:

issue_1

Started my usual visual inspection and didn’t notice nothing odd but when touched the PAL “B22-05” @IC33 I found it quite hot.Probing its outputs I found they were almost all dead so I programmed a GAL16V8 with the replacement hosted on this site (thank you Porchy and Macro for this).With the PAL replacement fitted the board succesfully booted but sometimes stuck on a static black/white striped screen , others times with bad/missing backgrounds:

tiles_issue

Since I repaired other Rainbow Islands (and similar hardware like Bonze Adventure) I knew tiles are generated by the custom marked ‘PC080SN’ @IC34.This custom is connected to two 62256 SRAMs so I analized them with a logic probe and found that most DATA lines of the one @IC3 were stuck HIGH or LOW.Without thinking twice I desoldered and tested it having confirm it was bad:

62256_testing

Fitted a new 62256 SRAM led me to this point:

blue_issue

All backgounds/tiles were restored but there was a clear issue with the blue color.As we know RGB colors are generated by the custom module ‘TC0070RGB’ which on this PCB was resoldered but after a comparison with a good board I couldn’t find anything strange so I decided to move ahead and look into other issues.In particular there was no sound at all, only a buzzing noise sign that the main MB3735 amplifier was good.There was also no sound ouput from YM3012 DAC and this convinced me look into the digital part of the audio circuit.Probing the 6264 SRAM  @IC44 revealed weird activity on its DATA/ADDRESS lines, testing it out-of-circuit confirmed it was bad:

6264_testing

Sound was fully restored but it was quiete and faint also at the highest volume.Connecting an external AMP to the inputs of the TL074 OP-AMP @IC67 gave me strong and steady volume so I rightly replaced this IC.

Back to the blue color issue I decided to go straight and remove the TC0070RGB module installing the Macro replacement resulting in a success.Board 100% fixed.

board_fixed_

 

 Posted by at 10:07 pm

Double Dragon repair log #6

 PCB Repair Logs, Repair Logs  Comments Off on Double Dragon repair log #6
Dec 152014
 

Yes, yet another Double Dragon repair log..

Found this PCB in the pile, honestly I can’t remember when and where I got it :

Double_Dragon_PCB

Once powered ON I was greeted by this title screen:

Double_Dragon_scrambled_screen(1)

Also sprites in game were all blocky with some parts floating on the screen:

D_D_sprites

I also noticed that some sound FXs (especially speeches) were missing so I decided to first troubleshoot this issue.Probing one of the OKI MSM5205 @IC81 I found that all four data outputs were not toggling.The chip read data from the two samples EPROMs not directly but through two 74LS157 multiplexers.I found that select line (PIN1) of the one @IC96 was stuck HIGH so data inputs were not selected at all.I traced it back to an output  (PIN3) of the 74LS393 @IC62 so I desoldered it but it was good.Probing the its CLEAR pin I found that it was stuck HIGH.Tracing it back lead me to an output (PIN6) of a 74LS74 @IC75. I desoldered it and tested it out-of-circuit  having confirm that it was bad:

74LS74_testing

With sound FXs fully restored I decided to come back to the sprites issue.Fault was located in the VIDEO board since I swapped a good one and issue sprites came back normal.Luckily we have schematics so I started to check for parts of circuits involved in the sprite generation and handling but after two days of troubleshooting and a lot of suspected ICs replaced in vain I came to a dead end.I was nearly to give up and declare the board as not repairable but checking the last part of the object generation schematics I found a missing signal input (called ‘OCGL’) on PIN9 of a 74LS08 @IC36.This signal is generated by an output (PIN5) of a 74LS174 @IC69 always on VIDEO  board.

OCGL_signal(2)

As I said this ‘OCGL’ signal was present as output of the 74LS174 but not as input of the 74LS08 so it was lost somewhere on the PCB.Following on solderside the traces between these two ICs I came across a via under a 74SL157 @IC34.I desoldered it and found this:

corroded pad

Oxid literally had corroded and eaten the pad and part of trace thus preventing the ‘OCGL’ signal reaching the input of the 74LS08.A tiny piece of AWG30 wire:

AWG30_fixed

and Billy e Jimmy Lee bros could fight again!

D_D_fixed_

 

 Posted by at 9:37 pm

Atari Jaguar repair log

 General  2 Responses »
Dec 142014
 

Got a Jaguar console for cheap as I originally wanted the cartridge slot but like so many of my idea’s like that I ended up repairing it and not wanting to harvest parts from it.

This was sold as not powering up. Its important to know from the start that the Jaguar will not power on without a cartridge inserted but in this case it made no difference.
Opening it up and removing the metal shield allowed me to see the problem straight away and it is apparently a relatively common fault.
IMAG1087
IMAG1091

The voltage regulator IC has blown.
I ordered a new one and fitted it and now it at least powers up.

I haven’t really been able to test it yet as I don’t have a Jaguar AV cable. Also this version of Jaguar didn’t have an RF modulator fitted as it was the French ‘Peritel’ version.
Ill tap the signals some day and properly test this thing out so if it doesn’t work then it looks like ill have my cartridge slot after all.

BINman update

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Dec 072014
 

As I get more experienced and learn new things in programming I like to go back and update my programs to test things out.
After many unreleased version updates and the end of 2014 approaching I’ve finally got to a point where I think an update is due.

bm3.3.2
Here is version 3.3.2 if BINman.
For those that aren’t familiar with it, I originally wrote this program in 2012 to allow me to quickly byteswap and interleave ROM files. Since then I’ve been adding to it as I needed the extra functionality.
There isn’t a great deal new here but the code has been overhauled quite a lot and is hopefully bug free.
There is also a basic hex viewer now too. It is basic but ive wanted to include one for a while now and here it is.

I hope other find this as useful as I do.
DOWNLOAD HERE
This requires the latest .NET to run (v4.5)

 Posted by at 6:59 pm
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