REPAIR GUIDE - Super CDROM2: Total capacitor replacement chart

[thesteve]

I actually solved this issue recently
The problem, was a dirty main board, near the 1000uf cap

[choijimmy]

I actually solved this issue recently
The problem, was a dirty main board, near the 1000uf cap

Thanks thsteve.

I did cleanup the board with alcohol / contact cleaner yesterday but No luck. Not sure why. Also, I don't see any leak residue close to 1000uf.

Indeed, I have 2nd Super CDROM which complete No sound for CD game ( but HuCard is good ). Let me try to clean that board thoroughly to see it helps or not.

Thanks again!
Jimmy

[thesteve]

When I found it I couldn't see anything on the board either as another tech had cleaned it
On the 7pin plug of the sound board the center pin is antithump
It must be 0 when running
It runs near a power trace under the board, and any residue pulls the voltage up

[BlueBMW]

Very good info to know there steve!   I've seen several super cdrom2s with this issue.

[pnauts]

Hi all, I'm trying to solve a SCDR² issue with very low sound (no crackles), I just try with Hucard (mono) for the moment. I started to draw a scheme for the small upper board (4558 is a 2 x amplifiers, BU4053BF is an analog mux/demux, M51131L is the volume/balance control).

I checked all electrolytic capacitors of this upper board with the capacimeter function of my Multimeter, the values are in the specs of the nominal values.
Is it a capacitor with good measured value could be defective ?

On the other side of the board, I checked the diodes in the transistors Q601/Q602/Q603/Q604, and the 2 x diodes with common anode from D601 are ok too.
I cleared the solder flux.
The supply on the CN103 connector between pins 6 (9V according to my memory) and 6 (gnd) seems ok, I thought initially it would be around 12V, if someone can confirm me ?
outputs audio signals are routed to 1 & 3 of CN103.
The voltage for volume control (from CN104 pin 4) seems at correct level (5V).
When I will investigate enough on this one I'll have a look on the audio section on the mainboard.

[BlueBMW]

I seem to remember Kieth Courage finding another issue on these units that caused low volume but I cant remember what it was... hopefully he will chime in here soon.

[pnauts]

He did strap a resistor on the transistor base, not the right solution imo.
on the pin4 of the 7 pin connector (on top or bottom board), anyone can tell me where this pin goes?
it's the command on the base of the transistor (through a diode and a 1K resistor on each)

edit: Keith courage mods, pictures on last post previous page, but as Steeve pointed the mod adressed the symptoms, not the cause.

[pnauts]

here a little schema.



what is routed to the pin 4 and where ?
Is voltage on pin 6 correct ?

[pnauts]

here are the voltages I measured, 0V console to earth with oscilloscope probe, with a Hucard:

CN104(1): 4V (Z io of the BU4053B)
CN104(2): 0V (ABC bits selections of the BU4053B)
CN104(3) 4V (IC521 pin 3 & 5 in+ of amplifier 4558)
CN104(4): 5V (volume control input of M51131L)
CN104(5): 0V
CN104(6): 4V (1st out amp 4558 IC506)
CN104(7): 4V (2nd out amp 4558 IC506)
CN104(: 4V
CN104(9): 4V

CN103(1): audio Left not measured
CN103(2): 0V (ground)
CN103(3): audio right not measured
CN104(4): 1,32V (Q603 & Q604 base, before diode ans 1K resistors)
CN103(5): 4V
CN103(6): 8V (V supply, from pump charge ?? because no other regulator than 7805)
CN103(7): 4V

M51131L (volume & balance control)
1: 8V (V supply)
2: 3.4V (input 1)
3: 3.1V (output 1)
4: 5.52V (Vréf)
5: 8V (Low pass filter)
6: not connected
7: gnd
8: 5V (volume control)
9: gnd
10: 2.8V (Balance control)
11: gnd
12: 5.52V (wire to 4)
13: 3.1V (output 2)
14: 3.4V (input 2)

if someone can make measurement to compare to my values, thanks for your help

[thesteve]

cn103 pin 4 is wrong
the board needs cleaned better

[pnauts]

thanks.
Do you know where is routed the pin, I try but for the moment I did not succeed to find.
I suppose the voltage should be closer to 4V ?

[pnauts]

cn103 pin 4 is wrong
the board needs cleaned better

after better cleaning, it improved a bit the volume (but more cracklings), I checked the voltage on pin 4, the value is lower (around 0.9V), so I suppose the value should tend to 0V to increase again volume.
This pin is routed to D303 cathode (2 x diode, one is wired to the PNP Q309, the other to PNP Q308.
Base of Q309 is wired to Vout of expansion port through 10K (R311). Base of Q308 is wired to D304 anode through 6K8 (R319). Cathode of D304 is wired to 8V.
There is a common point on Q309 and Q309 wired to cathode of ZD303 (I suppose it's a zener).
I think be close to the solution...

[BlueBMW]

How are you cleaning the board?  I found that the only way to really get all the old leaked fluid out is a dishwasher run.

[pnauts]

I use a flux remover and a brush
something like this

[pnauts]

I use only Hucard for testing right now, CD unit is remove for the moment.
I think cracking come from capacitors, I will try to change some of the 10µF/16V (even if measured values are ok)