Jaguar non working - black screen & high pitch light buzzing sound from motherboard near CPU

[Chandler]

Trying to repair a Jaguar i recently picked up which doesn't work

 

It has the original Jaguar PSU and that works ok and has the correct voltage

 

I have cleaned and cleaned the cartridge port and game cart contacts, they are both gold and clean!

 

Power on the jaguar stripped down to bare motherboard

 

Green light illuminated with game inserted - black screen, nothing more, tried this many times with different games

 

I can hear this high pitch buzzing / hissing sound from around the CPU area, nothing getting hot around there

 

I don't know it's history but it was bought new and is boxed so i don't assume it has had the wrong power adaptor inserted

 

I have looked for the usual U38 / REG 1 / Capacitor blown issue and there are no signs of damage on this machine

 

Is there anything else i can test?

 

I have tested voltages around the CPU and they are 5v so i don't think the console has a power issue

 

Any ideas?

[Machine]

From what I have read, sometimes it can be very difficult to see any signs of damage. Console 5 sells the Jag cap kit. It is cheap(like $8-9) but looks like it is a job for someone who has skills. That might be a good starting place.

When I bought a dead jag, the light would not come on.....it was totally doa. I just switched out the whole motherboard with a NOS. I do not think they sell those any longer though. Wish I would have grabbed a bunch of those.

[LinkoVitch]

Have you checked the voltages on the internal side of the regulator?  If the internal voltages are off/missing could still be something in the power subsystem.

[Chandler]

Well i'm going to change U38 then as it's easy, just purchased the part

 

But personally i don't think it's that as the green light is on and good voltages over the board, but who knows eh?

 

I am amazed though that there is so little about Jaguar repairs on the net compared to other Atari consoles...

[Zerosquare]

8 hours ago, Chandler said:

I am amazed though that there is so little about Jaguar repairs on the net compared to other Atari consoles...

It is not a popular console. And if the problem isn't one of the common ones, it isn't easy to diagnose/repair since the console is pretty complex.

[LinkoVitch]

9 hours ago, Zerosquare said:

It is not a popular console. And if the problem isn't one of the common ones, it isn't easy to diagnose/repair since the console is pretty complex.

Don't talk rubbish! everyone knows it's just 2 wires going into a FUMEZ(tm) emitter

[displaced]

In case it helps, the buzzing/hissing from around the processors is normal - my fully-working Jag does the same - and always has since I bought it on release.

 

In fact, it’s probably a good sign - shows activity!