29e31s went downhill

[Aaronr33]

I have a 29e31s that i installed a cap kit in.

When i powered back up i blew r456.

Replaced r456 and the HOT, powered up and blew both again.

Had a bright dot in middle of screen.


Now, there is no DC voltage on secondary of T803 (measured at diodes)

When chassis is powered, you can hear a low chirp like high frequency xfmr.

I measure voltage to the network before t803.

 

[nem]

Did you double check the cap values with what you took out? Triple checked polarity on all?

 

[Aaronr33]

Did you double check the cap values with what you took out? Triple checked polarity on all?

Yes and yes.

I usually do two at a time, desolder, install and solder.

 

[nem]

And it was working before? If so, something you have done is blowing R456 and the HOT. Take some pics of the chassis.

 

[Aaronr33]

And it was working before? If so, something you have done is blowing R456 and the HOT. Take some pics of the chassis.

Its more far gone now

Get no DC voltage on secondary of T803

Measure at each diode.

Will get some pictures

 

[nem]

Its more far gone now

Oh absolutely, but whatever blew R456 and the HOT is still there.

 

[Aaronr33]

Pictures

 

[nem]

The thing that catches my eye is the cap, resistor & diode combo on the solder side between C841 and R839. You're not shorting anything with that are you? I always rest it on a blob of glue to make sure.

 

[Aaronr33]

I will check, but that's a good catch, may of been pushed down on board when doing cap kit.

Would that cap/diode soldered on bottom be a factory "tweak" ?

 

[nem]

Would that cap/diode soldered on bottom be a factory "tweak" ?

It's a factory fix, yes. I made a post about it on AO a few years ago:

https://forum.arcadeotaku.com/viewtopic.php?t=39077

No idea what it's for.