CurtPalme.com Home Theater Forum

[that1crzywhtguy]

I didn't want this info buried in another thread, so I am reposting this info so that it might benefit others!

I acquired I really low hours (30 according to the previous owner) Sony G90. Initially I was pretty disappointed because when I swapped the Dallas and tried to fire it up, I found the dreaded error 88. Thankfully, my story had a happy ending!

From the previous post:

IT'S ALIVE!!!

I'm feeling pretty elated right now TBH.

Especially since I never heard back from Craig anywhere I reached out to him, I just kept trying to figure it out for myself. And eventually, WE GOT IT!

SO! Here is the update to tie a bow on my particular repair, and to maybe help another with this issue!

I had a very kind and smart buddy help me out with this over our local discord.

We tried various things. I inspected the whole board with a microscope looking for cracked solder (not uncommon from PCBs of this vintage, shortly after the switch to lead-free solder), and I did continuity/short checks for all the chips responsible for the boot. No issues found there, on to the next thing...

After pouring over the service manual... We finally realized bad ram (ICs 235 & 236 IDT 71024S15Y ) was more than possible. Especially since I noticed on various shots on the web different vintage ram chips in use (notably on Craig's eBay shots). This would be the first time bad ram fixed some old tech for me, or my buddy on Discord. So I tracked some NOS ram chips down from eBay.

Today I finally worked up the guts to get out the Chipquik and work those old chips off. I went slow, and it went fairly smoothly. Getting the new chips on was tricky. Drag soldering on those SOJ chips is a PAIN. The answer, as always, MORE FLUX! I got them on and looking good eventually.

Then in the board went. I held my breath, and flipped the switch.....

ERROR 30. Well that's new! What's that mean? Found the relevant page in the manual, and oh! Requesting to format the user area! The old Dallas was probably long dead, so no surprise there. I still had it in from the last check when Curt had me put it back in and unplug the tubes.

New Dallas goes in and back into the chassis. Error 30 again. Good. Depress S202, and 31 flashes, error screen cleared....

Press the power button and.... IT BOOTS!

I've got more testing to be done here, gotta plug the tubes back in and see if the other ram chips have failed too (same chip and vintage), they are part of the internal pattern generator so if the internal patterns work, I'm good. If they don't, glad I ordered 6 chips instead of two.

TL/DR: got a G90 with an error 88? It might be bad ram at ICs 235 & 236. The chips (IDT 71024S15Y) aren't that expensive, so be very careful, but try swapping them out!

[Curt Palme]

Sweet repair, good work!

[Curt Palme]

Sweet repair, good work!

[that1crzywhtguy]

Thanks! I'm very excited to play around with this G90 today! I obviously can't confirm how prevalent this issue is, and only Craig can confirm if this has often been a point of failure, but my suspicion is that this is a pretty common cause of that error.

[bluemoonhu]

This is a common fault ，My nearly brand new Sony G90 experienced the same malfunction shortly after running. After replacing the Dallas chip, the machine ran for a period of time, but the malfunction occurred again. Finally, the board was replaced and has been in use until now.

[that1crzywhtguy]

This is exactly why I posted this potential fix! I know probably most bad boards have been fixed or replaced by now, but just in case. Hope it can help someone!