Tempest BIP problem ?

[kold669]

My Tempest board recently started to have an issue with the BIP adjustment. I cannot get all the vectors allign perfectly in all test and gameplay.
In the statistics menu for example If I allign the left line to have a perfect rectangle, all the other text is totally off....
The trimmers move the vectors but not to the extent to have a perfect picture in all tests.

Could it be the DAC AM6012?

 

[andrewb]

Yes. When there's what appears to be a BIP issue, and it can't be adjusted out via the BIP pots, it's often the DAC. I've seen a few of those.

That's not to say that's the only possibility, but I'd start there. And if it isn't that, suspect the other analog parts in that area next (TL082, 13201, etc).

It also could be a digital issue, but in my experience the others are more likely.

 

[kold669]

Thanks for the feedback. I will order some AM6012 from China, hopefully they work

With this board I had already a pincushion problem solved few months ago by changing 1495@B/C

 

[kold669]

Small update: I have bought locally some TL82 and replace the one @D11 but still same problem.

I think I have to wait the AM6012 dacs to be delivered

 

[pcjohn]

Anxious to see how this turns out. I have a Tempest with the same problem.
I suspect the AM6012 as well which I do have in my parts bin but have been too
busy with other projects and haven't had the time to change it (pretty sure mine
is E10 in the Y section causing the distortion).

 

[kold669]

I will definitely update the thread once I get the chips.

 

[kold669]

The AM6012 from China have arrived and yes changing the one @F10 fixed the BIP problem
Now it's again perfect

I bought 10 from Aliexpress ,2 were not working properly + 1 had weak pins :-D

 

[andrewb]

The AM6012 from China have arrived and yes changing the one @F10 fixed the BIP problem
Now it's again perfect

I bought 10 from Aliexpress ,2 were not working properly + 1 had weak pins :-D

Thanks for the update.

For the ones that didn't work, how did they behave?

 

[kold669]

One was totally off. The display was like tilted 45° :-D

The other had similar issue to the original one, with some lines not alligning correctly and others good

The one with a weak pin in the end is working by soldering a piece of metal.

In general all the DACs need a little adjustment on the BIP trimmers but in the end they allign all correctly. I guess there are always some discrepancies between them

Btw Aliexpress is amazing, I opened a dispute and they reimbursed me already the 3 defective

 

[andrewb]

Yes, all of the chips in the video section are analog, and analog chips have natural tolerances and manufacturing variances. That's why there are pots to adjust everything. You always have to do some adjusting, that's normal. The only thing you want to watch for is if you're finding you need to max a pot out one way or the other. That's always a sign that something isn't right.

And yes, most of the companies on AliExpress (and AliExpress itself) are pretty good about caring about quality, and preventing counterfeit parts. AliExpress itself pushed for a lot of that, as they had a much bigger problem years ago. Many of the sellers there are also not the ones manufacturing the chips, so they want to know if what they're buying and reselling is bad. So they're happy to refund you if there are any issues, you just have to contact them.

Same goes with ebay, if you look for sellers that have a message in their listings that says, 'If you have any problems, contact us first, and don't leave negative feedback.' Those are the folks who will make things right, and the ones you want to buy from.

Glad you got it figured out!

 

[kold669]

i also learned, contrary to some belief, that for vertical games Y is the long axis of the monitor ( the horizontal one let's say).
that is confusing when you have games like major havoc where X and Y are swapped in comparison to Tempest