Transistor and Deflection board on Tempest - wobbly/jittery graphics

#1 · September 29, 2022, 4:55 pm

Hi!

I used the transistor and deflection board kit on my Tempest cabaret. Good news is it powers up and Tempest is running. Bad news is my Tempest now has the "jitters" or "the shakes" which it didn't have until I installed these kits (it's especially noticeable on text). Tempest was confirmed working before I installed the kits; I put them in as preventative measures since I had to replace two of the bottlecap transistors a little over a month ago. Just curious if anyone else has experienced this and if there's a fix out there? Overall I love the kit and want to keep it if at all possible, but the jittering is driving me a little batty. I've tried messing with the pots on the PCB but it hasn't fixed the issue.

Thanks in advance!

-Dave

#2 · November 7, 2022, 10:48 pm

Just a note to let readers of this forum know that we haven't abandoned AntonioBay! We've been working with him via email.

That said, if your issue is urgent, please use the Contact form, as there's one less step in the process between you and our engineers.

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#3 · January 17, 2023, 8:10 pm

Thanks for all your help guys! My Tempest machine is happy! 🙂

-Dave

#4 · June 29, 2023, 6:02 pm

What was the issue and how was it resolved?

#5 · March 13, 2024, 4:57 am

Ditto! What was the issue and how was it resolved?

I have what I think may be a similar issue on my Tempest where there is a slight jitter of about 1 line with in size that causes the vectors to move around and is quite annoying. This phenomenon seems to be worse on certain stages of the game - for example V, U and W levels seem especially bad sometimes. The effect will suddenly get worse almost like something broke into oscillation. Everything on all the boards have been recapped, no stray magnetic fields, RFI. I'm trying to get things rock solid so I'd like to know what the issue was.

#6 · March 25, 2024, 10:44 pm

Same here. Jittery vectors on Tempest!

I've come to the following conclusion:

They must have looked at the Amplifone boards and were inspired to remove the 28V voltage regulation section in the Wells. Lots of folks have been calling it the achilles heel. Heck that's why the LV2000 was invented. But on vectors, everything is about smooth analog power. Without the regulation you're sending the ripple off the diode bridge and caps to everything else.
The Wells has a standard voltage follower regulation using ZD100,ZD101,Q100 and Q101. All that's gone on Alan1.
This means the yoke drivers are running off a noisy 33V instead of 28V.
This means the HV is also running off a noisy 33V rather than smoother and lower 28V.
This explains why you can't use the Alan1 deflection without their transistor kit.
And finally, this explains why the 24V fan in their kit screams like a turbo jet.

I might try to drop my LV2000 on my Alan1 set and see if that improves things.

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#7 · March 27, 2024, 9:48 pm

FYI I was able to fix the sudden strong jitter/oscillation on certain levels by cleaning the wiring harness pins. However I still do have an overall very slight jitter/swim of about 1/2 of a line width. I'm a perfectionist when it comes to displays so would really like to hunt this one down if possible.