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Author Topic: Almost there! (Read 616 times)

Offline emptiness

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Almost there!
« on: 2022.April.18. 17:36:23 »
I've recapped my Enterprise 64 and replaced the voltage regulators. Today I replaced TR2 and the video output is the best I've ever seen it.

However, it still "wobbles". I've adjusted L2 to get the wobbling as slow as I can. I've tried adjusting C43 but it does not appear to make much difference.

Here's a short YouTube video showing the current video output via SCART.
https://youtu.be/QfPLyI8MAOU

Can anyone suggest what I should try next to get a stable display?

thanks

Dave

Offline gflorez

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Re: Almost there!
« Reply #1 on: 2022.April.18. 19:48:36 »
The next step could be to try it with other TVs. It happens that sometimes they don't auto-adjust to the slightly different syncs of the EP.

Offline emptiness

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Re: Almost there!
« Reply #2 on: 2022.April.19. 21:51:48 »
Thanks. I'll give that a go. I'm pretty sure I've tried a working EP64 with this TV and it was fine though. I'll check.

Offline Zozosoft

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Re: Almost there!
« Reply #3 on: 2022.April.20. 09:12:24 »
Check the 5V voltages not just at the regulators, check at chips, for example: U24, U25, U33 on +5A, ROM, onboard RAM, Z80 on a +5B
Nick chip use +5A, if it is lower can also result this wobbling effect. Also check +12V, for example on U35 Pin14,15,16.
And do you have a scope? Will be good check the Nick clock.

Offline emptiness

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Re: Almost there!
« Reply #4 on: 2022.April.20. 22:09:40 »
Thanks Zozo. I'll try those checks this weekend.

I've had this motherboard hanging around in my box of stuff for ~35 years I'm really hoping I can finally get it to a fully working condition.

Offline Zozosoft

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Re: Almost there!
« Reply #5 on: 2022.April.20. 22:42:48 »
One more hint: If it is built with Philips capacitors then recommended to replace all.

Offline emptiness

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Re: Almost there!
« Reply #6 on: 2022.April.21. 09:32:12 »
Replacing the electrolytic capacitors was the first thing I did :)