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Author Topic: UM1233 RF Modulator (Read 245 times)

Offline keyboardjunkie

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UM1233 RF Modulator
« on: 2019.July.13. 00:02:35 »
Hey All,

Has anyone got a spare, working UM 1233 RF modulator they are willing to part with?

I'm currently ressurecting a car boot sale find - an old EP128 (board only) that had been _very_ abused.  I've got it working but the RF ouput is making a buzzing noise on the picture and all the colours appear wrong (background on the flashing EP logo at first boot is a fuzzy blue colour) and all the text on the screen appears to be 'bleeding' a fair bit like it's off channel.  Tried everything to get it looking better and now I wonder if the RF modulator is broken..

EP appears to work fine apart from that - I'll attach a picture for you experts to take a look at!

Also, Had to replace a missing LM1889 IC - I think there should have been a resistor across 2 pins of the IC if I recall - anyone got any info about it?  I'll post a pic of the board too..

Thanks for any help you guys can give me!

Mark.

Online Zozosoft

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Re: UM1233 RF Modulator
« Reply #1 on: 2019.July.13. 07:23:30 »
There is brand new on Ebay.

But why using RF? RGB SCART is the best :-)

Have you tried to play with the variable resistor near the left side of the modulator?

I see EPower installed, nice!
« Last Edit: 2019.July.13. 14:01:42 by szipucsu »

Offline keyboardjunkie

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Re: UM1233 RF Modulator
« Reply #2 on: 2019.July.13. 22:56:32 »
Hi Zozo!

Hope you are well friend!

I wanted to get the EP as original as I possibly could - and a new modulator seemed like a must have :-)

I have tried the pot next to the modulator to no avail - I guess my next job will be to scope the video signal into the modulator to see if it looks good - but I think that the modulator is bad (the rust might be the cause!)

I may buy that one on ebay and replace it anhyhow.

I need also to get a 128k upgrade for it - do you have any for sale?

I will also need to look for a case to put it in, but I guess that will be very hard to find..

The power side of the EP was completely broken - it was much easier (and a better choice) to replace it with an EPower module - no need for a heatsink (which I don't have either and may need to try and make something)

If you have any parts - or know anyone with parts - a case, heatsink etc. I would love to find these.

Thanks Zozo!

Mark.

Offline Judge

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Re: UM1233 RF Modulator
« Reply #3 on: 2019.July.14. 12:49:01 »
Hello
I'm Judge from the ENTERPRISE FOREVER forum.
I have such a part. My daughter goes back to Newcastle on Monday. Where do you live and how can you get it?
Sorry, I could only write with Google Translate ...

23712-0
« Last Edit: 2019.July.14. 19:00:58 by Judge »
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