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Products => Test Equipment => Topic started by: tabajaralabs on February 21, 2021, 11:58:11 pm

Title: Noise on Philips PM5515 Colour Pattern Generator
Post by: tabajaralabs on February 21, 2021, 11:58:11 pm

Greetz ALL
I just got a pair of PM5515. The first one I recapped everything on the motherboard, and the diagonal bar noise kept running on screen. The second one, not yet recapped, shows the same noise. I see lots of noise on 5V line, tried recapping other boards, putting ceramic/elco caps around the board, nothing tames this noise. Am I being just dumb (as usual) or there is something wrong on these Philips colo(u)r bar generators?
Thanks!
Alexandre, PU2SEX

https://youtu.be/qpToDrAfVaI (https://youtu.be/qpToDrAfVaI)
(noise is very faint in youtube video, more noticeable on the end)

Title: Re: Noise on Philips PM5515 Colour Pattern Generator
Post by: tabajaralabs on February 22, 2021, 03:00:56 am

Update:
Changed all the capacitors of mainboard, Digital Board, Multiburst, PAL/NTSC, and the noise keeps there, nice and shiny.
I have no more options. Took off the mono audio board, changed nothing (this is the only board I haven't recapped). Power supply still looks noisy. One option would be change the regulators, but I don't believe the regulators would be responsible for this.
Any tips?
Thanks!

Title: Re: Noise on Philips PM5515 Colour Pattern Generator
Post by: tabajaralabs on February 22, 2021, 05:17:07 am

News from the front:
Now the noise keeps stationed on the screen, the bars keep stopped. The problem was in the master clock generator, the two crystals/trimmers besides the digital board. Adjusted the trimmer near the panel to the correct frequency, and voila! The interference - albeit present - is stopped. I'll put some photos tomorrow showing the exact problem and solution
Still needs to clear this interference. keep working...