Hi, i have a Samsung VCR, the SV DVD 3E, this unit was used only to play DVD, and the video head, and HIFI audio are working very fine... the tracking is also OK..
BUT i have a strange "static" noise on Linear audio... i was thinking this is related to bad caps, but after replaced any of them, the noise is still here.... the audio head is very clean and looks brand new
i removed the DVD secondary board, removed the TV-synt module, checked avery electrolitic on power supply... the noisy signal is only when a tape is played (no noise on DVD or on device MENU)
and completely disappear when HIFI audio starts...
checking on the board there is the A.OUT line as a test point , and the noise is present also here.
anyone has experience with foult like this? can be some sort of electric "interference"? something related to audio amplifier? (that for what i can see is all-inone with a digital IC).. something not filtered by NOT-ELECTOLITIC capacitors?
here 2 samples.. one from this samsung and one from a cheaper SONY..
for what can i see the linear audio is 70% volume compared to the HIFI one, and both are very high on level compared to other VCRs (90+%)
Last edited by BartoloniDavy; 09-07-2023 at 11:24 AM.
I've had somewhat similar issues with linear audio several Samsungs, and also late model JVCs (and to a lesser degree LGs). Never managed to figure out what caused it, I tried replacing a bunch of electrolytic and ceramic caps on one Samsung I have to no avail.
My Video gear overview/test/repair/stuff yt channel http://youtu.be/cEyfegqQ9TU
Perhaps a bad shielding of the ac head ? Might be worth it to attach to the head some cabling to ground. Just an idea.
I have completely removed the power ac/dc shield without any changes to audio noise ( but with a lot of "comets" on rotating head.. visible on the uploaded videos.) ... i tried also to increase grounds without any difference....
The linear signal off tape is quite weak and requires a lot of amplification, but that also amplifies the slightest electronic or magnetic noise from inside the VCR. So it can be tricky to get the VCR's own noise down to an acceptable level. Is it possible the Samsung linear audio is performing as per the design? On one or two of my VCR's I decided the linear audio was probably normal for that model from new so to lower the noise I made a couple of improvements to the original design. A fairly easy improvement can be replacing any cheap unshielded ribbon cable from the A/C head to the preamplifier with proper shielded cable, at least for the audio playback signal. Sometimes rerouting the cable away from noise sources inside the VCR might help. Another is to bypass the VCR's preamplifier altogether (obviously more difficult).
The noise from the VCR might be emanating from a combination of the SMPS, capstan motor and head drum motor, induced magnetically into the audio head. I've sometimes tested this by carefully holding a small piece of plastic covered mumetal over the face of the audio head while a silent passage of audio is playing, and rotating the mumetal slightly for maximum shielding while listening for any reduction in noise.
Where did you find a shielded ribbon cable? You can barely find normal replacement ones with the correct pitch these days without hunting on ebay or aliexpress these days. I've been meaning to test with one from my Panasonic NV-HS870 which does have one that seems to have shielding on it to see if it makes a difference in the decks that have issues but haven't gotten around to it. The euripean philips/grundig turbo drive decks also have what looks like shielded ribbon cables going to the a/c head even up to the very last models (and also decent linear audio for that matter) but those have 7 pins unlike most other vcrs that use a 6 head cables annoyingly.
My Video gear overview/test/repair/stuff yt channel http://youtu.be/cEyfegqQ9TU
Yes its annoying. I didn't find a shielded ribbon cable. I just took the audio output directly from the terminals on the back of the a/c head and used standard good quality two conductor shielded cable.
But in the first instance it's just a temporary test to see if, or by how much the ribbon cable is contributing to the noise.
Here's a small sample file of an LP VHS linear audio recording transfer (PAL). No digital processing. Straight off the tape.
Just to add, LP on PAL VHS is 50% speed of SP VHS. PAL linear tape speeds are 80% of NTSC.
So using NTSC SP as a 100% reference the PAL LP recording above is 40% speed. NTSC EP is 33% speed. The slower the tape speed the weaker the signal off tape, and any noise added by the playback deck is magnified.
Just swapped the audio head from another Samsung VCR (a cheaper one without audio erase head) and the noise is highter compared the original head... probably this is not related to the audio head, i will try to use shielded cable for the audio signal from head.
