Poor Video on Sony PVW2800P

[delaitt]

Good Evening

I've got a PVW 2800R and i'm new to that beast. it's not that antique compared to a TV22 but is becoming vintage! I'm posting here as some forum members might be familiar with that equipment.

I bought a beta cam SP tape at the NVCF and the person i bought it from said it has been used once and the tape had been demagnetised.

The problem is that the video prior to recording is perfect, however, playing back a recorded video shows a bad quality video.

I'm not sure if i'm doing something wrong or that the poor recorded quality is due to the tape or something else?

Thanks

Thierry

[Stuart R]

Hello Thierry,

That's a Component machine, with separate heads for recording luminance (brightness) and chrominance (colour) information and there seems to be a big lack of luminance on playback, I'm hoping it's not a serious failure.

I don't think you're doing anything wrong. Have you checked that on the sub-panel all the TBC controls are in local and preset? Pull the main control panel outwards by the small handles and that should reveal a hidden row of switches within. It's worth a shot, but I don't think the video control would have been able to remove that amount of brightness. I'm worried you've got a fault there.

Clutching at straws, it might be worth carefully re-seating the PCBs under the top cover (Remove power first!). The BVW machines also had two main PCBs accessible when the control panel was hinged upwards, but I think they were system control rather than video processing.

Your tape is the right one for that machine (probably a PVW2800P rather than 2800R?)

If you get stuck, I might be able to find a Betacam SP tape with some pictures already recorded to help test.

Sorry I can't offer anything more useful.

SR

[dj_fivos_sak]

As Stuart said, Beta SP is a component format. One or two heads might be shot on thie machine. Try with a pre-recorded tape.

[HurtyAC]

Hi. I did not do many PVW2800 but did many BVW75s. The fault you have posted is no luminance and a common problem with Sony VTRs at that time was the glue they used on the PCBs and in particular the Sony filters. These are metal rectangular items about an 3-4cms by 3cms by 1cm. Again the glue used within them goes brown/black and starts to conduct sometimes destroying transistors within the filters (they are d.c. supplied and coupled). Do you have and know how to operate an Oscilloscope as this will be needed?? Can you post a photo looking down on the top of the machine with the cover removed so I can identify the boards. I will then need you to photo the demodulator board, back and front so I can asses the glue. This should be fully repairable. If you have access to the menus I would like to know the Head drum hours, total and resettable (r)
Hurty

[delaitt]

Evening

Thanks for your replies.

All configuration switches for the video, black level and chroma are set to preset.

I've removed & re-inserted the PCBs but still the same issue.

The meter does not seem to display anything for some reason.

I've attached three pictures.

I've got a scope if the signals on the video amplifiers need to be checked. I'm trying to locate the schematic on the internet but no luck so far.

Thanks

Thierry

[delaitt]

Hello

While the tape was playing after doing some test recording, i noticed a section of the tape i bought had not been erased - see https://youtu.be/tKoJnhRUYwY

It therefore appears the brightness head is not dead. The quality is something affected by something else as shown in the video.

Thanks

Thierry

[Retrotechie]

Hi, have you checked playback with a known good tape ? Does the tracking control have any effect ? the RF meter only looks at one of the heads (on the 75 its normally one of the chroma heads) the fact that its not reading, could be an indication of the fault.
These machines only have one set of heads, the r/p heads (record/play) whereas the BVW-75P has another set for slo mo, called dynamic tracking heads.
I have a test tape and even the manuals that i may part with, as i rarely touch these machines these days.
Send me a PM and we can go from there.

James

[thx1138]

Hi,

if you want a test tape with bars and 1k tone let me know. I have a UVW1800P here with v low head hours and use it for archiving when needed. Granted were on other side of Europe, your welcome to post me a tape to prep. Hope you find a manual, dont have one here unfortunately.

regards David

[dj_fivos_sak]

Here's the manual for this machine:
http://elektrotanya.com/sony_pvw_280.../download.html

Fivos

[HurtyAC]

Hi, I have been a bit busy with work but now we have a copy of the manual (need circuit diagrams) we should be able to sort this out if you are o.k. with using your oscilloscope. Just give me a bit of time. The area we are interested in is the luminance f.m. demodulator where r.f. is converted to video and is then filtered with low pass filters to give clean video. It is this path we want to work through

Hurty