Sony PVM-8020 Worked until I messed with it :( - Page 1
Forum section: electronics / repair

author: enzoleet
author_rank: Newbie
timestamp: October 18, 2023, 04:17:52 pm
content: Hi All,I picked up a Sony PVM-8020 at the flea market over the weekend.The picture and color was flickering and the knobs on the front seemed to be very finicky.I took our the HA Board to clean the contacts and knobs and a capacitor came out with it.Now the TV doesnt power on. Can anyone point me to where this cap came from so I can solder it back on?Pictures attached.I have the manual herehttps://ia803406.us.archive.org/17/items/pvm-8020-sm-sony-en_202104/PVM8020_SM_SONY_EN.pdfBut I dont know how to read a schematic.If anyone can help point me to where this cap should go it would be greatly appreciated.

author: Runco990
author_rank: Frequent Contributor
timestamp: October 18, 2023, 05:33:17 pm
content: That capacitor should have come from around the flyback somewhere. They are usually on the sweep/hv board.As to those pots.... good luck with them. The wipers break off the plastic carrier inside. I used to have to de-solder the pots, open them up, do some surgery and re-assemble. They commonly go bad and contact cleaner usually does NOT help.

author: macboy
author_rank: Super Contributor
timestamp: October 18, 2023, 06:58:29 pm
content: 225 is 2200000 pF or 2.2 uF (microFarad)K indicates 10% tolerance2E is 250 V rating.So look in the parts list for a capacitor marked 2.2 250V, probably with 10% tolerance, but it may show something higher (a tighter tolerance part might have been used). Annoyingly, they use "MF" for "microFarad" in the parts list, a terrible convention, but it is what it is. At quick glance, I see only one, on the degauss (DC) board, C892.

author: enzoleet
author_rank: Newbie
timestamp: October 18, 2023, 09:52:22 pm
content: Thanks macboy that was it! It's powered on now.Still have tremendous problems with the pots knobs on the front like the other poster said no amount of contact cleaner helped. Any ideas how to fix or replace them?

author: Runco990
author_rank: Frequent Contributor
timestamp: October 19, 2023, 03:17:05 pm
content: Replacing the ORIGINAL pots isn't an option. They were discontinued ages ago.I used to de-solder them, cut the little rivets that hold them together, take apart, figure out how to re-attach the metal wiper to the plastic disk that held it... (2 little plastic welds break off) then re-assemble and I just used wire to tie the pots back together.This worked well. PITA to do, but.... what choice do you have OTHER than finding and making a suitable replacement.Some engineer should be shot for designing those pots.

author: enzoleet
author_rank: Newbie
timestamp: October 20, 2023, 04:18:08 pm
content: Thanks Runco. So I pulled a working pot out for the vsync and tested with a multimeter and it sweeps back and forth fine. I just wanted to see a working one.Next I pulled out the Sharp pot and tested it. Nada. So I decided to open it up and take a look. Here are some pictures. it looks like the little finger on the knob is fine so im not sure what is not functioning here. Any ideas?

author: Runco990
author_rank: Frequent Contributor
timestamp: October 22, 2023, 10:13:53 pm
content: Your pics don't show how the wiper is attached. Look closer.

author: enzoleet
author_rank: Newbie
timestamp: October 22, 2023, 10:20:07 pm
content: Yea I'm an idiot and have no experience with Pots. I opened it up further and inspected and wiper. It's so so so tiny. I cleaned and put back together but it's faulty.... I checked aliexpress and found some that look like they might work but without the push lock feature.In case anyone is interested in the resistance ratings10k rv507 vsync1k rv501 sharp20k rv505 hue1k rv504 color20k rv503 brightDual 20k/1k rv502 contrast10k rv506 volumeAfter these come in I'll update everyone if they fit

author: enzoleet
author_rank: Newbie
timestamp: November 01, 2023, 08:12:34 pm
content: Great News!The RK097 Pots I ordered from AliExpress fit! They lack the push to lock feature but they fit right on the board.There was a tricky little hurdle and I figured I would share the information in case anyone else ever heads down this path.On the HA Board, RV502 is a 6 pin dual Pot. 20k in the front and 1k in the back.... They dont make them like this so I ordered extra dual 1k's and 20k's. I took both apart and reassembled them to make a 20k/1k pot. Superglued them back together. The rest soldered in nicely and when reconnected to the PVM everything works and looks lovely.The only drawback is the knobs are very recessed now so much so that I have to add a screwdriver slot to each knob. Check out the pics!Thanks for your help guys!

author: Runco990
author_rank: Frequent Contributor
timestamp: November 01, 2023, 11:27:06 pm
content: That's awesome! These are pretty good little monitors. In general, you set the controls and left them alone, so it's not a problem using a screwdriver now.I repaired and color corrected thousands of the PVM series back in the SD broadcast days.The BVM's are King, but their complexity is causing repair challenges today.I keep a 9" PVM on my bench, perfectly calibrated.

author: enzoleet
author_rank: Newbie
timestamp: November 01, 2023, 11:48:24 pm
content: Thanks for all your help Runco. This was my first crt repair and I'm kind of addicted now. Lol. Keeping my eyes open at flea markets for another pvm.One question. I can't seem to find any alignment settings. The image could use a little shifting to the right. Is there anything I can do or just enjoy it for what it is?

author: Runco990
author_rank: Frequent Contributor
timestamp: November 02, 2023, 03:27:37 am
content: Oh man... it's been ages since I did these.... There ARE alignment pots. But do NOT touch the magnets around the CRT. Those do purity and convergence. That can be a nightmare if you don't do setups for a living. I used to replace CRT's and do it in my sleep, but it took time to get good at it.Edit: Found the manual. It's all there.https://ia903403.us.archive.org/20/items/pvm-8020-sm-sony-en/PVM8020_SM_SONY_EN.pdf