Panasonic NV-F55 poor chroma - UK Vintage Radio Repair and Restoration Discussion Forum

ben · 22nd Jan 2017, 6:54 pm

Yet another Panasonic video thread!

Just got this unit out with a view to putting it to use while my NV-HD680 is on the bench (that's another story). I had put a sticker on it some years ago, with 'chroma' and sure enough, when tested with a tape there was patterning/moirée on the picture. A cap change on the PSU cured that (4x680uF, 1x56uF, 1x47 uF, all leaking!).
However, when I hooked it all up I found weak, blotchy playback chroma (same on record) though the E-E pic was okay.

A quick look at the service manual suggests the area around IC302 on the chrom/luma pack seems to be the place to look. Any further tips? I'm assuming capacitors again.

Red to black · 22nd Jan 2017, 7:10 pm

There are two different chroma boards fitted to the NV-F55 that use different chroma ICs that are not interchangeable.

Apart from the usual G-deck problems caps in the PSU and the usual mechanics the only Chroma type faults I have had on this machine was caused by incorrect setting of the NTSC4.43 switch (it should normally be set to off).

I will have a look through my service notes later on to see if I have wrote down anything of note though.

ben · 22nd Jan 2017, 7:42 pm

Yes, this unit handles PAL plus both NTSC and MESECAM so I was careful to check those settings.

I've found what would appear to be IC 302. Mounted on the Y-C sub PCB on a little sub-PCB of its own, surrounded by SMD caps. And here I was, hoping for a quick fixer-upper !

Still, the E-E pic via the composite in and outs is perfect, so I am hoping this can be narrowed down quite a lot. The schematic is fairly intricate, I'm still trying to pinpoint components through which the signal passes in both playback and record.

Red to black · 22nd Jan 2017, 8:41 pm

One fault report does list IC 302 as giving no Chroma in play/record but that is about it, as noted there are two different incompatible ICs used on this and some other models, which version is fitted depends on which chroma board is fitted, I think I might still have the technical bulletin somewhere,

ben · 22nd Jan 2017, 9:02 pm

I think, since I don't have a scope to hand, that this one will have to go back on the pile for now. Plus the fact that access to that Y-C PCB is poor, requiring desoldering of about 15 pins on the main PCB then another 30 or so on the secondary sub-PCB, to get to IC302 and the SMDs and small electrolytics! Thanks for the information all the same

Grubhead · 23rd Jan 2017, 1:33 pm

Thanks for the link to the service manual Ben.
I had one of these, it had the best tracking that I ever had, but I lost it to an F09 fault. I didn't have the full service manual. So it's been stored away.
I put a partial manual and the user manual on part of my blog.
technical-help-tips.
It is part of a guide dealing with Headphone issues, Windows Media player album art display issues and some service manuals for things I own.

ben · 23rd Jan 2017, 3:18 pm

found the TV mag piece whcih confirms my suspicions and the two different boards - will scan in due course.

ben · 24th Jan 2017, 10:17 am

Attached scans. I vaguely recall having another F55 stored somewhere with a mech fault, so I suppose there's a slight possibility the paneles maye be interchangeable. Will update as and when I dig it out and see.

22nd Jan 2017, 6:54 pm	#1
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Panasonic NV-F55 poor chroma Yet another Panasonic video thread! Just got this unit out with a view to putting it to use while my NV-HD680 is on the bench (that's another story). I had put a sticker on it some years ago, with 'chroma' and sure enough, when tested with a tape there was patterning/moirée on the picture. A cap change on the PSU cured that (4x680uF, 1x56uF, 1x47 uF, all leaking!). However, when I hooked it all up I found weak, blotchy playback chroma (same on record) though the E-E pic was okay. A quick look at the service manual suggests the area around IC302 on the chrom/luma pack seems to be the place to look. Any further tips? I'm assuming capacitors again. __________________ Regards, Ben. Last edited by ben; 22nd Jan 2017 at 6:55 pm. Reason: link added

22nd Jan 2017, 7:10 pm	#2
Red to black Nonode Join Date: Mar 2010 Location: Sunderland, Tyne and Wear, UK. Posts: 2,476	Re: Panasonic NV-F55 poor chroma There are two different chroma boards fitted to the NV-F55 that use different chroma ICs that are not interchangeable. Apart from the usual G-deck problems caps in the PSU and the usual mechanics the only Chroma type faults I have had on this machine was caused by incorrect setting of the NTSC4.43 switch (it should normally be set to off). I will have a look through my service notes later on to see if I have wrote down anything of note though. __________________ I don't suffer from Insanity. I enjoy every minute of it.

22nd Jan 2017, 7:42 pm	#3
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: Panasonic NV-F55 poor chroma Yes, this unit handles PAL plus both NTSC and MESECAM so I was careful to check those settings. I've found what would appear to be IC 302. Mounted on the Y-C sub PCB on a little sub-PCB of its own, surrounded by SMD caps. And here I was, hoping for a quick fixer-upper ! Still, the E-E pic via the composite in and outs is perfect, so I am hoping this can be narrowed down quite a lot. The schematic is fairly intricate, I'm still trying to pinpoint components through which the signal passes in both playback and record. __________________ Regards, Ben.

22nd Jan 2017, 8:41 pm	#4
Red to black Nonode Join Date: Mar 2010 Location: Sunderland, Tyne and Wear, UK. Posts: 2,476	Re: Panasonic NV-F55 poor chroma One fault report does list IC 302 as giving no Chroma in play/record but that is about it, as noted there are two different incompatible ICs used on this and some other models, which version is fitted depends on which chroma board is fitted, I think I might still have the technical bulletin somewhere, __________________ I don't suffer from Insanity. I enjoy every minute of it.

22nd Jan 2017, 9:02 pm	#5
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: Panasonic NV-F55 poor chroma I think, since I don't have a scope to hand, that this one will have to go back on the pile for now. Plus the fact that access to that Y-C PCB is poor, requiring desoldering of about 15 pins on the main PCB then another 30 or so on the secondary sub-PCB, to get to IC302 and the SMDs and small electrolytics! Thanks for the information all the same __________________ Regards, Ben.

23rd Jan 2017, 1:33 pm	#6
Grubhead Heptode Join Date: Dec 2016 Location: Sheffield, South Yorkshire, UK. Posts: 539	Re: Panasonic NV-F55 poor chroma Thanks for the link to the service manual Ben. I had one of these, it had the best tracking that I ever had, but I lost it to an F09 fault. I didn't have the full service manual. So it's been stored away. I put a partial manual and the user manual on part of my blog. technical-help-tips. It is part of a guide dealing with Headphone issues, Windows Media player album art display issues and some service manuals for things I own.

23rd Jan 2017, 3:18 pm	#7
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: Panasonic NV-F55 poor chroma found the TV mag piece whcih confirms my suspicions and the two different boards - will scan in due course. __________________ Regards, Ben.

24th Jan 2017, 10:17 am	#8
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: Panasonic NV-F55 poor chroma Attached scans. I vaguely recall having another F55 stored somewhere with a mech fault, so I suppose there's a slight possibility the paneles maye be interchangeable. Will update as and when I dig it out and see. Attached Thumbnails __________________ Regards, Ben.