Ferguson C51N (ICC8) Frame Fault Help Needed

[IKC2E51R8]

Originally Posted by Red to black

if it is a wavy line then that suggests an open circuit field yoke/scan coil, I am not sure who else with more experience you are going to get

I meant more experienced than me,

The wavy line is sorted, you were right one of the vertical wires at the yoke had broken off, once i mended it the line is now straight again but still i have no deflection.

i think I'm just going to replace the field IC again and see what happens. everything else has pretty much been changed.

I found out CL09 vented previously because when i took it out of circuit to test i had put it back in the wrong way, misread the symbols on the board.

[Philips210]

Something worth keeping in mind when replacing ICs in general is the possibility of electrolytic caps in the circuit around the IC could under certain conditions be holding a charge. This could ruin the new IC if you're unlucky enough to bridge certain IC pins. I always check the voltage across associated electrolytics as a precaution. I remember being caught out like this in the SMPS of an Hitachi G8Q chassis and had to replace several components due to a simple lapse.

Regards,
Symon

[Maarten]

Originally Posted by IKC2E51R8

This chassis is literally impossible to work with, I've checked everything again, i reworked any damaged pads, I replaced RP62 again, The IC seems to be fine and still the set on power on has the EHT come up for a second, chips once then completely dead, no secondary voltages at all.

If I understand correctly, you have EHT again now?

Glad you found the cause of CL09 blowing up. The +65 supply is probably allright, so not too urgent to try and measure that.

Regardless, measuring, possibly using a scope, is probably a better way out than throwing rare parts at it. You might not have experience, but you will gain experience once you bite the bullet.

[IKC2E51R8]

After replacing the frame IC again, I got deflection back, I could hear it but the screen was blank probably because the G2 was turned down, when I went to adjust the G2 i tipped off the frame the chassis sits in and the set tripped off so there's an intermittent connection somewhere which probably explains all the other random tripping, I attempted to turn it back on and the deflection noise was gone and the set tripped off again. on checking it seems DF18 has shorted.

If the frame IC is again shorted also (which i havnt yet checked) then im probably just going to scrap this set, I cant replace a 4th IC mostly because i dont have one but also ive had to repair the traces where the IC sits because some of the pads have lifted from removing the IC so many times. It would be a shame to scrap it though as for the extremely short time it was working the picture on it is fantastic.

It may be me just making Assumptions but the Thyristor frame circuit in ICC5/IKC2 is far more reliable than this nonsense IC design. it seems you only have to whisper in the direction of the frame circuit for it to go BOOM.

[Maarten]

Whispering to make something go boom is business as usual with Thomson, not just the ICC8 chassis. The US contemporary of the ICC5 chassis (CTC175 I think) may have been the very worst in that aspect with critical grounds connected through soldered on shielding. To enjoy working on Thomson sets you will need a very keen eye for bad soldering and work carefully (also minimising the amount of soldering in the same place) as to not lift pads. I don't think Thomson sets are the best choice to gain more experience if you're slightly shy of the experience needed to deal with setbacks and hard to diagnose problems.

[IKC2E51R8]

I agree they're not particularly fun to problem solve, having said that my ICC5 that I finally managed to fix in January has been going strong ever since, I've fixed a few IKC2 sets also, the bad solder work and sensitive pads do make it difficult, 4 of the 7 pads have lifted off the board on this ICC8 for the frame chip due to being changed 3 times no matter how careful i was it was unavoidable it seems.

Ive since checked and DF18 isnt' shorted but the Field IC is once again destroyed, short between pins 3 and 5. I found a seller on eBay who apparently has 5 NOS TDA98178FS IC's so im trying to work out a price for them, if i get them i'll replace the IC once more and go over the board again looking for any bad joints i missed. I think the random tripping could be due to the chopper heatsink connections not being in the best shape.

I think the over sensitive trip circuit in the ICC range is a big annoyance also which doesnt help with narrowing down problems.

[Red to black]

Thomson, as did Sony, always used the heatsink tabs as ground returns, I mentioned this way back in your ICC5 topic

PS. the trip circuits themselves often caused more problems than the circuit they were meant to protect!

[IKC2E51R8]

Seems that way...Looking through stock faults for ICC5,7,8 and IKC2 the trip circuit transistors TV01/02 seemed to cause faults quite a lot. Could also be a contributing factor to the trips, but i haven't paid a lot of attention to them yet except a visual inspection of them for leaks/damage and checking for shorts with a meter and they seem to be OK, though i might just replace them anyway.

Until i get my hands on a new frame IC there's not much point doing anything else anyway for the moment.

I keep thinking how annoyed at myself i am for allowing the set to keep running those extra few minutes with the LOPT intermittently arcing (mostly so i could see where it was arcing from) I should have shut it down and left it off until i got a new LOPT. Frame stage most likely wouldn't have perished, live and learn.

[Maarten]

You might try to disable the vertical trip circuit (have not looked up how it works) and power up without the frame output IC so you can take some measurements without it blowing up and also without extra wear and tear to the pads.

[IKC2E51R8]

If I can get some new Field IC's I'll look into doing that so another IC doesn't get unnecessarily sacrificed.

Though before changing the last time voltages were OK but the IC was bad, when i changed that IC deflection temporarily came back but because the V2 was down the screen was blank and then the random tripping which I'm not sure if that caused the IC to die or not but it didn't help.

I might have to mount a replacement IC on a separate board and wire from that to the next components in the circuit, what's left of the pads and the repaired pads won't hold up much longer.

When a frame fault on these was repaired back in the day were they usually reliable afterwards or did they come back with the same/similar fault? I can't say so far that those TDA8178 ICs are much good.

[Maarten]

Of course since they're rare, there's a small change of forgeries. Only in that case the ICs aren't particularly good. Though I never repaired this exact chassis, I didn't have much repeats with similar frame IC's on other chassis. To make sure they're not forgeries, you could post pictures of the ICs. I won't say I can be 100% sure when looking at them, but a good sharp picture will expose most forgeries.

[ben]

I had limited luck with these TDA8178 and 8177 sets. One Schneider set I had that used that IC seemed to fail every three years despite voltages being okay, heatsinked, and the rectifier components being changed. In the end I got tired of it and scrapped it. The access in that set was terrible, and as you found, the pcb does not take kindly to more than a couple of desoldering operations.

One ICC7 I got asked to look years ago at had a blown SMPS, blown line o/p, and after I'd fixed those I found the frame cct IC dead too, all those problems I suspect caused by dry joints everywhere. I vaguely recall problems with the replacement IC and the set ended up scrapped. Too much time and money.

I vaguely recall having problems as far back as the early 2000s with these IC's being scarce and mod kits required, etc.

There are plenty of sets of that era that have a far better frame cct design, and that give pictures as as good as, or better than, these Thomson sets. I would cut your losses and invest your time in money in something more deserving!

[IKC2E51R8]

Originally Posted by Maarten

Of course since they're rare, there's a small change of forgeries. Only in that case the ICs aren't particularly good. Though I never repaired this exact chassis, I didn't have much repeats with similar frame IC's on other chassis. To make sure they're not forgeries, you could post pictures of the ICs. I won't say I can be 100% sure when looking at them, but a good sharp picture will expose most forgeries.

That's interesting, if i get hold of some more i'll post pics of them before fitting.

[IKC2E51R8]

Originally Posted by ben

I had limited luck with these TDA8178 and 8177 sets. One Schneider set I had that used that IC seemed to fail every three years despite voltages being okay, heatsinked, and the rectifier components being changed. In the end I got tired of it and scrapped it. The access in that set was terrible, and as you found, the pcb does not take kindly to more than a couple of desoldering operations.

One Icc7 I got asked to look years ago at had a blown SMPS, blown line o/p, and after I'd fixed those I found the frame cct IC dead too, all those problems I suspect caused by dry joints everywhere. I vaguely recall problems with the replacement IC and the set ended up scrapped. Too much time and money.

I vaguely recall having problems as far back as the early 2000s with these ICs being scarce and mod kits required, etc.

There are plenty of sets of that era that have a far better frame cct design, and that give pictures as as good as, or better than, these Thomson sets. I would cut your losses and invest your time in money in something more deserving!

I have more reliable sets in my collection but the difference being the sound, the ICC's have excellent sound that my other sets just can't compete with

[Maarten]

For good sound, I can also recommend Grundig Monolith series. Especially the somewhat older ones.

Reading Ben's reaction, I realise I must have been lucky, avoiding the hard ones. I mostly repaired Philips who mostly used their own ICs (but also a few chassis using ST chips), but now that I come to think of it, I have seen some bulletins from Grundig and/or Panasonic about replacing those ST deflection ICs and making some modifications amongst others to reduce the supply voltage. Maybe I should go and try to find a datasheet to check if the +65V auxilary voltage is just be a bit on the high side originally - if it gets any higher due to whatever fault it might blow up the chip.

[IKC2E51R8]

I've seen a few of those bulletins too, mostly seen for Mitsubishi sets that used them, they had to release a mod for them too. Looking at the datasheet the +65 should be fine for the chip as its rated to handle up to +90v. I think maybe in general they just were a bad internal design, i think the highest voltage i measured at that pin was +68v so well within what its capable of handling.

[IKC2E51R8]

Regarding Grundigs i've not much experience with them, didn't see a whole lot of them during the 90's, nobody i knew had one, they all had either, Ferguson, Philips or Sharp sets with a few Sanyos and Bekos thrown in here and there. In general most people i knew replaced a set with the same Brand they had before and only occasionally took the plunge and went with a different brand, My Nanny for example after having 3 Fergies in a row (TX100 i think, TX98 and Finally an IKC2) decided she wanted a bigger screen so it was replaced with a Sony (BE3D) set. It came as a package with a VCR and funny enough not a Sony VCR but a Grundig.

[hans]

Originally Posted by Red to black

Thomson, as did Sony, always used the heatsink tabs as ground returns, I mentioned this way back in your ICC5 topic

Who in their right minds figured this was a good idea? The worst i experienced were the mid 80's Luxors with a long metal "sheet/strip" used as a heatsink going across the whole chassis. This strip had solder tabs that distributed ground sround the chassis. Normally the tab closest til the BU508 (or similar) went first. This made the line driver break. Not much damage, but if some of the other tabs gave first that could blow up much silicone.

[hans]

Originally Posted by Maarten

For good sound, I can also recommend Grundig Monolith series. Especially the somewhat older ones.

B&O usually is good for sound. I liked the chassis of theit own design but if you like to torture yourself the had a selection of Thompson chassis.

If you want to have something that is easy to work on, Philps from the 80's is my choice. They had some models with good sound.

Grundig was more upmarket and more electronic that could fail.

[ben]

You don't need to limit yourself to Thomson to find good sound. In my experience, the sets with the best sound tend to be the wooden cabinet ones with the speaker above or below the control panel, on the right of the tube. Effectively they used the whole cabinet as a baffle. The rot set in with the move to squarer, monitor-style cabinet designs (much smaller speakers, and worse, often on the side of the set) and to add to the problem, plastic replaced woos and chipboard.

From the black plastic era I have a couple of stereo sets that stand out. A Philips G110 with speakers in separate enclosures that hung on the side of the set, and a Sony KV-27EXT with similar.