Ferguson C51N (ICC8) Frame Fault Help Needed

[IKC2E51R8]

Hi all

I've recently gotten a Ferguson C51N with ICC8, the set was appearing to work all be it the LOPT was arcing ever so slightly occasionally causing the set to trip, at one point there was a pop, i turned the set off and when i turned it back on, frame collapse. From everything ive read the TDA in the frame stage is a real nuisance on this and ICC7 chassis, and ive replaced the TDA and the result is the same, 0.5" white line on the screen with OSD and teeny bit of snow visable (but obviously shrunken) its like its squeezing the entire frame into that 0.5" white line.

Would anyone have any other suggestions on which parts to look for, the original TDA developed a short between pins 1&2 if that might help shed some light on it.

Every repair tip ive seen at some point mentions changing an RF33 1.8ohm resistor but there isn't one there, at least there's no RF33 on the board and its not in any circuit diagram of ICC8 or 7, yet nearly every tip on a frame fault mentions changing it and its a part included in the frame repair kit. But i cant locate it anywhere.

Speaking of, does anyone by any change still have any of these frame kits lying around, if so id be happy to purchase from you.

[its ur aerial]

Luke,
from memory, which aint good the resi came with the chip and was a mod, that went between two of the IC pins, but I cant recall which ones.

I must emphasise, any encounters I had in the past with the ICC8 chassis were never meet with much enthusiasm, so I am no expert on this chassis.
Glyn is probably the man who would know.

Ken G6HZG.

[Welsh Anorak]

Or not!
I'm searching for the ICC8 manual and can't find it. Like Ken, I'm sure there was a resistor but where?
Luke - start by tracing back the V+ voltage - should be around 28v. I'm sure the feed rectifier from the LOPT went via a fusible resistor. Meanwhile I'll keep searching.

[FIXITNOW]

for TDA8178/F replacement Thomson use to supply kit - IC STV9379, 2v1 Zener & 390R res

[gallowfields]

is the 1.8ohm fusible resistor before the 28volt feed diode .that would be the most obvious place ?
brian

[FIXITNOW]

a hunt round the web found this note
THOMSON ICC7 / ICC8 chassis, STV8178F can be put in place of TDA9379FS.
Only you need to set the voltage on the 7th leg 2.1 ... 2.2 V. It is possible with a divider from two resistors, but a zener diode (BZX75C2V1 for example) is better than the 7th leg - the body (anode to the body), and a 3.9k resistor between the 2nd and 7th legs.

[IKC2E51R8]

I got a NOS TDA8178FS as replacement for this, not the STV chip the kit mentions. there is a 24v feed from the PSU Secondary with RP62 0.27ohm resistor as the feed but i replaced that and same results. there's no 1.8ohm resistor anywhere on both ICC8 diagrams I have in the frame stage.

There's a 65v feed also from the LOPT going to Pin 3 of the IC which is fed via DL09 and CL09, both of which were replaced also and same results.

[Philips210]

Reading some fault reports in Television magazine it seems DF16 (BA157) in the field output stage is troublesome. It's been known to go s/c or go leaky causing some odd field faults.

Regards,
Symon

[IKC2E51R8]

Originally Posted by Philips210

Reading some fault reports in Television magazine it seems DF16 (BA157) in the field output stage is troublesome. It's been known to go s/c or go leaky causing some odd field faults.

Regards,
Symon

I've seen that tip and even though it tests good, I intended to replace it anyway and just when i went to grab one of the two BA157s i know I have left I couldn't find them, no idea where i left them so I guess until some new ones arrive I gotta play the waiting game.

in the meantime im going to change the LOPT as the replacement arrived and the old one has an intermittent problem with Arcing (which i think could be responsible for taking out the original TDA)

[IKC2E51R8]

I have replaced DF16,17,18 and 19 as per repair tips suggestions, also replaced fusibles RP23 and RP12. same results though now its intermittently deciding if it wants to turn on, it sometimes comes on with field collapse and other times it begins to start up then safety kicks in a set goes completely dead, no led, nothing.

Noticed the new RP23 i fitted has discoloured so i figure something has cooked it but i dont know what or where to look now.

[Red to black]

I may be able to provide some more information in a few days if you are not sorted by then, unusually the chip on this chassis has a separate field flyback power supply requirement design so you you need the correct IC, the suffix is very important in this case.

I have a feeling Welsh Anorak sent me his manual in with a batch of others.

I have just got back from a stint of 12 hour shifts working away so give me a day or two to recover some sanity

[IKC2E51R8]

Thanks, Id really appreciate any help with this, seem to be getting nowhere with it, the set wont come on now, on power up Red LED comes on, if i attempt to bring it out of standby EHT comes up for half a second green led briefly comes on, then a shrill chirp noise and everything dies no LED, nothing on secondary and only plugging it out for about 20 seconds and back in gets power back.

Checking the loptx ive got continuity on every pin of the secondary on the loptx to ground, surely thats not right?? same with the Chopper secondary, all pins have continuity like they're all jumped together.

I Checked the new Field chip and its not measuring short, nor are any of the diodes in the area or the power supply.

I think at the beginning of ICC5 production Thomson just wanted to watch the world burn and continued that philosophy with ICC7,8 & 9. From what ive heard IKC2 and ICC6 were spared the curse

[IKC2E51R8]

Just want to Add as it may help diagnose, I powered the set on as standby works cause i wanted to check some voltages, i wanted to see if the HT was climbing to high when i attempted to bring it out of standby, before i could look at the meter it did its usual short screech but instead of going dead EHT stayed up and it began tripping with the LED flashing amber/green in symphony with the trip, after about 3-5 seconds i saw smoke and the power supply started screeching louder, i plugged the set out and waited for the smoke to clear, Smoke was coming from CL09 in the field cct which has bulged and was extremely hot even 5 minutes after unplugging.

Im guessing a ton of voltage was dumped into it but im still only learning so i dont fully understand whats happening, i hope some of you can shed some light on this.

[ben]

You said initially the LOPT was arcing, for all you know this could be the source of the damage to the frame stage. I would look at replacing the LOPT and the components supplying the frame cct plus the IC all at once.

[IKC2E51R8]

Originally Posted by ben

You said initially the LOPT was arcing, for all you know this could be the source of the damage to the frame stage. I would look at replacing the LOPT and the components supplying the frame cct plus the IC all at once.

I already fit a replacement LOPT. Which was working fine (still with the field collapse though) until this new issue with CL09 overheating arose. I sourced a NOS Frame kit from spain, which is on the way to Ireland now, I cant really do much else till it arrives, but i dont wanna fit all the new Frame parts to have CL09 go bang again if theres something else that could be causing it

[Maarten]

What's the rated WV of CL09?

What was the part number on the old LOPT and what did you fit as a replacement?

[IKC2E51R8]

Originally Posted by Maarten

What's the rated WV of CL09?

What was the part number on the old LOPT and what did you fit as a replacement?

its a 100uF 100v, I checked for the correct Lopt replacement on the HR Diemen website, Original Part was 47317590 which is an HR6394

[nigelr2000]

Originally Posted by IKC2E51R8

its a 100uF 100v, I checked for the correct Lopt replacement on the HR Diemen website, Original Part was 47317590 which is an HR6394

Check you fitted it the right way round as that will blow a cap really quickly, worth a look

[Maarten]

Also it might be that this circuit calls for a high ripple / low ESR electrolytic. The rectifier diode could also be leaky.

[IKC2E51R8]

This Monster of a chassis is frustrating me beyond belief.

I bought a 2 NOS Frame kits and a standalone NOS TDA8178FS, ive installed the first kit and the TDA, Set didnt trip it came on, still with Field Collapse, i turned the set off, attempted to turn it on again about a minute later and the new TDA Popped - Leaked at pin 3 and Resistor RP62 had gotten very very hot and popped, i only know it got very hot judging by the heat mark left on a neighbouring cap.

I took the dead TDA out and replaced it with the STV chip that came with one of the Kits (Including the Mod) and attempted to power on again, it came on again but again with Field Collapse but this time the horizontal line wasnt straight it was wavy, i turned the set off again, and once again a minute later attempted to turn on and now it kinda ticks for a moment then EHT comes up then the set dies.

WHY did Thomson design the field circuit around this Awful TDA. Can anyone point me in the right direction on what to try next, I dont wanna fit the 2nd Frame kit only for it to go to waste also. Ive tested the new diodes that came with the cap and theyre testing good.

I cant believe i thought the ICC5 was bad when this monster exists.