Share:
Notifications
Clear all

Project 1969 Philips G22K511 Missing I/F & LOPT, Conversion

Page 34 / 42
 
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4617

It may not be easy for the other boards, but at least it will afford better access on this one.

In fact, I was wondering if it were practical to instead of soldering the wires directly to the boards, to use PCB connector pins and fit single suitable connectors to each of the cables. Thus, extension looms may be made up and any board could be operated out of the chassis.

Quite a bit of work maybe, but it certainly would aid fault-finding should it be required.... and I have the feeling it just could be. 🤒

To understand the black art of electronics is to understand witchcraft.
Andrew.

ReplyQuote
Posted : 16/05/2021 8:59 pm
malcscott
(@malcscott)
Noble V-Ratter Registered
Posts: 1443

@crustytv Common practice on the Rediffusion Mk1 decoder during production. Was called wigwam config.

ReplyQuote
Posted : 16/05/2021 9:26 pm
crustytv liked
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10555

I've been at this board all day, this evening I've extended & fitted 14 of the 21 wires. Its slow progress at this stage as I need to be certain, consulting notes and photos to not make mistakes. My head is banging, the hour is late, the other 7 will have to be completed tomorrow. Sorry for those wanting to see results on screen, fingers crossed tomorrow, and the rewiring gods have been kind to me.🙏

20210516 223731

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing
Vrat FaceBook: Follow us

ReplyQuote
Topic starter Posted : 16/05/2021 10:46 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10555

The board is wired back into the TV and had all its 21 connections extended. Now should the need arise, the timebase can be operated out of the chassis on the bench. I've double-checked all my wiring, and it appears to me to be correct. Now we find out, A) if the component changes have helped with my timebase errors, or B) I've made it worse with a man made fault. Sod's Law it'll be the latter!

Now to put the chassis back in the TV.

20210517 135354
20210517 113659

Edit: Chassis installed, hooked up to test card signal, ready for switch on after lunch.

20210517 135655

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing
Vrat FaceBook: Follow us

ReplyQuote
Topic starter Posted : 17/05/2021 11:44 am
malcscott liked
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10555

Oh dear, I must have made a mistake. Everything powers up, EHT comes up to 23kV but nothing on screen and no video on TR2144. Now to try and find what is amiss, and I thought I had been so careful. Self made faults, the absolute worst to find.

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing
Vrat FaceBook: Follow us

ReplyQuote
Topic starter Posted : 17/05/2021 2:08 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10555

First thing I did was to map the CRT voltages, and then it became clear why nothing on screen, my G1's are gone. Time to look at the cct and then fathom what on earth I've done.

RedGreenBlue
Cath 2,6,11169V166V171V
G2's  4,5,13480V640V620V
G1's 3,7,12-970mV-645mV-583mV

Looks like the mistake is around HT4, as checking it is missing there's -2V on R7248 feeding the PCF's. HT4 feeds field OSC, the PCF's for G1's and Chroma etc. HT4 is present on the PSU. The HT4 take-off is via K75 ending on D75 on the timebase, which should end up on the junction of R4099/C4021, that's where I must have made a boo boo. Glad I put all those long leads on, hope this is the only mistake I've made. 🙄

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing
Vrat FaceBook: Follow us

ReplyQuote
Topic starter Posted : 17/05/2021 2:25 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10555

Found the error and corrected HT4 reinstated and the raster returns, nice to be able to run the timebase out of chassis too.

20210517 154922
20210517 155045

However, as you can see above, the raster is blank and nothing other than noise on the base of T2144.

20210517 155832

So have I made any other errors, need to check. There are three feeds from the Timebase to IF panel L77, L79 & L81

L77 is to PL3/2 Heater
L79 is to PL3/3 Field sync
L81 is to PL2/2 Line sync

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing
Vrat FaceBook: Follow us

ReplyQuote
Topic starter Posted : 17/05/2021 4:08 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10555

Nothing else wrong all three IF links to the timebase are correct, so perhaps the no video is back to the original problem, wonderful. Guess its back to voltage checks on all the IF transistors again!

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing
Vrat FaceBook: Follow us

ReplyQuote
Topic starter Posted : 17/05/2021 4:30 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10555

Just about to start testing, and now I have field collapse, it never rains but pours! I'll try another PL508, I've not got any new only pulls, so the last one may have been on it last gasp.

20210517 164911[1]

Edit: Tried 3, unless all 3 were duff it looks like I've got to go field collapse hunting.

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing
Vrat FaceBook: Follow us

ReplyQuote
Topic starter Posted : 17/05/2021 4:50 pm
Katie Bush
(@katie-bush)
Illustrious V-Ratter Moderator
Posts: 5002

Hi Chris, it's worth checking the drop-off resistors, just above and left of the PL508. There should be two in parallel, mounted underneath their 'stand offs'. They are held in place entirely by the solder. Over a period of time and repeated heating and cooling/expansion and contraction the solder can become crystalline and brittle - effectively becoming a dry joint. Also worth checking the print side of the panel where the stand offs solder to their pads. That's another place prone to dry joints. It's just a hunch, but it's a quick and easy place to start - No HT to the 508, no frame output.

ReplyQuote
Posted : 17/05/2021 5:15 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10555

Hi Marion,

something has put its feet up for sure as I had a full raster earlier on, checking pin 6 I have lost the 260V to the anode of the PL508, there's nothing to drop through R4135, besides its OK and I reflowed the entire board yesterday. Now looking into what else might be up.

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing
Vrat FaceBook: Follow us

ReplyQuote
Topic starter Posted : 17/05/2021 7:08 pm
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4617

The loss of HT2 to the frame stage.... not FS1109, a 250mA gone O/C ?

Is there screen voltage to the PL508? (Watch it if so, the '508 won't like it for long.)

To understand the black art of electronics is to understand witchcraft.
Andrew.

ReplyQuote
Posted : 17/05/2021 7:58 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10555

I've followed HT2 from Fs1109, it's OK, 315V, into R1074, it's OK. It's got to be R1253 or the FOPT, I'm betting the FOPT the way my luck is going on this TV. Yes 64 on the screen, don't worry i'm only doing very quick tests then powering off.

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing
Vrat FaceBook: Follow us

ReplyQuote
Topic starter Posted : 17/05/2021 8:13 pm
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4617

I guess you could check continuity from pin 6 to HT2 and trace where it is open. Surely not the frame TX !

To understand the black art of electronics is to understand witchcraft.
Andrew.

ReplyQuote
Posted : 17/05/2021 8:19 pm
Jayceebee
(@jayceebee)
Noble V-Ratter Registered
Posts: 1457

I thought I was seeing things but no, the field shift pot R1074 has a 20,000uf electrolytic capacitor across it.

John.

ReplyQuote
Posted : 17/05/2021 8:22 pm
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4617

It is indeed.... and could be nasty for the cap if that pot did go O/C,  if the field centring was disconected.

Blimey, it's enough to make me want to stick to B&W set's.... (Taking everything else into the bargain too.)

To understand the black art of electronics is to understand witchcraft.
Andrew.

ReplyQuote
Posted : 17/05/2021 8:24 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10555

G6 wire ping-itus, I believe that's off the bottom of L1555. I must learn to look for the simple not the complex, what a waste of time. Get this back on then back to where I was, no video again!

20210517 203037

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing
Vrat FaceBook: Follow us

ReplyQuote
Topic starter Posted : 17/05/2021 8:33 pm
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4617

Ah-Ha !

Yeah, a casualty of just moving things around.

To understand the black art of electronics is to understand witchcraft.
Andrew.

ReplyQuote
Posted : 17/05/2021 8:34 pm
Jayceebee
(@jayceebee)
Noble V-Ratter Registered
Posts: 1457

Phew! thank goodness let's hope it's just that. BTW I'm sure there is on the timebase board that could cause loss of signals.

John.

ReplyQuote
Posted : 17/05/2021 8:39 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10555

care to elaborate

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing
Vrat FaceBook: Follow us

ReplyQuote
Topic starter Posted : 17/05/2021 8:55 pm
Page 34 / 42