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Pye 92 Rambler 169 Chassis. 17" Transportable

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Wed Jan 20, 2016 8:45 pm

A picture tells a thousand words ...

20160120_193555web.jpg

20160120_193632web.jpg

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Cathovisor » Wed Jan 20, 2016 10:14 pm

You're not telling us you've *finally* got a LOPT, are you?! :cca

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Wed Jan 20, 2016 11:10 pm

Not quite. But it looks graftable. Read the end of page 1 :qq1

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Till Eulenspiegel » Fri Jan 22, 2016 12:46 pm

Rough sketches of the connections to the line output transformer that was used in the Philips 300 series single standard TVs. In dual standard sets the tags D and F are connected to the 405/625 switch.
The Pye line output circuit will not differ all that much from the Philips.
Tag H connects to the C5005 which is the width control feedback capacitor. In the Pye 169 it might be located on the PCB.

Till Eulenspiegel.
Attachments
PH300_0226.jpg
PH300_0227.jpg

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Fri Jan 22, 2016 4:04 pm

Thanks Till. That should be enough to make a start.

I'll keep the thread updated.

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Till Eulenspiegel » Fri Jan 22, 2016 4:41 pm

Further examination of the service information for the 169 chassis reveals that line timbase stabilising feedback capacitor is C71 and it fitted on the PCB. If that is the case then the feedback capacitor on the Konig transformer (if fitted) should be removed. It's likely the same type of line output transformer was also employed in the dual standard 368 chassis. After 1967 many more Philips sourced components were being used in Pye group sets.
I'd reckon your Konig 300 series transformer will work in the 169.

Till Eulenspiegel.

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Rebel Rafter » Fri Jan 22, 2016 8:53 pm

Hi, Doz, RR here. Have you got a big soldering gun like the old weller 140 watt type? If so will that melt the glue holding that transformer together? better try it outside as it'll make dreadful fumes if it does work. Or is the glue inside between the former and the core where you can't get at it? RR.

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Fri Jan 22, 2016 8:59 pm

Rebel Rafter wrote:Hi, Doz, RR here. Have you got a big soldering gun like the old weller 140 watt type? If so will that melt the glue holding that transformer together? better try it outside as it'll make dreadful fumes if it does work. Or is the glue inside between the former and the core where you can't get at it? RR.


To what end?

The glue on the original transformer is like some form of cement. Nothing seems to soften it.

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Sat Jan 30, 2016 5:24 pm

Right, I've made a start. The big issue seems to be the Pye's lack of S-correction cap, the coils are fed in series with the line lin inductor.

I've removed the line line inductor, and it's damping resistor, and connected that across the pins of the Philips Lopt. I've added in an s-correction cap (2x1000pF in series).

Up with the volts.... and I've got about an inch of line scan. Width control makes no difference.

On the plus side, nothing caught fire.

line.jpg

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Sat Jan 30, 2016 6:35 pm

In the word of the Beatles ... "It's getting better all the time"

Shorted out pins C & D on the Philips lopt (where the line lin connects), and put the line lin coil back in series with the scan coils. Removed the S-correction cap, as I'm thinking C76 on the Pye 169 is actually the s-correction cap, just in between windings.

Better results this time, and the width control moves the foldover about a bit.

Can anyone point me in the next direction?

better.jpg


bypassed.jpg

All a bit of a mess at present!

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Sat Jan 30, 2016 7:04 pm

Boost is low at 380V

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Sat Jan 30, 2016 7:21 pm

No boost HT, as there was no HT at the transformer to Boost. HT1 connected to pin 5 of the Philips Loptx.

Looking much more promising now. Width control now working, but there's not quite enough there ....

Harmonic tuning?

improvedjpg.jpg

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Till Eulenspiegel » Sat Jan 30, 2016 9:52 pm

Lack of width. Check resistors R85 and 85. Both 4.7Mohms. The resistors are connected in series and are in parallel with feedback capacitor C71. S correction capacitor C74 is 0.18mfd in the 20" models.

Till Eulenspiegel.

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Tue Feb 02, 2016 8:29 pm

Thanks Till. Sadly those resistors I changed before I originally switched on last year, as they were somewhat outside spec.

EHT is somewhat lacking at 12KV. I'd be expecting around 17.5KV ...

Putting 111.11pF (9x1000pF in series!!) across C72A gives me a shade under 17.5KV and a good adjustment of width. Boost HT is also spot on.

I need to repair the stuck tuner and sort out the rapidly dropping height now to see what sort of picture I get. I spy a few Callins to evict!

Looking promising.

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Wed Feb 03, 2016 11:15 pm

Tuner now tuning. Frame now at full height and good linearity after changing C76, the cathode bypass.

Sound is fine.

Sadly lacking in video (You can *just* make out some picture) and sync is really weak. Changed the 3 Callins around the TAA700 and the 12V smoothing cap, C56. 12V is a touch low at 11.6V. No change. :zx:

Out with the 'scope. Test point E shows video coming in from the IF. Video coming in to the TAA700 on pin 10, about 1.3 V Pk-pk. Oscillograms on the service sheet show 1.5V pk-pk so I'm happy with that. Next to nothing coming out of pin 12. Disconnect the base of the video output transistor VT5, to see if it's loading it down. Still almost nothing on pin 12, so it looks as though my TAA700 has failed. When the set was running on it's original LOPT I had snow with pots of contrast, but I expect the TAA700 died along with the LOPTx. Parts drawer is bereft of TAA700's, so I'll investigate a source tomorrow.

On the plus side, the line stage seems happy with it's new transformer. Valves are not cherrying up, and the transformer is running cool. There appears to be some striations to the left hand side of the picture, but I've still got wires and croc-clips everywhere, so I'm hoping this will sort with a good tidy up of the wiring and some lead dressing.

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by malcscott » Wed Feb 03, 2016 11:23 pm

I could have a nos ic. I will check tomorrow, Malc.

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by crustytv » Thu Feb 04, 2016 1:28 am

Doz wrote:I expect the TAA700 died along with the LOPTx. Parts drawer is bereft of TAA700's, so I'll investigate a source tomorrow.


Hi Andy,

I have NOS TAA700 in stock, you're welcome to a spare one FOC. pm me your address and one will be in the post.

TAA700.jpg

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Thu Feb 04, 2016 9:19 am

Thanks folks. Chris, you have a PM. :aad

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Fri Feb 12, 2016 9:33 pm

New TAA700 fitted.

Exactly the same.... :stm:

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Fri Feb 12, 2016 11:24 pm

Checked and traced signals and voltages around the TAA700. Found R75 (68K), R88 (68K), R22 (68K) and R25 (68K) all up around 100K (I'm starting to wonder if I shouldn't just do a blanket change of 68K resistors!!!! R92 (120K) was a touch high at 140K, so it got replaced also. Pulses at pin 11 and pin 3 of the TAA700 now look correct. There is nothing on pin 14, however.

Things are now a little better. Sync is rock solid, and there is a smidgen more video modulation, although nothing like watchable.

Does the TAA700 do anything in the way of beam-limiting? I wonder if this is why I have precious little video.

20160212_222217web.jpg

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by sideband » Fri Feb 12, 2016 11:26 pm

I was looking for a data sheet for this IC.....don't seem to be able to find one on-line. I wonder if there is a blanking/gating pulse missing. Without any data, not sure which pin you'd check.

Might be worth checking supplies....maybe a duff decoupler on the I.C supply rail.

Doz wrote:Does the TAA700 do anything in the way of beam-limiting? I wonder if this is why I have precious little video.


I doubt it. I think only colour sets used beam limiting.....never came across it on mono sets.

Blanking or gating seems more likely.

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by freya » Fri Feb 12, 2016 11:35 pm

Some info on the TAA700 on the radiomuseum site.

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Sat Feb 13, 2016 12:30 am

sideband wrote:I was looking for a data sheet for this IC.....don't seem to be able to find one on-line. I wonder if there is a blanking/gating pulse missing. Without any data, not sure which pin you'd check.

Might be worth checking supplies....maybe a duff decoupler on the I.C supply rail.

Doz wrote:Does the TAA700 do anything in the way of beam-limiting? I wonder if this is why I have precious little video.


I doubt it. I think only colour sets used beam limiting.....never came across it on mono sets.

Blanking or gating seems more likely.


All the decouping caps are new.
I agree about beam limiting, there's no mask to distort! The search will continue with fresh eyes in the morning.

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by Doz » Sat Feb 13, 2016 12:31 am

freya wrote:Some info on the TAA700 on the radiomuseum site.


Sadly the info is very limited. Doesn't provide any help :(

I wonder if it was in the "little blue book" CPC did in the 90's ... wish I still had my copy now!

 
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Re: Pye 92 Rambler 169 Chassis. 17" Transportable

Post by nuvistor » Sat Feb 13, 2016 10:34 am

There was a version of this chassis, (569?) cannot remember that had a discrete circuit board to do the same job as the TA 770. Perhaps it was not the 569 but there was a version with the daughter card plumbed in. It was the very first sets that came with the daughter card, not plugged, but wired in. Perhaps due to supply constraints with the IC.
if you can find a circuit for that it will give you the workings of the IC.

Frank

edit. you may already have it but LLJ article Apr/May 1974 in the library has information on this topic.

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