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crustytv
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Well not so lucky with the Grundig, it has a flat A51 580X.

I cannot find which adapter on my B&K  to use, either its a 27 or 31. Nothing in the Leader LCT 910A for a A51 580X. Anyone from the trade here know what socket you need on the B&K? If I could get it on the tester I'm sure I could get some life back. Other than that I'm going to have to find a new tube.

gruncrt 1
gruncrt 2

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Topic starter Posted : 17/08/2018 9:51 pm
Lloyd
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That looks a good result so far, I didn’t know about the potential for the TX-9’s power supply to blow up, one to keep in mind! Just goes to show that Thorn had come up with some excellent chassis with the TX-9 onwards, they just seem to work really well!

Shame about the tube in the Grundig, I guess it was just a really reliable set which got used and used until the picture became too dim to watch! I’ll see if I have a base for the B&K..

B&O liked using little gold coloured electrolytics, I think they might be ROE branded, my MX-2000 uses them and quite a few have failed short, when I fired up the MX-2000 for the first time I got a good snowy raster, but a cloud of smoke began to rise, which was a resistor downstream of one of those caps going up.

Regards,

Lloyd

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Posted : 18/08/2018 10:20 am
crustytv
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Well the CR-23 adapter I made works, I connected the B&K up to the Grundigs A51-580X and it confirmed what I already knew, that the emission on all three were low, but what It now allowed me to see was to what degree.

Red is dead! Well hardly registering one division in the bad section.

Green  & Blue very low in Yellow region

I ran a clean and balance on G & B, this improved the emission reading but still not acceptable, just outside of the yellow region. I then bopped G & B, this brought both guns well into the green, enough I would think going on past experience, to give a reasonable picture.

What to do about Red though. I decided to give it a bop. This lifted it to about 4 divisions into the bad area, I imagine there's little or no cathode left to recover.

Feeding in a test signal and the picture is marginally improved but everything is virtually at max contrast and brightness wise. I did wonder about raising the red drive but I'm unfamiliar with the chassis and I seriously doubt it will help all that much.

So I need to find an A51 580X....

Before

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After

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Topic starter Posted : 18/08/2018 12:58 pm
crustytv
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Next the TX10 Anything to worry about on those like the TX9?

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Topic starter Posted : 18/08/2018 1:08 pm
Red_to_Black
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Hi Lloyd

Your TX9 won't  blow up like that as the mk 1 and 2 versions did not use the TDA4600 chopper circuit, mind you the earlier  Thyristor based versions had their own foiliables.

The faults JC  mentioned above holds good for any set that uses the 4600 type supply.

"This is my multimeter. There are many others like it, but this one is mine. My multimeter is my best friend. It is my life. I must master it as I must master my life. Without me, my multimeter is useless. Without my multimeter, I am useless."

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Posted : 18/08/2018 1:33 pm
Red_to_Black
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Posted by: Chris

Next the TX10 Anything to worry about on those like the TX9?

The TX 10 was a reliable chassis, the PSU works in a not too dissimilar way to the often much maligned ICC5 chassis.

check for dry joints around the chopper transformer (especially the pin obscured by the chassis strut) the chopper transformer in this chassis looks like a lopt as it is also the EHT transformer. The real Lopt is a small matchbox size transformer over on the other side of chassis.

The only really destructive fault on this chassis that I recall is a diode in the line stage that breaks down under load causing a ripply picture/raster after running for a while, if left in this condition with the set running for any length of time destroys the small lopt mentioned earlier, which may be a problem to obtain a replacement nowadays.

There are of course many other stock faults, some of which can be quite perplexing if you are not familiar with this chassis, however myself and Jayceebee will help you if you get into trouble.

Edit: the focus unit on the earlier version of this chassis was bolted directly to the metal chassis (similar to the earlier  9k6 tripler) and could flashover destroying silicon parts, it was later modified with insulated stand offs to alleviate this problem

"This is my multimeter. There are many others like it, but this one is mine. My multimeter is my best friend. It is my life. I must master it as I must master my life. Without me, my multimeter is useless. Without my multimeter, I am useless."

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Posted : 18/08/2018 1:50 pm
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crustytv
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The 3788 TX10 is a bit wonky, guess the scan coils need locking. The tube is good and damn these TX's are good. Out of all the sets thus far they've given the least trouble.

edit: Yep scan coils loose, corrected and locked up.

3788 tcf

I'm not plugging in the 9800 chassis fergy or the Bush CTV1120 before some thorough checks and I'm certainly not the Beo 3200. Leaving this interesting diversion for a while, it really is back to the Fergy 3712, time to fit that flyback cap.

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Topic starter Posted : 18/08/2018 3:30 pm
Red_to_Black
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Posted by: Chris

Damn these TX's are good. Out of all the sets thus far they've given the least trouble.

I literally grew up with the TX range (I do have a "soft spot" for these), nice solid reliable range, they were great to repair with a proven track record and a known fault history,  imo Thorns finest  achievement, the Thomson sets that followed were equally as quirky as some of Thorns earlier designs and were not really well liked in the trade, I did however appreciate these too.

"This is my multimeter. There are many others like it, but this one is mine. My multimeter is my best friend. It is my life. I must master it as I must master my life. Without me, my multimeter is useless. Without my multimeter, I am useless."

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Posted : 18/08/2018 3:48 pm
Red_to_Black
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Incidentally Chris  which versions do you have of the TX9 and 10 ?

You already no doubt know there were 3 main versions of the TX9, there are also 3 versions of the TX10, of which I will look up the pc numbers later.

"This is my multimeter. There are many others like it, but this one is mine. My multimeter is my best friend. It is my life. I must master it as I must master my life. Without me, my multimeter is useless. Without my multimeter, I am useless."

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Posted : 18/08/2018 4:02 pm
crustytv
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Posted by: Red_to_Black

Incidentally Chris  which versions do you have of the TX9 and 10 ?

No idea, this is the first time I've seen the inside of the TX range, I'm a TX virgin.

The TX10 has SCH/D sticker

The Main PCB has 1500/23A

The small flip up/down PCB has 1500/023A and 1551/H

pcb1
pcb2

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Topic starter Posted : 18/08/2018 7:31 pm
Jayceebee
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The signals PCB is the later version which has a stereo audio output stage although your set of course only uses one channel, the early versions only had a mono IC. Chances are the IF panel in the screening can is the also a later one using a Plessey SL1432 as IF amp/SAWF driver, earlier panels used an SL1430.

Chris I think your set maybe a 3785 as I don't see a RCU PCB, the 3788 did not have any visible front controls other than the mains switch.

John.

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Posted : 18/08/2018 10:17 pm
crustytv
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Hi John,

I went with what was on the back of the set 3788 but clearly my set has many visible controls on the front which looking at the brochure, you're correct is a 3785. I wonder if the back got accidental swapped in its service life or maybe its always been that way.

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Topic starter Posted : 18/08/2018 10:31 pm
Jayceebee
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Yes, I also believe it's had a back swap at some point. Check the orange serial number label top centre, this will normally have the model number printed in smaller type.

John.

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Posted : 18/08/2018 10:44 pm
Red_to_Black
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Thanks Chris ?

Yours is a MK1 version,

The early TX10 PC1500 chassis (MK1) metal chassis
The MK2 used the PC 1550 chassis (also metal).

Sadly I forget the main differences between the MK1 and 2, the line driver IC was definitely changed between the mk 1 and 2 but I cannot recall whether that was just a running change along the way, the metal strut across the chopper transformer was also different between the mk 1 and 2, one was the full width (depth ?) of the chassis, the other not but again I forget which is which, probably full width on the mk2

 Whilst the MK3 used a PC1560 which was the plastic chassis version, this version used a totally different layout, the main electronic differences were the use of a TDA3652 (later TDA3654) frame output chip and BU508A transistors for the PSU and line stages in place of the BU208A used in the earlier chassis versions

"This is my multimeter. There are many others like it, but this one is mine. My multimeter is my best friend. It is my life. I must master it as I must master my life. Without me, my multimeter is useless. Without my multimeter, I am useless."

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Posted : 18/08/2018 10:47 pm
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Jayceebee
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Hi Baz, you're correct about the line drive IC the later metal chassis, it was the TDA2576A but for the life of me I can't remember the original, TDA9503 or 4 or was it just simply a TDA2576? PC1550 was TDA2578A.

I'm pleased when replacing the obsolete TDA3652 with a TDA3654 in the PC1550 required only a single resistor change, did you ever try it on an Amstrad 2200? ?

John.

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Posted : 18/08/2018 11:10 pm
Red_to_Black
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Hi JC,

the original Line drive IC was I think the TDA2576, later changed to the "A" version TDA2576A, and then ended up the 2578A , but I could be wrong of course.

RE : the Amstrad CTV2200 and the TDA 3652 to 54  mod, oh yes indeedy ? such fun (not)  ?

mod sheet

"This is my multimeter. There are many others like it, but this one is mine. My multimeter is my best friend. It is my life. I must master it as I must master my life. Without me, my multimeter is useless. Without my multimeter, I am useless."

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Posted : 18/08/2018 11:28 pm
Jayceebee
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Do I see even more additions Chris?

John.

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Posted : 22/08/2018 9:31 pm
crustytv
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Indeed 🙂

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Topic starter Posted : 22/08/2018 9:49 pm
crustytv
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Some progress on the 1978 Grundig 4415-GB

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Topic starter Posted : 23/08/2018 11:11 pm
Cathovisor
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Chris, you're about to get a PM.

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Posted : 23/08/2018 11:32 pm
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