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New find Thorn BRC 1580

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mfd70
(@mfd70)
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Posts: 228

I thought I'd give a quick update on this as I'm waiting for some parts to arrive. There was some cabinet damage, the fixings for the tuner had broken off also one of the CRT mounts had broken, I'm working on these at the moment but other than that it's in reasonable condition. However on removing the main PCB, there was some contamination of the component side of the board near the volume control. It looks and feels like some sort of heavy grease and is very difficult to clean off, I've used foam cleaner and WD40, then isopropyl to clean it up. I've been waiting for some sunshine to dry the board thoroughly which we had today. It almost looks like someone had taken a grease gun to the volume control ?

 

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Topic starter Posted : 21/07/2020 8:50 pm
mfd70
(@mfd70)
Active V-Ratter Registered
Posts: 228

Here is some more detail on the cabinet repairs on the set, as I pointed out the tuner mounts were broken off, I was able to carefully remove the aluminum escutcheon and then fit two M5 countersunk nylon screws, the speaker grille molding was thick enough to countersink and allow the escutcheon to be re-fitted.

20200722 130104
20200722 130046 (1)

The other issue was the top corner CRT mounting was broken, I glued this back and added a small steel bracket screwed into an adjacent unused hole.

20200721 132825 (2)

 The cabinet is not in great condition but looks reasonable.

 

Now the electronics, one thing I only noticed when I took the cabinet apart whilst waiting for transistors was the dag earthing spring had fallen off and was tucked in by the side of the CRT. Now some years ago at work I wrote off a Fluke digital meter working on a TV with a disconnected dag. This may explain the semiconductor massacre in the IF stage, VT1,2,3,4 and 5 had all failed, I used up my stock of BF197 lockfits so investigated a more modern replacement, I found the BF199 had similar Hfe and better fT, it has the same lead out and is current production. VT6 had also failed, it measured OK but did not work in circuit, BF178's are readily available though. C53 and C54 had failed, so I did a partial replacement of all the electrolytics I had in stock, about half of the ones I removed definitely were bad, the rest marginal.

After fitting all those parts there was a nice picture and sound, the set is on soak this evening and runs quite cool considering the valve count.

Collage 2020 07 23 19 47 54 (2)
Collage 2020 07 23 19 41 46 (2)

I'd like to find a 1590 now to go with it.

 

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Topic starter Posted : 23/07/2020 9:22 pm
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