Notifications
Clear all

DER 5649

Page 1 / 3
 
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4980

Hi all,

After nipping to Cambridge and collecting this nice little set, I could hardly wait to see inside.....
It has a BRC 981 chassis with plenty of dust thrown in too. The speaker cover had come off, but luckily was present.
Here are a few pics as received.
Sadly the telescopic aerial is missing, but it has a nice bayonet plug to connect to the nearest table lamp :bba

ReplyQuote
Topic starter Posted : 01/08/2016 10:28 pm
Katie Bush
(@katie-bush)
Famed V-Ratter Moderator
Posts: 4884

My knee caps have dropped off as I turn green with envy! :bba

Will that be eleven valves I counted in there? Or did I miss one? - Ah, I missed one at least..... Now I see twelve :bba

ReplyQuote
Posted : 02/08/2016 12:38 am
Lloyd
(@lloyd)
Noble V-Ratter Registered
Posts: 1544

Very nice! Looks mostly untouched as well. What state is the screen surround in?

Regards,
Lloyd.

ReplyQuote
Posted : 02/08/2016 1:32 am
The_Teleman
(@the_teleman)
Reputable V-Ratter Registered
Posts: 254

Is this the set seen on gumtree ?, I was tempted but too far away from me
I'm pleased a collector got it look forward to the restoration
Well done for getting it

Chris

ReplyQuote
Posted : 02/08/2016 7:21 pm
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4980

Thanks everyone,
Yes it was on Gumtree.
The screen surround appears to be fine, no cracks, but a very minor scuff mark.
There are 12 valves and all Mazda types so probably original.

I have cleaned the chassis and it has come up nicely.
I have tested and replaced all 0.1 uf caps plus a dreadful Callins 1uf 350v as they were very leaky, plus a 0.25uf in series with the line scan coils.
One cap had split open.
There are one or two left, that seem ok, but will find out in due course :bba

ReplyQuote
Topic starter Posted : 02/08/2016 9:28 pm
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4980

I tried to re-form the Callins 1uf pictured above, but it was hopeless.
It got warm rather quickly and basically resembles a resistor.

The large main smoothing can however, has re-formed and is ok.

Update.... Believe it or not, the Callins cap HAS reformed after letting it cool and re applying volts from my cap re-former.

ReplyQuote
Topic starter Posted : 02/08/2016 10:36 pm
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4980

Well I guess it's first light time......

Here we go :aac

Switch-on via a lamp limiter and no smoke or bangs.... we have a dim raster eventually.... more power and all is still ok.
Full mains now and noise from the speaker plus brighter and fuller raster.
Feed in a signal from the converter with test card C.
Tune to CH1, adjust line and frame holds, alter fine tuning and we have sound and vision.
Good volume, contrast and brightness.

Clearly the frame stage needs some investigation (linearity pre-set at limit of travel.)
Also, there is too much width even with the pre-set at minimum.
Will have some further investigation tomorrow. dmm

ReplyQuote
Topic starter Posted : 03/08/2016 12:08 am
Marc
 Marc
(@marc)
Famed V-Ratter Registered
Posts: 2761

That's looking good Andrew :aad
I reckon a few resistors and you'll have it sussed :)

Marc.

ReplyQuote
Posted : 03/08/2016 12:13 am
Red_to_Black
(@red_to_black)
Noble V-Ratter Registered
Posts: 1745

I would ditch the Callins :qq1 , they were trouble back in the day :bba I cannot see them lasting any length of time even if they appear to reform.

Looking good though. :cca

ReplyQuote
Posted : 03/08/2016 12:16 am
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4980

Thanks Marc.

There are a number of caps in the frame stage that could probably do with checking/replacing, plus some further voltage checks etc.

I found a date stamp in the cabinet of March 1969.

ReplyQuote
Topic starter Posted : 03/08/2016 12:19 am
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4980

I would ditch the Callins :qq1 , they were trouble back in the day :bba I cannot see them lasting any length of time even if they appear to reform.

Looking good though. :cca

I have re-fitted the Callins, but will likely replace it in time :qq1

ReplyQuote
Topic starter Posted : 03/08/2016 12:21 am
Jayceebee
(@jayceebee)
Noble V-Ratter Registered
Posts: 1632

Excellent start, I thought that CME1602 would be pretty reasonable. :thumb

John.

ReplyQuote
Posted : 03/08/2016 12:45 am
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered
Posts: 5477

The picture you have shows the classic signs of a dead cathode decoupler in the frame output stage...

ReplyQuote
Posted : 03/08/2016 1:08 am
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4980

The picture you have shows the classic signs of a dead cathode decoupler in the frame output stage...

I know, but there isn't one. The cathode goes straight to ground on the frame output :qq1

ReplyQuote
Topic starter Posted : 03/08/2016 9:34 am
The_Teleman
(@the_teleman)
Reputable V-Ratter Registered
Posts: 254

Isn't this the chassis that the frame stage derives its bias fron the heater chain?
I seem to remember a similar chassis that did
If so check the heater circuit this could have a fault not evident from the glow of the valves

Chris

ReplyQuote
Posted : 03/08/2016 11:04 am
Focus Diode
(@focus)
Honorable V-Ratter Registered
Posts: 729

Looking good so far. As for the Callings cap it looks to be surprisingly in good condition. Many I've seen have split leaking its interior everywhere. Nevertheless I consider it essential it's changed asap.

I take it the CME 1602 is a rim band version of the 1601? One could presumably be used in the 16" 960 portable.

March 1969 would appear to be a late model.

Brian

ReplyQuote
Posted : 03/08/2016 11:15 am
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered
Posts: 5477

The picture you have shows the classic signs of a dead cathode decoupler in the frame output stage...

I know, but there isn't one. The cathode goes straight to ground on the frame output :qq1

Huh?! Oh, hang on, I remember this one.

IIRC the idea is that the heaters are fed via a diode acting as a wattless dropper, and by deriving the bias from the heater chain it would show up as a massive hum bar if the diode went short, thus alerting the user to a fault condition.

ReplyQuote
Posted : 03/08/2016 1:58 pm
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4980

Thats true...the frame stage derives bias from the heater chain as Chris The Teleman also says above.
An interesting arrangement.

ReplyQuote
Topic starter Posted : 03/08/2016 2:02 pm
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4980

So, this evening out came the Callins and I fitted a 1uf 400v modern "Suntan" polyester cap as it was pretty much the same physical pitch.
(Modern 1uf electrolytics are so small lol)

Excess width was due to R109 330k being completely open circuit which feeds boost HT to the top of the width control.
C62 0.02uf which provides feedback from the frame output to the linearity control was very leaky, replacement has brought about a big improvement.
Again, I have used the "Suntan" range of capacitors as they are the same reddish brown as the "Erie" types and have the same pitch size.
Whilst I was at it, I replaced a few others in the frame stage too.
(The manual is available in the library) :qq1

ReplyQuote
Topic starter Posted : 03/08/2016 9:14 pm
Focus Diode
(@focus)
Honorable V-Ratter Registered
Posts: 729

Wow, that's looking very good! Well done.

Brian

ReplyQuote
Posted : 03/08/2016 9:23 pm
Page 1 / 3