Hi Guys,

After having an interest in radiograms for a number of years and collecting and repairing a few, I picked up an Astor B/W television/radio gram with the cabinet in very good shape. I believe its about 1963 build year.

I have worked through a few issues and replaced most caps and a few resistors, but believe the set has been butchered a few times as there is a few cut wires which must have gone to something in the past.

I have it up and running now except for horizontal height issues with the raster only managing to fill about half the screen.

I haven't as yet been able to find a circuit schematic for it online, the chassis is stamped R31G-A4W.

Much appreciated if someone could point me in the right direction - hopefully its been out there right under my nose all along!

Thanks

John.

Hi John,

Welcome to the Forums.

Your Astor uses a Series 4 chassis. I'll post a schematic here.

Astor Series 4 A66 Circuit Diagram

Look for "gone high" resistors off the height pot.
From distant memory they were several meg and off boost HT.
JJ

Hey thanks guys the fast informative response is fantastic! I will check out more resistors tonight.

File uploaded to Post 2.

Check, in this order:

R91 High
R128 High
C71 (for O/C) this electrolytic cap is most likely degraded and should be replaced. Will affect vertical linearity at bottom of screen..
C70 (for O/C) If degraded, will cause crushing in area about 1/4 way down the screen as height is increased.

If C71 or C72 are the blue Ducon (electrolytic) types they are to replaced as a matter of course. These blue Ducons have a very high attrition rate. In fact it is pretty safe to say that anything with the word Ducon on it must go.

Also note that R82 in the Issue 1 schematic is 1.2K, and in Issue 2 is 820 ohms.

Here is some additional information regarding this model.

Astor Series 4 A66 Cabinet Fitting Parts List
Astor Series 4 A66 Control Head Parts List

Files uploaded to Post 7.

I've got one of these. The Ducon blue tubular polyesters will probably be OK. Regard Ducon papercaps with suspicion, and although the white tubular "Di-pols" look like polyester, they have paper inside them. C70 and C71 are two of the four small chassis-mount electrolytics that tend to leak goo.They are hard to find, and difficult to replace without the heat of the soldering destroying them.

Early Polyester caps and ring-ins:
==============================

With Ducon tubular caps, as you say, the blue ones are OK.

UCC made similar looking white tubular caps about the same time.

"Di_Pol" is polyester (and likely to be OK)
"Hi-Qual" is PAPER and should be replaced wherever seen.

The odd thing is, the 0.039μF Di-Pol boost cap on my Astor 4A was burnt out, and when I pulled it apart with the idea of restuffing, it was waxy paper and foil inside. Which is why I thought they were papercaps. A Hi-Qual mislabelled, perhaps?

I guess it's possible it was mislabelled. Also possible it was plastic film with a little wax or oil added as a lubricant to assist the winding process. I must admit I've never pulled a polyester foil cap apart.

Back in the day, Roy Brown and I had a "discussion" about just this in the workshop. It was settled by two spec sheets from UCC themselves, one for "Hi-Qual" and one for "Di_Pol" caps.

As I have mentioned in another post, some TV manufacturers were initially nervous about the ability of "plastic" caps to handle high currents so UCC kept making paper caps for a while, they just used the same encapsulation line for both.

There were still 0.056μF Ducon paper caps in the boost position in Philips hybrid modular TVs into the 1970s!

The set is improving.

I have a full raster now, but only on full horizontal size on the pot.

Also have the bottom half a bit crushed, and the CRT emission seems low, I don't know if its the CRT or if the set's just not putting out enough to drive it.

Pretty well all the resistors have tested out ok, as have the caps, but I have replaced the majority with what I have. I still have to track down some .0022uf's.

I get the odd snap crackle and pop from the audio which is not promising.

A quick check for CRT low emission:

1. Is the Brightness control fully clockwise and still not enough brightness? If so, check in this order:

R128 (replace if necessary with a 2 watt metal film resistor)
R71 (same applies)
R67, R69.
V6 (6DX8)

2. If you have SPARE brightness, a low emission CRT will generally show white crush and reversal (bright whites turning grey with a "silvery" effect. This is a sure sign of a low emission CRT.

Here's what I said before about the lack of height (this chassis doesn't have a pot for width)

Check, in this order:

R91 High
R128 High
C71 (for O/C) this electrolytic cap is most likely degraded and should be replaced. Will affect vertical linearity at bottom of screen..
C70 (for O/C) If degraded, will cause crushing in area about 1/4 way down the screen as height is increased.

R91 and C71 are your most likely culprits.

You DO NOT NEED to replace paper caps in most series 4 chassis. By this stage Astor had cut over entirely to polyester caps so there usually aren't any paper caps! Waste of time and money replacing ployesters! Trust me, I know, I was around when this chassis was new......

Warning! Do NOT replace the .0022μF caps! For example, C97 is a special type and if you replace it with something else the hor. hold will drift with temperature. Bad news.

The rule is - yes, replace wax paper caps wherever you see them but NEVER replace other caps unless you KNOW with certainty that they are faulty.

Your crackle in the sound is a classic fault, it will be due to V2, the other 6DX8. When you replace it, also check R19, the 150 ohm in the cathode circuit. It is probably a Ducon carbon composition resistor and will have gone low. Common fault. Slowly kills the 6DX8. To make life easier for your replacement 6DX8, use 180 ohms or 220 ohms. While you are at it, check R12, the 470 ohm dropper resistor to the audio.

Ian, my 1963 Astor Plymouth has a series 4 chassis, and there's quite few Ducon papercaps in it. Most were OK, but C104 in Horizontal Linearity was melting so it had to go. Unfortunately I replaced it with a new Asian-made polyester greencap that turned out to be dud, which sent me on a wild goose chase for the fault responsible for the resulting horizontal squeeze. A lot of work for nothing. I test replacement components before using them now.