Philips 663A combined radio/television 1948
 

Hi all,

Currently restoring the above set which so far has been very successful. Power supply chassis completed and a healthy looking raster has been obtained.

No sign of any signals however. The aerial input is a twin feeder arrangement via a two pin socket. I have connected my Aurora via the matched balum type adaptor shown which I have used on another Philips set of this era.

Before I delve deeply into the front end and risk a wild goose chase could any kind soul confirm this is indeed a suitable way of connecting the set?

Probing around V2 frequently changer (ECH35) will produce noise and white spots on the raster, suggesting the forward stages are functioning to a degree. HT appears to be perfectly adequate!

Re: Philips 663A combined radio/television 1948
 

I don't know this set, but are you sure this is the way the TV aerial would be connected? I would have expected a connection via a user accessible socket of some sort - that is, a connector that the viewer would use without requiring the back to be taken off. Rather like that 2 pin socket attached to the main chassis in your second picture...

BTW where is aerial input for the radio section of this set?

Re: Philips 663A combined radio/television 1948
 

Its certainly the correct TV aerial input socket - it gets a mention in the service book although it describes it as a 4 pin. On my set it is only a two pin.

The tuner aerial & earth sockets are in fact the ones you mention (2 pin sockets to the right on the vertical bracket) This is responsive when the tuner is selected.

I can't help thinking I'm doing something wrong here hence the request for advice.
With an ear firmly pressed to the speaker I can get the merest suggestion of an Aurora test tone on CH1.

There are no signs of any previous Band III conversions or any mods or bodgery, and everything looks original.

Re: Philips 663A combined radio/television 1948
 

Thanks for the info. A 1948 set that is a Superhet (you mention V2, a frequency changer) and not a TRF is interesting as there was only Ally Pally on Air - unless Philips were getting prepared for Tv in the Midlands due to come in 1949.

Re: Philips 663A combined radio/television 1948
 

Philips weirdness at it's best! Crazy early flyback EHT generation with TWO B4 based HVR2 EHT rectifiers in voltage doubler circuit with their 4V heaters fed from a separate mains transformer 6.3v primary, 2 X 4v secondaries. From whatI I can remember, three heavy mains transformers into the bargain. EBL31 video output valve! Crazy!

Yes a superhet using Mullard red E radio valves in the front end and a LOPT that looks like a PP9 battery.. There were a lot of superhets in early TV circuits including pre war. HMV 904, 1804, Murphy A56V and 114, plus the Vidor range and many more.
Good luck with that one Matt. Watch yer back when moving it! better to hire a crane. Regards, John.

Re: Philips 663A combined radio/television 1948
 

ECH35 as a TV frequency changer??? The mind boggles! How good was that at 45Mhz? I thought they struggled at 20Mhz shortwave but at low VHF......?

Re: Philips 663A combined radio/television 1948
 

I know! The I.F. is 10/14mc/s as were a lot of the early post war superhets. I think this is the only series that used an ECH35 as a frequency changer. Like all Philips products no matter how odd, this model performs very well as no doubt Matt will support.
John.

Re: Philips 663A combined radio/television 1948
 

I have the TV only version of this chassis which is more or less identical to yours. Just connecting the aerial co- ax and not even bothering with a balun produces good results results. I suspect the frequency changer might not be oscillating. I presume you have got the contrast turned well up?

Re: Philips 663A combined radio/television 1948
 

Does sound like the ECH35 isn't oscillating,
I had one in an old radio of that period
and it would work at lower frequencies
but just stop as one went higher up
the shortwave band, a new valve
brought things back to life.
Presumably the rf amp valve is OK?

Re: Philips 663A combined radio/television 1948
 

Doesn't the frequency changer employ two ECH35 triode-hexodes? The local oscillator is common to both vision and sound with the triode sections working together in a cross coupled arrangement.
I believe the pre-war model 2405 employed a similar circuit using ECH3 triode-hexodes.

DFWB.

Re: Philips 663A combined radio/television 1948
 

Hi Matt,
please see the attached info.
The manual seems to suggests it has two ECH35 valves, one for vision and one for sound, so if you have neither then it would point to the RF amplifier or the sensitiivity link.

Cheers
Andy

Re: Philips 663A combined radio/television 1948
 

Hi everyone,

Many thanks for your suggestions! here is the relevent bit of circuit.

There are a pair of ECH35's as frequency changers, one sound one vision. My first thought was something not right early on in the V1 area as there is no sound or vision, however I can't find anything amiss here. I have replaced the 0.004uf decouplers which were originals. All windings intact. Slowly adjusting S2 will produce some very slight noise with a signal applied.

Touching the anodes and grids of V1 & V2 will cause disturbance and HT is well up to spec. Could both ECH35's be low I wonder. My valve tester has thrown its toys out of the pram so I'm currently unable to test. The EF50 (V1) is a known good one.
I haven't explored the contrast circuit fully apart from the obvious. Pot intact but it doesn't have much of an effect on the raster when adjusting. The sensitivity link is in place.
Bit of a mystery this one but a fantastic set to restore. Any more thoughts gents?

Re: Philips 663A combined radio/television 1948
 

In the immediate post-WWII period, some of the standard AM frequency changer valves were claimed to be satisfactory for use up to 100 MHz, and so suitable for use in FM receivers. This group included the 6BE6 (X77) and X79 (6AE6). Both the ECH42 and ECH81 were used in this way, although a better FM application for the ECH81 was with the triode as a self-oscillating frequency changer, and the heptode as IF amplifier (pentode-strapped). In advertising, if not in the data sheets, the ECH81 was described as being suitable for use up to 100 MHz. The X81 and X79 were both used as frequency changers in a BBC FM receiver design; Lowther used essentially the same circuit in its first FM tuner, but with a 6AH8. Nonetheless, the realizable performance on FM with these valves was not very good, and in the case of the 6BE6, reputedly rather poor. Thus they were soon eclipsed by other solutions, typically the 6AT6 (ECC81) frequency changer preceded by an RF amplifier in the USA, and the ECC85 RF amplifier and frequency changer in Europe, the latter evidently an “economy” solution.

In that context, it is not so surprising that there would have been one or two applications from this valve group in Band I-only TV receivers, on the basis that “good for 100 MHz” implied “good for around 50 MHz”. Evidently Philips saw the ECH35 as being suitable.


Cheers,

Re: Philips 663A combined radio/television 1948
 

No, that was a 12AH8.

Re: Philips 663A combined radio/television 1948
 

I wonder what the noise floor was like? I didn't think they were particularly good at high shortwave....quite acceptable for normal broadcast bands.

Re: Philips 663A combined radio/television 1948
 

I imagine that the noise floor was quite high. I think though that the use of the ECH35 (and like valves) at VHF was predicated on their being preceded by a suitably high gain, low noise RF amplifier, such as an EF50 or an EF42, which would diminish the effect of the mixer noise. To some extent, that approach, noisier-than-ideal mixer preceded by high-gain, low-noise RF amplifier soon returned with TV front ends. Something like the ECC81 (6AT6) would have been a very good low-noise frequency changer for TV use at Band III, and would not have made undue demands on the RF amplifier. And in fact GE developed the 6AT6 for TV as well as FM (and FM-AM) frequency changer use. But the upward shift in TV IFs, which put the IF channel very close to the lowest Band I channels, created a potential regeneration problem that was most easily solved by using a pentode mixer. But that created a potential noise problem at Band III, where without any other constraints a triode mixer would be the logical choice. That problem was solved by the development of a very high gain, very low noise RF amplifier, namely the cascode. RCA had started that development programme in the late 1940s for other reasons, but it moved from being a desirable target to a very necessary target, and in the event arrived at the same time as the TV triode-pentode frequency changer.

At HF too, a good RF amplifier would have been highly desirable with the ECH35 and its ilk, both for front end selectivity and noise reasons. And it was not uncommon in the later 1940s to use a high-slope pentode for the RF amplifier. As far as I know, the early version of the Weyrad bandspread front end was based upon an EF50 RF amplifier and an ECH35 frequency changer.


Cheers,

Re: Philips 663A combined radio/television 1948
 

Some progress over the last couple of days.

I didn't have any replacement ECH35's so I swapped the pair over to see if this would make any difference. To my surprise doing so has put a test card on the screen, with terrible line linearity and a curious white line to the left!

Still no audio so a pair of new ECH35's are on order, along with an EA50 signal diode which I found has an o/c heater. Work can then recommence once they arrive.

Re: Philips 663A combined radio/television 1948
 

That is a very impressive set! The underside of the chassis is a bit daunting... well to me anyway!
8-o

Re: Philips 663A combined radio/television 1948
 

What a chassis and in such good condition! Pre war in appearance. The tube appears to have been changed for the MW31-16 with ion trap. I think the original was a MW31-7. Maybe a line drive fault causing that severe fold over. Good luck with it! John.

Re: Philips 663A combined radio/television 1948
 

I'm thinking exactly that John. The line and frame oscillators are both ECH35's also, so I shall try replacing both with new items to see if this corrects the line non-linearity. Both chassis although having required extensive cleaning are in remarkably good condition. The 663A has never been anywhere damp in its life by the look of it.
I've fitted a 31-74 as the 31-16 (itself a replacement from the original 31-7) was completely flat. I suspect this set had quite a life back in its day.

Re: Philips 663A combined radio/television 1948
 

Hi Matt,
great stuff so far.
I guess that given the set is on its third CRT, it is no surprise that the ECH35 valves don't want to play at VHF anymore.

Yes, your set has cleaned up very well, almost like new.
I once had a 1946 HMV 1804 that was like new (since sold to another BVWS member). On the rare occasions when sets turn up like that, it does make the restoration so much easier. Far fewer problems with noisy pots, valve holders and switches and also there is far less chance of failing transformers. Of course the cabinets are also much better if kept dry.
The set in question had the original Emiscope 3/4 that was also like new and the EHT transformer even worked! I've found some pictures of my actual set from before I restored it here :-
https://www.radiomuseum.org/r/hismasters_1804.html
The labels were fault dockets, stating that the owner was Mr Fox.

Anyway back to your set. Does it have a rubbr mask? If so then that has also survived well. 5:4 ratio 12" masks are hard to find.

Keep up the good work.

Cheers
Andy

Re: Philips 663A combined radio/television 1948
 

Hi Andy, yes she does indeed have a 5:4 ratio rubber mask, which appears to have survived very well. Gorgeous HMV 1804, bet you wished you'd kept hold of that one!

The cabinet on the 663A will require a lot of work but I'm confident I can retain much of the original finish when the time comes.

I've got a short update on the 663A and a small bit of progress.

I'm still waiting for 4 new ECH35's to arrive to try in the line and frame osc, and the sound and vision freq changers. Postage seems incredibly slow down South lately!

In the meantime having had a bit of a play around I've discovered the timing issue of severe line foldover can be improved by experimenting with the values of R91 (3k) and C120 (0.005) across the line coils and eht flyback transformer. Halving both values to 1.5K and 0.0025 provides the best compromise as shown. Any increase in values will damp the EHT and focus is lost. I'm thinking this issue may be being caused in the first instance by a poor line oscillator ECH35 having an effect on the drive/frequency. Substituting the EL38 produces identical results.
The width control R138 will not behave as expected and instead tends to move the entire image to the left and begin to reintroduce the foldover.

There is still no audio but massive noise and disturbance on screen causing jitter, line pulling and instability. Definition is poor and focus is fully advanced and could be better. The 663A is also suffering from velocity modulation as the picture brightness will vary along the scan, however this was improved somewhat by giving the EF50 in the first RF stage a good wiggle in its socket. I'm undecided if a lot of these problems are being caused by the reciever end or the line limebase (or a combination of the two) hopefully I can start ruling things out once those new valves arrive.

There are a few circuit differences, most notably R43, which instead of being returned to deck is actually connected to the plus side of C119, which is a polarised capacitor (8uf electrolytic) in my set. This all looked totally original and wiring it to circuit causes total loss of sync.

Resistors are all within spec and all capacitors have been restuffed/replaced in the area of the circuit shown, except for three low value items C121(220pf) C99(180pf) & C101(12pf) which I've left alone for the time being.


Still a great deal to do!! as always any thoughts on these fault conditions most welcome and appreciated.

Re: Philips 663A combined radio/television 1948
 

Can you reduce the line drive? It has the classic display of a chassis with the line drive variable cap screwed up hard! J.

Re: Philips 663A combined radio/television 1948
 

Shouldn't C119 be 25 µF (-25V)?

Did you replace C96 - 97 - 98?
(sorry if you already have done so and I read over it)

Jac

Re: Philips 663A combined radio/television 1948
 

Jac, yes it is indeed 25uf, quoted the wrong value from the circuit but the item fitted is correct. C96/97/98 are all visconols which I've restuffed with modern HV ceramic caps.

John I haven't discovered any line drive adjustment on this set (unless you know any differently!)

Re: Philips 663A combined radio/television 1948
 

Scraping the bottom of the barrel for ideas, but earlier pictures without the test card the raster looked evenly lit. Now the timebase is synchronised, its very non linear. What happens if you temporarily disconnect the sync and manually adjust timebase to display test card best as you can ?

Otherwise if its not R83/84/87 related then await the new ECH35.

I take it line hold and height pots aren't at one end of their range, which might mean they are masking the true cause ?

TTFN,
Jon

Re: Philips 663A combined radio/television 1948
 

There does not appear to be a line drive adjustment on this model. Just as an experiment try connecting a small value capacitor around 200pf from the junction of R86 and C100.

The line output transformers were very unreliable in this model if past history is correct but they normally break down completely. I don't think yours has that problem. John.

Re: Philips 663A combined radio/television 1948
 

I had a big breakthrough followed by a bit of a setback, but hopefully only a minor one.

The new ECH35's arrived and I began by replacing the suspect ones in the line and frame oscillator. Afterwards this produced a cogged but linear test card, with no trace of the previous velocity modulation and a massive improvement to the foldover that existed. EHT and focus was vastly improved also, showing 7.5kv on the meter.

Moving into the sync-seperator the cogging disappeared after replacing a 0.004uf coupling cap and a 75uf decoupling electrolytic, leaving a very respectable picture.
This was sadly short lived though and the width suddenly shot in leaving a narrow 3" raster. EHT is being damped to around 4kv.

HT has risen slightly, the line output valve (EL38) is slightly running into grid current. Examining the line drive waveform from the grid side of R86 is showing a sawtooth with a bit of a flat top.

I think I can rule out valve trouble as substituting the EL38 and even putting the old ECH35's back in are producing the same results.
I originally suspected a problem with the EHT doubler arrangement as such as failing HVR2's. EHT regulation was a bit poor when the Philips was working causing the picture to bloom when advancing the brightness. Could this be a bit of a red herring though?

The EHT transformer doesn't appear to be stressed and is running cool, so I'm hoping this isn't the culprit. Previously the line hold and width pots required critical adjustment. Line coils and componentry read ok.

Suspicion is now falling on C101 (12pf) along with C99 & C121. All low values which I don't have replacements for, so some are on order. Everything else in this area has been checked and/or replaced.

Would anyone tend to agree here?! bit of an unusual one.

Re: Philips 663A combined radio/television 1948
 

Line timebase circuit

Re: Philips 663A combined radio/television 1948
 

I hate to rain on your parade Matt, but I would be pretty sure that the line output transformer has shorted turns. I'd like to be proven wrong, but do be prepared to send off the transformer for rewinding. One might hope that it was all caused by the breaking down of heater supplies to the EHT doubling rectifiers, probably not that, but there is no harm in checking that with some silicon EHT diodes.

For the benefit of people who are not used to such early sets... Line collapse is a symptom that you won't see with a conventional combined line output and EHT transformer. We only see the symptom in this set because the rectifiers in the EHT voltage doubler do not have their heaters powered by the line output transformer. Mains EHT sets can also display line collapse, something I have unfortunately come across myself.

Cheers
Andy

Re: Philips 663A combined radio/television 1948
 

Thanks Andy,

I have today replaced the last few capacitors in the line oscillator which I didn't previously have replacements for but no improvements were forthcoming and I'm still seeing the narrow raster.
I disconnected the scan coils temporarily to see if this would produce any more EHT, checked their continuity again and made sure their tag connections weren't dry jointed but again no change. Similarily replacing the pair of HVR2's and re-checking the newly restuffed visconols didn't throw up any faults.
Running the set with the EL38 removed will produce a perfect sawtooth (line drive) waveform but re-inserting it will then flatten the top.
DC resistances of the line transformer are very close to what is quoted in the Philips manual.
Occasionally when powering up from cold a full scan is visible for around 10-20 seconds which will then collapse.
So by the process of elimination it would seem that the flyback transformer is really the only thing left now, could it have intermittent shorted turn(s)?!

I will now explore if this can be rewound as I'm not going to give up on this beauty. The transformer is in a small square pitch filled box, so no idea how it is wound or what it looks like.

Re: Philips 663A combined radio/television 1948
 

I would check all other possibilities first.
The line output transformer (T5) could very well have multiple wave-wound windings!

My 383A, which basically is the same set without the radio section, had a replacement LOPT, and this looks like this:
Attachment 234271

Jac

Re: Philips 663A combined radio/television 1948
 

It's a very interesting transformer and highly likely to be wavewound. The one in mine is potted with either wax or pitch I suspect. It's now gone off for rewinding (would love to see this process) so I won't get to see what lurks within. Out of circuit the primary is reading low. 58R when a figure of 80R is quoted. The secondary (2.7R) is spot on. The scan only failed once full EHT had been reached during the restoration, so would suggest it simply couldn't cope with what was being asked of it!

Re: Philips 663A combined radio/television 1948
 

Restoration of the 663A has now recommenced!

After further investigation it was decided that the primary of the small EHT flyback transformer was suspect, so this went off to Mike for a rewind.
On its return it went back in and a truly superb testcard and 6kv of EHT was obtained. I was very pleased.

Unfortunately a day or two later a timing problem has appeared and the set is now suffering from a foldover at the top of the picture. I've been through virtually everything in the frame timebase and have again substituted both valves (ECH35 frame osc, and EL33 frame output) but I can't cure this.

The only item I've found which isn't up to spec is the choke (S66) which reads 1.25K instead of the 900R quoted. Could this be a possible culprit?!

Any thoughts appreciated as always gents!

Re: Philips 663A combined radio/television 1948
 

Matt,

I had to rewind S66 in my 663A, so there may be a problem with that.
Try another (audio-amplifier-)choke you have, just to make certain.
After rewinding I measured the inductance at about 8 H, but I haven't noted down how I measured this...

You have a good picture otherwise!

Hope this helps.
Jac

Re: Philips 663A combined radio/television 1948
 

Hi Jac,

I'm thinking along similar lines, mainly as I can't find a fault anywhere else. I should hopefully have something suitable here to try. Fingers crossed!

Re: Philips 663A combined radio/television 1948
 

I take it you've changed any waxies?!

Re: Philips 663A combined radio/television 1948
 

Hi Matt,

Is R105 having any effect on the vertical linearity?

Jac

Re: Philips 663A combined radio/television 1948
 

Hi Jac,
All of the original pitch covered caps are modern replacements in disguise, and all electrolytics are restuffed.
R105 (frame lin) is also a replacement. Many of the wirewound pots were o/c. This is working and when backed off will correct the image but at the loss of amplitude.

Re: Philips 663A combined radio/television 1948
 

Hi Matt, all,

apologies for joining this discussion rather late.
Beautiful 663, the first time I see one "life".
The development of this chassis in the context of the total Philips TV development I have described here.
So some additions to earlier points raised:

• The CRT used by the simpler (non-radio) versions of the family (463, 563, 383) used the MW22-7, the 663A used originally the MW31-7 but this was quickly upgraded in production to the MW31-14. Impossible to say which version was originally used in this specific set, but the MW31-16 is clearly a later upgrade.
• The ECH35 is in view of later developments of course not a perfect RF mixer-oscillator. However, we need to see this in the context of developments then. The predecessors from 1939 (the 2400 family) used the ECH3 as TV MO, the Philips SX861 from 1946 used the ECH21. As described in my history, it seems that the ECH35 was a local Mullard favourite, since the more modern ECH21 should have been better. The next generation Mullard MT521/Philips 520 used a CCH35 as oscillator and EF50 as mixer but for the next 3 years a single self-oscillating EF/UF42 was used throughout Philips.

I am not a repair expert, but nevertheless some stupid questions/suggestions:
- given your problems with audio: because the TV and radio share the entire audio chain except for the RF pre-amplifier, did you check the audio chain for radio reception? That should say something on the ECH35 functioning too.
- are you using the correct IF frequencies? In the years 1946-1950 every Philips/Mullard chassis had different values! This one should be 13,2MHz VIF, 9,7MHz SIF.

I look forward to some nice pictures of the fully restored set, eager to add a few to my history site!

Cheers, Pieter

Re: Philips 663A combined radio/television 1948
 

Hello all,
I have a Philips 663A which is in very good condition. I plan to start its renovation in a few months. What I will say will not be very helpful, but it is an "armored" TV set. Once he traveled a long way to me in the side position and nothing was damaged, all the tubes remained in place, even the picture tube :). I keep my fingers crossed for the success of the current project.

Adam

Re: Philips 663A combined radio/television 1948
 

The 663A rebuild is now nearing completion after nearly 6 months.

She is now working beautifully and over the last week I have restored the scratched and battered cabinet.

I have stripped and repolished the top, let some new veneer into the front lower corners and retouched a lot of the damaged areas before a long polishing session.

Over the next few days the pair of chassis and crt will be reinstated!

Re: Philips 663A combined radio/television 1948
 

Great job done!:clap:
I would like to learn from you how you made this cabinet work....
We have here in these forums a good technical support, but the
bigger problem is the cabinet work.:shrug:

If you give these kind of jobs to a "woodworm", you are going to pay awful lot of money.:wall:
They promise you everything :blah: but sometimes the result
is between worse and lousy.:angry:

Regards,
German Dalek

Re: Philips 663A combined radio/television 1948
 

Fantastic work Matt!

The cabinet looks fabulous.

Jac

Re: Philips 663A combined radio/television 1948
 

Nice work matt. John.

Re: Philips 663A combined radio/television 1948
 

So what was the cause of the foldover in post #34?

Re: Philips 663A combined radio/television 1948
 

Absolutely!

Peter :)