Philips 1757U. - UK Vintage Radio Repair and Restoration Discussion Forum

FERNSEH · 1st Oct 2018, 3:15 pm

It has been my intention for some time to collect the chassis of this console TV for restoration. The chassis is now in the workshop for initials tests. The cabinet remains with it's owner.
The Philips 1757U is a full spec TV receiver. Three vision IF amplifier stages, sync cancelled vision AGC and flywheel line synchronising. The line sync discriminator employs two diodes supplied from a phase splitter transformer. Has this type line flywheel sync system been used in other Philips TV either in the UK or on the Continent? Later UK made Philips TV receivers used a coincidence detector in the line sync circuits.

The pictures show the magnificently over-engineered chassis.

Link to a previous topic of the table version, the model 1756U:
https://www.vintage-radio.net/forum/...d.php?t=129829

DFWB.

jayceebee · 1st Oct 2018, 6:36 pm

Hi Fernseh I also have the table model version 1756U, being a Philips it's filled with the usual black tar capacitors but after just half a dozen components it's giving a pretty good account of itself.

Your's like mine appears to have had a replacement field output transformer sometime in it's life, I know the original would have been coated in black tar as with the mains smoothing choke and sound o/p TX.

Is that smoothing capacitor original? As you can see with mine it's located on the signals chassis.

John.

linescan87 · 1st Oct 2018, 6:42 pm

Hi David,

The one I did was certainly an excellent performer. I shall follow this thread with great interest. The chassis is rather heavy!

John Joe.

FERNSEH · 1st Oct 2018, 10:14 pm

The 1756U chassis is now connected to the variac. The receiver is at the time of writing is supplied with 75 volts. Because of the presence of the thermistor in series with the heater chain and the employment of PY82 HT rectifiers it will be a considerable length of time before there is any indication of HT voltage across the reservoir capacitor.
There is evidence that the set was serviced sometime early 1965. Several replacement Mullard valves have yellow print on the glass with date codes such as B4K or L.
The original Mullard CRT has been replaced by a regunned MW43-64 tube processed by Liver Tubes Ltd.
One of the PY82 valves is a replacement made by Mazda. Can't allow that alien valve to remain in a Philips receiver, it will be replaced by a Philips or Mullard branded valve.

DFWB.

FERNSEH · 2nd Oct 2018, 4:27 pm

Encouraging results today. With 160 volts supplied to the chassis the line oscillator sprung into operation. Ten minutes later it was confirmed that the line output stage is working. There is a 4mm spark present at the anode connector of the CRT.
This evening I'll turn my attention to the frame timebase, at the same time the mains supply voltage will be increased to 180V.

DFWB.

Pieter H · 2nd Oct 2018, 9:56 pm

Would be very interested to hear what's on the labels of the tuners in both the 1757U and 1756U.
According the documentation it should be the MK 892 71 or MK 892 81. Can you confirm?

Cheers, Pieter

FERNSEH · 3rd Oct 2018, 10:21 am

Good morning Pieter,
There is no markings on the tuner box to indicate it's type numbers and although there is some useful information in the 1956/57 Radio and Television book there is no reference to the type of tuner fitted in the 1757U.
Is it safe to assume it is the same type of tuner that is fitted in the model 2155U? MK.892.82.
Results from yesterdays work on the chassis. The mains input voltage has been raised to 220V. Now the measured EHT is 7KV. The reason for this low figure will be due to the fact no scanning cols are connected to the chassis.
The frame oscillator is not working, it's most likely all the black tar capacitors will need replacing. A few RadioSpares capacitors have been fitted. After over fifty years it's most likely these will need replacing.

The Frame oscillator valve is an ECC82 used in a cathode coupled multivibrator circuit. Output valve is an ECL80.

DFWB.

1st Oct 2018, 3:15 pm	#1
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Philips 1757U. It has been my intention for some time to collect the chassis of this console TV for restoration. The chassis is now in the workshop for initials tests. The cabinet remains with it's owner. The Philips 1757U is a full spec TV receiver. Three vision IF amplifier stages, sync cancelled vision AGC and flywheel line synchronising. The line sync discriminator employs two diodes supplied from a phase splitter transformer. Has this type line flywheel sync system been used in other Philips TV either in the UK or on the Continent? Later UK made Philips TV receivers used a coincidence detector in the line sync circuits. The pictures show the magnificently over-engineered chassis. Link to a previous topic of the table version, the model 1756U: https://www.vintage-radio.net/forum/...d.php?t=129829 DFWB. Attached Thumbnails

1st Oct 2018, 6:36 pm	#2
jayceebee Heptode Join Date: Jun 2007 Location: Durham, County Durham, UK. Posts: 640	Re: Philips 1757U. Hi Fernseh I also have the table model version 1756U, being a Philips it's filled with the usual black tar capacitors but after just half a dozen components it's giving a pretty good account of itself. Your's like mine appears to have had a replacement field output transformer sometime in it's life, I know the original would have been coated in black tar as with the mains smoothing choke and sound o/p TX. Is that smoothing capacitor original? As you can see with mine it's located on the signals chassis. John. Attached Thumbnails Last edited by jayceebee; 1st Oct 2018 at 6:47 pm. Reason: typo

1st Oct 2018, 6:42 pm	#3
linescan87 Heptode Join Date: Mar 2014 Location: Meath, Ireland Posts: 551	Re: Philips 1757U. Hi David, The one I did was certainly an excellent performer. I shall follow this thread with great interest. The chassis is rather heavy! John Joe.

1st Oct 2018, 10:14 pm	#4
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Philips 1757U. The 1756U chassis is now connected to the variac. The receiver is at the time of writing is supplied with 75 volts. Because of the presence of the thermistor in series with the heater chain and the employment of PY82 HT rectifiers it will be a considerable length of time before there is any indication of HT voltage across the reservoir capacitor. There is evidence that the set was serviced sometime early 1965. Several replacement Mullard valves have yellow print on the glass with date codes such as B4K or L. The original Mullard CRT has been replaced by a regunned MW43-64 tube processed by Liver Tubes Ltd. One of the PY82 valves is a replacement made by Mazda. Can't allow that alien valve to remain in a Philips receiver, it will be replaced by a Philips or Mullard branded valve. DFWB.

2nd Oct 2018, 4:27 pm	#5
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Philips 1757U. Encouraging results today. With 160 volts supplied to the chassis the line oscillator sprung into operation. Ten minutes later it was confirmed that the line output stage is working. There is a 4mm spark present at the anode connector of the CRT. This evening I'll turn my attention to the frame timebase, at the same time the mains supply voltage will be increased to 180V. DFWB.

2nd Oct 2018, 9:56 pm	#6
Pieter H Tetrode Join Date: Sep 2017 Location: Waalre, Netherlands Posts: 67	Re: Philips 1757U. Would be very interested to hear what's on the labels of the tuners in both the 1757U and 1756U. According the documentation it should be the MK 892 71 or MK 892 81. Can you confirm? Cheers, Pieter

3rd Oct 2018, 10:21 am	#7
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Philips 1757U. Good morning Pieter, There is no markings on the tuner box to indicate it's type numbers and although there is some useful information in the 1956/57 Radio and Television book there is no reference to the type of tuner fitted in the 1757U. Is it safe to assume it is the same type of tuner that is fitted in the model 2155U? MK.892.82. Results from yesterdays work on the chassis. The mains input voltage has been raised to 220V. Now the measured EHT is 7KV. The reason for this low figure will be due to the fact no scanning cols are connected to the chassis. The frame oscillator is not working, it's most likely all the black tar capacitors will need replacing. A few RadioSpares capacitors have been fitted. After over fifty years it's most likely these will need replacing. The Frame oscillator valve is an ECC82 used in a cathode coupled multivibrator circuit. Output valve is an ECL80. DFWB.