Philips N1500 VCR - Head Drum Servo Fault - UK Vintage Radio Repair and Restoration Discussion Forum

Keith1973 · 17th Nov 2016, 2:17 pm

Hi,

Does anyone have any experience on these old Philips N1500 VCRs? This one I've had for long time now and will playback for a very brief period then the head drum speeds up.

This system appears to be designed to run the drum faster and then use eddy current braking in the head drum servo to slow it down to the correct speed. So my assumption is that the circuit cuts out completely allowing the drum to run at full speed. The best I can get out of the machine is maybe about a minute of playback. Once it fails the fault remains until the machine is left disconnected from the mains for some time.

Has anyone come across this fault before?

Thanks,

Keith.

Mikey405 · 22nd Nov 2016, 7:02 pm

Hi Keith.

I realise it's not terribly scientific (in my book, easy-ness comes before scientific-ness) but if it were mine then my first port of call would be a can of freezer-spray.

Do you have the service manual for the set as it's not very easy to identify components on those highly-populated PCBs.

Thanks Keith.

Kind regards.

From Mike.

P.Pilcher · 23rd Nov 2016, 9:41 pm

I don't know to what extent this will help but the N1500 was my first ever VCR which I bought 2nd. hand from a telly/radio shop in about 1978. It soon developed the fault of uncontrollable frame slip which I eventually traced to total loss of eddy current braking of the drum motor. The electromagnets are connected to a small board which is supposed to supply the necessary current and it was obvious that many repairs had been attempted here before. On close and careful examination of this board it was found that a lead from each of the output transistors had never been soldered in during manufacture. A cleanup and a blob of solder on each connection point of the PCB restored normal operation. Careful movement of each component should reveal if this is the case with your unit.
The other stock fault on this unit which happened to me was intermittent failure of the main rectifiers which caused the whole unit to trip out (when recording of course). Replacement was the appropriate cure.

P.P.

17th Nov 2016, 2:17 pm	#1
Keith1973 Retired Dormant Member Join Date: Mar 2007 Location: Bristol, UK. Posts: 64	Philips N1500 VCR - Head Drum Servo Fault Hi, Does anyone have any experience on these old Philips N1500 VCRs? This one I've had for long time now and will playback for a very brief period then the head drum speeds up. This system appears to be designed to run the drum faster and then use eddy current braking in the head drum servo to slow it down to the correct speed. So my assumption is that the circuit cuts out completely allowing the drum to run at full speed. The best I can get out of the machine is maybe about a minute of playback. Once it fails the fault remains until the machine is left disconnected from the mains for some time. Has anyone come across this fault before? Thanks, Keith.

22nd Nov 2016, 7:02 pm	#2
Mikey405 Octode Join Date: Jul 2006 Location: Solihull, West Midlands and Beaford, Devon Posts: 1,626	Re: Philips N1500 VCR - Head Drum Servo Fault Hi Keith. I realise it's not terribly scientific (in my book, easy-ness comes before scientific-ness) but if it were mine then my first port of call would be a can of freezer-spray. Do you have the service manual for the set as it's not very easy to identify components on those highly-populated PCBs. Thanks Keith. Kind regards. From Mike. __________________ G7TRF

23rd Nov 2016, 9:41 pm	#3
P.Pilcher Pentode Join Date: Jan 2010 Location: Lichfield, Staffs, UK. Posts: 150	Re: Philips N1500 VCR - Head Drum Servo Fault I don't know to what extent this will help but the N1500 was my first ever VCR which I bought 2nd. hand from a telly/radio shop in about 1978. It soon developed the fault of uncontrollable frame slip which I eventually traced to total loss of eddy current braking of the drum motor. The electromagnets are connected to a small board which is supposed to supply the necessary current and it was obvious that many repairs had been attempted here before. On close and careful examination of this board it was found that a lead from each of the output transistors had never been soldered in during manufacture. A cleanup and a blob of solder on each connection point of the PCB restored normal operation. Careful movement of each component should reveal if this is the case with your unit. The other stock fault on this unit which happened to me was intermittent failure of the main rectifiers which caused the whole unit to trip out (when recording of course). Replacement was the appropriate cure. P.P. __________________ "Ohm's law rules here" - Oxygen free speaker cable not required! (Quote: Quad Service lab)