Philips N4418 R2R Fault Finding

[DMcMahon]

I am considering purchasing one of these nice looking recorders, the one I am specifically looking at powers up but the tape transport does not work at all and the unit is always in Pause mode.

I know this model like some other Philips models uses the infamous "Flip Flop" boards as part of the tape control system electronics.

Cannot really tell from the service manual drawings but am wondering how easy or difficult it is to do live fault finding on the electronics particularly the Flip Flop boards, i.e. how practical it is to connect meter/scope etc test probes/leads for monitoring fault finding.

David

Edit Update - I do not why I typed Sony in the title ! can the mods please edit it to Philips.

[Sideband]

First thing is to check the rectifiers. If one supply goes down it can cause all sorts of weird faults.

[Sideband]

Originally Posted by DMcMahon

Cannot really tell from the service manual drawings but am wondering how easy or difficult it is to do live fault finding on the electronics particularly the Flip Flop boards, i.e. how practical it is to connect meter/scope etc test probes/leads for monitoring fault finding.

You probably only need a meter to check if they are working OK.

[Chris55000]

These series of machines have a special "service" position moulded into the cabinet sides and supports to allow you to operate the machine with the deck in the vertical "service" position and the leads/cable–forms are made long enough for you to operate the machine with the deck in the "service" position!

The oscillator and a number of other circuits are on pluggable modules that can be removed to service them, and I think there is a German document with a circuit description and diagrams of the modules free on the net!

The 'N4418 is a very well regarded machine with higher–power output stages than the 'N4416 and it is a three–head machine, so separate record monitoring is possible!

Go for it!

Chris Williams

[Chris55000]

. . .I recommend you get the N4418 Service Manual from HiFi Engine – its a good one with some colour–scanned bits, unfortunately it doesn't have the internal circuits of the modules but there are other documents available with this information online!

Chris Williams

[DMcMahon]

Thank you everybody for the useful inputs.

I do have the Service Manual from hifiengine plus others.

David

[Chris55000]

PS!

It's worth downloading the S.M. marked with the German Flag on HiFi Engine as this lovely coloured book includes a schematic of the wired remote accessory N6719 if you fancy making one!

Chris Williams

[DMcMahon]

Thank you Chris, now have it, yes the coloured drawings are good, so is the coloured German "schematics" document, I doubt I would ever get around to the wired remote accessory but good to have it for reference.

David

[DMcMahon]

Originally Posted by Sideband

You probably only need a meter to check if they are working OK.

Yes agreed, can be useful sometimes to check with scope as well as the DC levels, to visually see if any unwanted AC/noise present on the DC control voltages.

David

[DMcMahon]

Originally Posted by Chris55000

Go for it!

Chris Williams

I have bid on it, in fact currently have the winning bid but there are 2 others bidding so I may well lose it.

David

[DMcMahon]

Originally Posted by Sideband

First thing is to check the rectifiers. If one supply goes down it can cause all sorts of weird faults.

Thankyou, yes will carefully check all the various DC supply rails.

David

[DMcMahon]

Lost out on the auction bidding on the one I was following so unlikely now to be getting one any time soon.

David