Philips N2202 - UK Vintage Radio Repair and Restoration Discussion Forum

briskly · 29th Apr 2012, 11:32 am

I'm trying to repair my old Philips N2202 cassette recorder. I posted a question on a side thread a few days ago but maybe it is better to post on a new thread.

Initially I was trying to fix the erratic motor speed, and managed to do do thisafter help from the forum by fitting a new 100R pot on the motor board. But then the audio stating cutting out - record and playback. I noticed that some of the tracking had started to peel away on the audio board, near the end neares the control stick on the motor board side and including a connection to what looks like one of the first transistors. I tried putting a small piece of wire in place of the track, and the sound came back briefly, but the tracking is so small here I think I may have accidentally joined some track together and now there is no sound (but always a small click on switching to play, so I think the output transistors are OK). Does anyone have a pic of the circuit board I can check for reference and any tips on taking the board out for repair - it isn't that obvious to me how to lift it from the chassis. Would very much appreciate any help!

Refugee · 29th Apr 2012, 2:05 pm

If I repair a Philips PCB of that age I will link from the existing soldered joint to one ob the other side of the crack with flexible wire. Use Araldite to hold the broken bit in place if it carries any components and link all of them.

camtechman · 30th Apr 2012, 2:12 am

Altough you may have dodgy tracks elsewhere, it's worth spraying the volume control track with some switch cleaner and also make sure that the fixing nut and mounting bracket that holds the volume control is also secured, as well as checking the pcb tracks that connect to the volume pot. This can often lead to audio cut out.

camtechman · 30th Apr 2012, 2:36 am

Here's a picture of an N2202's internals but, like the EL3302 series (which it derives from & is also a cosmetic update) Philips made several updates during production, and this included the pcb layout & design and so, the one in the picture may not be exactly the one fitted to yours.

The extra wires seen in the photo have been added by the owner and not by me, as this is not my photo, it came from the web.

Note, the more common model, was the N2203 but this is an entirely different model to the N2202. The N2202 has a Manual Record Level (as does the EL33XX series), whereas the N2203 has Auto Record Level and hence, no record level control.

The N2203 was notorious for problems & failures with it's Auto Record Level system!

tri-comp · 30th Apr 2012, 6:23 am

You may be able to get something usefull from this:

http://www.petervis.com/Tape%20Recor...20EL-3302.html

rgds,

/tri-comp

PaulE27 · 30th Apr 2012, 8:58 am

Here's a scan of the PCB from the N2202 service manual - good luck.

Paul

PS Drop me a PM if you need higher res version.

briskly · 30th Apr 2012, 10:23 am

Thanks for all the help - now armed with pics, circuit and pcb layout I'm going to wait for a calm day and try to fix it!

briskly · 1st May 2012, 12:11 pm

Well, I've repaired the track but I'm only getting an extremely low (almost inaudible) sound from the speaker. I've measured the voltages at the transistors in the area of the danaged track and found the collector voltage at T428 way off at 1.4V instead of 4.1V. The base voltages are also too high at 1.9V for T428 (instead of 1.28V), 1.24V for T427 (should be 0.25V) and 0.6V for T426 (should be 0.37V). I'm wondering if these transistors have blown?

ricard · 1st May 2012, 9:34 pm

You could always measure the base-emitter and base-collector diodes in the transistors with a multimeter (possibly after having disconnected them, but reasonable measurements can often be had by measuring them in situ). If there's a short or o/c it should be obvious.

briskly · 17th Jun 2012, 11:32 am

I've finally managed to fix the audio side - I put a BC184C (all I had to hand) in place of the the old BC148A (T427 on the circuit) and all is fine, except at near max volume when I get a rumblng sound and heavy current drain - maybe should I get a more suitable transistor?

But I'm still getting a lot of speed variation - it starts slow and gradually speeds up over 10 minutes or so. I've measured the motor control board coil (R577) and this is reading 108K instead of 130R. Presumbly this is causing the problem. Would anyone know where I can get a replacement?

Thanks

'LIVEWIRE?' · 17th Jun 2012, 12:21 pm

Unless one of the component suppliers, such ashttp://www.rapidonline.com,www.cricklewoodelectronics.co.uk, etc.
stock a similar choke, you will have to bypass it, either with a wire link, or, perhaps better with a 120 ohm resistor. From your measurement, r577 is open circuit, so will be the cause of the fault. As to the BC184C, it should be a suitable replacement for a 148, though it will almost certainly have higher gain(hfe). Are the voltage readings now correct at the o/p stage?

briskly · 17th Jun 2012, 2:20 pm

Thanks Livewire,

I'll try using 120 ohm resistor until I can find a choke.

The voltage reading for the base on the BC184C is a bit high - 0.53V instead of 0.26V. The collector voltage is just a bit lower at 1.16V instead of 1.26V. I've wired it above the board (as viewed from taking the rear cover off) for expediency - perhaps I should make a better job taking the old transistor out and soldering it in its place - maybe that is causing some of the odd noise at high volume?

ricard · 18th Jun 2012, 11:03 pm

0.53 V sounds like a much more reasonable base-emitter voltage for a silicon transistor such as the BC184 or BC148 than 0.26 V, and hence base voltage measurement as T427's emitter is grounded. I wonder if it could be a misprint. 0.26 V would have been reasonable for a germanium transistor.

I wouldn't think the exact type would be critical, they're both small-signal silicon transistors. The letter at the end of the BC148A designation is the gain class, with A being the lowest and C the highest. I assume it's the same with the BC148. Substituting a higher-gain version should be ok as the gain is normally limited by the biasing arrangement anyway.

Interesting in this model how it's the push-pull output stage that drives the head in record mode.

29th Apr 2012, 11:32 am	#1
briskly Retired Dormant Member Join Date: Oct 2010 Location: Chelmsford, Essex, UK. Posts: 98	Philips N2202 I'm trying to repair my old Philips N2202 cassette recorder. I posted a question on a side thread a few days ago but maybe it is better to post on a new thread. Initially I was trying to fix the erratic motor speed, and managed to do do thisafter help from the forum by fitting a new 100R pot on the motor board. But then the audio stating cutting out - record and playback. I noticed that some of the tracking had started to peel away on the audio board, near the end neares the control stick on the motor board side and including a connection to what looks like one of the first transistors. I tried putting a small piece of wire in place of the track, and the sound came back briefly, but the tracking is so small here I think I may have accidentally joined some track together and now there is no sound (but always a small click on switching to play, so I think the output transistors are OK). Does anyone have a pic of the circuit board I can check for reference and any tips on taking the board out for repair - it isn't that obvious to me how to lift it from the chassis. Would very much appreciate any help!

29th Apr 2012, 2:05 pm	#2
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Philips N2202 If I repair a Philips PCB of that age I will link from the existing soldered joint to one ob the other side of the crack with flexible wire. Use Araldite to hold the broken bit in place if it carries any components and link all of them.

30th Apr 2012, 2:12 am	#3
camtechman Nonode Join Date: Jan 2008 Location: Milton Keynes, Bucks. UK. Posts: 2,552	Re: Philips N2202 Altough you may have dodgy tracks elsewhere, it's worth spraying the volume control track with some switch cleaner and also make sure that the fixing nut and mounting bracket that holds the volume control is also secured, as well as checking the pcb tracks that connect to the volume pot. This can often lead to audio cut out. __________________ When I die, please don't let my Wife sell my collection for the amount I told her I paid for it!

30th Apr 2012, 2:36 am	#4
camtechman Nonode Join Date: Jan 2008 Location: Milton Keynes, Bucks. UK. Posts: 2,552	Re: Philips N2202 Here's a picture of an N2202's internals but, like the EL3302 series (which it derives from & is also a cosmetic update) Philips made several updates during production, and this included the pcb layout & design and so, the one in the picture may not be exactly the one fitted to yours. The extra wires seen in the photo have been added by the owner and not by me, as this is not my photo, it came from the web. Note, the more common model, was the N2203 but this is an entirely different model to the N2202. The N2202 has a Manual Record Level (as does the EL33XX series), whereas the N2203 has Auto Record Level and hence, no record level control. The N2203 was notorious for problems & failures with it's Auto Record Level system! Attached Thumbnails __________________ When I die, please don't let my Wife sell my collection for the amount I told her I paid for it!

30th Apr 2012, 6:23 am	#5
tri-comp Heptode Join Date: Oct 2008 Location: Aalborg, Denmark Posts: 903	Re: Philips N2202 You may be able to get something usefull from this: http://www.petervis.com/Tape%20Recor...20EL-3302.html rgds, /tri-comp

30th Apr 2012, 8:58 am	#6
PaulE27 Pentode Join Date: Jul 2010 Location: London, UK. Posts: 222	Re: Philips N2202 Here's a scan of the PCB from the N2202 service manual - good luck. Paul PS Drop me a PM if you need higher res version. Attached Thumbnails

30th Apr 2012, 10:23 am	#7
briskly Retired Dormant Member Join Date: Oct 2010 Location: Chelmsford, Essex, UK. Posts: 98	Re: Philips N2202 Thanks for all the help - now armed with pics, circuit and pcb layout I'm going to wait for a calm day and try to fix it!

1st May 2012, 12:11 pm	#8
briskly Retired Dormant Member Join Date: Oct 2010 Location: Chelmsford, Essex, UK. Posts: 98	Re: Philips N2202 Well, I've repaired the track but I'm only getting an extremely low (almost inaudible) sound from the speaker. I've measured the voltages at the transistors in the area of the danaged track and found the collector voltage at T428 way off at 1.4V instead of 4.1V. The base voltages are also too high at 1.9V for T428 (instead of 1.28V), 1.24V for T427 (should be 0.25V) and 0.6V for T426 (should be 0.37V). I'm wondering if these transistors have blown?

1st May 2012, 9:34 pm	#9
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	Re: Philips N2202 You could always measure the base-emitter and base-collector diodes in the transistors with a multimeter (possibly after having disconnected them, but reasonable measurements can often be had by measuring them in situ). If there's a short or o/c it should be obvious.

17th Jun 2012, 11:32 am	#10
briskly Retired Dormant Member Join Date: Oct 2010 Location: Chelmsford, Essex, UK. Posts: 98	Re: Philips N2202 I've finally managed to fix the audio side - I put a BC184C (all I had to hand) in place of the the old BC148A (T427 on the circuit) and all is fine, except at near max volume when I get a rumblng sound and heavy current drain - maybe should I get a more suitable transistor? But I'm still getting a lot of speed variation - it starts slow and gradually speeds up over 10 minutes or so. I've measured the motor control board coil (R577) and this is reading 108K instead of 130R. Presumbly this is causing the problem. Would anyone know where I can get a replacement? Thanks

17th Jun 2012, 12:21 pm	#11
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Philips N2202 Unless one of the component suppliers, such ashttp://www.rapidonline.com,www.cricklewoodelectronics.co.uk, etc. stock a similar choke, you will have to bypass it, either with a wire link, or, perhaps better with a 120 ohm resistor. From your measurement, r577 is open circuit, so will be the cause of the fault. As to the BC184C, it should be a suitable replacement for a 148, though it will almost certainly have higher gain(hfe). Are the voltage readings now correct at the o/p stage?

17th Jun 2012, 2:20 pm	#12
briskly Retired Dormant Member Join Date: Oct 2010 Location: Chelmsford, Essex, UK. Posts: 98	Re: Philips N2202 Thanks Livewire, I'll try using 120 ohm resistor until I can find a choke. The voltage reading for the base on the BC184C is a bit high - 0.53V instead of 0.26V. The collector voltage is just a bit lower at 1.16V instead of 1.26V. I've wired it above the board (as viewed from taking the rear cover off) for expediency - perhaps I should make a better job taking the old transistor out and soldering it in its place - maybe that is causing some of the odd noise at high volume?

18th Jun 2012, 11:03 pm	#13
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	Re: Philips N2202 0.53 V sounds like a much more reasonable base-emitter voltage for a silicon transistor such as the BC184 or BC148 than 0.26 V, and hence base voltage measurement as T427's emitter is grounded. I wonder if it could be a misprint. 0.26 V would have been reasonable for a germanium transistor. I wouldn't think the exact type would be critical, they're both small-signal silicon transistors. The letter at the end of the BC148A designation is the gain class, with A being the lowest and C the highest. I assume it's the same with the BC148. Substituting a higher-gain version should be ok as the gain is normally limited by the biasing arrangement anyway. Interesting in this model how it's the push-pull output stage that drives the head in record mode.