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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
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17th Aug 2018, 10:49 pm | #1 |
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Philips N4510 flip flop transistors
Can I use BC550`s and BC557`s inplace of the BC147`s and AC128`s on this circuit. ? They are just being used as switches so I dont think its going to be critical what you use is it ? Voltage looks like its well within the specs of the BC 550 / 557`s range .
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17th Aug 2018, 11:07 pm | #2 |
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Re: Philips N4510 flip flop transistors
I don't see why not. Just about any transistors should work.
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17th Aug 2018, 11:24 pm | #3 |
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Re: Philips N4510 flip flop transistors
Thanks Paul . I kinda knew that but i`m still at that "i better just check " stage ..haha .
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17th Aug 2018, 11:55 pm | #4 |
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Re: Philips N4510 flip flop transistors
Fixed !
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18th Aug 2018, 4:16 am | #5 |
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Re: Philips N4510 flip flop transistors
Good that it's fixed, but it's worth pointing out that there is something fishy going on in that circuit. Now, why does each flip-flop have one Germanium transistor working against one Silicon one?
Without knowing what the thing does and what it gets connected to, it's impossible to guess what the designer was up to. I assume these flip-flops hold the tape drive status, play, fast forward, rewind. It may be that the germaniul transistors are used for their larger rating for reverse base/emitter voltage than silicon devices. If so, silicon parts could prove unreliable on the left side of each flip-flop. And the plus two volt supply may not let the trick of having a protective diode in series with the base of a silicon transistor work. Just a note of caution. David
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18th Aug 2018, 4:46 am | #6 |
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Re: Philips N4510 flip flop transistors
These flip-flops are odd (well, it's a Philips) and do indeed have a silicon NPN transistor cross-coupled with a germanium PNP one. The outputs (collector of the germanium PNP) drive the deck motors/solenoids.
Originally the NPN transistor was a BC148 (lockfit). Later production models seem to have a BC548 there (which is much the same in a TO92 package). The PNP transistor doesn't have to be germanium, but it does need to be able to switch a fairly high current. I found a BC640 to be a suitable replacement. |
18th Aug 2018, 8:36 am | #7 |
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Re: Philips N4510 flip flop transistors
I wonder if it's to make it come up in a known state.
Graham
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18th Aug 2018, 9:04 am | #8 |
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Re: Philips N4510 flip flop transistors
thanks everyone , i have replaced everything as i said and it is "fixed " but , the lights are certainly now dimmed , so i will be getting some 640`s as tony suggests (i know the pin-out is different)
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18th Aug 2018, 9:06 am | #9 |
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Re: Philips N4510 flip flop transistors
I've just repaired one of these in an N4418, I had an AC128 to hand anyway.
What I found very curious is that these machines were manufactured in 1974/5 long after Germanium technology was ditched in favour of silicon. There must have been higher powered silicon transistors in those days, or was it the PNP version that wasn't so readily available. |
18th Aug 2018, 9:16 am | #10 |
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Re: Philips N4510 flip flop transistors
I was blown away when i opened mine up. The simplicity of the machine with the definite "respect" for the tech . The "bonnet prop" the way the boards connect to the mech , I just love this thing . Totally underrated machine . Sounds amazing too . Was stuck in Rew when I bought it , so I swapped the flip flop boards around and sure enough it started working so it had to be one of the transistors on the flip flop, other than that and the counter belt gone to goo , this thing is in fantastic condition . £40 paid .
Last edited by NorfolkDaveUK; 18th Aug 2018 at 9:24 am. |
18th Aug 2018, 9:28 am | #11 |
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Re: Philips N4510 flip flop transistors
I dont know what these cost at the time, but i'm sure they weren't cheap, Certainly taking plug in modules to a new high! I personally would have preferred heavier duty reel motors directly driving the spools.
As has been said, it is a Philips who seem to love doing things in an unconventional manner. |
18th Aug 2018, 10:09 am | #12 |
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Re: Philips N4510 flip flop transistors
I personally think I would recommend this for a beginner in electronics mainly because they have individual circuits on teeny boards and you can see exactly what each circuit looks like . I certainly found it very informative , sometimes breaking down individual circuits on a board can be quite difficult but not on this . Its a great learning tool for sure .
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18th Aug 2018, 11:16 am | #13 |
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Re: Philips N4510 flip flop transistors
I also love this series of machines. I have an N4510 and an N4450. The former has 2 boards with 3 flipflops on each. The latter is an autoreverse machine with 6 heads (erase, record, play for each direction) and has 2 boards with 4 flip-flops on each one.
Mine both needed a complete set of belts. In the case of the N4510 one of the reel belts had turned to go, the goo has got into the motor and I could not get it to run. In the end a friend in the Netherlands got me a replacement motor (how I do not know!). The other main fault on these machines are the slide switches. It's worth getting the sliders out (they come out and go in from the opposite end to the actuator, if you get it wrong you can damage contacts) and cleaning them with IPA. I fitted BC640s to all the flipflops in both machines and they work well. With 2N3906s (my normal 'TUP' (as Elektor used to put it)) I had odd faults. There are pictures of my machines (in bits) in my flickr account (tony_duell). |
18th Aug 2018, 11:29 am | #14 | |
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Re: Philips N4510 flip flop transistors
Quote:
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18th Aug 2018, 11:35 am | #15 | |
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Re: Philips N4510 flip flop transistors
Quote:
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18th Aug 2018, 3:45 pm | #16 |
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Re: Philips N4510 flip flop transistors
Philips were well known for their "adventurous" designs, but to me our particular interests would have been much the poorer without their influence. However, as one of the driving forces behind semiconductor design and manufacture, they had access to any device they wanted. They would have chosen any particular one for a reason. Whether those reasons are still valid is another matter of course. For the same reason, they were driving the demise of obsolete devices. They would be unlikely to be caught with other than normal levels of surplus, and would have had established channels for disposal.
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18th Aug 2018, 4:33 pm | #17 |
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Re: Philips N4510 flip flop transistors
I must admit to liking (old-ish) Philips designs. This is partly nostalgic -- I learnt electronics from the Philips EE series kits, my first cassette recorder was Philips, so was my first minicomputer (!). But it's more that I like unconventional designs that make me think, particularly (as in the case of the N4510, etc) they work well.
Anyway... I have no idea why they used AC128s in these flip-flops. But I will confirm that, now, they are a common failure and that fortunately a common silicon transistor can be used to replace them. |
18th Aug 2018, 6:50 pm | #18 |
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Re: Philips N4510 flip flop transistors
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18th Aug 2018, 9:22 pm | #19 |
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Re: Philips N4510 flip flop transistors
The ones I bought are ECB so they just need rotating one stop clockwise .
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20th Aug 2018, 2:14 pm | #20 |
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Re: Philips N4510 flip flop transistors
OK just to draw a line under this one , 640`s arrived and fitted . All transport working perfectly even with the wrong belts in there so hopefully once I get the correct belts , we should be all good as far as operating goes .
One strange thing . The machine will FF whether I press FF or REW . Is this likely to be a transistor issue also or do you think its just because the reel belts are shot and the right one has a bit more ooomph (technical term) than the left ? Neither FF OR REW works with the tape in the path (the belts just slip), I have to lift it out to get any movement so the belts are definitely shot . I didnt think the Right motor would operate in REW though and it does . |