Philips GF808 connector question

[RetroRock]

Hi, I am looking into connecting my GF808 to my surround sound system. The deck has 6 pin and 2 pin din connectors, the original speakers that came with it use 2 pin din connectors. I need to be using rca cables so do i just get adaptors and plug straight into a phono pre amp? Or does this model not need the pre amp (I remember something about it maybe having amp built in cant remember). Also is there any bonus to using the 6 pin or were they there for something else? I don't know if they are an input for this player.
Oh and I noticed the arm drops quite fast when engaging, what maintenance needs to be done or is something giving out?
Thanks

[ben]

There should be a line-level (ish) output on the 5 pin DIN connector at the rear of your unit. Best way is probably to buy a DIN to 4xRCA phono cable and try each one until you get the two outputs. Use the line input on your surround amp.

[RetroRock]

Ok if that has line level then that would be excellent, thanks i will get that cable and give it a try
Are you sure I need the 4 cable as i see there is also a 2 cable option?

[RetroRock]

I also just thought the connectors are in pairs for each speaker, what should i do for this so that i get a complete signal through rather than each side?

[Edward Huggins]

Did you say a 6 pin connector? You will need a 5 pin DIN to 2 x RCA Phono socket connctor (Maplins). Your Surround Sound system is highly unlikely to have any kind of RIAA Phono input, so just use the Aux input socket on its amplifier.

[paulsherwin]

Some of them do have phono inputs, but it isn't suitable in this case.

[RetroRock]

Edward huggins, the player dosnt have any other ports but the din ones, no jack connectors unfortunately.
I meant 5 pin
Ok so in this case i should use the aux connection not the phono?
As the player has 2 5 pin plugs for each speaker i assume, would i need to connect both plugs to the surround sound or will i need another adaptor?

[Edward Huggins]

I suspect some confusion is creeping in here. You are right in that there are no RCA/Phono sockets at the rear of your Philips. Your Philips unit will have a 5 pin din socket at the rear to be used for feeding a signal into a tape recorder. Use this socket to feed a signal into your Aux/Line input on your surround sound ampilfier i.e a 5 pin din plug in the Philips and 2 x RCA plugs into your surround unit. (NOTE: If your Surround Sound unit does have sockets marked "Phono", the signal from the Philips tape socket might overload this). The Philips player does not have 2 x 5 pin sockets for the speakers, it has 2 x 2 pin sockets.

[RetroRock]

ok, i was a little confused.
Just to add, there are 2x5 pin connectors which was my initial confusion i guess they must be for multiple devises 2 tape decks for example.
So if there is no phono port it may overload, is there any way around this? as i thought vinyl players out put too low a signal for anything but the phono port, for example i heard it would play quietly through an aux port so i would possibly need a phono pre amp.

[RetroRock]

ah never mind i just re read what you put, sorry for the confusion. ok thanks good to know i wont need a phono pre amp (saves me money)

[RetroRock]

Final question on this, and thank you all for helping me I apologise for my ignorance of these connections and the player
Do I want to get the 5 pin to 4 rca or to 2 rca? or does it not make a difference

[Radio Wrangler]

Get a 5-pin DIN to 4 phono plugs cable.

There are four signal pins and one common ground in a 5-pin DIN. If you buy a 5pin DIN to two phono plugs cable, you have to worry about whether those two phonos are connected to the right pair of signal pins in the DIN. With the four phono plug cable, you get them all, and then you can try each plug in turn to find out which two have the signal you want. The other two you just don't use. Tape them up or something to prevent them making contact with anything.

The word "phono" has come to have two meanings and causes a lot of confusion. It was short for phonograph and in America, that meant a record player. They got it wrong because phonograph was Mr Edison's name for his machine which played cylindrical records. "Gramophone" was Mr Berliner's name for his machine which played flat disc-shaped records.
Anyway, RCA in America designed a cheap, pressed-metal connector to handle screened wires for the very small signals from the cartridge of a record turntable. They were dirt cheap and worked well, so they caught on.

People started using RCA Phono plugs for all sorts of other audio signals (and video in consumer gear)

So if someone says an amplifier has phono inputs, you don't know for sure whether he means it has special inputs for the tiny signals from a record-player cartridge, or whether it has who-knows-what level of signal inputs that just happen to be connected through RCA type phono connectors. You have to find out from the context, or dig a bit deeper.

For completeness, I'd better say that there are four types of record playing cartridge, and they all need different circuitry to handle them: Crystal, Ceramic, Moving-magnet, and Moving-coil. So where 'phono' means for a record player you still have to dig a bit deeper to find which things will work together.

The differences can be quite large. A CD player typically gives about 2 volts of signal on its phono connectors. A record turntable with a moving coil cartridge typically gives 0.0001 volts output on its phono connectors.

David

[Synchrodyne]

Something else to consider is that the 5-pin DIN socket might have been intended primarily for direct interconnection with a tape recorder. If so, whilst the input (taking a signal from a tape recorder) is likely to be of the conventional “line” type, the output (delivering a signal to a tape recorder) might well be of the DIN “constant current” type, incorporating a high resistance (it could be 470k or higher) in series with the signal feed. This would cause significant attenuation of the signal, perhaps to the point where it was inadequate to drive a typical line input on an external amplifier. (For tape recorders with “DIN” inputs, that is not a problem as such inputs are designed to accepts signals down towards microphone level, with sensitivities of around 2 mV.)

Where such tape outputs are fed from relatively low impedance internal amplifier stages, and not direct from input sources, those high resistances probably could be shunted by much lower resistances. But for a unit like the one at interest, it is quite possible, perhaps even probable that the tape outputs are fed directly from the cartridge, in which case cartridge loading would be upset, deleteriously so, if those high resistances were bypassed.


Cheers,

[TonyDuell]

The service manual for this player is on vinylengine. It's in German, but the circuit diagram is pretty much the same in any language.

According to the diagram there are 2 5 pin DIN sockets. One is for a tuner, and is input-only (it uses the amplifier and speakers of the player to reproduce the output of the tuner). The other is for a tape recorder and is both an input (to replay a tape through the player's amplifier and speakers) and an output (to record a record). That's the one you want. The signals are pins 1 (left channel) and 4 (right channel) with pin 2 as earth (as normal -- note that the pins are numbered in the order 1, 4, 2, 5, 3). And yes it is a 'constant current DIN' output, there's a 1M5 resistor in series with the output singals. But it does come after the (2 transistor per channel) preamplifier stage, not straight from the cartridge, so there's probably no problem in reducing the value of said resistors if you have to.

[RetroRock]

I have found an instructions in english, it says a max of 470kohms resistance from the tape recorder port.
I dont understand the previous comment (my electrical knowledge is lacking) when you are saying there would be probably no issue with reducing the resistance, are you meaning on the internal resistance or the resistance caused by the surround system?

[Synchrodyne]

I have since found a schematic for the GF808, snippet attached:



This shows the 1M5 series resistors in the tape output circuit. Primarily they are there to provide the DIN constant current characteristic.

Say for example there is 100 mV of average programme signal available at the input to those resistors. And say also that the external surround sound amplifier input has a resistance of 100k. Then the available signal divides between the 1M5 and 100k resistances in direct proportion, so 94 mV across the 1M5 and just 6 mV across the 100k. But the amplifier input would probably need most of the 100 mV to provide adequate volume at reasonable volume control settings; 6 mV would be far too little.

If the only function of those 1M5 resistors is to provide a DIN-type tape output, then they are non-critical, and could be replaced by say 10k resistors (which would provide reasonable standoff protection for the GF808 circuitry). More simply, 10k resistors could be wired in parallel with the existing 1M5 resistors.

Originally Posted by RetroRock

I dont understand the previous comment (my electrical knowledge is lacking) when you are saying there would be probably no issue with reducing the resistance, are you meaning on the internal resistance or the resistance caused by the surround system?

So that earlier comment applied to the internal resistors in the GF808 tape output circuit, not those in the surround sound amplifier input.

The information I have found indicates that a preamplifier (GH911) was used with some of the pickup cartridges that may be fitted, namely those of the “hi-fi” type, but not with all cartridges. If your unit has a preamplifier, then as Tony Duell has said, there should be no problem with replacing those 1M5 resistors with two of much lower value. But if it does not have a preamplifier, then those resistors have a second function of ensuring that load impedance seen by the cartridge does not drop low enough to affect sound quality. I suspect that the relatively high 1M5 value was chosen for cartridge loading protection when the preamplifier was not fitted, so any non-negligible reduction would be unwelcome.

I’d guess that the preamplifier would be a separate small circuit board, probably fitted close to where the wires emerge from the tone arm support.


Cheers,

[Edward Huggins]

There might be some information overload here for the OP. In my time with Philips, the tape output signal in their Budget and Mid-Range units was usually quite sufficient to load the DIN input sockets of their Cassette and Reel-to-Reel recorders. Suggest the OP tries this out first to check the signal level into his surround system, using its Aux/Line input and using the DIN to RCA adaptor as previously advised.

[paulsherwin]

Agreed, just try it before worrying about anything else, it will probably be fine. What Synchrodyne and others are saying is that the circuit can be easily modified if the result sounds too quiet.