Sansui reel - to - reel question

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A quad reel would definately help narrow this problem down.
 
+1 on the quad reel idea. Also, if playing a 2ch stereo tape with music on both sides (FF the tape if side 2 is shorter than side 1 to hear the end of the 2nd side) shouldn't you hear backwards music in the rears when the 2/4 channel switch is in the 4 channel position? I don't know the architecture of Sansui reel decks but if they used relays for channel switching and one contact is stuck that could cause a channel switching problem.
 
yes if you put it on 4 channel, plug the output in the rear outs, you hear music backwards (in forwards mode)
 
OK, I think I get it. An Auto reverse deck must have relays.
Do you have the 2/4 switch in the 4 ch. position while listening to FWD and REV with a stereo tape? If so, what happens when the switch is in the 2 ch. position with the same stereo tape?
I'm thinking the switch might be in the 2 ch. setting as it should be for a stereo tape but try it also in the 4ch. position which means you should hear Side 2 backwards in the rear speakers in decks I have used, just as a test.
If the deck is set to play in reverse with a quad tape then all four channels would be backwards.
 
yes if you put it on 4 channel, plug the output in the rear outs, you hear music backwards (in forwards mode)
What happens in reverse mode with the same tape? Rears should be forwards and fronts playing backwards. It seems it will play a quad tape in forward just fine and the problem is in the reverse switching.
 
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ok I hope i get this right, and this is for a STEREO tape, ill try a quad when i get one

Forward play
Front Left - Plays left channel
Front Right - Plays right channel
Rear left - plays left backwards
Rear right - plays right backwards

everything there is as expected

Reverse mode
Front left - nothing
Front right - PLays right corrently
Rear left - plays left channel correctly
Rear right - nothing
 
ok I hope i get this right, and this is for a STEREO tape, ill try a quad when i get one

Forward play
Front Left - Plays left channel
Front Right - Plays right channel
Rear left - plays left backwards
Rear right - plays right backwards

everything there is as expected

Reverse mode
Front left - nothing
Front right - PLays right corrently
Rear left - plays left channel correctly
Rear right - nothing

That's baffling because it seems like it is doing everything it should do in the Forward mode. The possible good news is it seems like it should play quad reels just fine.
 
You really don't even need to get a quad reel at this point. We know the issue. There is something wrong with the audio routing when played in reverse. This probably has to do with the internal switching system that routes the audio from the different channels between forward and reverse. Does anyone know what component(s) handle this and how to locate and possibly clean or replace them?
 
It seems likely that the switching is done with relays. I looked in the usual sources for a manual or schematic and can't find one. There was a mention on AK of someone had it in PDF, but I shy away from that place. There's only so much spare time and AK could be a huge rabbit hole for me!
 
The QD5500 plays tracks one (left front) and track three (right front) when in forward motion and with tracks two and four playing backwards if set in four channel mode.

The intention is that it should be set in two channel mode if a two channel tape is being played.

As I have three of them (one the silver QD5500S) and none have been interfered with the S model from new in 1973; the switching is carried out by relays.

Sansui was heavily into relays whilst its deck supplier Nakamichi used solenoid transports.

The decks came off the market when the latter no longer produced them and went to market with its own brand of open reel beating cassette tape machines.

The let down is the soft permalloy heads and long term wear caused by abrasive tape, particularly FE2O3 ferrous/chrome dioxide tape, popular in the 1970's.

Hope that this helps. Working properly with the reel cover and remote control they look and sound excellent.

Best wishes.
 
Hi, I am sure there is a more suitable part of the forum to ask this question but...here it goes:

In quad, how are tracks assigned on reel tape? I would venture to guess that tracks 1 and 3 are front left and right and 2 and 4 rear left and right. Is that so?

It is confusing because if this were 2CH, when the tape is flipped, track 4 would become track 1 and that would be left, not right. In other words in 2CH, left channel is always at the outer edge of the tape, whereas the two right channels are next to each other in the middle. There is no reason this should be followed in quad -- since the tape would not play properly if flipped -- but who knows...

I thought this would be easy to find on the web but, alas, no. I have been looking for hours. So I would really appreciate a response.
 
I have two Akai GX 270D-SS and that's how it's set up.

You are correct Top Tip.

When I first saw the video I was a bit suspicious of the tape he was using.
 
Hi, I am sure there is a more suitable part of the forum to ask this question but...here it goes:

In quad, how are tracks assigned on reel tape? I would venture to guess that tracks 1 and 3 are front left and right and 2 and 4 rear left and right. Is that so?

It is confusing because if this were 2CH, when the tape is flipped, track 4 would become track 1 and that would be left, not right. In other words in 2CH, left channel is always at the outer edge of the tape, whereas the two right channels are next to each other in the middle. There is no reason this should be followed in quad -- since the tape would not play properly if flipped -- but who knows...

I thought this would be easy to find on the web but, alas, no. I have been looking for hours. So I would really appreciate a response.

You are correct tracks 1 and 3 are front left and right and 2 and 4 rear left and right. Here is a page from a Service Manual, showing the track assignment.
 

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It is confusing because if this were 2CH, when the tape is flipped, track 4 would become track 1 and that would be left, not right. In other words in 2CH, left channel is always at the outer edge of the tape, whereas the two right channels are next to each other in the middle. There is no reason this should be followed in quad -- since the tape would not play properly if flipped -- but who knows...

If I understand what you're saying correctly, this arrangement might be counterintuitive from a purely quadraphonic standpoint, but it probably made the design and function of the stereo/quad switch much simpler. For quad, everything remains where it always was for stereo, but now you have two more tracks without the need to re-route anything.
 
As the tape is never flipped in Quad mode, I don't really see what is confusing or counter-intuitive about the track arrangement other than that track 3 is Rf not track 2; but that is done to remain compatible with stereo. The back channels are track 2 and track 4 L & R, it makes sense to me.
 
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