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Old 9th Jan 2023, 12:32 pm   #21
Restoration73
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Default Re: Akai 4000DS Mk2 track/head select

I have an original manual. Pull for mono (shown as SPST) connects the lower wiper of
SW4 (Tape-Source) to ground.
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Old 9th Jan 2023, 12:34 pm   #22
DMcMahon
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Default Re: Akai 4000DS Mk2 track/head select

So from Restoration73 Post 19, sounds like early 4000DS (Mk. I) did not have the "Pull for mono use switch", which would explain why I am struggling find it on the Mk. I schematic, maybe the schematic was never updated when the switch was added until the Mk. II came out.

Note - I do not think that the first version of the 4000DS was ever officially referred to as Mk. I in any Akai documentation.

David
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Old 9th Jan 2023, 12:41 pm   #23
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Default Re: Akai 4000DS Mk2 track/head select

Quote:
Originally Posted by Restoration73 View Post
I have an original manual. Pull for mono (shown as SPST) connects the lower wiper of
SW4 (Tape-Source) to ground.

It does on the Mk. II schematic, does your manual show the same for the original 4000DS, i.e. Mk. I ?

David
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Old 9th Jan 2023, 12:49 pm   #24
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Default Re: Akai 4000DS Mk2 track/head select

Quote:
Originally Posted by DMcMahon View Post
I have yet to see/find the "Pull for mono use switch" on the 4000DS schematic, can see it on the Mk. II schematic.
If you're looking at the same schematic I'm looking at you won't find it because there isn't one in that schematic, I suspect it could be because the track switching circuit is different to the later ones, there are some photo's on the web showing an Akai 4000DS without any reference to a pull switch to mute the R channel, an example is shown in the thread linked to below:

https://www.lencoheaven.net/forum/in...?topic=21712.0

The components in the photo I've attached are from an Akai 4000DS MKII, from that it can be seen that the pull switch contacts and wiring are as per the schematic and switch board layout shown in the 4000DS MKII's service manual.

EDIT: Post crossed.

Lawrence.
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Old 9th Jan 2023, 12:50 pm   #25
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Default Re: Akai 4000DS Mk2 track/head select

Rank did quite good copies of Akai manuals (not surprising as they were also Xerox)
but the original DS diagram has the switch drawn in by hand. So this mod predated
MkII models, but I don't know the date. MkII was available in 1973.
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Old 9th Jan 2023, 2:45 pm   #26
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Default Re: Akai 4000DS Mk2 track/head select

Yes I have at least three 4000DS (Mk.I) and fairly sure that all have the pull switch (need to double check to be sure) so knew that it came out before the Mk. 2 (which I have 2 of).

David
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Old 9th Jan 2023, 2:47 pm   #27
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Default Re: Akai 4000DS Mk2 track/head select

It was on the 4000D as well.

David
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Old 9th Jan 2023, 2:47 pm   #28
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Default Re: Akai 4000DS Mk2 track/head select

Quote:
Originally Posted by ms660 View Post
Quote:
Originally Posted by DMcMahon View Post
I have yet to see/find the "Pull for mono use switch" on the 4000DS schematic, can see it on the Mk. II schematic.
If you're looking at the same schematic I'm looking at you won't find it because there isn't one in that schematic, I suspect it could be because the track switching circuit is different to the later ones, there are some photo's on the web showing an Akai 4000DS without any reference to a pull switch to mute the R channel, an example is shown in the thread linked to below:

https://www.lencoheaven.net/forum/in...?topic=21712.0

The components in the photo I've attached are from an Akai 4000DS MKII, from that it can be seen that the pull switch contacts and wiring are as per the schematic and switch board layout shown in the 4000DS MKII's service manual.

EDIT: Post crossed.

Lawrence.
I hope Lawrence you did not disassemble a 4000DS Mk.II to show the wiring connections

David
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Old 9th Jan 2023, 2:58 pm   #29
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Default Re: Akai 4000DS Mk2 track/head select

Quote:
Originally Posted by DMcMahon View Post
I hope Lawrence you did not disassemble a 4000DS Mk.II to show the wiring connections
The photo was from from a completed sale Ebay listing.

Lawrence.
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Old 9th Jan 2023, 3:02 pm   #30
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Default Re: Akai 4000DS Mk2 track/head select

Funny I have an incomplete 4000DS here (no case, knobs, pinch roller) that has the
pull for mono switch. I am not sure if Akai recorded mods issued by serial number.

For example, the X1900D is a combined reel/cassette deck. The manual gives 7.5 and
3.75 ips speed. But mounted in the lid is an extra capstan for 15 ips and a reduced diameter pinch roller. No reference to this option in the manual !
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Old 9th Jan 2023, 4:15 pm   #31
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Default Re: Akai 4000DS Mk2 track/head select

Ref. the integral pull switch and the Akai 4000DS, in a copy of a service manual I have there is no pull switch listed in the spares list for that model but there is for the Akai 4000DS MKII as per the attached shots, 1st shot = 4000DS (Ref. 9-64) 2nd shot = 4000DS MKII (Ref. 9-140x)

I think the pull switch was introduced later on during the production of the Akai 4000DS.

Lawrence.
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Old 9th Jan 2023, 4:32 pm   #32
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Default Re: Akai 4000DS Mk2 track/head select

Quote:
Originally Posted by Restoration73 View Post
Rank did quite good copies of Akai manuals (not surprising as they were also Xerox)
but the original DS diagram has the switch drawn in by hand. So this mod predated
MkII models, but I don't know the date. MkII was available in 1973.
Do you think the hand drawn switch circuitry was done by Rank when they produced the manual or was it possibly added/annotated by a subsequent owner.

I have an original manual with no sign of the pull switch being hand drawn.

David
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Old 9th Jan 2023, 5:41 pm   #33
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Default Re: Akai 4000DS Mk2 track/head select

Just to add to the mix - The 4000D had two versions of the 'mono' switch. The first (as shown in the sales brochure) was operated by turning the right level control fully anti-clockwise:-

Click image for larger version

Name:	S005.png
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ID:	271139

The second the common pull-switch (in a photo from an eBay listing):-

Click image for larger version

Name:	4000D.jpg
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ID:	271136

Once again the relevant switch in the circuit diagram is unlabelled:-

Click image for larger version

Name:	S006.png
Views:	47
Size:	64.9 KB
ID:	271141

Cheers

Last edited by Trigon.; 9th Jan 2023 at 5:51 pm. Reason: Cct added
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Old 9th Jan 2023, 5:43 pm   #34
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Default Re: Akai 4000DS Mk2 track/head select

I think there's an error in the playback track selector circuit in the 4000DS MKII schematic, does anyone else agree?

Lawrence.
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Last edited by ms660; 9th Jan 2023 at 5:50 pm. Reason: Part schematic added
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Old 9th Jan 2023, 6:03 pm   #35
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Default Re: Akai 4000DS Mk2 track/head select

Is it the right channel p/b head ground not connected to the screen on 3-2?
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Old 9th Jan 2023, 6:38 pm   #36
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Default Re: Akai 4000DS Mk2 track/head select

As with any manufacturer, changes may not have gone over directly from one version to another. Sometimes problems are met with the supply of some part and an alternative, sometimes with differences in detailed performance or operation gets substituted and can remain. Mine was an early DS, so I wonder if they intended a slightly more extensive change and then decided soon to revert on cost or supply grounds. Hand-modified diagrams in manuals aren't then so surprising.

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Old 9th Jan 2023, 6:49 pm   #37
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Default Re: Akai 4000DS Mk2 track/head select

Quote:
Originally Posted by Restoration73 View Post
Is it the right channel p/b head ground not connected to the screen on 3-2?
Yes that's it, the lower playback head winding is connected between the signal lines feeding the L and R channel amplifiers when 3-2 is selected.

Lawrence.
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Old 9th Jan 2023, 8:45 pm   #38
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Default Re: Akai 4000DS Mk2 track/head select

Quote:
Originally Posted by Trigon. View Post

Once again the relevant switch in the circuit diagram is unlabelled:-

Attachment 271141

Cheers
Same on the 4000 schematic and similar on the 4000DB schematic, a shame it is not shown on the 4000DS (non Mk. II) schematic.

David
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Old 9th Jan 2023, 10:17 pm   #39
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Default Re: Akai 4000DS Mk2 track/head select

Thanks for all the extra info all.
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