SP25 MKIV switching off

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Jon123
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SP25 MKIV switching off

Post by Jon123 » 02 Nov 2019 16:05

Hi - I have just reinstated the auto function on this deck, normal problem with the trip pawl. All ok except that when the tone arm drops down onto the record the deck switches off. I never saw this fault before has anyone any idea please?
Jon

A70BBen
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Re: SP25 MKIV switching off

Post by A70BBen » 07 Nov 2019 15:49

Yes. There are linkages under the OFF-ON-AUTO control that get gummed up. One in particular gets too sluggish to move under tension of the spring that "pulls" it when you stroke the control. Check down there.

The exact problem with the SP25 Mk III, IV, V and VI, 135SB, 35SB and the various Belt Drive models is referenced, with illustrations, at a UK audio repair Tboard but I don't have its password on this phone. I'll have to look it up.

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Re: SP25 MKIV switching off

Post by A70BBen » 08 Nov 2019 07:09

Here is the item I was referring to. It does not refer to your SPECIFIC problem but the description of the repair could help. A sticking or bent shutoff/record size lever (C-D) could cause your problem.

When a normally functioning SP25 Mk III (or any of the SP25 Mk III through VI, 125SB, 35SB and the Belt Drive models with automatic single play) is switched to AUTO, the unit is supposed to start running; the arm lifts and automatically begins play. The SP25 Mk III under discussion didn't do that; the arm would always return to its rest and the turntable would shut off. This guide describes the most common malfunction that causes this problem. Like most other problems with these otherwise reliable and very popular Garrards, it is caused by the old lube grease drying out over many years. Refer to the attached photo of the bottom of an SP25 Mk III.

The mechanism is designed to operate as follows:

When you push the operating lever to AUTO, Pin A, which is attached to it, moves to the RIGHT. Pin A in the cutout in lever B has been holding lever B from moving, but when Pin A reaches the broader cutout area, lever B is allowed to move anticlockwise around its pivot E, under tension from spring F. The opposite end of lever B swings to the right and pushes lever C, the shutoff/record size lever, whose opposite end D then moves to its RUN position.

If lever B does not pivot anticlockwise because its pivot E is sticking or spring F is missing or damaged, the shutoff/record size lever C-D will remain in its SHUTOFF position. The turntable will always shut off and the arm will not set down. A sticking pivot E is the most frequent cause of the problem reported.

I would first remove the circlip securing lever B at its pivot E, and service that pivot with some solvent and oil so that it moves freely and its spring F can move it. You may be able to do this without completely removing lever B. If you do remove lever B, be careful as you do not want to stretch the spring F. If this does not solve the problem, check the shutoff/record size lever C-D and see that it moves freely but under spring tension. If not, service its pivot, which is much more difficult to reach.

This repair guide applies to the SP25 Mk III through VI, the 125SB, 35SB and the Belt Drive models with automatic single play. It does not apply to the related record changer models SL65B, SL55B, 40B and the SP20B, nor to the SP25 and SP25 Mk II, which do not have automatic single play.
SP25 III under.jpg
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DSJR
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Re: SP25 MKIV switching off

Post by DSJR » 08 Nov 2019 09:34

As a P.S. I think it's simpler to see than describe (well done A70BBen as I couldn't possibly have described it so well) ;)

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Re: SP25 MKIV switching off

Post by A70BBen » 12 Nov 2019 09:14

A lot of record changer fixes are better seen than written and described but being able to look at a mechanism, figure out how it is supposed to function and diagnose why it doesn't, requires a certain talent!

Some Garrard service manuals assume that the servicer possesses that talent, as they don't describe the step-by-step function of the mechanism...example is the Lab 80. Some do, both older (Type A) and newer (GT35).

amagasakii
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Re: SP25 MKIV switching off

Post by amagasakii » 13 Nov 2019 04:33

A70BBen wrote:
12 Nov 2019 09:14
A lot of record changer fixes are better seen than written and described but being able to look at a mechanism, figure out how it is supposed to function and diagnose why it doesn't, requires a certain talent!

Some Garrard service manuals assume that the servicer possesses that talent, as they don't describe the step-by-step function of the mechanism...example is the Lab 80. Some do, both older (Type A) and newer (GT35).
You definitely have the talent! My favourite are the Dual service manuals that are written like a novel: Don't you remember Secondary Cam Release Spring? We introduced it back on page 14, and it's integral to the plot at this point. It's Part 217, we'll wait while you go look...

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