Studer A810 Dead Capstan

[Cristo]

I am hoping the collective experience of the forum will help me solve a major headache.
This morning I decided to remove the MPU and various cards to take with me to the UK (I live in Cyprus), and have an electronics engineer friend recap the eloctrolytic and the Philips/Fracko Caps as per the advice from members.

Prior to their removal, I thought, "Why not remove the rear panel and lubricate the capstan shaft". I slid the retaining aluminium locking plate and removed the black capstan motor shroud. Pulled out the capstan shaft, wiped, lubricated and replaced it.

After replacing everything as was, I find my deck won't play; it FF and reverses, but no play. The PLL yellow light no longer lights up!
Actually, it lights for a few seconds whilst the deck is going through its ‘boot up’; i.e. Immediately after switching on the VU meters do their little ‘thump’ and the firmware version still flashes correctly.
The deck FF and rewinds, but does not play.

Have I missed anything when replacing the black motor shroud, or could anything have blown during the above operation. I have double checked all the ribbon cables in case I accidentally moved one in error.

Cristos

[Waltzingbear]

starting with the basics-

does the capstan motor turn freely by hand?

check for loose connectors, most likely something got bumped.

but all of this is a little odd as you are describing the capstan motor of a Revox machine, not the Studer A810.
The Revox uses a pabst motor with a removable shaft, the A810 uses a sealed motor that should not be taken apart, nor is it that easy to do so. There is no rear clip on the motor.

Alan Garren

[Cristo]

Hi Alan,
Thanks for your post.

I can confirm the deck is a Studer A810. The capstan shaft/black capstan motor shroud spin freely and easily.
The locking bar is on the rear of the capstan motor shroud and slides onto grooves either side of the end of the capstan shaff.
I removed the shaft with the following procedure:
1. Slid off the aluminium retaining/locking bar on the rear of the capstan motor shroud.
2. Removed the blacl capstan motor shroud
3. From the front of the deck, I gently and carefully pulled out the capstan shaft.
 After lubricating it, I reversed the above procedure.

I double checked all nearby connectors...could i have blown a cap/resistor or fuse? No evidence of such a thing occuring.

regards,

Cristo

[Waltzingbear]

did you knock the tach pickup out of alignment?

this will have to be troubleshot with a scope and basic functions in the motor drive checked.

Alan

[Cristo]

I might have done. Unfortunately, i do not know what or where the tach pickup is located, although I strongly suspect the small (tiny), protrusion on the very rear of the capstan shaft tunnel.

I did notice on the inside of the black rotor/capstan motor shroud, where the capstan shaft fits through, thee are 2 small cut outs..but can't seem to figure their purpose.
Unfortunately, I can't post photos larger than a few 100 kn on this forum. Otherwise, i could indicate where I suspect the issue to be.
Might i PM you with photos?

Cristo

[Cristo]

Alan,

Can you please direct me to the relevent page (tach alignment),  in the service manual?

Cristo