STUDER B67 MKI-supply reel won't spin when play pressed. - UK Vintage Radio Repair and Restoration Discussion Forum

scottdude · 15th Oct 2018, 3:48 am

I recently replaced the power transistor MJ411 for the supply reel for my Studer B 67 MkI. The original finally died, the sign being as when you power up the machine, the supply reel spins uncontrollably. I've replaced them in the past to resolve this issue with no major problem.

This time, it's a little different.

When I installed the new power resistor, on power up, it doesn't spin, which is a good sign things are working, but once you press play, the brakes release, but it doesn't spin at all. It just sits there, easily movable, but it should be spinning when play it pressed as that is normal operation.

flipping the transistor equals to shorting it out and the motor spins fine, so one would think the motor is not the issue.

Going over the manual for wire placement specs for the supply motor board It seems the wiring is correct for the wires I actually touched, so I am at a loss as to where to start to troubleshoot this issue really. I've never had this problem replacing any of the power transistors previously.

Any assistance for a starting point would be appreciated. It's a good machine and would like to get it up and running again.

Michael Maurice · 15th Oct 2018, 5:12 am

I was in Halifax a few days ago on a cruise, but wouldn't have had time to sort out your problem.

The most likely cause is a blown TCA561, there are as rare as hens teeth. First you MUST replace every RIFA cap on the motor supply boards and the relay board, do this before you do anything else.

Now disconnect the feed from the main logic board which connects to the base of the MJ411 (I'm in NYC at the moment so don't have access to a manual) Switch the machine on and press play, measure the voltage on this connector, it should go high, if it does then there's a possibility that the new MJ411 is duff.

You can also swap the two TCA's over, if the take up spool stops rotating, you know its that, if the left hand spool still won't rotate then the TCA is blameless and the fault lies elsewhere.

scottdude · 15th Oct 2018, 1:25 pm

Thank you for the assistance. I hope you had a chance to get off the ship and enjoy some of the city when the ship was in port. It's a busy time for cruise ships in September and October.

Sounds like there isn't a suitable substitute for the TCA 561, you'd think there would be given the popularity of studer even today.

scottdude · 31st Jan 2019, 4:14 am

well, after pulling the control board out of the deck, replacing a transistor I accidently broke, and flip flopping the TCA 561 IC's the deck transport is completely dead. I also accidently managed to unscrew the button off the board, but those were easy enough to replace again, but it still is dead. I'm concerned that the TCA 561 IC's are toast....not sure if you can actually test them to find out short of replacing them, as searching online suggest a few methods, but nothing absolute.

I'm open to suggestions on what my next steps might be. scrap the deck, or put $$ in it.

Restoration73 · 31st Jan 2019, 7:12 am

I have not tried this supplier, might be a possible source of info;

https://nagravox.com/products/tca-56...studer-a67-b67

scottdude · 31st Jan 2019, 3:17 pm

nagravox seems to be more about selling parts then anything else....and implies that it's a risk if you go to anyone else for the TCA561 chip, which may be right, but their tone in their details on the website seems more about almost threatening you...which really turns me off I admit.

15th Oct 2018, 3:48 am	#1
scottdude Retired Dormant Member Join Date: Jan 2008 Location: Halifax, NS Canada Posts: 14	STUDER B67 MKI-supply reel won't spin when play pressed. I recently replaced the power transistor MJ411 for the supply reel for my Studer B 67 MkI. The original finally died, the sign being as when you power up the machine, the supply reel spins uncontrollably. I've replaced them in the past to resolve this issue with no major problem. This time, it's a little different. When I installed the new power resistor, on power up, it doesn't spin, which is a good sign things are working, but once you press play, the brakes release, but it doesn't spin at all. It just sits there, easily movable, but it should be spinning when play it pressed as that is normal operation. flipping the transistor equals to shorting it out and the motor spins fine, so one would think the motor is not the issue. Going over the manual for wire placement specs for the supply motor board It seems the wiring is correct for the wires I actually touched, so I am at a loss as to where to start to troubleshoot this issue really. I've never had this problem replacing any of the power transistors previously. Any assistance for a starting point would be appreciated. It's a good machine and would like to get it up and running again.

15th Oct 2018, 5:12 am	#2
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,222	Re: STUDER B67 MKI-supply reel won't spin when play pressed. I was in Halifax a few days ago on a cruise, but wouldn't have had time to sort out your problem. The most likely cause is a blown TCA561, there are as rare as hens teeth. First you MUST replace every RIFA cap on the motor supply boards and the relay board, do this before you do anything else. Now disconnect the feed from the main logic board which connects to the base of the MJ411 (I'm in NYC at the moment so don't have access to a manual) Switch the machine on and press play, measure the voltage on this connector, it should go high, if it does then there's a possibility that the new MJ411 is duff. You can also swap the two TCA's over, if the take up spool stops rotating, you know its that, if the left hand spool still won't rotate then the TCA is blameless and the fault lies elsewhere. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

15th Oct 2018, 1:25 pm	#3
scottdude Retired Dormant Member Join Date: Jan 2008 Location: Halifax, NS Canada Posts: 14	Re: STUDER B67 MKI-supply reel won't spin when play pressed. Thank you for the assistance. I hope you had a chance to get off the ship and enjoy some of the city when the ship was in port. It's a busy time for cruise ships in September and October. Sounds like there isn't a suitable substitute for the TCA 561, you'd think there would be given the popularity of studer even today.

31st Jan 2019, 4:14 am	#4
scottdude Retired Dormant Member Join Date: Jan 2008 Location: Halifax, NS Canada Posts: 14	Re: STUDER B67 MKI-supply reel won't spin when play pressed. well, after pulling the control board out of the deck, replacing a transistor I accidently broke, and flip flopping the TCA 561 IC's the deck transport is completely dead. I also accidently managed to unscrew the button off the board, but those were easy enough to replace again, but it still is dead. I'm concerned that the TCA 561 IC's are toast....not sure if you can actually test them to find out short of replacing them, as searching online suggest a few methods, but nothing absolute. I'm open to suggestions on what my next steps might be. scrap the deck, or put $$ in it.

31st Jan 2019, 7:12 am	#5
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: STUDER B67 MKI-supply reel won't spin when play pressed. I have not tried this supplier, might be a possible source of info; https://nagravox.com/products/tca-56...studer-a67-b67

31st Jan 2019, 3:17 pm	#6
scottdude Retired Dormant Member Join Date: Jan 2008 Location: Halifax, NS Canada Posts: 14	Re: STUDER B67 MKI-supply reel won't spin when play pressed. nagravox seems to be more about selling parts then anything else....and implies that it's a risk if you go to anyone else for the TCA561 chip, which may be right, but their tone in their details on the website seems more about almost threatening you...which really turns me off I admit.