EEVblog Electronics Community Forum

Electronics => Repair => Topic started by: Rollin Hand on May 16, 2019, 11:48:25 pm

Title: tds 724 power supply
Post by: Rollin Hand on May 16, 2019, 11:48:25 pm

Does someone know how to start the power supply board out of the scope for testing all the voltages.
the service manual calls for a temporary short on pins 3 and 5 of J26 ,but I dont find J26.
Thanks

Title: Re: tds 724 power supply
Post by: picburner on May 17, 2019, 05:03:02 am

J26 is located on the CPU board and it connects to J6 on the power supply via the larger flat cable.
The pins 3 and 5 should also match on J6, check anyway.

Title: Re: tds 724 power supply
Post by: Ordinaryman1971 on May 17, 2019, 05:37:57 pm

If it's dead... It's probably problem with two suppression diodes and the transistor. I've had 744 with the same problem.
The transistor in mine was BU508.. if I remember.

Title: Re: tds 724 power supply
Post by: Rollin Hand on May 18, 2019, 03:47:31 pm

Thank you
I already have the bu508 and the 2 supresor diodes,the function is the 15v stand by supply,if the 15v are not present does not work.
thanks for the response.

Title: Re: tds 724 power supply no bu408 in mine
Post by: Rollin Hand on May 18, 2019, 08:53:11 pm

after checking my ps had the top200y for the stanby ps 12v in this case .
find r1476 out of value, replaced and burn out.After removing  some withe silicone arround the top200y I notice c116 had a litle black  hairline crack
and it was almost short .
After replacement for another .01 500v and the 2.4 ohm resistor now I have the 12 v bias  .
I had in stock the top225 this will work too? in case I need replacement?
R.