My 1050 just died!

[TZJB]

4 hours ago, Sid Pokey said:

Another update from OP.

 

For comparison, I got my original 1050 out of storage that stopped working about 30 years ago. They're both rev 1E, both made in Singapore. Oddly though, the original one has a bodge wire connecting the grounds of U14, Q7 and S2.

 

As a matter of interest, any experts know why this might be needed? And as they're the same model, shouldn't the recently failed 1050 have it too?

 

S2 has a good ground plane so connecting it to Q7, the 7805 5V regulator and U14, the clock divder circuit, may make it more stable but I have not seen this necessary on any other 1050 main boards.

 

1 hour ago, Sid Pokey said:

Just like Jan's bad 1050, initial tests suggest the 5v side is probably fine. It's the 12v side that's problematic on both of them. Guessing by the end, as a minimum, I'm looking at a capacitor and regulator replacement. Which might be a bit above my competency, but we shall see.

 

If 5V is okay at TP13 but TP14 is not indicating 12V, start by removing C70 with your soldering iron and measuring it's resistance. If it is low or short circuit it will need a replacement.

 

Otherwise check CR15 & CR16 and C68 for continuity. C68 may charge when the ohmmeter presents a positive potential to the positive terminal, then the resistance may be seen to rise if it is okay.

 

 

[spookt]

11 hours ago, Sid Pokey said:

Another quick update. While they're both rev 1E, it looks like they have different manufacturers; Reliance and what looks like Ciiv? On the latter, all the points connected by the bodge on the other are connected to earth anyway, so assume can rule that out.

 

Been watching a video from Jan Beta on YouTube as he fixes a 1050. Getting some good tips there. Cannot promise I won't have more stupid questions here though. 😉

 

Just like Jan's bad 1050, initial tests suggest the 5v side is probably fine. It's the 12v side that's problematic on both of them. Guessing by the end, as a minimum, I'm looking at a capacitor and regulator replacement. Which might be a bit above my competency, but we shall see.

I had a 1050 go bad whilst sitting on the shelf a while back. There was no motor activity at all. On inspection it turned out to be bad and leaking capacitors in the motor control circuit. After replacing those and doing some trace repair the 1050 is back to work. 
 

Think it was in the region of C69/C70 (which would agree with the advice above) plus maybe one more. There are some pics on my page here and here. Might be worth a  look around that area for shorted caps. 

Edited June 10 by spookt
Clarification

[Geister]

It's amazing how reliable these drives are.  I haven't bought a bad 1050 yet.  A little cleaning and away they go.  

 

I've been buying them locally and finally have to listen to my wife and stop buying them.  What am I going to do, build a wall of 1050's?

[_The Doctor__]

You only need 15 of each to fully exploit SDX

 

[Sid Pokey]

On 6/9/2024 at 10:52 PM, TZJB said:

 

If 5V is okay at TP13 but TP14 is not indicating 12V, start by removing C70 with your soldering iron and measuring it's resistance. If it is low or short circuit it will need a replacement.

 

Otherwise check CR15 & CR16 and C68 for continuity. C68 may charge when the ohmmeter presents a positive potential to the positive terminal, then the resistance may be seen to rise if it is okay.

 

 

Thank you for this advice. Tonight I had another cackhanded prod around with both of them. Each seemingly have different problems.

 

The older drive (which broke a long time ago) that did not have a 12v coming out of the regulator. So after much swearing, I pulled C70 as you suggested. It is indeed shorting and 12v now comes out of the regulator without it. Although I assume if that one's gone, they should all be replaced.

 

The newer drive (which broke recently) that has both 5v and 12v coming out of their respective regulators. Yet still it remains motionless. Any advice where next to go with diagnosis on that one?

[Sid Pokey]

Oh, and a secondary question if I may: Is there anywhere UK based that sells capacitor kits? In case I pluck up the courage to have a crack at it myself. 😬

 

[TZJB]

On 6/15/2024 at 10:59 PM, Sid Pokey said:

Thank you for this advice. Tonight I had another cackhanded prod around with both of them. Each seemingly have different problems.

 

The older drive (which broke a long time ago) that did not have a 12v coming out of the regulator. So after much swearing, I pulled C70 as you suggested. It is indeed shorting and 12v now comes out of the regulator without it. Although I assume if that one's gone, they should all be replaced.

 

The newer drive (which broke recently) that has both 5v and 12v coming out of their respective regulators. Yet still it remains motionless. Any advice where next to go with diagnosis on that one?

 

Replacement of C70 will be all that is required. I had a similar problem with C69 and just replaced that to restore full function.

 

With the newer drive, as the fault is more likely to be one of the larger chips, you may need you to swap chips out from the immobile one to the 'working' one until you find the culprit.

 

After you have taken the boards out of the refrigerator to help release the chip legs, first swap the ROM OS chip U10. If programmed bits have changed it can cause that problem, but then so could any of the other large chips.

 

As previously stated, just cleaning the chip contacts may restore function anyway.

 

 

Edited June 17 by TZJB

[TZJB]

On 6/16/2024 at 5:58 PM, Sid Pokey said:

Oh, and a secondary question if I may: Is there anywhere UK based that sells capacitor kits? In case I pluck up the courage to have a crack at it myself. 😬

 

 

Not specific kits. I buy my capacitors from CPC usually, with a preference for Panasonic.