Enterprise Forever

:UK => Hardware => Maintenance => Topic started by: teopl on 2021.March.05. 17:15:34

Title: Fix EP64 no video out and maybe more
Post by: teopl on 2021.March.05. 17:15:34

Hello I have started adventure of fixing one EP64 from Egypt with help from a neighbour who knows electronics, since I don't know anything about hardware :)

I know there are a lot of topics regarding fixing EP64 but I would like to create new for this special case.

I already read some of those topics and from issue I have (less then 12V on video and no video output on OSSC device - "no sync" as compared to working one "15.60Hz 50.02Hz") I we did:

- replace TR2 (BC337)

After this, it's still 7.7V on video.

Btw machine is never used with Philips capacitors, and there is red light in the middle when connected to power. Also, keyboard membrane is cut off but I guess this doesn't count when fixing the rest.

We didn't replace C9 (as I saw this is common issue) because we were not sure if it's good voltage - can we put "3db, 100uF, 16V" instead of "3db, 100uF, 10V" for C9?

Next thing for me is:
- replace C9 and TR2 (at the same time!)
- read more on the forum
- buy some electric device to do some measurement?

Meanwhile it would be great if someone has to add something (which is not easily found on other topics) and which a total hardware noob like me can do :)

Thing is that every visit to the neighbour is costing money so I would go with precise requests to him what to try next...

Thanks!

Title: Re: Fix EP64 no video out and maybe more
Post by: Zozosoft on 2021.March.05. 18:02:35

Possibly the faulty C9 killed the TR2 again. It also happend to me at first times :-)

Higher voltage rated capacitor has no problem, it can be used.

If the problem still persists, check: L1 are broken?

Title: Re: Fix EP64 no video out and maybe more
Post by: teopl on 2021.March.05. 20:32:51

Thanks Zozo, I will update here the results!

Title: Re: Fix EP64 no video out and maybe more
Post by: dangerman on 2021.March.06. 22:42:25

A quick warning. When you replace C9, make sure that you replace it the same way round as the original - minus to the left.

Title: Re: Fix EP64 no video out and maybe more
Post by: Judge on 2021.March.07. 08:14:55

Quote from: dangerman on 2021.March.06. 22:42:25

A quick warning. When you replace C9, make sure that you replace it the same way round as the original - minus to the left.

Or better yet, use a bipolar capacitor...

[attach=1]

[attach=2]

Title: Re: Fix EP64 no video out and maybe more
Post by: szipucsu on 2021.March.07. 10:32:37

Quote from: Judge on 2021.March.07. 08:14:55

Or better yet, use a bipolar capacitor...

I like the colour of these capacitors. They are like ENTER or some other keys.