Search found 612 matches

by 1024MAK
23 Jul 2020 19:17
Forum: HARDWARE
Topic: No picture.
Replies: 89
Views: 3495

Re: No picture.

Due to the design of the circuitry inside the MTX computer, I’m not happy with that fuse arrangement. Rather than providing protection, it severely affects the voltages inside the computer has has unintended consequences for the negative supply rail. Do you have. 40W or 60W conventional tungsten fil...
by 1024MAK
22 Jul 2020 23:00
Forum: HARDWARE
Topic: No picture.
Replies: 89
Views: 3495

Re: No picture.

BTW the fuse is a T1.6a, and why would you put a fuse inside a sealed case??? Also I was thinking when testing the tabs in the PSU the reading is always going to be false if as it seems 1,2 &4 are connected! Would it be a good idea to disconnect the wires then test? It’s rather common to put fuses ...
by 1024MAK
22 Jul 2020 08:17
Forum: HARDWARE
Topic: No picture.
Replies: 89
Views: 3495

Re: No picture.

With that transformer, there are a number of possibilities: It’s an earlier version (unlikely given the moulded ‘euro’ plug)’ It’s a later version than the type we have seen before, It’s a type that was only intended for use in Europe, Someone has replaced the original transformer with another trans...
by 1024MAK
21 Jul 2020 17:02
Forum: HARDWARE
Topic: No picture.
Replies: 89
Views: 3495

Re: No picture.

So all the diodes appear to be okay. Next would be to open the case of the PSU. I’m out at the moment, so can’t talk you through the actual method to open it. And the last time I opened one, was over ten years ago! Do make sure that the mains plug is NOT plugged into a socket. As long as it is unplu...
by 1024MAK
21 Jul 2020 16:26
Forum: HARDWARE
Topic: No picture.
Replies: 89
Views: 3495

Re: No picture.

1 to 2 = 0 = okay
2 to 3 = OL = not good :-(
3 to 4 = 0 = okay
4 to 5 = OL = not good :-(

Diodes test.

Diode D14 = 555, OL = good :-)
Diode D19 = 554, OL = good :-)

Mark
by 1024MAK
21 Jul 2020 16:23
Forum: HARDWARE
Topic: No picture.
Replies: 89
Views: 3495

Re: No picture.

Err “test diodes D14 to D19” meaning D14, D15, D16, D17, D18 and D19...

Mark
by 1024MAK
21 Jul 2020 15:09
Forum: HARDWARE
Topic: No picture.
Replies: 89
Views: 3495

Re: No picture.

Does your multimeter have a diode test range? If yes, with the power off and the PSU NOT plugged into the computer, test diodes D14 to D19 one at a time, each one with the leads around one way, then the other way round. One way the diode should conduct and the meter should show a voltage of 0.6V ap...
by 1024MAK
21 Jul 2020 14:49
Forum: HARDWARE
Topic: No picture.
Replies: 89
Views: 3495

Re: No picture.

Okay, still with the power off, and still with the multimeter set to the 200 ohm resistance range. Now test between the following pins of the PSU DIN plug:

1 to 2

2 to 3

3 to 4

4 to 5

Report back your results.

Does your multimeter have a diode test range?

Mark
by 1024MAK
21 Jul 2020 10:00
Forum: HARDWARE
Topic: No picture.
Replies: 89
Views: 3495

Re: No picture.

All the following tests are to be done with the PSU and computer disconnected from the mains supply. Switch your multimeter to the 200 ohms resistance range. Test this is working by touching the probes together, the meter should indicate around zero ohms or just above (0.1 to 0.9 depending on the re...
by 1024MAK
20 Jul 2020 23:50
Forum: HARDWARE
Topic: No picture.
Replies: 89
Views: 3495

Re: No picture.

That’s definitely not good. C53 should not be more than 15V.

I’ll have to have a think about this...

Mark