Problems booting beeb issue 4

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Wheel_nut
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Re: Problems booting beeb issue 4

Post by Wheel_nut » Thu Oct 03, 2019 8:50 pm

DaveLecky wrote:
Thu Oct 03, 2019 6:32 pm
UPDATE.......UPDATE.......

Pins 27 and 28 are open circuit between the Ic leg and the solder joint on the rear of the board.

Looks promising... I just have to pluck up enough courage to desolder the little sucker...

Hints and tips gratefully accepted.

Dave
You need to replace the socket with a good quality Augat - preferably Turned Pin Socket.... but to test that the fix will work, you could run a wire from the underside of the board and tuck it into the Pin28 socket on the top. That would prove the fix necessary.

Do you have a Solder Sucker? I could post you a Socket if you like but I wouldnt attempt it without a Solder Sucker ... unles you want to cut off each leg and extract it through the board and then wick out the solder with desoldering braid!

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DaveLecky
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Re: Problems booting beeb issue 4

Post by DaveLecky » Fri Oct 04, 2019 8:15 am

Hi Wheel nut,

Thanks for the offer,

I’ve got soldering gear and sucker, I’ve also got a socket.

I just don’t have much time before I go on holiday on Saturday for a week.

Don’t have much experience at component level, but lots of enthusiasm...it’s always worth a go.

Most I’ve done is the cassette Ic on my electron...cut off the legs....it did work though.. :D

Dave
Electron, A3000, A3010,A4000,A5000, A7000+,RiscPc, PC....dumped or sold most.....Started again....now have, Electron, Plus1/6, Plus3, Pres3/4, BBC B, Master ........retired early to play.....8bit...and Elite Dangerous on PS4 of course.

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1024MAK
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Re: Problems booting beeb issue 4

Post by 1024MAK » Fri Oct 04, 2019 8:26 am

Definitely wise to remove the old socket by cutting the pins. Then you can desolder one pin at a time. As always with desoldering on double sided boards, be careful and make sure all the solder has melted, so that the pin comes out freely. Otherwise you risk track/pad or damage, or the plated through hole coming out with the pin :(

Mark

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Re: Problems booting beeb issue 4

Post by DutchAcorn » Fri Oct 04, 2019 9:30 am

Of course desoldering the socket is the way to go but if you have a turned pin socket you could try plugging that into the old socket and putting the rom in there. The larger pins of the turned pin socket may make better contact than the ic pins.

If that does not work then no harm done, if it does work you can plan the desoldering for a convenient time...
Paul

Image

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DaveLecky
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Re: Problems booting beeb issue 4

Post by DaveLecky » Fri Oct 04, 2019 10:22 am

Hi there, I hardwired the two pins to the back of the board, switched on, still nothing on screen, S25 north.

Checked continuity of wires....ok

I took the last requested set of measurements again ....no change.
DaveLecky wrote:
Mon Sep 30, 2019 10:45 am
Hi 1024MAK,
here are the readings, taken twice to confirm.

IC51 pin 1 to IC1 pin 25 (6502 CPU A15) = 0.4
IC51 pin 1 to IC51 pin 28 (+5V / VCC) = 0. Open circuit
IC51 pin 27 to IC1 pin 24 (6502 CPU A14) = 0.4
IC51 pin 27 to IC51 pin 28 (+5V / VCC) = 0 open circuit

Dave
Put the adapter in again....no change

Removed adapter....inserted Trickys test rom......S25 north.

A6C7DE83-E71A-4CD9-B860-EDCFF73B9C28.jpeg
And got this....

4B8F8873-0F92-4460-8205-34AEE7D02525.jpeg

The image is flashing, but not changing or progressing, even when hitting Break.
Looks like the first frogger screen of the test sequence, I wasn’t getting that before.

Must be more than one fault.

I’ll change the socket first to eliminate it from the equation.

Dave
Electron, A3000, A3010,A4000,A5000, A7000+,RiscPc, PC....dumped or sold most.....Started again....now have, Electron, Plus1/6, Plus3, Pres3/4, BBC B, Master ........retired early to play.....8bit...and Elite Dangerous on PS4 of course.

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Re: Problems booting beeb issue 4

Post by Wheel_nut » Fri Oct 04, 2019 10:30 am

DaveLecky wrote:
Fri Oct 04, 2019 8:15 am

I’ve got soldering gear and sucker, I’ve also got a socket. ...

Dave
Hi Dave,
If you can cut each pin at the top and lift off the socket, and then extract each pin individuallt, that would be safest.

Because the plated through hole is only microns thin, it doesn't conduct heat well so it is best to flood the hole with fresh solder and then solder-suck each hole. If the hole doesn't clear, flood it again with fresh solder and use the sucker again.

If you can't cut the socket out first, after solder-sucking each pin, get a pair of tweezers and waggle each pin free in its hole. This is to free any adhesion between the shoulders of the pin and the PTH wall. If you take your time and free each pin, the socket will fall out. ... but don't use any force or you will tear out the PTH.

DutchAcorn, Dave has established that the pins are severed from the board under the socket so plugging a Turned Pin Socket will likely not work in this case.

Robin
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Re: Problems booting beeb issue 4

Post by DaveLecky » Fri Oct 04, 2019 1:24 pm

Thanks everyone, I don't expect I’ll have time to do anything else before I go on holiday early tomorrow morning.

I’ll progress when I return next week and let you know the results.

Dave
Electron, A3000, A3010,A4000,A5000, A7000+,RiscPc, PC....dumped or sold most.....Started again....now have, Electron, Plus1/6, Plus3, Pres3/4, BBC B, Master ........retired early to play.....8bit...and Elite Dangerous on PS4 of course.

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Re: Problems booting beeb issue 4

Post by maniacminer » Fri Oct 04, 2019 4:36 pm

A very interesting thread. As I had my Beeb in bits, I thought I'd check what the power was between the octal memory drivers (81LS95) between pin 10 and pin 20. I get 5.06V, whereas, some of the readings I've seen in this thread are 4.5V, that suggests, perhaps, something is drawing down the 5V rail or the 5V rail isn't 5V. I do like these mysteries, it is now that a logic analyser is worth its weight in Francium :wink:

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Re: Problems booting beeb issue 4

Post by 1024MAK » Fri Oct 04, 2019 8:35 pm

Good spot maniacminer 👍

Dave

Can you please examine the three red power supply connectors that connect the +5V supply to the main board +5V/Vcc connection points. Do the same for the three black power supply connectors that connect the 0V/GND supply to the main board. Look for any problems, including loose connections. Also using your multimeter, test the voltage between each pair of the spade connectors (+5V/Vcc and 0V/GND) on the main board. Please report back on what the voltages are.

Mark

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Re: Problems booting beeb issue 4

Post by DaveLecky » Sun Oct 13, 2019 10:42 am

Hi Folks,
I’m back from my hols and back into this problem.

I have replaced the faulty ic51 socket successfully.

Here are the voltages asked for by 1024MAK...
VLCC 1 = 4.96
VLCC 2 = 4.93
VLCC 3 = 4.87

When I initially switched on I only got one beep, but after the third attempt I got the normal screen.

E00E12C5-2C23-4909-A17D-FA4FB43DD247.jpeg

I then installed my MMC card and chip

42D03A1A-7870-415F-8678-C7A4D22A02CF.jpeg

I booted to the menu successfully

F74A66A8-CFC1-467F-840E-83BC74ACC28E.jpeg

I chose a game and got the on screen instructions, but when I ran the game I got this

25B2F48C-3CAA-4348-9792-E56FA46EB8CB.jpeg

I tried several games I new worked on another beeb , but the result was the same.

Any suggestions on where to go next will be appreciated.

Thanks

Dave
Electron, A3000, A3010,A4000,A5000, A7000+,RiscPc, PC....dumped or sold most.....Started again....now have, Electron, Plus1/6, Plus3, Pres3/4, BBC B, Master ........retired early to play.....8bit...and Elite Dangerous on PS4 of course.

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1024MAK
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Re: Problems booting beeb issue 4

Post by 1024MAK » Sun Oct 13, 2019 12:26 pm

DaveLecky wrote:
Sun Oct 13, 2019 10:42 am
Here are the voltages asked for by 1024MAK...
VLCC 1 = 4.96
VLCC 2 = 4.93
VLCC 3 = 4.87
They are a little bit low, but are within +/- 3% of 5V.
DaveLecky wrote:
Sun Oct 13, 2019 10:42 am
Any suggestions on where to go next will be appreciated.
Sorry to say Dave, but we rewind a bit.

Can you please try the memory test program in this thread.

Mark

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Re: Problems booting beeb issue 4

Post by DaveLecky » Sun Oct 13, 2019 2:04 pm

Hi there
I can’t get past the first hurdle, the beeb won’t go into any mode, as per first line of instruction MODEn

I just get rubbish on the screen again...

Dave
Last edited by DaveLecky on Sun Oct 13, 2019 2:55 pm, edited 1 time in total.
Electron, A3000, A3010,A4000,A5000, A7000+,RiscPc, PC....dumped or sold most.....Started again....now have, Electron, Plus1/6, Plus3, Pres3/4, BBC B, Master ........retired early to play.....8bit...and Elite Dangerous on PS4 of course.

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Re: Problems booting beeb issue 4

Post by DaveLecky » Sun Oct 13, 2019 2:55 pm

Hi there again.....

The beeb has now reverted to the same symptoms it had in the first post in this thread.....SH////.

7FC6B095-6A69-4F62-A8A8-446836AFE827.jpeg
4508B3F2-8D36-4E02-BED6-85605BDB96F9.jpeg
6BEBA264-788A-41BF-8EF6-D47D165E8C90.jpeg

I’ll go through the whole post again this week to see if I can get to the position I was in this morning,
It looked so promising too.

Dave
Electron, A3000, A3010,A4000,A5000, A7000+,RiscPc, PC....dumped or sold most.....Started again....now have, Electron, Plus1/6, Plus3, Pres3/4, BBC B, Master ........retired early to play.....8bit...and Elite Dangerous on PS4 of course.

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Re: Problems booting beeb issue 4

Post by DaveLecky » Mon Oct 14, 2019 11:41 am

Hi there,

Tried the memory test with S25 south,

DFAD5700-2173-4106-BED0-13FCC4A5C366.jpeg
Input MODE 7
8C3C3704-8FC8-4CFC-90EA-DAE9CA0BF410.jpeg
Press return, and this is the result without any other input from me.
976AA5EA-704F-41C7-8004-1F724666E4E8.jpeg

HOWEVER.....my other beeb had one bank of socketed ram.
I ran the memory test with s25 north, it ran successfully with no faults.
I then swapped out each bank in turn from the other beeb, both banks came up with no faults.

So with S25 south and removed, I get as above in the top pic.

With S25 north I get random gobbledegook......

Dave
Electron, A3000, A3010,A4000,A5000, A7000+,RiscPc, PC....dumped or sold most.....Started again....now have, Electron, Plus1/6, Plus3, Pres3/4, BBC B, Master ........retired early to play.....8bit...and Elite Dangerous on PS4 of course.

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