long beep and nothing else

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2j4ez
Posts: 52
Joined: Sun Jan 21, 2007 11:27 pm

long beep and nothing else

Postby 2j4ez » Tue Sep 12, 2017 11:11 pm

Hello all my beeb just starts up with a long tone with no display.
I no the keyboard works as I have verified all keys and cable to computer with a DVM meter with a continuity checker.
when I managed to get it to boot it it showed the BBC basic screen but none if the keys worked?.

Yesterday after checking the keyboard I put it all backed together and all keys worked fine and I was able to play games fine
Tonight the escape key did not work to I rechecked it with the DVM and it bleeped
and now the beeb just beeps when turned on and thats it

Anybody got any ideas?
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1024MAK
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Re: long beep and nothing else

Postby 1024MAK » Wed Sep 13, 2017 3:10 am

Given that it has recently worked, I suggest you check these first:-
  • Possible intermittent or poor connection of IC3 (6522 VIA) pins in it's socket.
  • You could also try swapping the 6522 for IC59 (the user port VIA) with IC3 (which is the system VIA).
While there, also check for:-
  • Possible intermittent or poor connection of the cable that links the keyboard and motherboard.
  • Possible dry solder joint (poor connection) on either the keyboard connector or the motherboard keyboard cable connector.
Mark
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2j4ez
Posts: 52
Joined: Sun Jan 21, 2007 11:27 pm

Re: long beep and nothing else

Postby 2j4ez » Wed Sep 13, 2017 3:59 am

I'll check them later . It's a issue 7 motherboard
I'll check for a dry joint on the keyboard connector may be just need a blob of solder on each pin of the keyboard connector ?

Is it best to take the board out and test the keyboard pins with a continuity checker?
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20 let x=rnd*49
30 print a
40 next a

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DutchAcorn
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Re: long beep and nothing else

Postby DutchAcorn » Wed Sep 13, 2017 5:39 am

A quick way to check if the system VIA (IC3) is the culprit (likely) you can simply remove IC3 and switch on. It should then start up normally but with continuous beep and no keyboard function.

Then, before removing the PCB and reflowing solder joints you can
- try swapping the 6522's (as Mark suggested)
- cleaning the pins of the 6522 to improve connection. Note that the chip-side of the pins normally make the connection
Paul

2j4ez
Posts: 52
Joined: Sun Jan 21, 2007 11:27 pm

Re: long beep and nothing else

Postby 2j4ez » Wed Sep 13, 2017 3:23 pm

I'll try that when I get home . But I'm new to repairing BBC micro computers where about is the the part that needs to be removed ??
10 for a=1 to 7
20 let x=rnd*49
30 print a
40 next a

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DutchAcorn
Posts: 1543
Joined: Fri Mar 21, 2014 9:56 am
Location: Maarn, Netherlands

Re: long beep and nothing else

Postby DutchAcorn » Wed Sep 13, 2017 5:00 pm

This site may be helpful: http://8bs.com/inbbc.htm

The system VIA is the chip marked 6522, just north of the socket that fits the keyboard flat cable to the main board.

To get to the user VIA (which you can use as a temporary replacement) you need to remove the keyboard. It is the bottom / south most chip of the column of 3 chips running along the middle of the main board, also marked 6522.
Paul

2j4ez
Posts: 52
Joined: Sun Jan 21, 2007 11:27 pm

Re: long beep and nothing else

Postby 2j4ez » Wed Sep 13, 2017 7:39 pm

I removed the chip and reseated it reconnected the cable to the keyboard and

BUP BEEP ! its alive .

Now some of the keys didn't work (ESCAPE and Y) so I took out the keyboard again looked at the underneath of the key and could see a cracked solder joint. reflow of solder and then checked it with a continuity checker and beep and same for the Y key now all keys seem to work.

At the moment its counting to 500 over and over just to test it out and so far so good.

Now to find out why my opus drive doesn't work when I power on the beeb I can here a faint noise. if I do a *. no light comes on.
Iam now going to take it apart and take a look

Thanks for all your help so far with my issue
10 for a=1 to 7
20 let x=rnd*49
30 print a
40 next a


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