Search found 179 matches

by Sniffer
Sat Apr 06, 2019 11:39 am
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

The sound chip (IC18, 76489) is connected to the ‘slow bus’ from the system VIA (IC3) and controlled by the /WE signal (pin 5 on IC18). This control signal also comes from IC3, but via IC32 (74LS259). Ok, got IC 33 back in, still the same situation. So, in an attempt to check sound, got my (cheapo)...
by Sniffer
Fri Apr 05, 2019 10:05 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

Yay! :D

Some hints and links to guides on using an oscilloscope are here and here ;-)

You can either use your logic probe or your ‘scope to trace signals.
Ok, thanks for the info. If tomorrow I get the bits I'm waiting for I'll start having a play with the probe.
by Sniffer
Fri Apr 05, 2019 7:32 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

By the way, what test gear do you have / have available/ can borrow or pinch?
Well I have a Fluke (179) and a logic probe which I can use confidently, I have a Siglent SDS 1052DL which I'm not so proficient with. In fact, I'm not proficient at all with it, but I would like to be :D
by Sniffer
Fri Apr 05, 2019 4:59 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

Default start-up is in MODE 7, the teletext mode. So if there is one or more defective RAM chips, the resulting bit errors will result in the wrong character being displayed. If you know what should be shown (compare to a normal start-up screen), you can use the table of teletext characters in the ...
by Sniffer
Fri Apr 05, 2019 9:49 am
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

More info: So, with the inverter fitted I pressed BREAK, typed MODE 6 and typed in the simple memory test prog, as below. Typed characters appear correctly in mode 6. 5 MODE 0 10 ?&4000=0 20 A=?&4000 30 IF A=0 THEN GOTO 20 40 PRINT A This produced nothing but the cursor at the top of the scr...
by Sniffer
Fri Apr 05, 2019 9:22 am
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

With the inverter fitted the symptoms are similar to those with S25 south. Cannot type until break is pressed . Then th 32k message disappears and typing is possible, albeit with musical tones. The beeeeeeeep continues. Typing in the startup MODE (cant remember what mode that is) produces random cha...
by Sniffer
Fri Apr 05, 2019 8:03 am
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

That suggests a problem with either the RAM providing the screen memory or the data lines (or IC15, a 74LS273) between the screen memory and the teletext chip. Also possible is a fault with IC14, a 74LS245 transceiver. Also possible is an address line problem with the RAM or the feeds to it. Can yo...
by Sniffer
Thu Apr 04, 2019 11:23 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

Posting from my phone as no internet due to Zen maint.

Thought I'd give the 74ls04 inverter a go whilst im waiting for some bits.

I get a sort of booted 32k beeb, but still the continuous beep but also a messed up screen. Attaching a foto.
by Sniffer
Thu Apr 04, 2019 9:15 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

Fixed the housing and I've now tried 3 or 4 Vias in IC3, all with the same result. So I'll focus on IC31 & IC32.
by Sniffer
Thu Apr 04, 2019 8:34 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

To check it and make sure, you could use a multimeter to do a continuity check between IC25 pin 1 and IC37 pin 10 (the generator of the 2MHZE signal) or any other pin that's labelled as being linked directly to 2MHZE, such as IC7 pin 10, IC59 pin 24, etc. Great, thanks. Track not broken. So I'll se...
by Sniffer
Thu Apr 04, 2019 8:11 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

That’s too bad. Anyway, these things are sent to try us. Had a good look under where the plastic housing was, it seems somebody in the past has had a bit of a dig with a screwdriver (which is what I often use) or some such implement as there is some gouging and the track from pin 1, IC25 is damaged...
by Sniffer
Thu Apr 04, 2019 7:06 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

Since switching S25 to get your machine booting, have you tried switching the two VIAs (IC3 and IC69) around? No, I haqdn't. I was pretty confident in both as they came from the good board. However, I thought I'd do it anyway and sadly, using the chip puller has pulled the pastic housing of IC3 off...
by Sniffer
Thu Apr 04, 2019 4:44 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

Does the beeeeb stop after you press break? On switch on the monotonous tone continues. On pressing 'BREAK' I get a second tone which fades away quickly and is replaced by an undulating whistle, the first tone keeps going. At this point, when pressing keys, its like playing some kind of wierd elect...
by Sniffer
Thu Apr 04, 2019 4:35 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

Does the beeeeb stop after you press break?
Only if I remove the speaker lead :D
by Sniffer
Thu Apr 04, 2019 2:20 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

Some of the I/O lines used by the System VIA to communicate with the keyboard and sound chip are latched by IC32 (74ls259), which is in turn clocked by one half of IC31 (74ls74), so they're also worth checking. Ok, thanks. Before I go through the pain of desoldering and replacing those I think I mi...
by Sniffer
Thu Apr 04, 2019 1:11 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

By the way, thank you both for your inputs thus far, it's very miuch appreciated.
by Sniffer
Thu Apr 04, 2019 12:53 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

The sound chip (IC18) is controlled by the System VIA (IC3), so if the VIA's not there, the OS can't tell the sound chip to shut up (as it normally does at boot).
The implication being that the System Via is missing or faulty? It's not though so maybe a board/track problem. I'll take a closer look.
by Sniffer
Thu Apr 04, 2019 12:51 pm
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

No, it’s not. Does the keyboard work? Did you (correctly) replace the system VIA (6522, IC3)? Yep, both VIAs in situ. Keyboard Caps Lock & Shift Lock leds lit, keyboard does NOT respond until break is pressed. At this point I can use the keyboard but apart from the default MODE, no others seem ...
by Sniffer
Thu Apr 04, 2019 11:20 am
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

Well, I can't explain this but, I put all the ICs back (actually the ICs from the good board because I left this faulty boards original ICs in the good board, as it was working) and tried booting with S25 completely off but again no change. So, I tried with S25 south, which I had already tried, and ...
by Sniffer
Thu Apr 04, 2019 10:58 am
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Re: Non bootong BBC/B Issue 7 - Continuous beep

I don’t see you mention trying S25 south? See this (very recent) post: viewtopic.php?f=3&t=16852&view=unread#p232947
Sorry, yes, I tried that, no change. I didn't try with S25 off completely though. Thanks for the link, I'll check it out.
by Sniffer
Thu Apr 04, 2019 10:09 am
Forum: 8-bit acorn hardware
Topic: Non booting BBC/B Issue 7 - Continuous beep
Replies: 60
Views: 4678

Non booting BBC/B Issue 7 - Continuous beep

I've googled myself to death almost and read through tons of articles, including one here but still no joy. So if anybody can help .... I have an issue 7 BBC/B that when powered on gives a continuous beep (or beeps). I say 'or beeps' because it sounds like I get the first beep and the second but all...
by Sniffer
Sun Mar 31, 2019 7:29 pm
Forum: 8-bit acorn hardware
Topic: WE SOLDERLESS 12 ROM Board
Replies: 3
Views: 645

Re: WE SOLDERLESS 12 ROM Board

It's a 74LS04N
Thanks for that.

Replaced the two caps, a little clean up and all looks good. Taken the battery 'off' the board to avoid any future spills.
by Sniffer
Sun Mar 31, 2019 12:30 pm
Forum: 8-bit acorn hardware
Topic: WE SOLDERLESS 12 ROM Board
Replies: 3
Views: 645

WE SOLDERLESS 12 ROM Board

I'm looking to get this working but before I start I thought I'd make a note of all the ICs in case any need replacing. There was a battery attahced which must have leaked at some point. No major visual damage. Any body any idea what the IC is, third row up second from left (ringed in red on attachm...
by Sniffer
Fri Mar 29, 2019 12:08 pm
Forum: 8-bit acorn hardware
Topic: BBC B Issue 1 board documentation/service manual
Replies: 1
Views: 368

Re: BBC B Issue 1 board documentation/service manual

Ok, ignore my ramblings, I've obviously gone senile.

It's a B+, hence the Issue 1 board. :oops:
by Sniffer
Fri Mar 29, 2019 11:36 am
Forum: 8-bit acorn hardware
Topic: BBC B Issue 1 board documentation/service manual
Replies: 1
Views: 368

BBC B Issue 1 board documentation/service manual

Anybody know if any exists? Anybody got a service manual that caters for the Issue 1 motherboard? I'm under orders to sell some of my hoarded BBC kit (as we are downsizing) and one of the Beebs I have is an Issue 1, but for some reason and I can't remember why, there was no PSU in the case (I do hav...
by Sniffer
Tue Mar 26, 2019 1:53 pm
Forum: wanted
Topic: Wanted Intel 8271
Replies: 2
Views: 619

Re: Wanted Intel 8271

Hi,

Beebmaster (Ian Wolstenholme) used to sell a 8271 Disc Upgrade kit, have you tried him?

I have just had a look at my block of removed chips and I do have a couple if you are struggling. Not sure why I have them, maybe I fitted 1770's in their place in the dim and distant past.

Mike.
by Sniffer
Tue Mar 19, 2019 3:01 pm
Forum: 32-bit acorn hardware
Topic: Poorly A440/1
Replies: 4
Views: 639

Re: Poorly A440/1

All back together and booted up fine. Great stuff. The initial issue of running any software immediately locking up the machine was still there though. That turned out to be the SharedCLibrary (v5.59) that is in the Etherlan 500 podule. It had become replugged. Unplugging it again solves that problem.
by Sniffer
Tue Mar 19, 2019 12:48 pm
Forum: 32-bit acorn hardware
Topic: Poorly A440/1
Replies: 4
Views: 639

Re: Poorly A440/1

Some of the later machines didn't have tantalum decoupling caps but it's worth checking and removing the 16v/25v tantalum caps if they're fitted, especially the ones on the 12v rail. Not sure which tantalum caps you are refering to to be honest, however, on removing the motherboard for close inspec...
by Sniffer
Tue Mar 19, 2019 11:26 am
Forum: 32-bit acorn hardware
Topic: Poorly A440/1
Replies: 4
Views: 639

Poorly A440/1

The A440/1 that I recently aquired has become very poorly. Not a good sign. I fitted a scsi podule and the machine booted but at some point, running any software, for example the scsi setup program or sparkplug just hung the machine. The podule is known good, or was. I removed the scsi podule and th...
by Sniffer
Fri Mar 15, 2019 2:40 pm
Forum: wanted
Topic: A440/1 3.5" Floppy Drive
Replies: 4
Views: 726

Re: A440/1 3.5" Floppy Drive

Thanks for the link, I'll take a look. Having done some rudimentary checks I suspect the step motor is dead.

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