Search found 2482 matches

by Dave
Tue Aug 11, 2020 4:48 pm
Forum: Hardware
Topic: Power supply
Replies: 9
Views: 473

Re: Power supply

In the QL, the AC feed is immediately rectified into DC. This derives +12V and -12V. The DC feed is immediately regulated to 5V for running the system. There's nothing in the QL that relies on the AC frequency. A QL will happily work on AC from about 38 Hz up to around 225-260Hz without problems. Ch...
by Dave
Fri Jul 10, 2020 6:42 am
Forum: Hardware
Topic: SGC Power Supply
Replies: 5
Views: 775

Re: SGC Power Supply

My SGC draws 320ma under load and 260ma idle.
by Dave
Mon Jul 06, 2020 11:43 pm
Forum: Help for New Users
Topic: Microdrive Refelting with "Fix-o-moll" for Furniture
Replies: 3
Views: 385

Re: Microdrive Refelting with "Fix-o-moll" for Furniture

Glider felt is not anti-static. It will build up a static charge in use which can create noise in the head, and read/write errors.
by Dave
Sat Jun 06, 2020 3:12 am
Forum: Compatibles Corner
Topic: Q68 netwrok port hardware
Replies: 43
Views: 3281

Re: Q68 netwrok port hardware

Sorry about that. Nobody seemed interested so I dropped the project.
by Dave
Tue Jun 02, 2020 9:46 am
Forum: Hardware
Topic: a bit off topic , microdrive head question
Replies: 1
Views: 295

Re: a bit off topic , microdrive head question

Yes.

Scuffing and corrosion not on the line taken by the tape doesn’t matter. Very light corrosion or scratches in the tape path can be polished out with jeweller’s rouge on a lint free cloth wrapped around a small dowel.
by Dave
Tue May 26, 2020 5:49 pm
Forum: Hardware
Topic: Issue 6 VM12 & resistors confusion
Replies: 79
Views: 4257

Re: Issue 6 VM12 & resistors confusion

What did you see when you checked the power to the DRAm area? Was it nice and smooth, or dipping? What about at the 8302?

The inconsistency of this is similar to a QL I repaired many years ago where the DRAM wasn't refreshing properly, and it turned out to be a power/bounce problem.
by Dave
Mon May 25, 2020 7:27 pm
Forum: Hardware
Topic: Issue 6 VM12 & resistors confusion
Replies: 79
Views: 4257

Re: Issue 6 VM12 & resistors confusion

Are you using the EPROM directly? EPROM chip select is active low.
by Dave
Thu Apr 23, 2020 8:05 pm
Forum: Compatibles Corner
Topic: Q40/Q60 Roms
Replies: 18
Views: 1128

Re: Q40/Q60 Roms

Would it be reasonable to do a flash adapter and IC to go there? Would it be in system programmable?
by Dave
Fri Apr 17, 2020 3:33 pm
Forum: Hardware
Topic: 5.25" floppy drive configuration
Replies: 27
Views: 1601

Re: 5.25" floppy drive configuration

What is the situation with termination resistors on the drives? If they're terminated incorrectly, they may accept "motor on" signals but not recognize data properly. On 5/25" drives, usually only the data lines were terminated on the last drive, with a resistor pack.
by Dave
Tue Mar 31, 2020 7:31 am
Forum: Hardware
Topic: QL Add-on ROM
Replies: 34
Views: 2278

Re: QL Add-on ROM

You could have a physical witch to connect /WR. If you tie it to 5V it can’t be written. A mechanical pull-up.