Search found 8 matches

by bagpuss22
Wed Aug 08, 2018 1:34 am
Forum: Hardware
Topic: ZX Spectrum+ 128K Toastrack Repair
Replies: 11
Views: 2656

Re: ZX Spectrum+ 128K Toastrack Repair

Hi Mark,

Not sure where that has come from then as it was on the end of that capacitor and on the board too.... :shock:

Russ
by bagpuss22
Wed Aug 08, 2018 1:19 am
Forum: Hardware
Topic: ZX Spectrum+ 128K Toastrack Repair
Replies: 11
Views: 2656

Re: ZX Spectrum+ 128K Toastrack Repair

OK gents,
Had to put a hard wire in between pin 40 of the ULA and the emitter of TR6. Replaced the 100pf cap.

System now boots correctly and is happily running the diagnostic as well as the keyboard is fine....

Phew, sorted.... Never seen a leaking cap of that type before!

Russ
by bagpuss22
Tue Aug 07, 2018 11:51 pm
Forum: Hardware
Topic: ZX Spectrum+ 128K Toastrack Repair
Replies: 11
Views: 2656

Re: ZX Spectrum+ 128K Toastrack Repair

Think I have found the problem! A cap next to the ULA looks like it has been leaking!!! https://s8.postimg.cc/orpbm0hhh/cap.png I think this is C129, can anyone confirm( I think the mask above is incorrect)? can any 100pf cap do? Looks like it has killed the track between TR6 emitter and ULA pin 40 ...
by bagpuss22
Tue Aug 07, 2018 10:40 pm
Forum: Hardware
Topic: ZX Spectrum+ 128K Toastrack Repair
Replies: 11
Views: 2656

Re: ZX Spectrum+ 128K Toastrack Repair

Just checked the 5 connections to the ULA on the small KB1 and their associated pull up resistors and all seems OK.

No shorts between each other or earth either..
by bagpuss22
Tue Aug 07, 2018 10:23 pm
Forum: Hardware
Topic: ZX Spectrum+ 128K Toastrack Repair
Replies: 11
Views: 2656

Re: ZX Spectrum+ 128K Toastrack Repair

Thanks for the replies gents,

I get the same results with the new membrane, a 48k membrane and nothing attached.

I did notice the keyboard connector is loose but I buzzed it out with reference to the ULA and
all seemed fine. I will check both keyboard connectors again...

Russ
by bagpuss22
Tue Aug 07, 2018 3:22 pm
Forum: Hardware
Topic: ZX Spectrum+ 128K Toastrack Repair
Replies: 11
Views: 2656

ZX Spectrum+ 128K Toastrack Repair

Ok gents, Looking for a little advice as I am quite a novice to fault finding on the 128K. ;) I had a 128K, issue 6K Toastrack that originally had a back screen with white lines and blocks on the paper. I found that the ROM (EEPROM) was faulty and replaced it with a new OTP 27C256. Now I get the fau...
by bagpuss22
Wed Jun 01, 2016 12:31 am
Forum: Welcome Area
Topic: Another Newbie ish
Replies: 1
Views: 1005

Another Newbie ish

Hi All,

My name is Russ and I am a keen Sinclair hoarder! :lol:

Recently added a couple of TS1500s to my collection.

Thanks
by bagpuss22
Wed Jun 01, 2016 12:28 am
Forum: WANTED
Topic: Faulty ZX81
Replies: 2
Views: 1259

Re: Faulty ZX81

Mark,

I have a spare one, if you are only looking for the main unit?

It seems to be working OK apart from keys 1 - 5. Issue 3 mainboard.

Let me know if you are interested.

Russ