Refurbing an issue one zeddy
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- Posts: 2173
- Joined: Sat Nov 26, 2016 2:42 am
Re: Refurbing an issue one zeddy
My zeddy now has 16k of RAM!
It turns out desoldering the existing RAM was significantly easier than trying to cut the tracks with a craft knife and screwdriver...
I also learnt the hardway that I needed to make a bigger allowance for the cable underneath that goes near the screw hole - I allowed for the hole but not the material of the case where the screw fits. Had to shape it to fit!
So it now has:-
16k of RAM
New power regulator (badly soldered in - first one I did)
New capacitors
I have not had chance to test it thoroughly but it takes a few extra seconds to switch on and I can just about make out (ZX8-CCB required) DIM A(3000) working so looking good.
It still needs:-
New keyboard
ZX8-CCB (hoping for some to come on sale soon!)
But these are both pretty trivial to apply (get me!)
Thanks to all who passed on their knowledge.
Lardo
It turns out desoldering the existing RAM was significantly easier than trying to cut the tracks with a craft knife and screwdriver...
I also learnt the hardway that I needed to make a bigger allowance for the cable underneath that goes near the screw hole - I allowed for the hole but not the material of the case where the screw fits. Had to shape it to fit!
So it now has:-
16k of RAM
New power regulator (badly soldered in - first one I did)
New capacitors
I have not had chance to test it thoroughly but it takes a few extra seconds to switch on and I can just about make out (ZX8-CCB required) DIM A(3000) working so looking good.
It still needs:-
New keyboard
ZX8-CCB (hoping for some to come on sale soon!)
But these are both pretty trivial to apply (get me!)
Thanks to all who passed on their knowledge.
Lardo
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Refurbing an issue one zeddy
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
-
- Posts: 2173
- Joined: Sat Nov 26, 2016 2:42 am
Re: Refurbing an issue one zeddy
Just when you thought it was safe to go back into the water...
Looks interesting though! What do I need to buy for this one? Answers aimed at the idiot level please...
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
-
- Posts: 2173
- Joined: Sat Nov 26, 2016 2:42 am
Re: Refurbing an issue one zeddy
Hi Mark
Having read the threads a few times would I be right in saying I need to do the following: -
Desolder R1 from point 2 to point 1. Do I need to remove the modulator to get to the ground? I can just see a small amount of it exposed.
Solder new transistor TR3 pin C to pin B of TR1 (point 3)
Solder new transistor TR3 pin B to pin C of TR1 (point 4)
Solder new transistor TR3 pin E to new resistor R35 (point 5)
Solder new 10K resistor R35 to motherboard (point 6)
I assume C2 is not affected by this work?
What are the part numbers for the transistor and resistor? Looking on CPC a 10K resistor gives a number of matches and I cannot find the transistor at all based on the part number PN2907A (or NTE2362 from the second link). Not having a working knowledge of this stuff I have no idea what the modern equivalents are.
Many thanks!
Lardo
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Re: Refurbing an issue one zeddy
http://sinclairzxworld.com/viewtopic.php?f=7&t=1935
See if this helps you should be able to find one.
There is not a PNP from the manufacturer of the OEM transistor onboard for TR1 (I forget the company name) I looked trying to make the upgrade more authentic...
See if this helps you should be able to find one.
There is not a PNP from the manufacturer of the OEM transistor onboard for TR1 (I forget the company name) I looked trying to make the upgrade more authentic...
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Refurbing an issue one zeddy
I've found where I posted some pictures and there are some additional details - follow the link, follow, follow the yellow brick road link
(sorry, brain failure, just done a night turn...
It would be better if a transistor with a fast turn off time is used, but PNP plastic types like this are hard to find
I used a BC307 because it was not too high a gain, and I had some in my spares stockpile
I have an idea on using another type, but I would like to test it first, and it's waiting behind other projects at the moment...
Mark
(sorry, brain failure, just done a night turn...
It would be better if a transistor with a fast turn off time is used, but PNP plastic types like this are hard to find
I used a BC307 because it was not too high a gain, and I had some in my spares stockpile
I have an idea on using another type, but I would like to test it first, and it's waiting behind other projects at the moment...
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Refurbing an issue one zeddy
Lardo Boffin wrote: ↑Thu Jul 06, 2017 12:59 am Having read the threads a few times would I be right in saying I need to do the following: -
Desolder R1 from point 2 to point 1. Do I need to remove the modulator to get to the ground? I can just see a small amount of it exposed.
Solder new transistor TR3 pin C to pin B of TR1 (point 3)
Solder new transistor TR3 pin B to pin C of TR1 (point 4)
Solder new transistor TR3 pin E to new resistor R35 (point 5)
Solder new 10K resistor R35 to motherboard (point 6)
I assume C2 is not affected by this work?
What are the part numbers for the transistor and resistor? Looking on CPC a 10K resistor gives a number of matches and I cannot find the transistor at all based on the part number PN2907A (or NTE2362 from the second link). Not having a working knowledge of this stuff I have no idea what the modern equivalents are.
- R1 details - correct. No need to remove the modulator. Do need a powerful iron though.
- Too early(late) for my brain to confirm the transistor pin-outs - will check later...
- 10k ohms resistor - yes correct. Any 1/4W carbon film, or 250mW/400mW/600mW metal film type, 1%, 2% or 5% type will do
I can send you a 10k resistor and a BC307 transistor if you want.
Or later I can browse CPC... - No capacitors are harmed in the making of this modification. Absolutely no testing on farm or native wild life animals. Only tested on humans...
- Ahh! Yes, don't bother looking for those transistors, I tried a few years ago. I went for a BC307 to see if it worked. It does. Not sure if the Zeddy is as fast as Wilf's, but then I forgot to test the ZX81 before the mod. After the mod, the ZX81 is faster than another issue 1 board that I tried, when running a BASIC test program.
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
-
- Posts: 2173
- Joined: Sat Nov 26, 2016 2:42 am
Re: Refurbing an issue one zeddy
Hi Mark
If you can let me know the modern equivalents that would be great thanks!
I suspect it may be a while before I give this one a go - my soldering iron is only a 40w cheapie.
Lardo
If you can let me know the modern equivalents that would be great thanks!
I suspect it may be a while before I give this one a go - my soldering iron is only a 40w cheapie.
Lardo
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Re: Refurbing an issue one zeddy
I looked up a cross reference and there are no exact ones for parameters
I am US and am able to get NTE2362...
Remember has to be a switching PNP...though I bet most any will do. $5 down!
I am US and am able to get NTE2362...
Remember has to be a switching PNP...though I bet most any will do. $5 down!
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
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- Posts: 2173
- Joined: Sat Nov 26, 2016 2:42 am
Re: Refurbing an issue one zeddy
I did see one 2362 for sale on eBay but was put off by the cost of postage from USA.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA