600XL capacitors

[Tezz]

Does anyone have any advice for how to remove/replace the key switches for the AWC keyboard?

[flashjazzcat]

There are two pins on the back. Heat them with a soldering iron and you can gently work the switch out if the board. New switch drops right in.

[Tezz]

There are two pins on the back. Heat them with a soldering iron and you can gently work the switch out if the board. New switch drops right in.

Great, thanks Jon. So it was just the two pins to desolder With any luck the spare parts 800XL I have in storage will be an AWC keyboard also.

[Tezz]

I eventually retrieved the spare parts 800XL this afternoon, sadly it was an Alps keyboard which at some point in the past had been punched or had a heavy weight on it so the keyboard PCB was badly cracked. The motherboard has survived thanks to the shielding, it's fully socketed but the previous owner had removed all the ICs so no luck there either for any spares so I might need to take you up on the offer of the spare AWC switch Jon

[flashjazzcat]

No problem. If you PM me your address I'll drop one or two in an envelope for you. We are definitely talking about the fully enclosed switch with the white plastic top?

[Tezz]

No problem. If you PM me your address I'll drop one or two in an envelope for you. We are definitely talking about the fully enclosed switch with the white plastic top?

Thanks Jon, I'll sort you out for the cost of course

 

Here's a photo of the switch attached. Will PM shortly.

 

 

[+Stephen]

There's actually a dry residue inbetween the "3" "W" and "E" keys so something is likely to have been spilled there at some point in the past. It doesn't look like a large spill but the residue suggests a sugary drink so that may have corroded the switch or caused a short there. I'll try carefully popping those keycaps off tomorrow to investigate.

Before desoldering and replacing the switches, I would try a good electrical contact cleaner. NOT WD-40 or the like. Since the keycaps are off, you can get a really good spray down inside those switches, and just work the living crap out of them. Fill up with spray, cycle the key 25 times, and keep repeating. It may just clean everything up to a working state again.

[Tezz]

Before desoldering and replacing the switches, I would try a good electrical contact cleaner. NOT WD-40 or the like. Since the keycaps are off, you can get a really good spray down inside those switches, and just work the living crap out of them. Fill up with spray, cycle the key 25 times, and keep repeating. It may just clean everything up to a working state again.

Thanks, that's a good idea, I didn't think of that. I should have some contact cleaner with my car products. Hopefully the cola or whatever it was that was spilt there 30 years ago hasn't made too much of a mess of the switch

[Tezz]

I have a SECAM 800XL in storage, I'm not sure whether it's functional at all. The ROSE board has the main ICs : CO61991-29 Freddie, CO21698-01 ANTIC, CO14806C-29 Sally 6502C, CO20120-01 GTIA, CO12294-03 POKEY, CO14795-12 PIA Chip.

 

I vaguely recall reading about differences with SECAM ICs in the past, would I be able to use any of them to get my spare unpopulated PAL 800XL board up and running?

 

Only Freddie and the GTIA are socketed on the SECAM board.

Edited March 29, 2018 by Tezz

[flashjazzcat]

I think it's just the GTIA which deviates from the PAL standard on SECAM machines, so everything else should be usable in your spare PAL 800XL board.

[Tezz]

Great, thanks Jon. I'll desolder the ICs in the morning and transfer them to the PAL board. I should hopefully just need a GTIA if the RAM is good too.

[Tezz]

I removed all the ICs and RAM from the SECAM Rose board to transfer to the spares PAL board, it turns out that was actually a CO61851 board so I don't need Freddie. I've got a PAL GTIA on the way so I'll see how things are when that arrives. I stripped down the SECAM keyboard for cleaning, it was one of the lower quality type with the loose springs sat under each keycaps, it was extremely dirty and took an age to clean and put back together. I retr0brighted the individual keycaps after cleaning so it looks good again now it's back together. I'll test that out when the board is up and running hopefully.

 

With the 600XL, I didn't find my electrical contact cleaner, no doubt I probably gave that to someone to use and never got it back so I'll have to buy another one when the shops are open again after the Easter break.

[Tezz]

I'm having no luck with the spare PAL 800XL board. The PAL GTIA arrived this morning, I also found the original set of ICs stored away so I had two sets of ICs to try, the original set and the ones taken from the untested Rose board. The Rose board had 8x4164 RAM and I also had 8x (Micron) MT4264-15 and 8x (Hitachi) HM4864P-2 (4164 equivalent) to try. The DC input socket was loose so I reflowed all of those pins. There is a dent across the lid of the modulator can from where the keyboard was hit and broken in the past but the modulator looks fine inside. I get just a black screen from both the RF and monitor outputs. I've tried every combination of ICs and RAM but no change. I'm using one of my new old stock PSU's which was being used previously with my XE. I did also test it with the multimeter however just to be sure. The ROM is not socketed and I don't have a spare unless I remove the one from the Rose board but that board is also untested. I don't have a logic probe so not sure now what to do next.

[Tezz]

I'll start redoing all of the sockets in the morning and checking continuity to take that out of the possible problems first. I'll check all the ICs in a known working board after that if that doesn't turn out to be the issue. Certainly at least one of the set of RAM came from a working board that I'd upgraded previously. I drove out to get the electrical contact cleaner after checking stock online but it turned out the store messed up the stock taking and they didn't have any in so that'll be another trip elsewhere tomorrow. It was not a very productive day off

[tjlazer]

I fixed a broke key on my type 2 keyboard from the wiki page where you unsolder the key, dismantle it by unscrewing the two pins, and fix the metal leaf inside. Was fairly easy.

Edited April 3, 2018 by tjlazer

[Tezz]

I fixed a broke key on my type 2 keyboard from the wiki page where you unsolder the key, dismantle it by unscrewing the two pins, and fix the metal leaf inside. Was fairly easy.

I'll certainly take a look inside the switch if the contact cleaner doesn't do the trick and I have to remove it.

[Tezz]

I eventually got the contact cleaner this morning so I'll try that on the key switch shortly. With the 800XL board, I removed all the ICs again and resoldered all the pins on every socket and also put some contact cleaner into each socket. Visually everything looks good with the board, no bad solder joints, no broken tracks or scratches, no corrosion. So I cleaned up the resoldering with IPA and placed the ICs back in checking that the pins were all aligned and in the socket correctly, powered on and ... black screen as before, no change. I'll need to test the ICs in a working XL board to make sure they are all functional otherwise I'm working with unknowns. I have a 600XL in storage but that one is also faulty. Maybe for once I'll be lucky and that will turn out to be only a RAM fault and I can use that to test these ICs. I'll have to buy some 4464 or 41464 as I don't have any however

[Tezz]

Will 120ns 41464 be ok for the 600XL? Hopefully if that system is working, I can then do the simple 64K mod after testing the 800XL ICs.

[manterola]

Will 120ns 41464 be ok for the 600XL? Hopefully if that system is working, I can then do the simple 64K mod after testing the 800XL ICs.

I got the ones from the picture and these chips are working in my 600xl and 65xe, but I have not tested it very thoroughly, like using pagefind, I guess, but I've been playing many games since I installed them months ago.

These are TMS 4464-10nl

Edited April 4, 2018 by manterola

[Tezz]

I got the ones from the picture and these chips are working in my 600xl and 65xe, but I have not tested it very thoroughly, like using pagefind, I guess, but I've been playing many games since I installed them months ago. These are TMS 4464-10nl

Thanks, original 4464s are harder to find in the UK now, I can buy 41464s quite readily though, just not sure if 120ns will be ok

[Tezz]

I made some progress on the spare 600XL this morning. I was lucky, it turned out just to be simply a dead CPU. It was going straight to self test once it was running but fortunately the BASIC ROM socket had a couple of bent pins so once that was sorted and cleaned everything was fine. I did install the two 120ns 41464s which were also ok. Before I do the small modification for 64Kb I'll desolder the MMU from the 800XL board and install a socket to see if the working 600XL MMU identifies the issue. Happily the SECAM keyboard that I totally stripped down for cleaning also works 100% so that's ready for the 800XL. I had a full day of sunshine during the week so I took the opportunity to retr0bright the 800XL case which has turned out very well. I just need to get the 800XL board repaired and that'll be two XL's back in service.

[+tf_hh]

Thanks, original 4464s are harder to find in the UK now, I can buy 41464s quite readily though, just not sure if 120ns will be ok

 

4464 is just another name for the same thing: 256 Kbit DRAM organised in 64 K x 4 Bits. Some manufacturer uses 4464, some 41464 and for sure there are more in the wild.

 

Everything starting with 250 ns or less is fine.

[Tezz]

4464 is just another name for the same thing: 256 Kbit DRAM organised in 64 K x 4 Bits. Some manufacturer uses 4464, some 41464 and for sure there are more in the wild.

 

Everything starting with 250 ns or less is fine.

Thanks, good to know I noticed most of the 64Kb modified 600XLs that I looked at were using 150ns so I thought 120ns would be ok.

[Tezz]

I removed the MMU from the 800XL board and installed a socket, tested it with the MMU from the now working 600XL and no change, still a black screen. I'll order a new OS ROM next and try swapping that out.

[Tezz]

I removed the OS-ROM from the 800XL board and installed a socket. Tested that ROM in the working 600XL and it was faulty. Testing the working OS ROM from the 600XL in the 800XL board and there was still no change so obviously more than one fault to deal with.

 

I have a lot of new 41256 RAM that I bought when I upgraded my XE's to 320K in 2007. Will 41256 work in the XL board? IIRC pin 1 had to be soldered to ground to use them so maybe not.

Edited April 8, 2018 by Tezz