The 464 I bought on ebay seemed to be in reasonable condition. However having now tried it and then taken apart and cleaned a few areas with iso it seems that a mug of coffe or coke has been spilt on it. There's brown stains that came off. I've cleaned the board as much as I can but the outcome remains the same. I now also have a 6128 and it works fine with the same power/video output connections.
Power on - LED shows. No beeps. No signal at all to the screen. Removing and reseating the Z80 has no impact. Same for the 400008 gate array.
Leaving the power on for 10 minutes results in no warm chips apart from the gate array, and I did not have the heatsink back on it.
There does appear to be a damaged trace on the rear of the board but a continuity test with a multimeter shows continuity.
I've ordered a Z80 and some RAM chips on ebay in case swapping those out helps.
I'm looking for any advice on what to start looking into next.
Here's some images in case that helps.
LED, but no image. https://i.imgur.com/sSRFXaS.jpg
The 6128 works fine with the same wiring. https://i.imgur.com/1Eu1oTm.jpg
Back of the board showing stains. https://i.imgur.com/R6M9W9N.jpg
Front of board https://i.imgur.com/HX29Ea3.jpg
The white stuff on the Z80 is I think the thermal paste that's under the gate array, the thermal paste was not dried out which surprised me.
A closer shot of the Z80 https://i.imgur.com/b4nvgUe.jpg
Cleaned socket https://i.imgur.com/mZ5RsF9.jpg
You can see some grime on the cotton bud tip. This was with iso alcohol.
Filth on edge of board https://i.imgur.com/y61dQ9T.jpg
You can see where the liquid has drained down to and stained the board, and also wicked up the screw.
Damage trace https://i.imgur.com/nfpeYFd.jpg
There is continuity here though.
Here's some of the manky stuff coming off on a bud with iso https://i.imgur.com/PYk2h4W.jpg
I noticed this taped on wire https://i.imgur.com/HJmwoTr.jpg
Is that normal? It doesn't look like it should be like that?
Hi
I'm not a specialist but I think the last pic with the taped on wire should be under the PLAY key. (relay switch?) Otherwise nothing on screen and no beep, you did well with RAM, even if it could be something else.
I've done a bit more nosing and when I cleaned the grease off the gate array I found a bit of the brown muck between it and the heatsink. That means to me that the brown liquid had got in there before the grease was reapplied. Which makes me think someone has tried to repair this even to the point of reapplying thermal grease and reseating chips, perhaps cleaning it up a bit.
A few points: Nobody spilt anything into it, that brown stuff is a type of PCB coating used on very early machines. Clean it off if you like, but there's no problem leaving it there either.
The "damaged" trace just missed the solder wave, it will work perfectly.
The taped switch is a problem. It should be screwed to the bottom of the tape deck frame and it's the reason the tape isn't doing anything. Try fast forward and then gently press those two metal prongs together and the motor should turn. This needs to be fixed, but the main computer needs to be fixed first.
Someone was definitely inside and couldn't repair it. It will most likely be the RAM or ROM that has failed. Does it produce any picture on the screen?
Bryce.
No picture on screen at all. https://i.imgur.com/sSRFXaS.jpg
Ok. There's a lot to be done. What equipment do you own and how would you rate your electronics skill level?
Bryce.
I have a cheap multi-meter. A crap soldering iron (that I've been off and on trying to find a decent replacement for, I've looked at a few Chinese ones but nothing has really grabbed me). I have a lot of miscellaneous soldering stuff on the way, stuff like braid, flux etc, solder wire, IC extractors, also some magnifying goggle things.
I don't have an oscilloscope but I was looking at https://www.amazon.co.uk/KKmoon-Handheld-Digital-Oscilloscope-Soldered/dp/B01HZ1Q26M/ (https://www.amazon.co.uk/KKmoon-Handheld-Digital-Oscilloscope-Soldered/dp/B01HZ1Q26M/) and wondering if that would do the job.
I've only done one bit of soldering, and that was just a loose connection on something, but I've been watching loads and loads of videos recently so I'm quite keen to do something like this.
My understanding is I'll be checking continuity, checking voltages on ICs and if needed checking the oscilloscope (I'm vague on this!).
I've got the patience for it, I'm not in any rush to get it working and I like the idea of a project. I got lucky on a 6128 that's in great condition and works so it's not even as if I need to get this working to play CPC games.
Ok. Most of the soldering you'll need to do is relatively "safe" as you should use sockets when replacing any chips. The most difficult bit is removing the old chips, so read and follow this carefully: http://www.cpcwiki.eu/index.php/IC_Repair Especially the bit about desoldering the pins from the TOP of the board. Not doing this can destroy your CPC as one user here unfortunately recently discovered.
Forget that KKMoon toy. It has a bandwidth of 200kHz, not even enough to properly display a bit change on the data bus, let alone view the CPC clock which is running 80 times faster than that scope can handle. Any scope for 15 pounds isn't going to be of any use. What's your upper limit that you could spend on a scope?
Bryce.
Ah I read that guide last night about removing ICs. They can't be removed without cutting the legs off? I've seen people use hot air or a desolder station and get them off. I'm going to have a look into that board destroying thing because I didn't know that could happen and I'll need to avoid it.
Which I think means no just desoldering every IC on there and socketing everything. I'd be wrecking a chip by desoldering it so I'll only desolder dead chips and socket before putting the replacement in.
How would you do it and preserve the IC if it was one that wasn't easily replaced?
For the oscilloscope, whatever would serve me for the CPC and the ST if I need to, without wishing I'd got a "proper" one. I don't really have an upper limit, but I don't think it's something I'll use a lot.
For the soldering iron, I cannot recommend the TS100 enough, as long as you run it off a 20-24V power supply (surplus laptop power bricks work great.)
I even recommend it over the "professional" base stations that cost a few hundred dollars, it's that good.
Quote from: Velociraptor on 09:35, 16 July 19
Ah I read that guide last night about removing ICs. They can't be removed without cutting the legs off? I've seen people use hot air or a desolder station and get them off. I'm going to have a look into that board destroying thing because I didn't know that could happen and I'll need to avoid it.
Which I think means no just desoldering every IC on there and socketing everything. I'd be wrecking a chip by desoldering it so I'll only desolder dead chips and socket before putting the replacement in.
How would you do it and preserve the IC if it was one that wasn't easily replaced?
For the oscilloscope, whatever would serve me for the CPC and the ST if I need to, without wishing I'd got a "proper" one. I don't really have an upper limit, but I don't think it's something I'll use a lot.
Here's what happens... Not pretty: http://www.cpcwiki.eu/forum/technical-support/me-and-my-schneider-cpc-464-again/msg171427/#msg171427 Those copper tracks are only glued to the PCB and if they get too much heat or pushed away from the PCB, they will quickly float and break off, leaving you with the messy job of having to bridge all the breaks. Destroying the chip isn't an issue if you have a replacement, but destroying the PCB can be game over.
If you need to remove a chip that still works, it's a difficult process that takes quite a bit of practice. It can be done with hot air or with braid, but the chances of destroying the chip and / or from heat is very high and I wouldn't recommend it unless absolutely necessary. On a CPC it is rarely necessary, replacements are easily sourced and relatively cheap.
As for scopes, you can get a half decent USB scope for about 60 quid: https://www.ebay.co.uk/itm/Hantek-6022BE-PC-Based-48MSa-s-Car-Automotive-2CH-USB-Digital-Oscilloscope-NEW/113796575904?hash=item1a7ecdf2a0:g:P7UAAOSwmftdEZMc (https://www.ebay.co.uk/itm/Hantek-6022BE-PC-Based-48MSa-s-Car-Automotive-2CH-USB-Digital-Oscilloscope-NEW/113796575904?hash=item1a7ecdf2a0:g:P7UAAOSwmftdEZMc) This is 20Mhz, which will much better serve you than that KKMoon toy and the display size is whatever your laptop has, not some postage stamp LCD. If you can spare the extra cash, there's a 50Mhz version too.
If you prefer a standalone unit, then the price will be around the 200 pound mark, but you have the freedom to use it with having a laptop with you.
@pelrun (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1106): Yes, the TS-100 is a fine device, I have one too. However, I only use it for mobile situations and the tip is a bit too long for me for everyday use.
Bryce.
Hmm. I don't have a laptop other than my work laptop so I'm not sure if I'd want the USB one. Would it work with an android phone though? - Edit : Yes. Apparently there's an app. Out of time now but I'll have a look when I'm home from work.
What would you recommend for a soldering iron then? Let's say that I wanted to spend no more than £100 on it, or maybe more if it was hot air too, or was otherwise some kind of 2 in 1 thing for something else I'd need.
No, they don't work with Android.
As for irons, it's difficult. I stick to known brands to ensure I can still get the tips I need in a few years, but I go through quite a few tips per year. There are no name brands that are ok, but I don't have much experience with them. Hakko is probably the cheapest known brand (if you can live with the blue/yellow Lego design). Just make sure that you can regulate the temperature, the tips are available as spares and that the tip is not too long.
Bryce.
I have found 3rd party software which claims to work with them on Android. That aside though I think it'd be best to get this option as even without a laptop I can just use my desktop. Once I've moved house I'll have a room where everything will be so it's not important to be mobile. I shouldn't have started on the 464 until after the move but I got temped to try it out.
Where's a good place for me to find out what I need to be testing on the board to narrow down the fault?
Quote from: Velociraptor on 20:40, 16 July 19
Where's a good place for me to find out what I need to be testing on the board to narrow down the fault?
You're already there :)
In a case like this, I would normally connect a LowerROM board to bypass/test the internal ROM. Once I know that works, I would run Geralds RAMTest from it to see which RAM has failed. You don't own any of these devices though, so you will have to measure things manually and that will require an oscilloscope.
Bryce.
Ok. Well I move house in a month so I need stop this until I've moved. I should be spending the time packing stuff up. I didn't do this before because I felt I didn't have the space and that's the position I'm at now, so it'll wait a couple of months.
Once I've moved the CPC will have it's home on a desk and I'll be able to do what I want whenever I want without having to put it in a box afterwards.
Once I've moved I'll then work out what I need to do to it.
http://hscope.martinloren.com/ (http://hscope.martinloren.com/)
In the mean time I'll get hold of that oscilloscope and try that android app for it. Might work. Ideally it will, but I can manage if it doesn't work on android. I still have the ram chips and z80 coming so hopefully they'll be here by the time I might want to use them.
Will I need a better micrometer than the very cheap one I have? Or is there anything else that you think I should have, I now have time to wait on stuff coming from China.
Edit : So yeah I went and bought a Hantek DSO5102P so never mind that stuff :)
Micrometer? You mean a Multimeter? Which one do you have at the moment?
Bryce.
https://www.amazon.co.uk/dp/B00TM0W8ZY/ (https://www.amazon.co.uk/dp/B00TM0W8ZY/ref=pe_385721_51767431_TE_dp_1)
I went and bought a soldering iron and hot air thing too. So I think I've got what I'll need when I get to it.
https://cpc.farnell.com/duratool/d00673/soldering-station-uk-eu-plug-60w/dp/SD01385 (https://cpc.farnell.com/duratool/d00673/soldering-station-uk-eu-plug-60w/dp/SD01385?CMP=TREML007-005)
https://cpc.farnell.com/duratool/d03329/station-hot-air-bs-plug/dp/SD01139 (https://cpc.farnell.com/duratool/d03329/station-hot-air-bs-plug/dp/SD01139)
The Duratool devices are fine, but don't even consider putting that multimeter anywhere near the 600V they claim on the front. It's only safe up to about 60V so I wouldn't even measure the 240V of a socket with it.
Bryce.
Is there one you recommend to people? Don't worry if there isn't, I can always look around if I find a need to measure mains voltage.
The best low-cost meter you can get is the Aneng AN8008: https://www.amazon.com/Alloet-True-RMS-Digital-Multimeter-Voltage/dp/B072JMBLJS
You can safely stick this into any socket you like :)
Bryce.
Got one ordered, and I can't wait to jam it in my sockets.
I think/hope I've got everything I need now. I'm going to move house and ordering from China will be a pain because I don't know exactly when I'll move and when the stuff will come.
I now have the desoldering hot air thing. The soldering station. The sillyscope. Some solder. Some braid. A solder sucker. Some flux. Some single strand wire. Tip tinner. A soldering mat. Some magnifying goggles. RAM and a zilog on their way. Some ram sockets and some 40 dip sockets.
Hope I've not missed anything :)
You're sorted. The only other thing required is experience, but you can't buy that, it will come with practice.
Bryce.
Yeah, the 464 isn't a disaster if I completely kill it, since I have the 6128. However I'd very much like to bring it back to life and I won't be doing what happened in that thread you linked. Bizarre that he wrecked it and sent it to you, you then did that beautiful repair and it was then snapped in two on purpose. I can smell a bit of a rat there. I do wonder what happens if I put solder braid along the top of the board along the pins on an IC, and then use the hot air gun and then reposition it and repeat, finally flipping it over and seeing if I can wiggle each individual leg with a plastic spudger. Not going to do that without a good reason though. Which means I'll hopefully identify a dead chip and remove it by cutting it's little legs off one by one.
I won't touch it now until I've moved house, but once I have moved house I've no idea what I need to look at. Is there some kind of reference somewhere of where I should be looking for voltages and clocks?
Quote from: Velociraptor on 20:46, 24 July 19
I do wonder what happens if I put solder braid along the top of the board along the pins on an IC, and then use the hot air gun and then reposition it and repeat, finally flipping it over and seeing if I can wiggle each individual leg with a plastic spudger. Not going to do that without a good reason though. Which means I'll hopefully identify a dead chip and remove it by cutting it's little legs off one by one.
I won't touch it now until I've moved house, but once I have moved house I've no idea what I need to look at. Is there some kind of reference somewhere of where I should be looking for voltages and clocks?
You can try that, but you'll discover after it takes you about 30 minutes to remove the first IC, that it's just not worth it and the chance of damaging the board is still high. There can be a lot of solder behind the pin (underneath the IC) that the braid won't have removed and is impossible to get to.
There's no real guide, just because so many things can cause problems. When you have moved and are ready to repair the PCB, come back and we can go through the options in stages.
Bryce.
Quote from: Bryce on 07:52, 25 July 19
You can try that, but you'll discover after it takes you about 30 minutes to remove the first IC, that it's just not worth it and the chance of damaging the board is still high. There can be a lot of solder behind the pin (underneath the IC) that the braid won't have removed and is impossible to get to.
My curiosity is outweighed by my trust in you :)
[/size]Quote from: Bryce on 07:52, 25 July 19
There's no real guide, just because so many things can cause problems. When you have moved and are ready to repair the PCB, come back and we can go through the options in stages.
Bryce.
Sure! In the mean time I'll watch whatever youtube vids I can and do a bit of sniffing in the forums.
I want to say.. if you absolutely, positively must must must remove the ICs in an intact form you need a proper vacuum desoldering station.. even then you can still damage traces if you're not careful, but I would almost guarantee if you try it with solder wick you end up having to do more repairs than when you began.
Quote from: MikeSDK on 18:45, 25 July 19
I want to say.. if you absolutely, positively must must must remove the ICs in an intact form you need a proper vacuum desoldering station.. even then you can still damage traces if you're not careful, but I would almost guarantee if you try it with solder wick you end up having to do more repairs than when you began.
Ok, at some point with something, if I stay interested in this I'll want to try it I'm sure. But I won't be trying it with this 464 unless it's dead and I'm trying to salvage components or something like that.
I'm curious in that I want to give it a shot, but I'm not daft enough to ignore advice from experts.
I have the hot air station, the soldering station and I haven't bought the vacuum gun thingy yet but I intend to.
Go to a flea market, buy some random broken 286/386 Mainboard from the 80's / 90's for a few cents and practice on that PCB until you are confident that you can remove IC's without frying them. Avoid devices like telephones and radios, because they are usually single sided PCB's. If you can successfully remove a TTL chip from an 8 layer PC PCB with internal VCC and GND plains, then you're there.
Bryce.
That's a cracking idea. I'll give it a punt.
Time for an update :
I now have Duratool tools - a hot air rework station, a soldering station and a desoldering station. I also have an Oscilliscope, a better multimeter and an ESR meter.
I wasn't able to find any 286/386 boards. Even broken ones are going for a fair amount. I did however get someone to send me some boards from a Sky box and some of those were similar. I've removed several components including ICs from them. I've done some SMD soldering to assemble a DIN to VGA for an Atari ST and a basic USB powered board. I've assembled the serial port board for the CPC too. So while I'm hardly an expert on soldering I now at least have done some. Solder wick is the most disappointing thing on the planet!
I now have the broken 464, and a working 6128 and a working 664. I also have a CTM644. I mentioned in passing to someone that I might need a gate array and before I knew it I had a donor 464 board, it lacks the YM IC but that's all.
The 6128 and 664 work fine on the CTM644 (although I will recap, or at least test the caps at some point and clear out the dust/filth).
The 464 still doesn't work, which is no surprise because I've not changed anything. However when I plug it into the CTM644 I do get output. I get raster bars across the whole screen like you'd see when something was loading.
Because the donor board has the gate array and Z80 socketed I've swapped them over and it has no effect.
I'm now ready to try to diagnose the problem - where do I get started? :)
Are they raster bars with a border around them, or do the bars go to the very edge of the CRT?
Bryce.
https://i.imgur.com/4V850j3.jpg (https://i.imgur.com/4V850j3.jpg)
I can take a video if you think that would help?
Ok, my guess would be a failed CRTC. Have you tried swapping the Gate Array for a good one yet, or do you not have a spare to try?
What you can measure now is pins 39 and 40 of the CRTC. They should both show regular pulses on the scope. Either of these missing could cause the effect you're seeing and also mean that the CRTC is dead.
Bryce.
I have tried swapping the gate array and it made no difference.
So next step is for me to get the scope out and find where the CRTC is, and then with the power on measure it. The scope hasn't been out of it's box but I'm sure I can work all that out!
Can the keyboard be disconnected for this? So I can have the 464 case open hinged on it's right hand side so that the connector is still in which would allow me to use the power switch to turn it on?
The CRTC is the big 40pin soldered chip with 6845 written on it. The keyboard doesn't need to be connected. When I repair 464's I have a jumper to short pins 1 and 3 on the cassette connector, which is the connection the power switch makes, so the PCB can be completely removed from the case.
Bryce.
Yeah I found it through the power of google and realising that if I need to measure 39 and 40 then it has to be a big chip :)
I'll see about a jumper for 1 and 3 on there because I don't want to put strain on stuff.
https://www.youtube.com/watch?v=dFB9JJjwJuU (https://www.youtube.com/watch?v=dFB9JJjwJuU)
https://i.imgur.com/awOTWDZ.png (https://i.imgur.com/awOTWDZ.png)
A big ominous cross!
Edit : I have desoldered the CRTC from the donor board. I thought even if I don't need to swap it out, then it won't do any harm to have it. I'm really pleased with how neatly I got it out.
https://i.imgur.com/xXSNZeO.jpg
A better result than that other guy's attempt you warned me about Bryce, I think :)
You do realise other people try to achieve this output for years, right? :D /sorry
Ok, the "big ominous cross" is because the scope is set up wrong. You need to set the vertical to around 1V/Div and the horizontal to around 20ms/Div. Then you should see something completely different :)
If I have time later I'll connect up a scope and make screen shots of what you should see and what settings I used.
Bryce.
Ah ok. Well.
In the meantime I desoldered both CRTC from the 464 I want to repair and the donor board, and then fitted a socket on the repair board and put the other CRTC in and it still gives the same output.
I'll go get the oscilloscope and try to work out how to set it up.
https://cdn.discordapp.com/attachments/444419003419721750/622092622772568072/Screenshot_20190913-163307_Video_Player.jpg (https://cdn.discordapp.com/attachments/444419003419721750/622092622772568072/Screenshot_20190913-163307_Video_Player.jpg)
So that does look how it should I think.
Meaning the problem lies elsewhere?
Interresting case :D
I grabbed the following picture from the video you posted.
We can clearly see a proper VSYNC (the black bar at top of screen), but the screen did not sync on it
Then the beginning of a proper screen with border, with garbage on the screen section, but the screen sync properly on the HSYNC
The on screen garbage may hint a RAM failure.Then at the bottom, everything goes bad.
Did the screen lost HSYNC, did the CPC really send garbage ?
I would
- 1st check that we have a proper 5V supplies (also, do you have a way to know how much you CPC is consuming ?)
- Checking that the various clocks are OK
- 16MHz clock is OK at gate array input - 4MHz to the Z80 (it may have a bit of jitter)
- 1MHz to the CRTC
I know that we have the right supply because the 664 and 6128 both work from it. I don't have a way to check the power consumed.
Is there a way and do you want me to check the voltage while it's on across two points?
How do I check the 3 clocks you've asked me to check?
So I thought I'd socket and replace all the ram to see what would happen. I didn't cut the legs, I very carefully desoldered. It was a little more difficult than the other ICs as it seems solder had gone up the legs of the ram ICs so I had to resolder and desolder some of them up to 3 times.
I'm now getting a different screen - the screen is a sort of green and purple chess board. I don't know if this is progress or not.
https://i.imgur.com/19xYBEe.jpg (https://i.imgur.com/19xYBEe.jpg)
Ran out of time tonight but there's lots more chips I could desolder, socket and then bring across from the donor board to see what happens.
I think tomorrow I might want to put the old ram chips back in to see what happens and then try swapping out one at a time.
Quote from: Velociraptor on 00:45, 14 September 19
So I thought I'd socket and replace all the ram to see what would happen. I didn't cut the legs, I very carefully desoldered. It was a little more difficult than the other ICs as it seems solder had gone up the legs of the ram ICs so I had to resolder and desolder some of them up to 3 times.
I'm now getting a different screen - the screen is a sort of green and purple chess board. I don't know if this is progress or not.
https://i.imgur.com/19xYBEe.jpg (https://i.imgur.com/19xYBEe.jpg)
Ran out of time tonight but there's lots more chips I could desolder, socket and then bring across from the donor board to see what happens.
I think tomorrow I might want to put the old ram chips back in to see what happens and then try swapping out one at a time.
Did you replace the RAM or did you just left the socket empty ?
If you have new RAM in, then the next suspect would be the address multiplexers (4x74ls153 IC104 IC105 IC109 IC113)
I replaced the ram after I added the sockets. Next up is those 4 guys then!
Looks like I might end up with the whole 464 socketed. :)
Quote from: Velociraptor on 16:35, 13 September 19
https://cdn.discordapp.com/attachments/444419003419721750/622092622772568072/Screenshot_20190913-163307_Video_Player.jpg (https://cdn.discordapp.com/attachments/444419003419721750/622092622772568072/Screenshot_20190913-163307_Video_Player.jpg)
So that does look how it should I think.
Meaning the problem lies elsewhere?
Woah, you really need to sit down and learn how a scope works first. You haven't connected the GND'S to anything (those two crocodile clips). They need to be connected to the GND of the CPC. The waves you are seeing there are 50Hz, ie, the stray frequencies coming from the mains via you.
Here's what the two pins should look like. Use the settings I've used (as seen in screenshots) and set the trigger to about 0.5V.
Bryce.
I know I should work out the oscilloscope, and I will, but I was on a bit of a desoldering run so I've desoldered the entire donor board.
In addition to desoldering and socketing the ram yesterday I've now done the same to the 153 chips and once I'd put the donor ones in I got a black screen, no output.
Turns out the power supply from the monitor has died. However when I use a different PSU. I'm thinking it's the cable, the coil was very reluctant to unwind and maybe something has snapped inside it.
https://i.imgur.com/BOTlALQ.jpg (https://i.imgur.com/BOTlALQ.jpg)
Using desoldered chips, without knowing whether they survived the desoldering is a bad idea. The parts aren't "known good", so you may be removing good parts and testing with bad parts.
Bryce.
I didn't know that desoldering ICs could damage them. Last night I got it working and then went through all the other 153s, ram and everything else I had socketed on the 464 and made sure all the chips I have worked. All but the 2 damaged RAM and the 1 damaged 153 work so it does appear that I have a nearly full set of CPC ICs.
After some contact cleaner the dk'tronics 64K and the Multiface 2 also work.
https://i.imgur.com/tIwUKcE.jpg
https://i.imgur.com/ncSFWv5.jpg
That means for my 464 I need a DDI-1, to change the ROM for a 6128 one, and to add a cassette port for the tzxduino and I'll then have it to 6128 functionality.
However it does need a very thorough clean, and I've not gone near the cassette deck yet. Back at the start of the thread you commented that someone has been in at the tape deck so I don't know how I'll get on with that. I have spare belts, and thankfully the main belt has not melted. I replaced the belt on the 6128 the other night and it had basically turned to glue, it took a lot of IPA to get it clean so I'm glad I don't have that with this one.
So on to the next problems with the 464.
There was a disconnected leaf switch and going back to what you said in your very first reply Bryce when that is closed the tape deck has power, when it is open the tape deck has no power.
It took me a lot of puzzling but I think I've had a revelation as to how it works. You said it's mounted by the play button and I can see 2 little screw holes and either of which I think it could go on to.
I could not work out how pressing play could close the switch. Then I realised that if FF and RW don't work until the switch is closed then it should normally be closed. This would mean that pressing play wouldn't work until the CPC sent some kind of override signal - this is how the CPC works if I remember right. You press play and nothing happens until the CPC wants it to happen and there may even be an audible click.
So am I correct to mount this in that position where the leaf switch is normally closed, and pressing play releases it to an open position? I'm not sure how I'll mount it, perhaps hot glue or solder.
The tape counter appears to be damaged. It looks like the button has snapped off. I think I may leave the tape counter belt off and keep the tape counter at 000, I don't recall it ever being useful.
I need to strip down the volume and power controls and clean them out. Also the keyboard to remove any dust and muck that's reached the membrane otherwise over time it will destroy it.
Heat destroys chips. Whether soldering or desoldering, too much heat for too long will fry what's inside.
Yes, the leaf switch is normally closed as far as I can remember. Gluing or soldering is a bad idea, and if the contacts touch the metal frame of the player you'll have bigger problems. Can't you mount it like it originally was?
Bryce.
Sadly not. The screw is missing and I've not managed to find any that fit. I do have one that's too small though so I'll use that to hold it exactly in place and then use hot glue on it. Worst that can happen is it doesn't work properly. Then I'll have to start randomly buying packs of small screws I suppose in the hope I get exactly the right size.
Hot glue has it solidly in place. There's actually two holes in the metal to mount it on, one is for a black plastic tag and the other is for a screw. By putting it in in place and letting the black tab hold it I was able to use hot glue to fix it in place.
I've cleaned out the keyboard which was full of debris but thankfully there's no visible membrane damage.
I've reassembled it and....
The tape fix i did works! Tapes FF and RW when I want, but only play when the 464 wants them to play. However the pause button doesn't work.
The keyboard works perfectly.
The 464 is now fully functional!
Remaining to be done -
Fix the pause button
Fix the eject button - might not work while the tape window is missing
Sand down and polish the tape window
Clean the keys more thoroughly
Find out what happens with the little spring thing that I don't know where to refit - possibly pause and/or eject related?
My pause button doesn't work either...
Waiting for your tips after you fix it ;D