🇯🇵 Panasonic RL-H1400 Handheld Computer: Part 2 [TCE
ฝัง
- เผยแพร่เมื่อ 27 ก.ย. 2024
- It's been a while since Part 1 in which I had almost finished pulling the printer apart - I finish that off in this video (thanks to a reminder from @colinebyuk).
The reason for the delay is I've been trying to get replacement NiCd batteries but keep getting sent NiMH batteries despite specifically buying NiCd batteries. sigh
I might have another go, and then give up ... can I convert the charging circuit in the Panasonic to support NiMH ... ?
Dunno. Further research is required. First stop, finish watching EEVblog's #35 video:
• EEVblog #35 2of2 - NiM...
I also have a quick look at the 8Kbyte mod RL-H1800. This one again comes with insurance related ROMs.
That's all - just want to give a quick update
Summary from Part 1:
They use a full-sized, socketed Rockwell 6502 running at 1MHz and come with 2KBytes (RL-H1000), 4KBytes (RL-H1400) or 8KBytes (RL-H1800) of RAM ... the 4Kbyte model seems to be the most prevalent on ebay. The RL-H1000 can be expanded to 4Kbytes.
It has 16Kbytes of internal ROM and can take up to three 16Kbyte ROM "capsules" - these are usually 24-pin 8Kbyte Motorola 68764 EPROMs ... note that these are a bit different to 28-pin 2764 EPROMs.
It can run programs written in BASIC and SNAP, but there are also capsules with FORTH and MS-BASIC available as well.
The HHC itself has an internal 5 x 1.2V AA NiCd battery pack and the printer has a pair of 2 x 1.2V AA NiCd battery packs.
![🇺🇦 Орель БК-08 (Oril BK-08): Part 4 [TCE #0508]](http://i.ytimg.com/vi/G2FpETESSqo/mqdefault.jpg)
I bit the bullet and just bought individual NiCd AA cells, rather than pre-made 2-cell and 5-cell batteries. Guess I'll need to make up my own batteries. And it seems that YT lost this bit in the video description ... very handy video by Dave at EEVblog about NiCd vs NiMH charging: th-cam.com/video/_ROhH9EkhtU/w-d-xo.html
I ended up sourcing NiCd batteries for mine. They were solder tab cells, so I made up my own packs. I don't have paper to test the printer yet, but the HHC itself seems happy enough. Of course I did end up doing it all three times. Learned a few lessons along the way. Lesson 1, if you don't have the HHC's fuse locked down properly with its original sleeve, you are going to short against the back panel and smoke all the positive leads. Ask me how I know this. And yes, it all survived. In the final config I shrink wrapping the fuse assembly on both the HCC and the printer. Thanks for the videos and advice!
Huh! Yes, I was thinking about the fuse the other day - was just going to re-use the existing one and put new, clear shrink-wrap on. Haven't checked if that paper type is still available - happy to send you leftover part of a roll from one of my printers if you like (if I have any, can't remember). I finally got NiCds as well on Tuesday - I ordered NiCds ... and they actually delivered NiCds ... got Panasonic branded ones. Will also try out the NiMHs as well in another machine.
I had bought the biggest 4-cell pack that I could find and it was only 2400ma (as well as being a NI-MH pack). I had forgotten all about it until yesterday when I was cleaning up in my den and came across the pack and realized that I was supposed to do something with it... That, and I couldn't remember what device I had purchased the pack for.
And then you posted this video. Timely!
I just removed mine, and they had just started to leak, so I lucked out. The batteries in mine (and possibly yours) are "Sanyo Cadnica" 600ma solder-tabbed batteries, part number "N-550AA". I'll put a photo up on Discord.
YT ate another post. WTF?
In any case, I had bought a 4-cell pack, and it too was a NI-MH pack. I then forgot what I had been intending to do with it. The pack popped up yesterday and I was planning on asking you why I had bought it (I too have about 4K in memory). And then this video showed up. Timely... :)
Mine came out without any trouble other than the rat's nest of wires that Panasonic left us. No serious leakage either. The cells are "Sanyo CadNica" N-550AA 600ma solder-tabbed batteries. I would throw your printer frame in a tub of white vinegar and leave it there for a few days.
As for your pack, the electronics in the charging cable will keep the battery charged but not overcharged (to the limits of Chinese technology and dedication). But you would have to split the pack into two 2-cell packs to make them fit. -I'm going to split my 4-cell pack and use it-. Your section on the circuitry in the charger made me open mine up and the chip inside is a TI MC34063A Buck/Boost inverter. What it isn't is a charging circuit. What theses are is a constant-current charger that fills a "One size fits all" niche. So I'll be looking for a better solution too.
Video notes: Yeah, I noticed the screw. And the 7808! They're popping up all over! Your previous video kept me from making a mistake. I didn't see the second screw holding down the circuit board and I had already tried some gentle prying when I brought up your earlier video. Thanks!
Arghh ... you are remembering to copy the text before posting? No idea why YT does this ... I've got you as a "standard moderator" even ... when other people report issues, and they're frequent commenters, then I'll add them to the "approved users" list but that also doesn't seem to stop YT from dumping comments or stripping links ... ?!
@@Brfff "you are remembering to copy the text before posting?"
We've already discussed my memory... :)
I think that it was because I must have exceeded some arbitrary time limit while looking up battery info. I don't know what it is about YT. I guess that they get to do what they want to do.
Why don't you just use the NiMh batteries? - They should work as a direct replacement, just better.
It’s the end of charging detection, which is different - I’m assuming that there’s something to detect this and stop … maybe there isn’t … ?
@@Brfff Not on those battery packs. Now whether or not the 250ma charging current is more than what would be a safe trickle charge is another question (I would say probably so).
It's a case of low-budget engineering. The chip controlling the charger is obsolete, TI doesn't recommend its use in new designs. The charger is designed to cover any pack capacity up to one that supports a 250ma charge, and given that it doesn't specify how many cells it supports, it could be for a 1 to 4 cell pack (which means a constant-current charger). No indication of any end of charge detection circuitry (and based on the wide range of cell capacity that it can charge, how would it know?)
NiCd cells are no longer produced. Cadmium is nasty stuff! Someone in China might still be making them, but they are best avoided.
I've replaced all of the cells in my handheld radio packs with NiMH many years ago and they're still going strong without the leakage problems of the old NiCd nasties. I do unplug the charger after I'm sure it's run long enough to be fully charged.
The circuit you showed has only a resistor for limiting current. The diodes prevent the battery from discharging through the power supply and to direct charging current through the resistor. There is no charge termination. You could replace those components with an IC based circuit designed for NiMH cells, but that would be a LOT of work for something that would see very limited use. With either cell type you would need to pay attention to how long it's been charging so there's really no reason to try to use NiCd which end up leaking dangerous chemicals anyway.
The universal charger is just a voltage regulator/current limiter done with discreet transistors. Effectively the same thing as the LM7808 version. The pot allows for trimming the output voltage.
I ordered some individual NiCd cells so I'll try making up my own batteries ... but as I've got these NiMH batteries then I might as well try them out too - I think I've somehow acquired three H1400s and one H1800 so have plenty of "volunteers" to try the different batteries out on!