Cassette Loading problems

About original Memotech hardware.
Nassimbakir
Posts: 29
Joined: 24 Dec 2021 20:26

Cassette Loading problems

Post by Nassimbakir »

Hello dears,
I’m no professional Technition here , but I manage replacing chips and capacitors.

I’m having problem loading cassettes to my MTX500.
It nighther recognise the game name nor hearing the sound of loading . Sometime it do , sometimes it don’t and sometimes loses the sound in the middle of the loading .
By reviewing some topics her about that fault , it seems that I have to change the …374N chip for that . And when I opened the computer I found 3 of them . I’m not a schematic reader … so can any one show me please which one on board needs to be changed???

Thanks buddies.
Last edited by Nassimbakir on 24 Feb 2022 21:11, edited 1 time in total.
Nassimbakir
Posts: 29
Joined: 24 Dec 2021 20:26

Re: Cassette Loading problems

Post by Nassimbakir »

Real photo
Real photo
3B1C1B43-7AED-42DE-A0A6-64831431D20E.jpeg (4.05 MiB) Viewed 6266 times
User avatar
1024MAK
Posts: 757
Joined: 24 Dec 2012 03:01
Location: Looking forward to summer, in Somerset, UK

Re: Cassette Loading problems

Post by 1024MAK »

Slow down there!

How are you trying to load?

Are you using a cassette tape deck and an original cassette tape? Is this a commercial (prerecorded) tape? Or a “home made” recording?

Or are you using a modern item (such as a smartphone, MP3 player, computer or other digital device)?

What lead(s) are you using?

Do they have mono or stereo plugs?

Mark
:!: 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 in Somerset later in the year :D

Not as many MTXs as Dave! :lol:
Nassimbakir
Posts: 29
Joined: 24 Dec 2021 20:26

Re: Cassette Loading problems

Post by Nassimbakir »

Hi
I’m using a mono tape player and original cassette .
Just like the old times setup.

Sometimes I hear the sound of loading and sometimes not …
I repeat the process until once i succeed. Some time ,and it’s a lot, it just stops loading and I can’t hear the sound anymore …

I’m confused here … is it a fault ic or just normal which I don’t think it is …

So … helpppppp
Martin A
Posts: 799
Joined: 09 Nov 2013 21:03

Re: Cassette Loading problems

Post by Martin A »

Starting with pratical stuff:
First, round the edge of the PCB are letters and numbers. So down the left of your photo are the letters A to J. Across the top are the numbers 10 to 1. On the MTX schematic the chips are labled by a "grid" reference. For example the Z80 CPU is 10A, ie top left of the photo, Video ram bit 7 is 4G ie lower left of the block of 8, 4116 DRAMs.

Second, there is no hardware connection between the sounds system of the MTX and the tape interface. The tape loading software turns the sound on and off when tape hardware indicates to the CTC it's found a signal transition on the tape. The tape circuit is on page 226 of the new manual (and page 215 of the old one). There are a dozen or more passive components and 2 chips involved before the input is fed to the Z80 CTC. There's no LS374 involved.

So if you have a working sound system, you can hear the ctrl-G bell and the output from SOUND statements in basic etc, then changing the LS374 that feeds the sound chip isn't going to have any effect. IF you have no working sound system then that LS374 (chip 4E) could be the problem, but even if it is, replacing it still won't change the tape loading, just your ability to hear the "echo" of what the tape interface picks up.

Tape loading issues are not necessarily a problem in the MTX, getting the tape levels and tone correct was a tricky enough problem in the past**. As the tapes get older the problems don't get any easier.

IF you're getting a tape header, with the correct name appearing on screen, and some of the file loads, then to me that suggests the tape is more likely to be the problem than the MTX.




** Which is why "disc" systems like CFX and rememorizor are popular now.
Nassimbakir
Posts: 29
Joined: 24 Dec 2021 20:26

Re: Cassette Loading problems

Post by Nassimbakir »

thank you Martin .
yesterday i loaded TOADO perfect from the first time starting the computer, and i let it playing for hours without any issues in graphics or sound.
after i reset it to load another one , it didnt even recognize the name of the tape or any loading sound. sometimes after some seconds passed i start hearing the program sound but in pieces that come and go not continuously ...
now , all loading sound is gone , and the MTX cant recognize any program from tape.

this is the situation now, any hints ??

can you please refer what are the ic's and other components i have to check ?? as i said before ,i have the skills to solder and de-solder but not schematic reading.

thanks
btw, i just tested the sound by CTRL G and a small basic prg . it is all working well , except the loading matter ???
User avatar
1024MAK
Posts: 757
Joined: 24 Dec 2012 03:01
Location: Looking forward to summer, in Somerset, UK

Re: Cassette Loading problems

Post by 1024MAK »

It may be that the magnetic coating (particles) on the tape are becoming detached and then clogging up the tape head in the cassette deck.

Try cleaning the tape head with a tape cleaning fluid. Or if you can’t get that, use IPA.

Mark
:!: 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 in Somerset later in the year :D

Not as many MTXs as Dave! :lol:
Nassimbakir
Posts: 29
Joined: 24 Dec 2021 20:26

Re: Cassette Loading problems

Post by Nassimbakir »

Hi Mark ,
It’s not the cassette or the player as I can hear the program purely when I unplug the wire form it .and I also tried different original cassettes and different players .
The main problem is that the MTX DOESN'T RECOGNISE any thing , no program name , no sound … nothing …

😔
Martin A
Posts: 799
Joined: 09 Nov 2013 21:03

Re: Cassette Loading problems

Post by Martin A »

So Toado loaded first time.

Does Toado load every time ?
Or does it only load sometimes, and no apparent pattern ?
Or only when the system is cold, or warmed up ?

Because if Toado loads, and loads every time then that says to me the MTX is fine and the problem lies with the other tapes.

Toado loading at all is strongly hinting that the tape pickup to CTS electronics are fine.

If Toado only loads on a cold system, or only on a warm system, thats possibly an indication of, expansion issues, a cold joint or the CTC not tight in the socket.

If someimes yes, sometimes no, and no pattern. then it could be the tape lead has break and is making intermittent connection.
Nassimbakir
Posts: 29
Joined: 24 Dec 2021 20:26

Re: Cassette Loading problems

Post by Nassimbakir »

Thank you Martin .

If it loads it loads . I even once tried to load blobbo , it loaded first time - only when switching the computer on first time , then nothing .
Now , it is nothing all the way . No matter it’s cold or hot … I checked all wires , even new ones , and got a Sony tape player brand new - which I loaded Toado and Blobbo on it , then nothing …
I’m afraid it’s a chip or something is bad , but which one to replace , that is the question …

Sorry for the delay , I was out .
Post Reply