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General Category => Technical Support => Hardware related => Topic started by: Audronic on 05:59, 11 November 18

Title: CPC 464 Tapes not loading, ERROR A and B -- FIXED -- Finally LA6324
Post by: Audronic on 05:59, 11 November 18
Hi All


CPC 464 Tapes not loading, ERROR A and B, Help please.
The tape I have used is a known good one which works OK.
I have changed mother boards and the fault Stays with the Tape Deck.
Cleaned Tape Path, Heads, Pressure Roller, etc
Have recorded a small program and on Playing back ERROR A/B on the Faulty  Tape Deck


Any help would be Appreciated.
Thanks.     Ray
Title: Re: CPC 464 Tapes not loading, ERROR A and B Help please
Post by: AMSDOS on 06:17, 11 November 18
Just hope it's not the Motor. Many years ago when we had a 464 the Motor wasn't running properly causing the tape to run unevenly causing Read Error A and B.
Title: Re: CPC 464 Tapes not loading, ERROR A and B Help please
Post by: Audronic on 08:33, 11 November 18
@AMSDOS (http://www.cpcwiki.eu/forum/index.php?action=profile;u=330)


I will get a small audio amp and have a listen to the Wow and Flutter.


Thanks.     Ray
Title: Re: CPC 464 Tapes not loading, ERROR A and B Help please
Post by: LambdaMikel on 09:17, 11 November 18
I still have the Tapedeck from Hell. The motor should be fine.You can have it if you like.
Btw, I had the same problem with my childhoof CPC 464... it was serviced twice for that. It never really got fixed. I stopped caring when I got the disk drive. The audio was very uneven... the up and down in pitch was clearly noticable. Almost 20 % change in pitch or so. Still, tapes worked fine! That was the most amazing thing. Since the problem reoccured even after they replaced the tape deck (at least they said so), I suspected it was the power supply in the monitor that was somehow responsible for that. Can be completely wrong of course. Just guessing.
Title: Re: CPC 464 Tapes not loading, ERROR A and B Help please
Post by: Audronic on 09:29, 11 November 18
@LambdaMikel (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2172)


Thanks for the offer, the motor seems fine.


I have made up an external connector powered by a Linear power supply (Lab).
am listening on the internal speaker. Red link


I will record some 3 Khz tone and replay it on the deck.


The amplifier chain seems VERY Noisy ???


Thanks.      Ray


Title: Re: CPC 464 Tapes not loading, ERROR A and B Help please
Post by: LambdaMikel on 09:31, 11 November 18
Maybe it is the head.. I had to replace a tape head recently. It was corroded. That resulted in very low signal quality, almost zero.
Title: Re: CPC 464 Tapes not loading, ERROR A and B Help please
Post by: llopis on 09:36, 11 November 18
A couple of thoughts:
- Did you change tape belts? That’s the most obvious part and you didn’t mention it, but I suspect you already did.

- The solder joints of the tape cables to the tape PCB are often very fragile and worn. Sometimes the cables are hanging literally by a thread. That could explain why things are so noisy. Have a look and refreshed the solder joints if they look iffy at all.


Sent from my iPhone using Tapatalk
Title: Re: CPC 464 Tapes not loading, ERROR A and B Help please
Post by: Bryce on 10:54, 11 November 18
Tapedeck testing steps (all done with tapedeck powered but Mainboard disconnected):

1 - Check the voltages to the motor and PCB.
2 - Check the speed of the tape.
3 - Measure the signal coming out of the tape head. (Scope)
4 - Measure the signal coming out of the amplifier/comparator circuit. (scope)

One of these will not be correct and tell you which part of the circuit isn't doing its thing properly.

No signal at all = Voltages or tape head.
Frequency wrong = Motor speed problem.
Signal level wrong = Amplifier issues, possibly the capacitors.

If the signal levels are correct, but go wrong when the deck is connected to the Mainboard, then I'd suspect the AY.

Bryce.
Title: Re: CPC 464 Tapes not loading, ERROR A and B Help please
Post by: Audronic on 13:00, 11 November 18
@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225)
@LambdaMikel (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2172)

@llopis


Thanks I will have a look at all the suggestions.


Thanks.   Ray
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: Audronic on 05:30, 12 November 18
Thanks All


I have resolved the Problem.


The pressure roller has a bad depression in it , it looks like it had been engaged in play whilst in the Cupboard Grrrrrrrrrrr
The effect is that the tone that I recorded plays back with a momentary rise in pitch as it hits the depression on the Pressure roller.Hmmmmmm
I just have to find a Pressure roller.


Thanks again for all your constructive comments


Ray
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: LambdaMikel on 08:58, 12 November 18
Happy to send it to you if you want it.
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: LambdaMikel on 09:20, 12 November 18
This one, right?
Btw, it "snaps off" easily; you can simply pull the plastic cap.
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: Bryce on 09:38, 12 November 18
The armatures aren't standard, but the wheels are. So you can use the rubber wheel from any tape deck.

Bryce.
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: Audronic on 10:13, 12 November 18
@LambdaMikel (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2172)
Thanks for the Part


@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225)
Thanks for the Info.
These 10 Cpc464's and 2 CPC6128s that I have been working on have had a range of challenges ?
Thanks to all concerned.
Ray





Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: Bryce on 10:14, 12 November 18
@LambdaMikel (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2172)
Thanks for the Part


@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225)
Thanks for the Info.
These 10 Cpc464's and 2 CPC6128s that I have been working on have had a range of challenges ?
Thanks to all concerned.
Ray

All great troubleshooting experience though. You've probably learnt quite a bit while fixing them.


Bryce.
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: Audronic on 10:25, 12 November 18
@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225)


Yes it has been interesting, I only asked questions when I was struggling.


I have made up quite a few tools, Special cables, for the Tape deck, etc.
My Major tool was Geralds Ramtest Rom to mostly prove in principle that the mother boards were Ok or suspect.  Thanks
And the Speed test for the disk drives , I found that I had put the ribbon on the edge of the motor spindle (running a bit fast).


Thanks.   Ray
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: Bryce on 10:43, 12 November 18
Other than real test equipment, the homemade bits that I regularly use for CPC repair:

Standard jumper to switch on 6128 PCB.
Homemade 1-3 Jumper to do the same on 464's at the tape header.
PAL jumper (IC socket with links to swap upper/lower RAM on a 6128.
Geralds RAMTest on a LowerROMBoard.
SyX's Drive Speed test (On my HxC).

Bryce.
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: Audronic on 11:03, 12 November 18
Other than real test equipment, the homemade bits that I regularly use for CPC repair:

Standard jumper to switch on 6128 PCB.
I will have to make one of these.

Homemade 1-3 Jumper to do the same on 464's at the tape header.
Yes in the Kit

PAL jumper (IC socket with links to swap upper/lower RAM on a 6128.
I made one of these up (Header pin Version) (Bryce suggestion) for my " FIRST " Amstrad repair.

Geralds RAMTest on a LowerROMBoard.
Yes I use the Xmem to do that.

SyX's Drive Speed test (On my HxC).
I will have to find that Drive Speed test.

Bryce.


Thanks.   Ray
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: Bryce on 11:44, 12 November 18
You don't have to make the 6128 power jumper, it's just a standard 2.54 jumper.
The Disktest is here: http://www.cpcwiki.eu/forum/applications/dsktest-v0-1b/

Bryce.
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: LambdaMikel on 17:26, 12 November 18
@LambdaMikel (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2172)
Thanks for the Part


@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225)
Thanks for the Info.
These 10 Cpc464's and 2 CPC6128s that I have been working on have had a range of challenges ?
Thanks to all concerned.
Ray
Wow, you fixed 10 CPC 464? Curious - some people are saying that a logic analyzer and oscilloscope are the most important tools required for fixing CPCs. I disagree with that (so far I was lucky enough to fix all CPCs with logic probe and continuity tester). What are the tools you needed for fixing them (besides soldering iron and the things you listed of course).
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: Bryce on 17:33, 12 November 18
A logic analyser is luxury, but can be useful for debugging something you're developing, especially if you're debugging the firmware too. It's not something I'd invest in for repair. A scope, even a relatively low-end scope can be extremely useful for repair and there's nothing else that comes close as an alternative.
I'd also recommend a decent Bench powersupply.


Bryce.
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: Audronic on 23:48, 12 November 18
@LambdaMikel (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2172)
@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225)

Most of my testing is done with, Logic probe (One that can handle 4 MHZ at least) I had an old one that led me a merry chase around the Oscillator section. It is now in the rubbish bin. A Multimeter, and a 10Mhz CRO (Analog, OLD), a small Audio Amp (Battery Powered) to trace the audio in the analogue section.
A hard copy of the relevant area of the schematic I am working on (and to make notes on).
Ray
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: LambdaMikel on 00:12, 13 November 18
@LambdaMikel (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2172)
@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225)

Most of my testing is done with, Logic probe (One that can handle 4 MHZ at least) I had an old one that led me a merry chase around the Oscillator section. It is now in the rubbish bin. A Multimeter, and a 10Mhz CRO (Analog, OLD), a small Audio Amp (Battery Powered) to trace the audio in the analogue section.
A hard copy of the relevant area of the schematic I am working on (and to make notes on).
Ray



That matches my experience, thanks for sharing.
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: LambdaMikel on 06:38, 13 November 18
@LambdaMikel (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2172)
@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225)

Most of my testing is done with, Logic probe (One that can handle 4 MHZ at least)
The good thing about logic probes is that even the most basic ones can do 20 MHz these days - and have the pulse mode as well:
https://www.elenco.com/product/logic-probe/ (https://www.elenco.com/product/logic-probe/)  Priceless for any retro computer repair.  Just being able to point that thing at any pin on any chip and get feedback immediately about proper functioning (without even needing to turn your head to look at some screen) is extremely helpful.
Title: Re: CPC 464 Tapes not loading, ERROR B -- FIXED -- AGAIN -
Post by: Audronic on 00:43, 17 November 18
Hi All

A Second CPC464 with " ERROR B ". Hmmmmm

This one had me ? Confused ? .
It would play back some previous tapes OK.
It would Play back the ID that I had recorded and then " ERROR B "

After some time I thought that there was to much  Electronic noise coming out of the replay chain.
THE FIX. 1 - 47 uF 16 Volt put across pins A and B on the Motherboard of the Tape connector

NB:- Late amendment :-  It has NOT completely resolved the problem ----

Ray
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED --
Post by: Bryce on 16:39, 17 November 18
If that helped a bit, then there's a good chance that C234 is damaged. Remove it and put the new capacitor in its place.

Bryce.
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED -- NOT YET.
Post by: Audronic on 22:41, 17 November 18
@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225)


Ok Thanks for that I Missed seeing the one on the Erase Power line.


I have been listening to the various tones that are sent on REPLAY and:-
it starts with a lower frequency warble before the Data ID and the same for the real Data.
On the Faulty Cassette Player the Lower Frequency part is MUCH lower in Volume than on a Good working Cassette Player.
I am also looking at C319 (Near PlayHead)as this would affect the Lower Frequency's if it had lost capacitance ?
and the 1 Meg Resistor R316.


Thanks.   Ray
 
Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED -- Finally LA6324
Post by: Audronic on 08:34, 19 November 18
Hi All


Finally fixed.
Replaced the Electro at the input to the Replay amp from .47uf (should have been .022uf) with a .1uf Greencap (small).
and finally the IC. LA6324.
Record and replay tests all passed --Phew.
Ps I did not put a socket on the board it looked like it would hit some Mechanical bits ??


Thanks for reading


Ray

Title: Re: CPC 464 Tapes not loading, ERROR A and B -- FIXED -- Finally LA6324
Post by: Bryce on 09:30, 19 November 18
Correctly spotted. There isn't enough space for sockets on the amplifier PCB.

Bryce.