Hi All, Some forward progress at last. This morning I replaced the (SMD) SG3524 which has now restored the 5 Volt supply to the FDD controller. The 5 Volt rail appears immediately at switch on and the

Hi All, I spent a little time this afternoon investigating the FDD controller PCB. Attached is a sketch of what I have found so far. The SG3524 chip is a PWM device which can be as in this case used i

Hi Pmecnc, Unfortunately I have not found a Datasheet for the PJ200. It would appear to be an encapsulated inductor from the tests I have done, It only has 2 pins. Maybe it was specially made for this

Hi All, It is a high speed avalanche diode according to the datasheet. I have now re-drawn the sketch including the IC (SG3524) that feeds the transistor. (BD244). Keith

Hi Pmecnc, JG, Thanks for the datasheet PDF re the Philips SMD device. Not sure how I missed that one as I have read through several. The part appears to be a Zener diode which makes sense in the circ

Hi All, I have now acquired an EPROM programmer so I have attached a HEX dump of the FDD onboard EPROM. At the moment I have not had time to remove the main EPROMS from the machine but I will as soon

Hi Dieter, Thanks for your email. Yes it is strange that my EPROMS or numbered as they are. Maybe EMCO started to renumber them when they changed over to Disk. I your post you said,. Keith, you said:

JG, Robin, et al, A little more information following some close inspection of the FDD. The FDD is a TEAC FD235-HF as pictured in Robins post. According to the data sheet from TEAC pin 34 is "Disk Det

Hi Robin, Thanks for the photos of your FDD and the controller board. You have confirmed something I have been trying to find out. The small orange/red link for the 5 Volts is in place and there are n

Hi JG, Some progress this afternoon. I tested the FDD with my bench PSU feeding the 5 Volts in past the now removed link. The FDD draws a standing current of 200mA and around 350mA when the disk is ru

Hi JG, Thanks for the two attachments I'm sure they will be very useful. As far as soldering goes I would at one time have thought nothing of unsoldering a 40 pin chip with an iron and de-soldering pu

Hi All, I replaced the 6821 PIA this morning. As they are soldered in the only way to get them out without specialist soldering equipment is to cut the pins off and then remove the pins from the PCB.

Hi All, An update on the FDD. This afternoon I monitored the pins from the PIA on the CPU board by connecting my Chinese 8 channel logic analyser. First I loaded a CNC programme from the PC to the C5.

Hi JG, Thanks for your reply. As you say the black box approach is probably best. I do have quite a lot of test gear but it doesn't seem to be getting me too far at the moment. I used a double beam sc

OOPS forgot the sketch. Keith

Hi, My machine stores 210 lines of G Code. I have the same ideas about vintage machines and prefer to get them working "as designed" if possible. I have two CNC lathes the Compact 5 and a Conect Cadet

Hi Dieter, It isn't easy to get at the back of the lathe at the moment due to restricted space in my workshop. I assume that it is one of the later EPROMS as the instruction to save brings up the word

Hi, My machine works perfectly as far as the steppers are concerned so I am loathe to change anything. I like restoring machines to their original specification so I'm afraid the Chinese Upgrade is no

Hi Ron, As far as I am aware the floppy only stores the G Code which is currently in the machine memory. I have never had the disk working so I couldn't say if it stores anything else. Hopefully I wil

Hi Robin, Its good to hear that someone else has a FDD on their C5. Mine shows no sign of life whatever not even a flashing light. I have read that some of the machines will only work with certain flo