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Yamaha CDR-HD1500 problems

Neither the HDD nor the CDR work on this machine (The HDD occasionally works but is intermittent) I've checked the PSU and replaced several Electrolytic Caps. with poor ESR readings) and the IDE Cable. connections, etc. Following the procedure outlined in the service manual, on page 16 it states 'Check the RESET signal - Refer to the Waveform at point 'C' on page 45' However Page 45 is the schematic diagram of the OSD circuit & video/audio signal lines. I cannot find a point 'C' anywhere on that page, nor are there any waveforms shown anywhere. Presumably there is a misprint, and the relevant info. is elsewhere in the manual, although I can't find it. Can anyone please point me in the right direction?



Re: Yamaha CDR-HD1500 problems

They mean manual page 45; if you download the manual here, the page numbers down't match up. 'System Reset 'C' is below the ACDR IC. Reset is usually just a pulse signal; you should be able to see it with an oscilloscope.

Re: Yamaha CDR-HD1500 problems

Thanks for that info, Johnnysan. I did indeed download the manual from this site, so will check again for the location of 'System reset 'C', and then check for a reset pulse.

Re: Yamaha CDR-HD1500 problems

Having found the relevant test point, I checked, both with a DMM and a 'scope. The reset pulse is definitely there, so further investigation is needed. I did remove the CDR Drive & take the cover off. This revealed that the pickup had not returned to the rest point at the centre so the 'disc detect' switch was open. I haven't stripped the drive further, and can't even see whether the load/eject mechanism is belt or gear driven. If the former, the cause could be as simple as a stretched or broken belt, but this doesn't explain the non-operation of the HDD. That, too, was intermittent and now doesn't work at all, 'Check Disc', or 'Check Drive' being displayed.