AK79

Eventide H910 aka the unrepairable
« on: March 02, 2011, 02:02:46 PM »
Hi Folks,
I got a H910 for really cheap - of course not working.

Delay section is ok, unit passes audio ok, but when the "manual" pot is turned to bring the ptich-shifted signal into play the signal gets distorted. The clean signal is still good, but FX-Signal sounds like its been put through a distortion box.

I have the servicemanual and did the calibration - all testpoints can be tweaked to show the correct values. I also checked all the caps on the upper board, everything looks ok. the schematics are somewhat rough so I have no idea what to check next.. Powersupply is ok also.

I know the H910 is totally unreliable - but maybe someone has at least come across this particular error and has one or two hints for me ??

any help appreciated

Cheers
Arne


okgb

Re: Eventide H910 aka the unrepairable
« Reply #1 on: March 02, 2011, 02:06:35 PM »
check & clean any daughterboards connections ?
don't know if that is relevant or not , good luck
GKB Audio / Greg Boboski

radardoug

Re: Eventide H910 aka the unrepairable
« Reply #2 on: March 02, 2011, 03:05:40 PM »
H910's are very difficult to work on. They used three different logic families and had conversion issues between them, and the circuit is quite complex. Add to that the usual Eventide power supply and connector issues and you have a can of worms!
First thing to check is power supply rails. The 910 used Molex connectors to transfer power around and these are VERY unreliable. Check for signs of heating or burning and replace accordingly. Then check supplies at their final destination for value and noise.
After that you are on your own!. If the delay function works cleanly then you are looking for what is going wrong in the harmonise section. On the output there are a pair of DAC's that crossfade the audio to try and splice it, but this is always a bit glitchy.

AK79

Re: Eventide H910 aka the unrepairable
« Reply #3 on: March 03, 2011, 08:46:49 AM »
thanks so far.

shame on me : PSU is not exactly ok, the -5V rail gives -8V actually. dunno if that´s causing the error. the psu is a weird constuction.

Re: Eventide H910 aka the unrepairable
« Reply #4 on: March 07, 2019, 03:51:19 AM »
Hi, Did you end up fixing your H910?

I have one similar issue.. would be great to know how you got on.. and if you still have manuals and schematics etc..
Many thanks Nick


 

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