VM1000 Replacement Chips

johnp19 · #1 07-11-2014, 02:26 PM

Does anyone know of suitable replacements for the signal processing chips on the analog board of a 2001 series VM1000?

At least one of my chips is bad.

The installed chips are Intersil DG407DJ chips. I cannot find any of these, or the newer DG407DJZ's, in stock anywhere in the country. I looked at some specs on other brands of this series of chip and found some significant differences in current capacity and input voltages.

If anyone has any knowledge of what other chips will work I would appreciate your input.

Thanks,

John P

eaglen92ce · #2 07-11-2014, 02:35 PM

John,

There is a gentleman named Reggie who is on this site who support the VM1000 systems. He is a good guy and sells parts and repair services. I have bought parts from him and have been 100% satisfied. His screen user name is Glas467 on the board.

digidocs · #3 07-11-2014, 02:38 PM

It looks like Mouser has Vishay parts in stock for $6.65/ea:

Siliconix DG407DJ-E3

I took a quick look at the datasheet and didn't see anything obviously incompatible, but I didn't spend too much time. If there's any particular specification difference that concerns you, just post it and I'll check it out further.

Hope that helps,
David

johnp19 · #4 07-11-2014, 02:47 PM

David,

Thanks for the response. The specs I have for the Siliconix voltage and current supply are 12V, ±5 V ~ 20 V and 30µA. The specs I have for the Intersil are 5 V ~ 34 V, ±5 V ~ 20 V 80µA.

This may be perfectly acceptable but it is beyond my limited knowledge as to whether this would be a acceptable substitute.

Thanks,

John

johnp19 · #5 07-11-2014, 02:47 PM

Bill,

Unfortunately Reggie is on vacation until the 16th.

digidocs · #6 07-11-2014, 02:59 PM

John,

The specific part I linked above is rated to +44V maximum, so that shouldn't be an issue. The 80uA current is the amount consumed by the IC itself. The Vishay part consumes less so you?re also good there. (You?ll have to click the link to the manufacturer?s data sheet, as the specifications listed by Mouser are inaccurate.)

David

johnp19 · #7 07-11-2014, 03:04 PM

David,

Thanks,

I have a couple ordered.

John

johnp19 · #8 07-15-2014, 11:50 AM

In case anyone else has been following this thread. I installed the replacement chips yesterday and put the DPU back in the plane today. Everything is now working as it should. Previously there had been problems with intermittent manifold, oil pressure, and fuel flow indications.

Troubleshooting everything else led me to suspect that the signal processing IC's might be the cause of my problems. Swapping the three IC's around resulted in loosing EGT and CHT's but in regaining all other functions. I wish I had tried this earlier.

My DPU is one of the last VM-1000's made and has the D-sub connectors. The earlier versions may not use the same IC's.

Hopefully this information will help someone else that is having similar problems.

John

digidocs · #9 07-15-2014, 12:26 PM

John,

Glad to hear you got it working well again. Always fun to be able to fix these sort of things, especially cheaply!

David

Omega232Devils · #10 07-15-2014, 09:29 PM

John,
Glad you solved your problem. I am sure Reggie would have helped if he were not on vacation.

Do you have more information on what you were seeing that made you suspect the IC chips? Are they individual chips for each indicator? I have fluctuating fuel flow indications. I have replaced the fuel flow meter with the newer style that is suppose to be more accurate, but it is not. Generally ranges about 2-3gal per fill up off. Or about 0.8gal/hr more than it actually burns.

Thanks,

Dan