Repair of a Vintage Simpson 461-2 DMM

[macboy]

These icl series chip fail quite frequently. Most just show strange values (or strange digits) or show non linear behaviour. Havent seen any draw too much current though.
A lot of (older) 3,5 - 4,5 digit lcd voltmeter modules use these chips too. Thankfully you can still get new chips after 15-20 years.

Oh I think it's been closer to (maybe over) 40 years since those exact chips hit the market. I have a couple around 30 years old.

[Panchdara]

Well done! When you started you mentioned the movie "The Money Pit".. well, is your new nickname Walter Fielding? (Hope not) (But it was funny watching that turkey fly!)

 

[xrunner]

Well done! When you started you mentioned the movie "The Money Pit".. well, is your new nickname Walter Fielding? (Hope not) (But it was funny watching that turkey fly!)

 

LOL - thanks.

OK - it's certified as working now! I also dug out a 7.5V wall wart from my junque box and made up an AC adapter for the thing.

All I have to do is put it back together (without anything else breaking) and see what we got. 

[xrunner]

Well it's put back together and it works like a champ. Got the calibration tweaked up and pretty satisfied with that. Parts required were:

ICL7107CPLZ Intersil Analog to Digital Converter + socket

Two HP hp 5082-7731 vintage seven segment LEDs

2N2907 PNP transistor

7.5 V wall wart for external power

Simpson test lead set in transit from Chile (thanks Lightages).

First pic checking cal

Second pic shows it atop another similar meter in Simpson's line - the 467.

[lowimpedance]

Doesn't that look great, and still useful  .
However the last pic is not complete yet............... needs a 'nixie' Simpson (did they ever make such a meter ??!.), and a moving coil meter for completion.
 
I like the oldies too, Well done.

[xrunner]

However the last pic is not complete yet............... needs a 'nixie' Simpson (did they ever make such a meter ??!.), and a moving coil meter for completion.

I do believe I've seen an older Simpson model on Ebay with nixies. Now I need to go find one for my next restoration. I'm off to Ebay for a search!
 

I like the oldies too, Well done.

Thanks. 

[Excavatoree]

I do believe I've seen an older Simpson model on Ebay with nixies. Now I need to go find one for my next restoration. I'm off to Ebay for a search!
 Thanks. 

Be careful. That's how it starts.  I thought "I'll fix this one Fluke, then maybe get another from E-bay to fix."

Do you want/need another 267 for parts or repair?  I've got one I don't think I'll do anything with.

[ModemHead]

Nice job, it looks great!  Thanks for posting the progress reports.  I like old stuff, too.

I may have to get some of that mag wheel polish myself.  Turns out car care products are quite useful for restoring old electronics.  Meguiar's headlight restoration kit works great for DMM LCD lenses.

[xrunner]

Be careful. That's how it starts.  I thought "I'll fix this one Fluke, then maybe get another from E-bay to fix."

Do you want/need another 267 for parts or repair?  I've got one I don't think I'll do anything with.

Oh no another one  what do you want for it?

Nice job, it looks great!  Thanks for posting the progress reports.  I like old stuff, too.

I may have to get some of that mag wheel polish myself.  Turns out car care products are quite useful for restoring old electronics.  Meguiar's headlight restoration kit works great for DMM LCD lenses.

Thanks, yea you never know what will work on what. I have all manner of car product in my garage so it was only a matter of time. 

[xrunner]

Update:

Just arrived from Chile, courtesy of Lightages. Set of NEW Probe Master test leads for the older Simpson meters (reverse banana plugs). Wow. Many thnaks to Lightages! 

[Excavatoree]

Update:

Just arrived from Chile, courtesy of Lightages. Set of NEW Probe Master test leads for the older Simpson meters (reverse banana plugs). Wow. Many thanks to Lightages! 

Don't the newer Simpson 260 meters (series 7 and series use these?  I've heard them described as "Reverse banana."  Or is my memory hopeless?   

[xrunner]

Don't the newer Simpson 260 meters (series 7 and series use these?  I've heard them described as "Reverse banana."  Or is my memory hopeless?   

I don't think so. I think the newer Simpson meters are "normal" banana plugs, from what I see Googling pics. Some bright guy back in the day had the idea that the "pointy" end of the connection should be on the meter, so that if the leads were connected to a high voltage, and also not in the meter, the end of the lead would be safer. Of course it's all changed in the modern era.

[Excavatoree]

Ah, it's the latter case, as I expected.  I still consider this one:

http://simpson260.com/260-8/simpson_260-8prt.htm

to be a "new" one. I'm sure the 8X and 9x types are newer, and they have the "normal" leads.   So they changed, then changed back. (series 7 and the "black" series 8 260s have the "reverse" leads)  It's all too much to keep up with. 

[Robbdoe1]

Hello. I’m in the learning process of meter repair and need help from you all. I too have a very nice 461-2 that has similar responses to the original post. I seem to get random numbers on the display. The volts in both AC and DC don’t respond to any input. All the resistance ranges display a 1 when either the leads are shorted or any resistance measured the display starts to show numbers that always count down to -000. I’m doing my tests with no batteries in the unit and running off the AC charger.

I’ve checked the basics like F1 and F2. I know very little about this type of logic. Based solely on the original post I jumped straight to ICL7107. According to what I see on the schematic I should have +5V between pin 1 and pin 21 of ICL7107 and I do. This is where I’m completely lost as I can see pins 30, 31 & 32 are Common, Input Hi & Input Low but don’t know how to test them and don’t want to smoke anything if possible. I have a logic probe if this is where I use it? I have used one once and that was 20 odd years ago.

Can somebody please point me in the proper direction to continue troubleshooting this meter?  Any and all help is greatly appreciated. Thank you in advance for helping me struggle through this.
Robb