| Author |
Message |
    
Teraforce88
Tinkerer
Username: Teraforce88
Post Number: 35
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 15, 2011 - 07:35 pm: | 
|
I was performing some measurements on my Minolta XE-7's metering circuit to determine if I need to replace the Rp resistor or not (I need to anyway since one of the lugs for the Rp resistor is broken off). I was able to determine the value of the Rp resistor that I need through the measurements I performed and the chart in the Service Manual (143Kohms, which rounds up to 150Kohms in the parts list)
My question is this: is there a specific kind of resistor that I need to use? The Rp resistor that's there now looks like a little yellow drop--it looks more like a capacitor than a resistor. Can I get away with a standard "peanut" resistor or do I have to use a specific kind?
Here's a link to a picture of the XE-7 meter board; the Rp Resistor is just below the back CdS cell:
Minolta XE-7 Meter Board |
Marty1107
Tinkerer
Username: Marty1107
Post Number: 12
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 18, 2011 - 08:02 am: |
|
Hello - I would guess that a standard metal film resistor (which has a low temp coefficient) would be OK. The only way to tell would be to measure another Rp and then heat it to see how much it changes. And btw you can clean the aperture sensing resistor and the ASA sensing resistors fairly easily. They're located under the left side cover(viewed from the back). |
Teraforce88
Tinkerer
Username: Teraforce88
Post Number: 36
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 27, 2012 - 07:06 am: |
|
I tried a 1/4 watt 120 K-OHM resistor metal film resistor, which seems to work just fine. I really needed a 150 K-OHM, but Fry's was sold out of those. It was noticeably larger than the old one, but I managed to get it to fit. I probably could've gotten away with a smaller 1/8 watt resistor, but Fry's didn't carry any 1/8 watt resistors that were close enough to what I needed.
Right now, the meter underexposes by about 1 stop at EV 5, but is spot-on at higher EVs. The problem is, the low-brigtness pot is turned as far as it can go. I think with a 150 K-OHM Rp resistor, I'll be able to get the meter spot on, even at EV 5. I'll update this thread if I ever get around to buying some 150 K-OHM resistors. |
|
