Pentax 6x7 TTL Prism Repair and Exposure Meter Adjustment

The TTL Prism on my Pentax 6x7 camera has a built in exposure meter that was starting to go a bit whacky. The needle would jump all over at random and the view finder area would go black if I tried to use the camera in any position other than the default horizontal position. And it was consistently under exposing everything by 1-1/2 stops.




I decided I would have a go at repairing it and document what I did and hopefully some other folks with similar problems will find this helpful and be able to repair their prism meters also.

First thing you need to do is get the top of the prism off. You will need to have a spanner wrench type tool for removing the top cap screw of the shutter speed dial. I have one of these. I am sure some of you creative folks will make something else work, that is fine.

There are 8 small screws around the outside that you need to remove. 2 of the screws are behind the front name plate so that must be gently pried off to get those 2 screws out.

Here is the front name plate removed and you can see where the 2 screws are located

Gently pry off the front name plate to remove the 2 screws holding the top on

After you remove the 8 screws and the shutter speed dial you can gently tap the edges of the prism top with something soft like a plastic screwdriver handle to get the top to slowly come off.

NOTE: You do not need to remove the on/off button switch to take the prism top off

You should end with this

Note the shutter speed dial spring and washers, don't lose them!

Adjusting the exposure meter when it is off a bit is not to hard, there is one big adjustment screw you can use to correct the exposure needle alignment.

Here you can see the large plastic adjustment screw. I only needed to adjust mine a couple millimeters clockwise to correct the 1-1/2 stop underexposure. Look closely and you can see the black felt pen marks I used to mark the original position and how it is now turned just slightly clockwise.

Large "POTS" adjustment screw for the built in exposure meter

 
I had 2 more problems though, the meter would go black when I tilted the camera and also the needle was very erratic. Turns out the erratic needle was a loose +6v cable on one of the prism contacts and the meter going black was from the reflecting prism being loose inside the small slot it sits in.

Here you can see the +6v wire that has come loose

Loose +6v wire

Basically I just soldered on another piece of wire and sealed it with some shrink wrap

This next photo is not very good but it is trying to show you the small refective viewfinder prism the meter uses when you look thru the viewfinder. I used some contact cement to glu it back into position. It is the rectangle glass looking thing between the two electrical posts at the bottom of the viewfinder opening.

Here is the top of the meter with the new wire soldered in place and all tucked in ready for assembly. I still need to adjust the exposure first.

Notice the exposure meter and needle assembly on the left

To adjust the exposure meter I just manually triggered the on/off switch with my hand and made several test exposures with different ISO, aperture and speed settings. I used my DSLR in center weighted mode and my Sekonic Auto Studio II light meter as the test metric devices.

Testing the exposure settings

After thorough testing with different ISO, aperture and shutter settings in both bright daylight and dim light at night I feel I have it calibrated it about as good as it can get. It is almost spot on with my DSLR and 90% spot on with my Sekonic. It is one happy prism and exposure meter now!

Happy Prism and exposure meter!

I hope this post will be helpful to anyone else looking to repair their Pentax 6x7 TTL Prism

Out of balance Washing Machine repair / upgrade

More Performa Washing Machine repair fun. After my last washing machine finally gave out due to a rusted inner tub I decided to just buy the cheapest, cheapest washing machine I could find which of course was another quality Performa. The old saying "You get what you pay for" is certainly true with the Performa models. This DIY is more of an "upgrade" project than it is a repair. This washing machine would start to spin out of balance with anything more than a couple of T-shirts and a pair of socks which made it impossible to wash clothes for a family of five.

Looking underneath the machine I could see there were (3) flimsy springs that controlled the spinning of the tub. After a trip to the Home Depot and picking up some springs in the fence / gate isle I went to work replacing them. The springs I found were quite a bit more heavy duty and needed to have the ends twisted to match the original ones.

Here is one of the original springs looking at it from underneath



Here is the original spring on the left and the new replacement on the right


This is the new spring with the end twisted to match the original. I did this with a pair of Vise Grips and a vise.


I used a headlight spring removal/installation tool to change the springs




After replacing the 3 springs with new stronger ones the washing machine works great, it barely ever goes out of balance now!

Rusted Washing Machine Tub Repair

Welded Tub center mount

I admit it, I bought one of those piece of crap Maytag Centennial Washing machines. It is 1 1/2 years old and it has done nothing but break. Granted we use it 24/7 but it has a "Commercial Technology" stencil right on the front panel, it is not ""Commercial" quality at all. Regardless, it has broken again and I will describe how I fixed it in hopes that others may also be able to repair their busted washing machine.

You may have read my post about repairing a hole in the plastic tub and it turns out the cause was from a rusted inner spindle mount point on the main ceramic tub. I actually repaired this about 8 months ago and it is now due for another repair weld. It seems what happens is the inner ceramic tub rusts out near the main spindle and begins to crack. This causes the tub to spin out of balance and eventually begin to rub on the outer plastic tub which in turn wears a hole in it (see repair link above). The solution (temporary) is to weld up the rusted tub. I did this about 8 months ago to half of the spindle that was rusted out and now the other half has rusted so I figured I might as well take some pictures and post it.

Start by taking off the spindle cap and water sealer cap. You will need to remove the center bolt and pull out the main spindle. From there you should see the rusted tub, mine had cracks all around the center. Using a MIG welder you can weld up the cracks and make the washer usable again. I first centered the tub and spot welded it in a few places to keep it in place. Also use a wet rag to cool the welding area as there may  be rubber seals or O-rings below that can melt if overheated. Once it is all welded up I recommend a "no clothes" run on the rinse cycle to clear out any debris.

Looking down into the tub

The final weld

My MIG welder

--

Maytag Washing Machine Plastic Tub Repair

Don't leave stuff in your pockets before you wash your clothes!

Plastic tub washing machines may have benefits but if you leave objects in your pockets before you wash them this is what will happen and then your washing machine will leak all over the garage or laundry room. I am not entirely sure what was left in it this time but I did find a Sharpie marker and some buttons and some loose change in the bottom of the washer. 

Symptoms were increasingly loud wash cycles during the week and then water leaking with medium to large loads. What happens is the main mettalic tub spins inside of the outer plastic tub and when something gets caught between them it will rub and wear a hole in the outer plastic tub. I am not sure what a new plastic tub would cost but for me that was besides the point because it would have required special tools to replace. I opted for the quick handyman fix...follow along to see how you can repair a hole in your plastic tub for just a few dollars and a few hours of your time.

My washing machine is a Maytag Centennial model, I am sure any Maytag will be similar. Start by unplugging the electrical plug, removing any clothes still in it and draining any water in the machine. You may need to tip it over for this. Next remove the (2) screws holding the control upper knob control panel in place.

Next, use a putty knife to compress the spring that holds the top to the main shell, you will need to do this on both sides

Push straight in and gently lift the top up

After popping up the knob control panel, you ill need to pry up and pop out the retaining clips that hold the back panel to the front main enclosure.

Pop out the retaining clips and then remove the entire enclosure

Removing the entire enclosure away from the back panel. This provides access to work on the washing machine.

Move the entire enclosure away from back cover

The damage to the front of the tub is now obvious once we remove the enclosure

You will need to pry up the tabs holding the top ring around the tub. This will allow you to get access to the inside of the tub and remove and other items still loose in there and also to clean up the mess of repairing the hole afterwards.

Be gentle when prying these up

After prying up the tabs , lift out the ring assembly

You can see the ring assembly suffered some damage as well

You will need to remove the drain tubes from the pump and inspect everything to make sure nothing is still inside them, this would cause a problem once you put it all back together again.

Use pliars to pinch together the hose clamps and slide them back to remove the hoses

Pop off the 2 retaining clips and remove the pump assembly. Make sure to clean and inspect the inside for an loose items

Now comes the fun part. You are going to need to clean and prep the plastic tub for repair. Start by scraping and peeling off all of the material that has built up from rubbing on the plastic tub and outer ring. It took me probably a good 30-40 minutes to do this, it is important you do a good job of this, if you leave old built up material on the tub or ring there is a good chance it will start rubbing and cause the same problem all over again. Use a putty knife, screwdriver and your hands...be careful not to make any holes!

Peeling off some the old rubbed on plastic material

After all of the rubbed material is cleaned off we get to actually do the repair. You will need a hot glue gun and some fiberglass repair materials and an old plastic bottle, I used an empty laundry detergent bottle. The idea is to clean up the hole, sand with sand paper to prep and then fiberglass a patch over the hole.

You can see I cleaned up the hole and sanded it with 60 grit so the fiberglass will stick to it

Cut out a patch piece from some old plastic container

Hot glue the patch in place first so it is all ready for fiberglass

This is what the patch looks like from the inside of the tub

Now you need to do the actual fiberglass work. I will not go into fiberglass repair techniques and will assume you can figure out how to cut a couple pieces of fiberglass cloth to cover the patch and mix up the resin. If not, just read the instructions on the resin container. BTW, you can buy a fiberglass repair kit at any hardware store for probably less than $10. I had some in the garage from the last surfboard repair job.

The patch with fiberglass applied

The fiberglass will dry enough in about an hour so you can start putting everything back together again.

--- VERY IMPORTANT ---

You will need to clean out the tub and hoses before you assemble everything. There will be lots of small plastic pieces and material left over from sanding inside the tub. I just got the garden hose and flushed everything out letting the tub drain from the hoses we disconnected earlier. Once everything is flushed out and clean you just need to reassemble it back together.

Last important notes on reassembly

I hope this post will be helpful to others out there who have suffered the same fate as I with these new plastic tubs. This repair has worked out well for me so far, we probably have 100 washes in it after I did this repair. One other kinda funny thing, I did the repair on a Saturday afternoon and in the mail that same day I got a letter from Maytag stating my warranty had expired and I could buy an extension..yeah..ok...