The " Save Time and Trouble With These Hints and Tricks" Thread!!

[NavLinear]

Well, I do believe I've gotta have me about 8 of those. 4 at least if quantities are short. I missed the 20 minute deadline, golldurn it...
Do you have a toll free number that I can call???

No worries - more can be "grown". Like Lee said - if you use Joe's backplane board you won't need these. If not we can help - but act now before they are all gone. Two for one special. 0 dollars now or 0 dollars later - your choice.

 

[NavLinear]

Dennis, you're workmanship is exemplary!!!

Thanks Lee - it was a little sporty getting things lined up with sufficient clearance as I wanted something smallish for the bench. I really enjoy doing one off stuff. That sometimes translates to more than one tho...

 

[laatsch55]

With your skills it'd be a shame if things were limited to one.

 

[premiumplus]

OK , in all honesty if you are going to install the pl700 backplane boards the FaboNav brackets are now a moot point. Not necessary as Q6 will then be mounted on the BC board, IF HOWEVER, you seek to capitalize on the COLLECTIBLE value, then they shall be on the way with the still not shipped 410's....

Ahhh, thanks Lee, you remembered! I'm pretty sure that I am going to leave them quasi comp for now, having just replaced all the output transistors in both amps...
Thank you, gentlemen. That's waaaaay cool.

 

[Gepetto]

Ahhh, thanks Lee, you remembered! I'm pretty sure that I am going to leave them quasi comp for now, having just replaced all the output transistors in both amps...
Thank you, gentlemen. That's waaaaay cool.

We'll see

 

[laatsch55]

I'll send em , just for their historical value. 24 MJ21195's and you're in business....you won't last long.......you are afflicted........don't fight it.....you'll just be tired and broke......

 

[Gepetto]

Cleaning the old white heat sink compound out of heat sink holes on PL700/400

The old compound gets trapped in the holes and dries out over time. This can interfere with a good electrical connection or thermal connection.

Use a #22 drill bit for the small holes (the ones the transistor leads go through) and an "A" twist drill bit for the larger holes (the ones that the mounting screws go through). Push the butt end of the drill bit through the hole, it will push the old compound out to the other side. Using a paper towel with a small amount of alcohol on it, wipe the end of the drill bit before you extract it so that you do not pull the compound back into the hole again.

This works very well and gets the job done quickly. Final cleanup with a new paper towel with alcohol will make your heat sinks nice and clean.

 

[Gepetto]

Checking out your backplane assemblies before attaching the control board

This method allows you to check for leaky transistors prior to installing the control board. Troubleshooting after the control board is installed is much more difficult both physically (because the board is in the way) and theoretically. All other installation wiring is installed and in place, ready for the control board installation.

Tape off all the wires that lead to the control board from the backplane (13 of them for each side for full comp, 12 for quasi comp plus 3 for the bias transistor wires) so that they cannot accidentally short out.

Connect a 10K 1W resistor to each set of speaker binding posts, one resistor lead to the output post and the other lead to its respective ground post.

Attach your DMM minus lead to one of the resistor ground connections you just made to the speaker binding posts. Attach the DMM plus lead to either the right or left channel output (where the other end of the 10K resistor is terminated). Set the DMM to DC Voltage scale.

Using a Variac, slowly bring up the chassis with backplane assemblies while monitoring the voltage reading on the DMM. Move the DMM plus lead back and forth from one channel to the other at each voltage step until your Variac is up to the full 120V input. Voltage steps at 20, 40, 60, 80, 100, 120VAC input.

On a good backplane assembly, you should measure no more than 500mV (at worst case spec of the transistors) on either of the resistors. Typically this will be much, much less that the limit. The backplane I just tested was about 1mV.

Hope this is useful and saves you some time.

 

[laatsch55]

Uh........would have saved me about 4 hours last night....

 

[Gepetto]

Uh........would have saved me about 4 hours last night....

Your experience prompted me to write out this hint and trick. I use it when I bring up new backplanes.

 

[laatsch55]

Glad I could make a lasting contribution...

 

[Gepetto]

Glad I could make a lasting contribution...

I think you do Lee...

 

[laatsch55]

I know Joe and I thank you for the opportunity, just being flippant. Always this way on test night. This latest thing Joe is amazing. I did not expect the clarity of a 400 in a 700, but ITS THERE>

 

[NavLinear]

Uh........would have saved me about 4 hours last night....

Thanks Lee for being the guinea pig! Sometimes it's a bitch being the lead.

 

[laatsch55]

Wouldn't have it any other way, good, bad or indifferent, it's there on my sleeve Bud...

 

[premiumplus]

Fluke DMM meter current fuses

I got careless and blew one of the current fuses in a Fluke 87 type III meter. They're not cheap...They cost about $10 each last time I looked.
So here's a good workaround that I've used for years without problem.
Take apart a cheap AGC fuse and solder the fuse wire across the terminals of the blown Fluke fuse. The Fluke value is 44/100 A, but I use a 1/2 amp for it, and it's worked fine for me over the years.
Heating the metal end of the AGC fuse with your soldering ironmakes it pop loose from the glass enclosure. Then the other side comes off and the fuse wire is harvested.

 

[laatsch55]

Nice trick, works on my 179 too!

 

[premiumplus]

Best tip...never be too proud to ask for help.

I'm 61 and I've been repairing everything I could get my hands on since I was a 6 year old tyke and took all the tubes out of my dad's favorite radio. He didn't approve...
When I was in my late 20's I worked at Bank of America in the Los Angeles area as a Senior Service Technician. The bank had it's own mechanical department that went around and repaired all of the banking equipment. Everything from calculators to mechanical adding machines, to proof machines and microfilmers, currency and coin counters, typewriters, copiers, and in the 80's, ATM's...you get the picture. It was a great gig, one of my favorite jobs ever. We went from branch to branch and when things were slow we'd meet out at Elysian Park by Dodger Stadium for a long lunch of sandwiches and beer. If we didn't have any calls we'd spend the afternoon playing hearts and drinking. Ahh, those were the days. We had so much freedom, it was before cell phones and we could disappear at will.
Anyway, about asking for help...
Once I had just finished a complete tear down and rebuild of an old NCR adding machine. This was a beast of an adder, with a full size platen, 90+ keys on the keyboard, a full mechanical "calculator". The things weighed close to 50 pounds. An awesome example of mechanical engineering, these old machines had literally thousands of parts. Springs, cams, racks, keepers, washers, screws, nuts...and it needed 'em all to work right.
I came in the morning after finishing the rebuild and was ready to case it up when I noticed a tiny spring laying in the bottom of the case. There are hundreds of these in the machine, and I didn't have a clue as to where it belonged. The guys in the shop were kind of quiet that morning and finally after I had spent a half hour testing the machine and trying to determine where the spring went, they all busted up laughing and told me that they had planted an extra spring in the bottom of the machine that morning before I got there. We (they) all had a great laugh, but they used the occasion to remind everyone to ask for help if there was ever a question that we couldn't solve alone. The only dumb question is the one that is never asked... And I've never been afraid to ask for help since that day.