Update 6/2/18: I completed the discrete op-amp modification after I got the replacement diodes. You need to replace Diodes 11, 12, 13, & 14 with 16V Zener diodes. If you fail to do this, your op-amps will be getting +18 and -18V (36V total). This is a pretty high voltage to use on op-amps, these […]
High Res Photos of My New Sprague Tel-Ohmike TO-6A
Update – May 15, 2018: I have almost finished restoring the bottom of the unit (where most of the components are) and expect to have it working in the next week or less! Update – May 12, 2018: Here is the Schematic with the parts labeled, this way you can easily see where you are […]
Hallman Labs Capacitor Analyzer : Sprague Tel-Ohmike TO-6A
After weeks/months of trying to get my Cornell Dubilier BF-50 cap analyzer to show what is expected for a good cap vs. a known bad cap, I reached out to Cornell Dubilier. Well Cornell Dubilier didn’t have any more information to offer me besides what I already knew from the BF-50 owner’s and service manuals. […]
“Help”: My Cornell Dubilier BF-50 Is Testing Open Circuit as Good | Note : Treble Bleeds Halted
I was using my Cornell Dubilier BF-50 (vintage) capacitor analyzer with all of the right things showing on the “Magic Eye” 6E5 (Philips JAN (Mil-Spec)) electron tube’s eye for leakage, short, and open tests. By the way, the BF-50 uses a 12A7 (Tungsol) electron tube for both rectification of the AC input and amplification. Both […]
Hallman Labs 1st Product for Sale (Soon): Fixed Resistance Treble Bleed Kits V1.0 & V2.0 (Thoughts on V3.0 & V4.0)
Hallman Labs first official products for sale will be treble bleed circuits for guitars! When you dial down the volume on your guitar (with any pickups) the high frequency is rolled off sharply. The treble bleed counteracts this rolling off of the highs by bleeding high frequencies directly into the potentiometer output leg. Thus acting […]
Ultra Rare ELNA Vintage Capacitor
EBay is by far one of the largest online selections of vintage electronic components in the world. I shop here when I see a deal worth buying, usually in bulk. I am now going to begin selling tested capacitors that I am certifying are working or your money back. I will be using the Cornell […]
Cornell Dubilier BF-50 Capacitor Analyzer
In order to verify the vintage capacitor collection I slowly attained all perform to spec, I started to look for capacitor analyzers. The most well known is the Sprague TEL-OHMIKE series. Trying to find one of the Sprague designs at a reasonable price is difficult though. The TEL-OHMIKE brings $175-$250 on Ebay and I wasn’t […]
Sansui AU-517 Works!! (Schematics & More Inside)
Thanks to Hifiengine.com I was able to get my hands on the official service manuals and the owners manuals + every schematic!! HiFiEngine is free to register and after that you can download their entire catalog if you wanted. This gives you details on where to put volt meter terminals and check the biasing for […]
More Sansui AU-517 Internal Shots
For being 39 years old, this amp is nearly spotless inside. I’d venture to say it may have been opened once before I inspected it myself. Keep in mind that this thing was on the way to the trash compactor (when it had space), my friend found it before that point and grabbed it. Every […]
First Amp Donation! Sansui AU-517
To my surprise someone donated a Sansui AU-517 to me for free, thanks again for that! Here we have a stereo amplifier that weighs in at 40lbs! This behemoth is highly regarded in the vintage audiophile communities, with many of these bringing $100-$200 broken! I am looking forward to giving this baby a run with […]