The Talking Machine Forum — For All Antique Phonographs & Recordings

Exactly! Also, Professor Azzalina advises that the wirewounds can fail suddenly and disastrously. So I’m taking my amp back for replacement with modern ones.

My goal is for the thing to work reliability well past the time of my expiration, so that when my kids sell it, it can be sold as demonstrably working. This is to increase its odds of survival as an Electrola, rather than as a shabby chic liquor cabinet from which the non working internals have been discarded.

I’ll put a (removable) warning label on the back cover of my 9-40:

WARNING: NON-ORIGINAL COMPONENTS INSIDE. MATURE AUDIENCES ONLY. EYE PROTECTION ADVISABLE.

But seriously, everything I’ve done and plan to do is 100% reversible, with original bits retained in the cabinet for future viewing. And if the next schmuck wants to glue the original pot metal bits back together and use ‘em, I say bravo.

I would like to question a few of the items here. Did you check the capacitors for leakage? In the pre-electrolytic days, the filter capacitor dielectric was not paper and was less likely to leak. I have repaired dozens of late twenties Radiola series equipment from the introduction of the a.c. tuxes in 1927 and can recall only one occasion with a failure of the original filters. I do not see the need to replace the filters unless they are bad.

Please note that you cannot place the 10ufd capacitors in series like you are doing unless you provide a bleeder resistance across the capacitors to equalize the dc voltage across them. The leakage resistance of a capacitor is indeterminate and you will run into problems.

The capacitors used in the late twenties were generally of high quality and after more than 50 years repairing early equipment, it is tragic to find the wholesale replacement of 90 year old components which would have likely lasted a further 90 years.

I am happy to debate this.

Governor Flyball,

Thank you for your input and I respect your experience. As I mentioned in my initial posting, I seek all input and am grateful for it.

I have been in the market for a Solar or EICO capacitor checker and I understand its superior testing capabilities over my multitmeter with a basic cap test feature. The 4uf caps tested between 6uf and 13uf. These measurements are not the 4uf they are suppose to be, like all my new ones test out to be, but I bet that these values are fine as long as the caps don’t leak, right? I look forward to be able to test for that in the future. I am under the impression my new caps are superior to those made 90 years ago and that is my goal. Just from my inexperienced observation of these old caps, they do seem to have a wax paper dielectric.

I am aware (recently informed) of the addition of the balancing resistors and had pointed out their use in Peter’s amp in the following posting:

http://forum.talkingmachine.info/viewto ... 084cb0530f

Btw, I’m not the one using the 10uf capacitor pairs you saw posted in this posted topic. I did question that member why he wasn’t using the resistors via a PM. He assured me he was using them and provided pictures showing them hiding under his 10uf caps. I personally won’t be using them because the caps I’m using are 1200v 4uf caps.

I have several Electrola's that have original resistors and have played them for 20+ years, some daily. I have only found the 2500 ohm sections bad on occasion. I guess your luck is different.

Skihawx wrote:I have several Electrola's that have original resistors and have played them for 20+ years, some daily. I have only found the 2500 ohm sections bad on occasion. I guess your luck is different.

Agreed!

Well, my luck has always been such that it has created many challenges for me. Persistence has been my only way of dealing with it.

To see how my luck continued with the forth amp’s group of resisters, I tested them. Apparently the 2000 ohm resistor was previously bad and was replaced with a group of four 8000 resistors in parallel. My ohm test results of the six resistors (counting the four parallel 8000 ohm resistors as one), was that only two tested good, the 2000 ohm and the 2500 ohm. FYI, I have double checked my results with a second multimeter.

Btw, I got an email from a member who has had multiple resistor failures with his AP-997A. He also had a bad power transformer and an open in his coil in the Fuzz Filter. Though I feel bad he’s had to deal with that, it is comforting to know I’m not the only one with multiple component failures.

PS: I just bought an EICO Capacitor checker model 950. I saw that there was a 955 model but due to it not being tested as functional, I passed on it, though it’s model number seemed to call out to me.

All the new capacitors have been verified excellent via the tests the Sencore LC53 can perform and they all have been soldered into position on the post that will go into the cans. These caps were first mechanically connected utilizing wire wrapping methods. I’m now ready to stuff the cans.

I have verified the transformers of all four amplifiers with a ohmmeter and found values the same when comparing the same transformers of each amp. I did the same with the choke in the Fuzz Filters. Though things looked good from that perspective, I realize this isn’t considered a satisfactory test. So I therefore made a very significant investment into another piece of test equipment, the Sencore LC103. This will allow me to not only fully test out transformers and inductors, it will give me more specific information on capacitors that passed on the LC53. Additionally, a very cool feature is that it can test these components in circuit without having to unsolder and isolating them.

I have installed about half of the new clothed wires and ring terminals on three of the amps. Even though I took a lot of notes and have good documentation regarding how things are to be wired up, I left the fourth amp with it’s original wires until I complete the first three amps.

Looking good Wayne !

Carlton smith

Wayne, I'm very impressed with your total dedication and inspiring work that you are doing on these neglected, until now, Victrola Electrola sets! Keep up the great work! Your friend, Marc.

Great information Wayne! I've got half a dozen early amps in line to be worked on too. Those big power resistors seem to be the second most common failure after capacitors. I install fuses in the power input and the audio output circuits to protect the irreplaceable transformers. Got a spare amp and speaker for a 10-70 by any chance? Cheers, Russie

PS, Gov'flyball is correct about placing a bleeder resistor across at least one capacitor, when you serialize two capacitors. I usually install a 1 to 4 Meg ½ Watt from the center (between the two capacitors) to ground. That will keep DC voltage from building on the lower capacitor. The other capacitor will bleed on its own through the circuit.