Lesle tube amp giving me fits.. Amp guys can you help?

[Leo_Gnardo]

I also like "Holy Grail" caps, the temp rating is 105C. The availability seems to be few and far between.

Holy Grail caps are Ceriatone house brand, modeled after Sprague Atoms (but without the big shell full of stuffing) according to Nik Azam head honcho at Ceria, and made in Penang Indonesia. So we won't find 'em thru the usual channels. I s'pose you could inquire at Ceriatone & ask whether they'll sell you some.

I get 105C rated filter caps from Ruby/MagicParts. They won't tell me who makes 'em but they look an awful lot like F&T. I opened one up and it's full of capacitor, not any Sprague Atom stuffing nor some lesser cap masquerading as quality.

[Rich Rice]

A quick follow-up here.. Still messing about with the amp. As things turned out, I had lots of work in diagnosing it.. When push came to shove, two of my friends (both serious electronics guys) came by to help me out. The three of us worked together for five hours checking and measuring everything in the amp. I have now learned a great deal, and finally have a better handle on why things are as they are in there. I replaced the diodes, resistors, and electrolytics myself. Thought that would do it, but NO...

Still had a short in there as soon as the amps got hooked into the newly rebuilt power supply.. Eventually, we found one of the output transformers was showing a resistance. Trying to obtain a replacement OPT from another Leslie has proven to be an exercise in futility. Once again, it was time to study and grow.. lol

I eventually fund a transformer that should be an upgrade, via CE Dist.. Waiting for it to come in now. It will be tight, but I think I will be able to get it mounted on the chassis (may have to move one of the smaller ones over a bit, or some such minor modification), but the turns ratio and power handling capacity look to be a good fit. With luck, this should get it running. Once I took the bad channel out of the circuit, the other three seem to be holding. Naturally, the OPT that went bad is the larger one, for the bass- go figure. I'm going to replace it with a Fender OPT for a Hot Rod Deluxe.The old xfmr was rated primary 9.3k/16ohms, the replacement rated 4250k/8ohms. Running that into a 16ohm load should double the primary to 8.5k, which should be acceptable for the 7189 output tubes. The new transformer weighs 3.3 lbs, the original weighs 2lb., 5 oz.

It feels great to have finally had some hands-on direction from good guys who know their stuff. Either of them could have identified the problem more quickly, but they took the time to explain to me what needed to happen, why, what to expect, and how to deal with things that didn't turn out as they should have. A second visit from one of them helped find the root of the trouble, and I will do the rest of the repair myself.

I really need to get a Variac- what a great tool..

I ended up replacing all that stuff with discrete parts, and will clip the contacts on the cap cans to leave them in the sockets (for good looks).

the culprit.. sure looks nice from the outside. I removed the bell ends, everything looks great inside- it just doesn't work right.. Bummer

[tedmich]

I hope the Fender transformer has the same frequency response as the Leslie, it probably should, remember to label the impedance requirements well so no one misloads it.

I liked a few of your guitar builds, the Guitardis was especially fun!

[Audiotexan]

Yeah first glance at pic DSCN1400.JPG had me wondering if the one OT had been replaced. Color is close, but construction made me wonder since is was so different from the other 3 OTs and also the PT. I'd definitely be wondering about that segment of the circuit given the above.

Also have to agree with replacing all the electrolytics in that puppy. It looks like too nice an amp to risk trannies on, much less vintage 7189's! =)

Edit: Assuming now, that the tranny you're replacing is T2 (second from left in the DSCN1400 pic), that would explain the size difference, but the construction difference in that OT still 'grabs my attention' for whatever reason. lol

[Rich Rice]

Yeah first glance at pic DSCN1400.JPG had me wondering if the one OT had been replaced. Color is close, but construction made me wonder since is was so different from the other 3 OTs and also the PT. I'd definitely be wondering about that segment of the circuit given the above.

Also have to agree with replacing all the electrolytics in that puppy. It looks like too nice an amp to risk trannies on, much less vintage 7189's! =)

Edit: Assuming now, that the tranny you're replacing is T2 (second from left in the DSCN1400 pic), that would explain the size difference, but the construction difference in that OT still 'grabs my attention' for whatever reason. lol

Yep, T2 was the one that went south- bummer. That's the original, as weird as it looks. I have another 4 channel Leslie amp that has the larger transformers on all channels, I guess the bean counters got involved with the designers to cut costs by the time this one was made. I don't remember if I specified the ages, this one was built in 1966. The other amp with the bigger xfmrs was from 1963..
Nice and neat.. I mounted all the new stuff inside with 3M permanent foam tape. Seems very strong. I guess time will tell...

[Rich Rice]

As she sits waiting.. Did I mention I just hate waiting?? LOL

[Rich Rice]

Well.. The transformer should be here Monday.

Anybody know the power rating for a 1966 Jensen C15L? I can't seem to find the specs for it anywhere.. Mine is a 16 ohm version. Thanks!

[tedmich]

it started out being able to handle about 40w max but I'd only feed it about 1/2 that for its second half century.

[Rich Rice]

it started out being able to handle about 40w max but I'd only feed it about 1/2 that for its second half century.

Thanks! Sounds about right. I'll stick with a pair of 7189's, should max out around 18 watts (more or less).

[uboat229]

looks like an amp from the 4 channel 101 series amps.... not worth beans... unless maybe you want to make a 4 channel guitar amp or you get a Guilbansen Rialto organ.... thats what it was made for.... again... get on the hamtech.org web site and you can get all schematics and help .... more than you ever desired.... best thing about the the 101 is the 15'' jensen speaker ... the tubes.... i think they were 7189's and a nice cabinet for an end table....the c15 jensen is about a 40 watt at @16 ohms,,, also used in 122,142, 145,147 leslies

good luck

Frank uboat