Author Topic: 120 model, not far off  (Read 460 times)

Offline thelonious_crunk

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120 model, not far off
« on: April 01, 2021, 01:04:06 AM »
Hi all,

Finally, after getting rid of a 112 model 16 years ago (stupidly), I have purchased another Wurly.  A 120 model!  I am absorbing all the old posts here best i can.  Few questions:

1.  Death cap, which one is it?  And do you just snip it out, or do you have to bridge a connection from where its cut?  This amp is fairly quiet and i fear changing the tone by recapping it.  Maybe just the power supply caps are worth replacing? 

2.  Damper rail - can i just take it all off at once?  If so, how?  I need to get to the reeds to clean any corrosion on a couple notes that don't naturally sustain long enough.  I feel like in my old 112 it was easier to access.

3.  Seems like when i blast the volume past 90%, the speaker lightly overloads and not in the good way only while played.  However, i feel the new speaker replacement could help.

As far as the action, its pretty darn enjoyable as is.  It was lightly used by a lady in a country western band in the 60s/70s!

Offline pianotuner steveo

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Re: 120 model, not far off
« Reply #1 on: April 01, 2021, 12:50:08 PM »
The death cap is connected between the AC jack and the chassis ground. DO NOT bridge it! Cut it right out.

A shorted cap is bridged and is a shock/ and possible fire hazard
1960 Wurlitzer model 700 EP
1968 Gibson G101 Combo organ
1975 Rhodes Piano Bass
1979 Wurlitzer 206A EP
1980 Wurlitzer 270 Butterfly Grand
2004 Hammond XK3
2009 73A Rhodes Mark 7
2009 Korg SV-1 73
2017 Yamaha P255
2020 Kawai CA99
....and a few guitars...

Offline thelonious_crunk

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Re: 120 model, not far off
« Reply #2 on: April 02, 2021, 08:35:12 AM »
Thanks pianotuner steveo.  Are you the seller of the let off tool on eBay?  Just picked one up, and i have been absorbing the service manual and schematic.  Is the hand drawn part on the schematic a revision for a Line Out? I noticed none of my outputs liked my 30s PA amp

Offline pianotuner steveo

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Re: 120 model, not far off
« Reply #3 on: April 03, 2021, 08:33:53 AM »
Yes, I am shipping the tool today.

There is no line out mod for a 120 that I'm aware of. You can make an Aux out, but not line out. There is a difference.
The present outputs are too "hot" to connect to an external amp. VV sells (or used to sell) a small box that connects to your present output to make an Aux out. I know you can DYI with a resistor and a cap, but I don't remember the values. The resistor will be a big one, and I think a 5 watt.

You shouldn't try to connect to an external amp at least until the "death cap" is removed...
1960 Wurlitzer model 700 EP
1968 Gibson G101 Combo organ
1975 Rhodes Piano Bass
1979 Wurlitzer 206A EP
1980 Wurlitzer 270 Butterfly Grand
2004 Hammond XK3
2009 73A Rhodes Mark 7
2009 Korg SV-1 73
2017 Yamaha P255
2020 Kawai CA99
....and a few guitars...

Offline thelonious_crunk

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Re: 120 model, not far off
« Reply #4 on: April 04, 2021, 07:04:41 PM »
No worries, i am taking my time on this one.  I appreciate you sending that.  And yes, i snipped that death cap right out of there.  What's funny is someone mounted fuse holder to the outside of chassis so they could easily change them.  Its the only mod i see non original in there.  I ordered a Tropical Fish electronics replacement kit as well.  Another oddity, i noticed that instead of 2 matched 6v6gt tubes, it sported one 6v6gt and a 6L6gc!  Obviously not good for the amp at all. 

Offline theseacowexists

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Re: 120 model, not far off
« Reply #5 on: April 05, 2021, 02:02:42 PM »
Judging from the cheek block, it looks like yours might have the 700 amp in it. The giveaway is that your pilot light is a jewel with an incandescent bulb behind it. The 120 amp has a neon pilot light. They're the same amp, but there is a significant difference in the wiring to the cheek block. Does your speaker plug into a socket on the amp, or is it wired up to the cheek block?

https://www.tropicalfishvintage.com/s/wurlitzer-700-schematics-diagrams.pdf

Offline thelonious_crunk

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Re: 120 model, not far off
« Reply #6 on: April 06, 2021, 04:45:24 AM »
Judging from the cheek block, it looks like yours might have the 700 amp in it. The giveaway is that your pilot light is a jewel with an incandescent bulb behind it. The 120 amp has a neon pilot light. They're the same amp, but there is a significant difference in the wiring to the cheek block. Does your speaker plug into a socket on the amp, or is it wired up to the cheek block?

https://www.tropicalfishvintage.com/s/wurlitzer-700-schematics-diagrams.pdf

It has wiring to the cheek block no plug on the amp.  Can't tell if the year says 1958 or 1959.  I noticed the fuse holder is wired on the outside of the chassis which looks like it was done afterwards in the 70s or so.  Maybe the death cap blew a bunch of them for them to move it?  So is the .1uf 600v white cap that was wired to the fuse a still gonna be the death cap in a 700 amp?

Offline theseacowexists

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Re: 120 model, not far off
« Reply #7 on: April 06, 2021, 07:47:38 AM »
If I remember correctly, yes, that white one is the "death cap" in this amp. Have you got a picture of this modded fuse holder?

Offline thelonious_crunk

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Re: 120 model, not far off
« Reply #8 on: April 07, 2021, 06:12:48 AM »
If I remember correctly, yes, that white one is the "death cap" in this amp. Have you got a picture of this modded fuse holder?

I only figure its modified since there is an extra drill hole where I presume it used to be

Offline thelonious_crunk

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Re: 120 model, not far off
« Reply #9 on: April 07, 2021, 06:14:21 AM »
The guts, before i cut out the death cap on the right side.  It was connected to the fuse

Offline 4kinga

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Re: 120 model, not far off
« Reply #10 on: April 07, 2021, 07:40:36 AM »
I'll let other more knowledgeable people chime in, but that looks very scary.

Offline theseacowexists

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Re: 120 model, not far off
« Reply #11 on: April 07, 2021, 12:28:18 PM »
The original fuse holder would have been in the hole that's next to the mains socket. Probably broke at some point and someone replaced it with a more conventional mount. I wouldn't worry about it. I would, however, worry about that electrical tape. Whatever connection that is covering should probably be redone with some heatshrink, or just replacing the entire length of wire. It's hard to see which wires it's associated with, but I'm guessing it probably is the wire that was spliced in to reach the new fuse location.

Have you worked in a tube amp before? Do you know how to discharge the capacitors before working on it?

Offline thelonious_crunk

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Re: 120 model, not far off
« Reply #12 on: April 07, 2021, 05:48:47 PM »
That tape is gone with the death cap, it was just where they soldered a new lead from the fuse before.  I will add wire sleeves. Yes i have worked on a couple, and completely recapped a push/pull first try recently.  I had too many bad experiences bringing these to amp techs when i was younger 17 years ago.  I know how to use a multimeter to discharge them yes, but should I be building some alligator clipped lead wire with a resistor?  I use tools with rubber handles, work with one hand, and wear gloves.  I never touch the leads with my bare hands.

Offline theseacowexists

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Re: 120 model, not far off
« Reply #13 on: April 08, 2021, 09:31:05 PM »
Awesome. Have fun!

Offline thelonious_crunk

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Re: 120 model, not far off
« Reply #14 on: April 09, 2021, 01:37:36 AM »