Layout of the Ford Amp #102

[bluesfendermanblues]

Hi Tony, Thanks for the layout it already been put to use for an upcoming build.

[erwin_ve]

Here are some points that may IMO perhaps be worth a double check:

- All orange drops 6PS?
- Really a h.f. taper circuit?
- 2.2uF cap connected to terminal 2 of the presence pot really a ceramic disc?
- Treble pot for sure a linear pot? Which brand and kind of pot precisely?
- PT correct (export?). On some videos, which show the back of #102 and already in the tan cabinet the switch to change the preset voltage is obvious in my opinion
- Really two .01 caps in series between treble pot and rock/jazz switch just as in #124?
- In the "Today you chose.." thread (OP ampdorc) AFAIR there has been some discussion about how to read the snubber values. So are you all sure now that these are 250pF in #102 and not 25pF?
-

That HF taper circuit was added in the lay-out; One of my clones has RF #102 values. If you run this amp without a dumblelator it's painfully bright. With a dumblelator it's heaven IMO.
Brandon also mentioned somewhere; 68pF master cap was a mica.
I doubt the HF taper circuit will sound nice with the 68pF master cap(amp without a dumblelator), someone else tried?

Max, Since Brandon was the one that has been in the real one and measured components, I'll quote him, this may answer some questions;

"6ps series orange drops, Sprague Q-line Resistors throughout.
250K Linear treble, 250K Audio Mid, Bass pot marked 500K but measured around 400K with .001 Bypass 390PF treble cap on the Mid switch was Mica

Mid cap was something "Different" composition wise, not an orange drop,

220K feeding 100K trimmer measured +/-26K to ground with amp on
.01, .005 couplers v1B 100K LINEAR pots (Why an audio taper would make it some how "Better" is beyond me, just turn the damn knob down)
Snubbers were 250pf ( I used caps that were marked 270 but measured 250 in the amp Shad Poked around in)

100K Feeding Drive pot, 150K feeding Ratio Pot, Grid stoppers for V2 were 68K/180K

4K7 Negative feedback resistor, Standard PI (820, 24K, 390R) 2.2uf presence

110K/120K on the PI with .1uf couplers.

Dropping string was 2.7K, 22K, 2.2K

220uf caps in series to the plates
22uf to the screens
22uf to the PI
40/40 UF cap can feeding v1 and v2

PT looked like a Peavey/magnetic components out of a deuce or 5150 or ultra 120, and was a fwb type (no center tap on the b+)arrangement, Plates were around 455-460 depending on bias setting

Choke and OT were out of a Twin/Showman."

[Max]

Max, Since Brandon was the one that has been in the real one and measured components, I'll quote him, this may answer some questions;...

Hi Erwin,

Thanks for posting Brandon's #102 specs again.

As far as I understood this right up to now, this layout shall be based on the real specs of the real #102. Because of this I would recommend to approach this project with the same precision as the #124 project after Gil had been so generous to post all the #124 info.

Of course no pictures of #102 have been posted up to now, but as far as I understood Scott’s posts concerning this amp correctly up to now, there are at least two eyewitnesses (Brandon and Scott). This would IMO make it possible to note the precise specs of the parts in the layout, like what is really written on the pots, what coax precisely has been used, what kind of cap the presence cap is etc. – just like Tony did it in his 2nd generation "pre-classic" layout - and not only to specify "treble 250KL" as an example. IMO only if everyone knows precisely what parts are in the original amp, everyone has the creative freedom to decide how to replace them with an item that will in his opinion have a most similar influence on the tone as the original part, if these should be no longer available as NOS or used parts.

BTW: as far as I know there are replicas available now of the Fender "2-35" pots and of the 500K IRC / Central Lab / CTS (C)BA 881… Gibson guitar pots, too, offered as "true vintage taper" or something like this. Just some examples of a quick "true vintage taper" Google search:
http://www.doctorvintage.com/drv1_controls.html
http://retrospec-guitar.com/store/index ... ducts_id=9
http://retrospec-guitar.com/store/index ... ucts_id=40

PT looked like a Peavey/magnetic components out of a deuce or 5150 or ultra 120, and was a fwb type (no center tap on the b+)arrangement, Plates were around 455-460 depending on bias setting

The PT part number in Tony’s #102 layout is AFAIK no Peavey part number, as Brandon posted, but a Fender part number. So perhaps Tony and Brandon should find out in a phone call what now is really in this amp?

Here's a picture on which you can clearly see the back of #102 with the switch to set 4 different preset voltages: http://ampgarage.com/forum/download/file.php?id=13665

And here's a link to a picture and the specs of the Fender 026554 PT, which Tony specifies in his #102 layout: http://angela.com/fendertonemasterpowertransformer.aspx

BTW: Obviously no DIN for the footswitch as currently specified in the #102 layout, but a Switchcraft – just as in all 2nd, 3rd, transition and 4th generation ODS amps I know.

Cheers,

Max

[dogears]

No HF trim in the amp.....

[talbany]

The PT part number in Tony’s #102 layout is AFAIK no Peavey part number, as Brandon posted, but a Fender part number. So perhaps Tony and Brandon should find out in a phone call what now is really in this amp?

Max
I have discussed this with Brandon..His response was that he thought it looked like a Peavey due to the wiring colors but didn't say he knew for sure and that he saw no such markings..
The notes I have were taken from the actual amp but don't know for certain when these were taken and could have been changed before Brandon cracked open the amp on his bench..
Since we can't really ID the power accurately right now we should keep the # on the layout as a reference.. If Dumble or someone did change the power (which I don't doubt) he more than likely replaced it with one similar in specs to that of the Tonemaster/Red Knob twin power that was in it.. We know the amp sounded pretty good throughout it's life time and IMHO worth the reference point..(I will update to read amp at one time had said part #)
The Pot codes I have seem to correspond with the date of delivery 77/78 and the stockpile of Fenders 67 pots so no reason to believe these were not accurate..Some of these # don't represent tapers or types just source/manufacturer and date..

all of the info I used on the layout was taken from people who have actually been inside the amp.. Brandon being the most prominent at this time

This is what we know of the amp so far and any changes we do(aside from typos on my part) need to come from those who have actually been inside the amp and willing to share the info..
Thanks for those who looked over the layout for me!!

Tony

[talbany]

No HF trim in the amp.....

Thanks Scott.. Taper removed Rev 4 up

Tony

[Max]

Since we can't really ID the power accurately right now we should keep the # on the layout as a reference.. If Dumble or someone did change the power (which I don't doubt) he more than likely replaced it with one similar in specs to that of the Tonemaster/Red Knob twin power that was in it.. We know the amp sounded pretty good throughout it's life time and IMHO worth the reference point..(I will update to read amp at one time had said part #)

Hi Tony,

I am rather sure, that PT 026554 is still in this amp:

- the pic of the back I've posted is one from the last years because #102 is on it already in the tan cabinet
- in this pic you see a 4 step voltage selector
- the specs of 026554 say exactly: "four selectable voltages (100, 120, 230, 240). These are all voltages Robben Ford needs on tour.
- On the back-pic you can get a glimpse of the PT. It is obviously mounted in the same way as 026554.
- Brandon is not sure that it is a Peavey
- Your info is obviously that at one point in the past the PT was a 026554.

My conclusion: 026554 is most probably still in this amp.

The Pot codes I have seem to correspond with the date of delivery 77/78 and the stockpile of Fenders 67 pots so no reason to believe these were not accurate..Some of these # don't represent tapers or types just source/manufacturer and date..

This is why I don't understand your opinion concerning this:

021832 (master) usually measures somewhere around 20% taper AFAIK
021873 (ratio, level) is a linear AFAIK
The 500K CTS BA 811... (bass) from '67 usually measure around 30% taper AFAIK
Mid pot is 30% you write (CTS 021857? or what is your info?)
treble is linear, as Scott tells. Perhaps changed (your first version had a 021857 treble, too, AFAIR) after the infos of your first layout version have been collected?
Volume again is a 021832.

So why do you think that the tapers are not known? As far as I know the part #s all correspond to known tapers (those I posted above)?

If you or Scott could tell me the part numbers and date codes of the middle and treble pots I am rather shure that I could find out what they are precisely. Just an offer.

Robben tells that #102 has been delivered in 1982. So at least the two 1M and the two 100K pots seem to be still the original ones - Level and ratio the last (8238). And if the current mid pot should be a 021857, and if a previous documented treble pot should have been a 021857, too, these two could perhaps be the original "classic" bass and treble pots (depending on their date codes). That is one of the reasons why I would like to know what precisely is written on the current middle and treble pots.

The date codes of the Atoms would be very interesting, too, of course?

What is written on the mid cap and how precisely it looks would be a further valuable information?

What kind of cap is the presence cap?

All the best and have a fine day,

Max

[talbany]

Max thanks for getting back with me on the pots..here is what I have


Volume and Master: 1M AUD 021832 1377738
Level and Ratio 100K AUD 021873 R1378238
Treble 250K AUD 021857 2-35 R8242
Mid 13 1377402
Bass BA 8113220 1376702

I have no such records nor could I find any of the 02 # specifying the pot types and tapers if you have this info or a link and could post this I would appreciate..
AFAIK.. the 7 digit starting in 13 I know are the part/date codes (although the 6 digit does not indicate decade just year) the 2-35 indicates a Fender special taper ordered by Fender..?..
This is what I know.. Perhaps these pots have been changed in the update however since the middle pot is one that would have been changed in the skyliner mod I don't have the so called taper # you have info on..Help if you can..

I believe the Power transformer was taken from a red knob twin same # (sound familiar) as you could get these with the multi-taps(The 026554 transformer has exactly the same output taps As Showman but can be wired for 100/120/240 voilt input). I don't know if Peavey made a Deuce w/multitaps.. Could have I have never heard of or seen one..EI606 code says Schumacher..

Tony

[Max]

Max thanks for getting back with me on the pots..here is what I have


Volume and Master: 1M AUD 021832 1377738
Level and Ratio 100K AUD 021873 R1378238
Treble 250K AUD 021857 2-35 R8242
Mid 13 1377402
Bass BA 8113220 1376702

I have no such records nor could I find any of the 02 # specifying the pot types and tapers if you have this info or a link and could post this I would appreciate..
AFAIK.. the 7 digit starting in 13 I know are the part/date codes (although the 6 digit does not indicate decade just year) the 2-35 indicates a Fender special taper ordered by Fender..?..
This is what I know.. Perhaps these pots have been changed in the update however since the middle pot is one that would have been changed in the skyliner mod I don't have the so called taper # you have info on..Help if you can..

Tony

Hi Tony,

Volume and master: 021832 is the Fender part number of this CTS pot. 137 the CTS code, 7738 the date code: year 77, week 38. 1M AUD the value and taper. The taper of these pots usually measures somewhere between 15% and 25% AFAIR.

Level and Ratio: 021873 is the Fender part number of this CTS pot. These are linear pots usually labelled "- D -". 137 = CTS; 8238 = week 38 in year 82. "AUD" is for sure a typo in your notes. 021873 are linear.

Treble: Fender part # = 021857; "2-35" indicates indeed a special AUD taper (AFAIR 2% at 10% turn and 35% at 50% turn). The taper of 021857 pots usually measures around 30% AFAIK. R8242 indicates week 42 in year 82.

The 500K bass pot is IMO a Gibson guitar pot. The date code indicates 137 = CTS and and week 02 in year 67. This makes sense because AFAIK Gibson had changed from Central Lab to CTS already in '67. These 60ies 500K CTS guitar pots are AUD and AFAIR their taper usually measures around 30%.

All these pots would make sense in an amp that has been finished at the end of 1982. This may well be the case, as Robben once told that he did use #102 for the first time for a recording in '83.

Skyline update: AFAIR the early classics below around #110 all used 021857 for treble and bass and 021873 for middle. So if you would use the "classic" 021857 bass pot for the "skyline" 250K middle, then you would only need an additional 500K bass pot. But I will not imply that this is the way Alexander usually did these updates. But it would match with your notes - whatever this may be worth.

I'll look for some links concerning pot specs and codes.

Take care,

Max

[hitchcaster]

cool info.. FWIW, robben uses a variac to run his amp at the voltage he likes (forget but it was around 125v). so overseas he uses the variac to drop the voltage down to that..

[Max]

I believe the Power transformer was taken from a red knob twin same # (sound familiar) as you could get these with the multi-taps(The 026554 transformer has exactly the same output taps As Showman but can be wired for 100/120/240 voilt input). I don't know if Peavey made a Deuce w/multitaps.. Could have I have never heard of or seen one..EI606 code says Schumacher..

Hi Tony,

026554 PT: Here is a schematic of "The Twin" with the 026554 export wirings: http://www.blueguitar.org/new/schem/fender/the_twin.gif

Angela lists the Fender 026554 as:

"Fender Tone-Master Power Transformer. "Multivolt" primaries easily configurable for 100/120/230/240V." http://angela.com/fendertonemasterpowertransformer.aspx

All the best,

Max

[talbany]

I believe the Power transformer was taken from a red knob twin same # (sound familiar) as you could get these with the multi-taps(The 026554 transformer has exactly the same output taps As Showman but can be wired for 100/120/240 voilt input). I don't know if Peavey made a Deuce w/multitaps.. Could have I have never heard of or seen one..EI606 code says Schumacher..

Hi Tony,

026554 PT: Here is a schematic of "The Twin" with the 026554 export wirings: http://www.blueguitar.org/new/schem/fender/the_twin.gif

Angela lists the Fender 026554 as:

"Fender Tone-Master Power Transformer. "Multivolt" primaries easily configurable for 100/120/230/240V." http://angela.com/fendertonemasterpowertransformer.aspx

All the best,

Max

Max
Foot note here..AFAIK the 026477 and 026554 are basically the same (Both list output 477 no load) transformers except the 554 has the multi taps and the 477 does not.. This is the one listed in the twin schematic you posted..

Tony

[Max]

Max
Foot note here..AFAIK the 026477 and 026554 are basically the same (Ce-Angela list output 477 no load) transformers except the 554 has the multi taps and the 477 does not.. This is the one listed in the twin schematic you posted..

Tony

Hi Tony,

You find the 026554 wirings in this schematic, too:

http://www.blueguitar.org/new/schem/fender/the_twin.gif

Just take a closer look to the left of the 026477.

Have fun,

Max

[talbany]

OK!!
I was looking at the other end of the schemo..didn't see that..Thanks..

T

[hitchcaster]

why the 40/40uf cap and not a 20/20? seems more intuitive it would be a 20uf..