Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: delray on January 17, 2023, 03:50:38 pm
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I bought this box of parts assuming that it was a complete mojotone british 50 kit but it looks like a got a lot of miscellaneous parts. I have what appears to be a mojotone 45 chassis and faceplates along with a mix of classic tone transformers and other misc bits. At this point i would like to build in to a plexi style amplifier. Ideally 4 input like a JTM45 or 59 style.
I was thinking of buying a hoffman board and kit of parts for a 50 watt and then some compatible tubes but will my transformers, pots, etc. work?
(https://mobolr.com/amp/IMG_5740.jpeg)
(https://mobolr.com/amp/IMG_5744.jpeg)
(https://mobolr.com/amp/IMG_5745.jpeg)
(https://mobolr.com/amp/IMG_5739.jpeg)
(https://mobolr.com/amp/IMG_5742.jpeg)
(https://mobolr.com/amp/IMG_5743.jpeg)
(https://mobolr.com/amp/IMG_5741.jpeg)
(https://mobolr.com/amp/IMG_5738.jpeg)
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IDK. Looks legit. Nice turret boards, quality parts, expensive USA made transformers. A kit means you need to build the board first by soldering in parts. Match up the parts available to whats needed to finish the
board. If you are missing stuff or are not entirely comfortable with what you are doing--send it back. If you search the forum for an amp technician listing ( https://el34world.com/Forum/index.php?board=27.0 ) and order a pre-fabricated board from him--he can help you with selecting an appropriate chassis. Jim
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I'm with Jim. That looks like you have all you need to build a very nice amp. maybe build it as is first.
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I bought this box of parts assuming that it was a complete mojotone british 50 kit but it looks like a got a lot of miscellaneous parts.
You should be talking to mojo.
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I bought this box of parts assuming that it was a complete mojotone british 50 kit but it looks like a got a lot of miscellaneous parts.
You should be talking to mojo.
I should have noted in the original post that I did talk to them. Their response was "That appears to be our small parts kit but I am not sure about the chassis and we do not sell Classic Tone transformers".
I am pretty sure this is their 50w chassis kit https://www.mojotone.com/British-45-Style-Chassis-Set-with-Front-Back-Faceplates (https://www.mojotone.com/British-45-Style-Chassis-Set-with-Front-Back-Faceplates) but they didn't confirm it. I guess with my limited knowledge how can I know if these transformers will work with one of the hoffman board kits?
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So you did not buy this from Mojo? Do you have a parts list? If not can you make a parts list? The transformers are the key - I think I have a spreadsheet with all the MC Classictone tranny specs.
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I thought you had bought from mojo but that does not seem to be the case? Who sold you this kit?
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So you did not buy this from Mojo? Do you have a parts list? If not can you make a parts list? The transformers are the key - I think I have a spreadsheet with all the MC Classictone tranny specs.
Correct this was a local facebook marketplace find. Yeah I can work on a parts list.
The transformers are:
Output 40-18023 / 166-1325
Choke TRIM100D / 1320
Power TR-PW-05 / 40-17372 / 166-2035
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Looks like you've already got most of what you need to complete the amp guts. Were there tubes in the box?
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You can find documentation on mojo's website. If you throw a Hoffman kit in the mix you will probably just get more frustrated.
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The transformers are:
Output 40-18023 / 166-1325
Choke TRIM100D / 1320
Power TR-PW-05 / 40-17372 / 166-2035
Let's have data.
Power (NOT output!!):
https://www.digikey.com/en/products/detail/tubedepot/40-18023/10487984
https://cdn.shopify.com/s/files/1/0357/4769/2679/products/IMG_1835_1500x1500.jpg
690VCT, 150mA (so 480V DC)
ANOTHER power transformer!!:
https://www.digikey.com/en/products/detail/tubedepot/40-17372/10487978
https://s3.amazonaws.com/tubedepot-com-production/spree/attached_files/tr-pw-05.pdf
Real similar/same-as above? (Check me.)
Choke (is a choke!)
5 henries at 120mA DC. 115 ohms DC
http://triodeelectronics.com/tri-m100d.html
That's all your iron? Then you need to get an output lump and can trade a power lump.
This webshop lists 7 different OTs but they site won't copy/paste right and anyway I don't know who they are; maybe the numbers are helpful.
https://shop.amppartsdirect.com/search?q=Marshall+Style+50W+Output+Transformer
Everybody! Check my look-ups!! I may have cross-circuited something.
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The transformers are:
Output 40-18023 / 166-1325
Choke TRIM100D / 1320
Power TR-PW-05 / 40-17372 / 166-2035
Let's have data.
Power (NOT output!!):
https://www.digikey.com/en/products/detail/tubedepot/40-18023/10487984
https://cdn.shopify.com/s/files/1/0357/4769/2679/products/IMG_1835_1500x1500.jpg
690VCT, 150mA (so 480V DC)
ANOTHER power transformer!!:
https://www.digikey.com/en/products/detail/tubedepot/40-17372/10487978
https://s3.amazonaws.com/tubedepot-com-production/spree/attached_files/tr-pw-05.pdf
Real similar/same-as above? (Check me.)
Choke (is a choke!)
5 henries at 120mA DC. 115 ohms DC
http://triodeelectronics.com/tri-m100d.html
That's all your iron? Then you need to get an output lump and can trade a power lump.
This webshop lists 7 different OTs but they site won't copy/paste right and anyway I don't know who they are; maybe the numbers are helpful.
https://shop.amppartsdirect.com/search?q=Marshall+Style+50W+Output+Transformer
Marshall Style 50W Output Transformer 4/8/16 - APD-8025H $89.00
Everybody! Check my look-ups!! I may have cross-circuited something.
Thank you.
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The transformers are:
Output 40-18023 / 166-1325
Choke TRIM100D / 1320
Power TR-PW-05 / 40-17372 / 166-2035
Let's have data.
https://www.digikey.com/en/products/detail/tubedepot/40-18023/10487984 (https://www.digikey.com/en/products/detail/tubedepot/40-18023/10487984)
Everybody! Check my look-ups!! I may have cross-circuited something.
Says 'audio transformer' in one part of the description on that link - but another part of the description says 'PLEXI/JCM800 50 WATT PWR TRANS' so :dontknow:
FWIW, I grabbed a bunch of Classic Tone output transformer specs/schems off the Magnetic website before they folded, but they're all for Fender equivalent OTs (if there's any interest in such obsolete information). Here's the inventory list of spec sheets I have. Some of them will be 'suitable for any 50W tube amp' but it just won't be the same as a 'Marshall' LoL
Classic Tone 40-18002 (125A1A 022640 041318)
Classic Tone 40-18007 (125A9A 022855 45249 036485)
Classic Tone 40-18008 (021009 125A13A) 4k2 to 4 8R 60W
Classic Tone 40-18011 (125A13A 022871)
Classic Tone 40-18012 (125A29A 022689 022889 037612)
Classic Tone 40-18013 (125A29A 022689 022889 037612) Multi-tap secondary
Classic Tone 40-18022 (50246 5E3 OT)
Classic Tone 40-18031 (125A35A 125A3A 022905)
Classic Tone 40-18045 (125A10B 022913)
Classic Tone 40-18045 (125A10B)
Classic Tone 40-18061 (3778 T3778 E3778A 340-8 340-3778)
Classic Tone 40-18087 (125A1A 022640 041318) 6k6 to 4 8 16R
Classic Tone 40-18088 (45216 1846 1848)
Classic Tone 40-18102 (125A29A 022889 022689 022899 037612)
Classic Tone 40-18105 (022848 125A6A 125A7A)
Classic Tone 40-18113 (125A29A 022689 022889 037612)
PS: when I posted this, some of the number sequences auto-formatted themselves as phone numbers which prompt you to call the number if you click on it with your smartphone. Not so smart then. Call at your own risk.
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> Says .....- but another part of the description says
So get more data until a preponderance happens. Try this:
https://el34world.com/Forum/index.php?topic=24137.0
https://el34world.com/Forum/index.php?action=dlattach;topic=24137.0;attach=74640
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Disregard, I see you have already contacted Mojotone. That looks like a mix of their British 50W, 45W and some other misc. parts. I guess coming up with a schematic and layout for what you want to build with what you have is the challenge. You may have to order some new stuff too.
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Attached is the Magnetic Components spreadsheet I mentioned.
You do not need it now, as you now have the data for the iron, but others may find it useful.
If you are game to move forward, I'm sure this Forum can get you there - you have some good parts. The chassis you have is set up for a laydown PT and the one you got hopefully fits. It seems its a JTM-45 spec.
Hoffman's instructions on this site are great. And some kit instructions post downloadable instructions.
A parts list and what you want to build will allow you to fill in parts gaps - including the OT. You will have multiple options.
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Thanks everyone for the help. This helps me sort out what I have. It looks like either way I got I am going to need to buy some parts.
JTM45 build
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JTM45 Style Chasis
TR-PW-05 Power transformer, "laydown" mounting, for Marshall style JTM45/50 amps.
Wiring board (possible JTM45)
Missing output transformer, choke, tubes, all other parts
JMP 2204 Build
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Mojotone parts kit for JMP 2204
Classic Tone 40-18023 PLEXI/JCM800 50 WATT PWR TRANS
Choke TRIM100D used in Marshall 50 & 100 Watt Plexi & JCM 800 Amplifiers.
Mojotone Wiring board
Missing chassis, tubes, output transformer
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Wiring board (possible JTM45)
Missing output transformer, choke, tubes, all other parts
You have two turret boards (wiring boards) If you look up layouts you can match them - different suppliers layout the boards somewhat different, but its easy to figure out. Hoffman, Mojo, Ted Weber, Trinity, Ceriatone, etc. all post layouts of 45/50 Marshalls, I believe.
And - you have a choke, tube sockets, capacitors, faceplate, resistors, jacks. You are not going to need much besides that OT - and some studyin' and patience.
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heres a layout for comparison to your boards
http://site.triodestore.com/JCM8002204Stock.pdf
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Mojotone 50w 2204 schematic (https://www.mojotone.com/Amp_Kits/British/British_50W_1976_2204_WD.pdf)
Mojotone 50w 2204 layout (https://www.mojotone.com/Amp_Kits/British/British_50W_1976_2204_WD.pdf)
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Sorry to bombard you - these are the Mojo schematic and layout for the JTM45