I have a 1973 100w PTP head. Have had it for about 8 years. Hated it from the moment it arrived at my door. Kinda stuck it in the corner and forgot about it, figured "it's"collectible" leave it as is. Took it out every now and then to see if I could develop a relationship with it, but nope. So, finally I decided it was time to go. Took it to Billy Penn @ 300 guitars to be checked out, cleaned bias check......etc. just to be sure it was A-OK for its future home. So after bringing it in to the shop, he suggested I try new caps,tubes,etc. Removed a .68uf cathode bypass resistor some one had bastardized it with. He was very confident I would reconsider selling it. So, OK, go for it! Returns home after a week or so and....... Holy shit, it's the voice of God! Point of all this being change those caps! If you intend to actually play your old amp Never had one all freshened up before. It really makes a huge difference!
Ooh, that one has green filter caps. I've been looking to get the date range those were made in. Can you please take a good look at those caps and either make a photo of the labels on them or tell me what they say? There's a date code on them, which is a four digit number. Something like 2373, which would be 23rd week of 1973. Or maybe it' s 7323, same meaning but reverse date/week order. I'm trying to identify when the green caps were made. Oh...it's definite that those caps should be replaced. They've outlived their rated service life with years to spare. If they were tires they'd be on the cords, tread long worn off completely. They're going to fail sooner or later and probably are already not doing their job well due to age related deterioration. Should they fail in the wrong way, it's going to cost you a power transformer. Get them replaced. SOON. As in, before you use the amp again.
All been replaced. Those photos are from when I bought it. I;ll get pics of the parts after work. I can say the amp was born on Jan. 23 1973.
There must have been something wrong, because how often do you hear, "yeah I have a 100 Watt Mashall from 73 and I hate it"???
72 40. 40th week of 1972. Thanks! In '73 and beyond the caps were blue. Come to think of it the last time I saw green caps, the amp was earlier than a '73. So that sort of established an upper date range.
The blue caps also come in black and yellow print versions. The only thing consistent about old Marshalls is that nothing ever stayed the same for very long. The yellow printed caps were printed on the blue heatshrink. The black print versions had a label applied UNDER the heatshrink, eliminating the need to print on the heatshrink. And this is ODD....I Googled for images of many vintage Marshall chassis, and if the chassis features blue label Daly capacitors with yellow print, then the date code line is always exactly the same: J4 75/28 BTD In fact, it looks like ALL of them have identical labels. Every character is the same. I'm suspicious that Daly may have just chosen to print cap labels ONCE, in one lot with all the same date codes. If you have a blue label yellow printed 50/50 cap in your Marshall, and it's date code is NOT 75/28, please take a picture of it and post it. I don't think it exists without a photo! I have some black label blue caps I saved from recapping my two, and their date code line reads J4 75/28 BTS. So if that IS the date code, then they were doing both black and yellow print caps at the same time. Bizarre again.
