Dating a marshall amp
The YRM-1 is good sounding, but not as responsive, raw, or soulful as my YBA-1. presently using the yba-1 through an old sound city 4x10 which i respeakered with 80 watters. breaks up like a champ when driven and sings sweetly when i turn down the pickup volume(s). It's a beautiful computer-drawn schematic, but an error was made in transcribing the previous schematic.
Some of the older amps have an inspection sticker on the top of the chassis and they usually have the day, month and year the amp was made or inspected.
July 1969 - December 1983 EXAMPLE: SL/A 24523 D SL/A = Model Code 24523 = Serial Number E = Date Code This amp would have be a 100 Watt Super Lead 1972 January 1984 - October 1992 EXAMPLE: S/A T 24523 S/A = Model Code T = Date Code 24523 = Serial Number This ampwould have be a 50 Watt 1985 JCM900's The JCM900's began using a Bar Code system which consists of 9 digits which are broken down into three sections.
EXAMPLE: 950322589 95 = Year 03 = Month 22589 = 5 digit serial number This amp would have been made in March 1995.
I have swapped out the 4M volume pots for 1M, and put a 47K resistor in the NFB loop. Professional repairman required, although schematic is included, weird defects possible. The YBA-1 serial number is 8011108 the YT-15 serial number is 7125596.
These mods are worth doing to any Signature/Bass-Master, IMO. CAD 3 used, bad price, amp in average (5/10) condition, Song Bird Music, Ottawa, Canada, summer 1998 US 5 [used], needed a little work but playable, cheap buy US 9.99 [used], seen at September 1998 CAD 9 [used], good condition, seen at Used Music, Ottawa, September 1998 CAD 0 [used], shabby condition, very early (pre October 1966) wrap-around type case model with tube rectifier, seen at Used Music, Ottawa, September 1998 CAD 5 [used], ca.