Mallory type FP multi-section capacitors for Wirlitzer 4020R - Page 1
Forum section: electronics / repair

author: egup1066
author_rank: Newbie
timestamp: August 29, 2015, 05:08:14 pm
content: I have a WIrlitzer 4020R that does nothing but blast 60Hz when turned on. The power amp works as I can connect my own signal to it and it comes out correctly (albeit still hummy) and the main filter caps are clearly faulty (6V ripple on one of the power rails) so I suspect they are the only problem. The issue is some dingus decided the thing to do about leaking capacitors was to shove sponges between them and the cases are completely corroded so I can't tell what they were. They are Mallory triple-section type FP capacitors. One has all three sections rated to 35V with the first section 1000uF and the other has all three sections rated to 25V and is part number 235-7029. This is all I know and I would really like to know what the ratings are to fix it properly.Most of these type of capacitors are rated to about 450V and intended for use in tube equipment so it is difficult to search for much information on them.If anyone can shed some light on what these caps are or has the schematic/parts list for the Wirlitzer 4020R it would be much appreciated.

author: SeanB
author_rank: Super Contributor
timestamp: August 30, 2015, 08:57:53 am
content: Top one would be 3 sections, probably 1000uF, 1000uF and 220uF 35V. Lower would work with similar replacement 25V units, around the right size.

author: sunnyhighway
author_rank: Frequent Contributor
timestamp: August 30, 2015, 11:33:41 am
content: Schematics do seem to exist.http://www.ebay.com/itm/Wurlitzer-Electric-Organ-4019-4020-4020R-4020D-Service-Manual-Schematics/301718336495?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D33097%26meid%3D9fabcd231928436aa4f932e28ffeb4ec%26pid%3D100011%26rk%3D2%26rkt%3D10%26sd%3D301693360888Haven't found one for free.

author: Deathwish
author_rank: Unknown
timestamp: August 30, 2015, 12:25:19 pm
content: No idea when these were made a I am not into organs but i hope this is of use.http://www.technicalaudio.com/pdf/Electronics_Catalog_Extracts/Mallory_general_catalog_1985.pdfhttp://www.technicalaudio.com/pdf/Electronics_Catalog_Extracts/Mallory_capacitors_1966_REM_E30.pdf.pdfhttp://www.technicalaudio.com/pdf/Electronics_Catalog_Extracts/Mallory_capacitors_1960_REM_24.pdf

author: Stray Electron
author_rank: Super Contributor
timestamp: August 30, 2015, 12:47:55 pm
content: Multisection capacitors were commonly used in the old vacuum tube TVs but getting an exact replacement was from anyone other than the capacitor OEM or the TV manufacturer was nearly impossible. There are just too many combinations of values and voltages and I think most of them were custom built to suit that one product. But the good thing is that you can replace them with several individual capacitors with similar ratings that the item will work as good as new. The replacements also don't need to be in twist lock type cans. You can just mount them anywhere that you can find the room and access to the circuit connections. Occasionally we had to resort to hanging them elsewhere in the cabinet and using longish wires to connect them to the circuit board.In order to keep their items original looking, some people are now also gutting the twist cans and installing smaller, more modern capacitors inside of the can and then putting it back in the chassis. IIRC they call it "recanning". You might look that up.

author: SeanB
author_rank: Super Contributor
timestamp: August 30, 2015, 12:54:54 pm
content: Exact value is not really critical here, as they probably are all used for smoothing. 6 1000uF 35V capacitors in the space of the old ones will probably work just fine.

author: egup1066
author_rank: Newbie
timestamp: August 30, 2015, 01:13:11 pm
content: Quote from: SeanB on August 30, 2015, 12:54:54 pmSomething like that is exactly what I am going to do if I can't get any more information. The first section is almost always the largest so I am quite confident 1000uF will do just fine for the 35V caps, but there is a second 25V can (different part number-I checked) that is 3500-1000-1000 which makes me think 1000uF might be too small for one or more of the 25V sections.

author: SeanB
author_rank: Super Contributor
timestamp: August 30, 2015, 01:48:21 pm
content: 2200 or 4700 uF will do as a replacement. 1000uF might even be good enough, worth a try in the first case.