otisboss

Thanks for the support!!! Currently awaiting parts from Digi-Key to complete the service bulletin repair. I did briefly look inside and see the board discoloration as anticipated and addressed in the service bulletin. Wasn’t quite ready to get down to testing at that time. I’ll do a separate thread and can hopefully upload pics. I do intend to test and hopefully address any issues before cap replacement and service bulletin repair. Appreciate the references for technicians in case it is beyond my scope. 👍 B

Thanks wrf. I got it in 1989 when heading off to college (Marquette University) playing through some old AR-35BXs that have been lost to time. I loved the speed and punch of that set up. And it got loud! Later, the TFM25 was weak and or cutting out in one channel and that is when it got boxed. It is in mint condition externally, but obviously I will need to look carefully inside. I have some experience with electronics, pretty nifty with a soldering iron, and enough sense to be careful of dangerous voltages. I did intend a cover off inspection first, then to fire it up with a dim bulb test and see if anything appears grossly off. I will definitely be checking those items you mentioned above. I looked through the TFM-25 library at many of the issues - service 2 resistor and transistor replacement, comments on capacitor replacement (and failures to discharge caps!), and input regarding replacement of output relays. Unfortunately, I did not do all this research before sourcing a "rebuild kit" from HiFiAudio on ebay - it includes a near-full cap set, several transistors, and a number of diodes, . . . but not the resistors for service bulletin-2. Also, seems to be lacking caps C451 and C510. Instructions for the capacitors is fine, but absent for the transistors or diodes. AFTER researching, I see that Les (@circuits&concepts) has a power supply capacitor rebuild kit - now I am wondering the quality of components I purchased (kicking myself). I did see Jazzman's list of parts for the TFM-25 rebuild - excellent resource, thanks! So any info on HifiAudio's TFM-25 kit, anybody? I do see some Chemicon and Nichicon smaller caps, but not clear if the larger ones are real or knock-offs? Any advice for identification, testing, ??? (Can't post pics quite yet, too new!) Since I have yet to even start, would it be worth sourcing those 6 power supply caps to be sure??? https://www.ebay.com/itm/222548677988?hash=item33d0ef5564:g:S1wAAOSwjk9ZRGza&amdata=enc%3AAQAIAAAA4L2l75jzTqzkVA5oZTwh8wDvHjNVTWvRk5K6cen%2BPAxYDPGbXj9fASMAhY32Wy%2BVV9nUeoyCGiCoguuWJ5xPpeuACP9t0XMzJu1xcVLcsH90T98i%2B58M5QJymVcNrb9Dph1fCgEIL4vbPijkDuArtUfnBG6w1Ef2%2BaAP1ZUm2Rm%2BLVkGqiehZ0Ix9jykr7cYnTzLQ%2FV65045zApgnmULptnySATCydDAPCvGT0xT76GYkl%2FItWzyF82T%2F1CQDjPrdYxmBv6LIphRdu4ja0cqnc3KzDRLxXQzAiZbQhYF6lpe|tkp%3ABk9SR76Lgb-aYw Also, when replacing binding posts and/or RCAs, any preferred manufacturer? If there are obvious 'upgrades' for these amps it would be great to have it spelled out clearly rather than strewn over a multitude threads 'to discover' - For example, I have a couple cars that lend themselves to upgrade paths and there are some nicely codified threads on EvoM.net and S2k.com that review typical upgrade path - instead of wider tires, 18" rims, improved turbos, discussing benefits and tradeoffs expected with the upgrade in question; Maybe I missed a similar 'recipe' for the TFM-25 in my initial foray. If planning for upgrading performance (not just spending $ on fancier parts) what replacement caps would be recommended (and the like) - saw this for a tube amp I'm building, basic set, higher level, top tier. The future paired speaker would be a modest KEF floorstander, yet unpurchased. I have some various bookshelf speakers to play via digital and analog sources in the meantime. Thanks again any and all - happy to get in touch with my OCCD!!! Brian

Hey all, I have been hanging on to a TFM-25 as a first owner with the original box and stryofoam (much to wife's discontent ) for past 30 years - Got a kit for rebuilding from eBay that likely spent too much on. Gonna replace the caps and do the 4/15/92 service bulletin upgrade. Wish me luck! Cool site - read a couple cool threads already! Brian