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Messages - Harry

#1
Amplifier Discussion / Re: Fender Frontman 65 distortion
February 06, 2020, 04:23:59 AM
Hi ..I havent been here for few years. Just stumbled back looking for something else and saw my old post Re the Fender frontman 65 distortion problem. If Hefty or anyone else is reading this  i'd just like to make couple quick comments. Roly and i spen tweeks on the problem. It wasn't till i by chance got a  scope photo of the horrible waveform that progress was made. Roly suggested replacing the bad transistors with BD139/140 as he felt they were much better ,  better specs and he knew they were reliable. I bought the BD139/140 from Jaycar, nice and handy as well . Took bit of fiddling  and care to replace both but ......let me tell you to this day the amp  is still going strong, not a problem at all.
Roly was a great friend - mentor and i'm sure lot of people not just me , miss him. A great man and great talent.
I now take a 50 watt valve amp to gigs  as the Fender DSP 90 i have has also sh...t itself 8 times or so in 10 years . Do i like Fender amps ???? silly question !
#2
Hi Everyone !
                    Yep finally got here . First of all i need to thank the one and only Roly for his help and guidance over the last 12 months or so not only with this  crazy intermittent problem but also with the two valve amps i've built . . And let me say i think its great people like him  and Enzo and others help those with problems.
This is roughly the chain of events with this amp..
The Fender Frontman 65 r was  just out of warranty when i first   saw it . This amp was bought new in 2011 . It seems these amps are old now in USA . The printed circuit has 2005 stamped on it  . I offered to look at it simply to save the friend some money. I have a DSP 90 which has over the last 8 years stopped 6 times so figured it would be a  fairly simple problem. Boy did i get sucked in ! The amp was distorting badly  at  odd times . I replaced two  very high resistors and ran the amp over few days . All good. Then  it started to distort again. Further searching i found the main PS caps were bad ...... they are 2200uf caps..one was reading 3 uf ...yes THREE the other one 1900uf  and had one leg loose inside , good for a 13 months old amp !! . so figured great  found the problem. Replaced the caps , all went well for 6 weeks .Then it started distorting again.  At this time the owner wanted to take it to a Fender specialist which was fine by me ! After 4 weeks owner was told ' can't fix it '  .. So  then  went directly to Fender  .just out of warranty too bad cant  do anything  and if tech mr XX cant fix it neither can we  !! So the amp landed back in my lap ! I was in contact with another Tech that knows these amps very well , but he slowly vanished ... I think he gave up . A few other techs (friends ) i spoke to didn't help either , just would say "oh thats a bad problem' ..You don't say !! After lots of e mails between Roly and myself, and lots of testing and taking out parts to check them etc etc  . Finally it's now  fixed . This problem was extremely hard to  fix mainly because of the very intermittent nature . I could turn the amp on in a distorted state pick up  the meter leads and by then it would be fine again. Or some days turn it on and be good all day. I hope i never come across another one like it ! As for Fender ....good way to get a bad reputation me thinks . And .. a set of new  Fender PU's for my guitar ...two failed inside 6 weeks !  Thank you Roly  and Enzo .
                                                                                                                 Harry