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You likely have leaky drivers. Never just replace output devicesThe amp (Valvestate VS100R with ECC83 Glass Valve) packed in a few
months ago. Two of the 4 darlington transistors (2xBDV64 & 2xBDV65)
had gone short circuit, also taking out the 1A anti surge fuse. I
replaced them (using heat sink paste as well) and it happened again,
so I replaced them once more and left the amp on (guitar & effects
unit unplugged / overdrive off) to eliminate external possibilities.
After about 15 mins I measured the temperature of the transistor heat
sinks - 3 were 40-50deg C and 1 was cooler. After an hour I went out
of the room for 5 minutes and returned to find it had blown again. The
heat sinks were hot - one of them was 100 deg C. Any ideas what could
be causing this? The amp is a few years old but hasnt had a great deal
of use. Thanks in anticipation.
Taken out =/= leaky.Eeyore wrote:
boardjunkie wrote:
You likely have leaky drivers.
Made of silicon ? !!!!!
Bwahahahahahhahahhaa !
Umm....WTF are you talking about? You never heard of drivers taken out
as a result of output device shorting? Happens all the time.
No ! CROOKS at work.On Oct 17, 8:07 pm, "Phil Allison" <philalli...@tpg.com.au> wrote:
** Just one more try:
Did YOU buy the BDVs from Farnell or off eBay ???????
I ask because there are so many **fake** devices offered on eBay.
Never buy semis from eBay.
..... Phil
Fakes aren't just reserved for Ebay.......I've gotten fakes from MCM
recently. Last I checked they were still offered in spite of me
telling them they were junk and sending them back. Bean counters at
work.....
Report them to the genuine manufacturer.On Oct 17, 8:07 pm, "Phil Allison" <philalli...@tpg.com.au> wrote:
** Just one more try:
Did YOU buy the BDVs from Farnell or off eBay ???????
I ask because there are so many **fake** devices offered on eBay.
Never buy semis from eBay.
..... Phil
Fakes aren't just reserved for Ebay.......I've gotten fakes from MCM
recently. Last I checked they were still offered in spite of me
telling them they were junk and sending them back. Bean counters at
work.....
Umm....WTF are you talking about? You never heard of drivers taken outboardjunkie wrote:
You likely have leaky drivers.
Made of silicon ? !!!!!
Bwahahahahahhahahhaa !
Graham
** Just one more try:
Did YOU buy the BDVs from Farnell or off eBay ???????
I ask because there are so many **fake** devices offered on eBay.
Never buy semis from eBay.
..... Phil
Hi Mr Philosopher,
it's very remarkable that you don't recognise one of the most polite
answers Phil.A ever made.
Let me assure you - his statement's correct, yours' not so...
There also were KT88 Marshalls, although they are a completely different
story. IIRC the indeed evolved from generic Mullard or the GEC designs.
But - the bread and butter Marshall began 1962 with the 5881/6L6/KT66
equipped JTM45 - an almost 100% copy of the 5F6-A - and they (Ken Bran)
have publicly admitted that they were clearly aware of that fact. The
evolvement to the usage of pentodes (EL34s) was mainly driven by
economical reasons. The similarities to the mullard designs may come from
the fact, that there ain't so many possibilities to connect a pentode or a
beam power tetrode to a circuit - and - the 5F6-A was also based on a
common available basical circuit (from WE or RCA IIRC).
The preamp of the marshall *was* the same as a 5F6-A and the future
evolvement was only incorporated by the addition/alteration of some
components to fit the sonic tastes of the upcoming rock musicians (cathode
Cs, mixer Rs, bypass Cs, different B+ filtering etc). Even the MV
Marshalls just rewired the existing preamp circuit to a cascaded design.
OK some Rs and Cs were added but that was all. Up to the generic JCM800
the circuit still clearly showed it's origins.