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PostPosted: Mon, Mar 25, 2019 7:07pm 
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Artist Edition head purchased new around 12mo ago
Worked fine and not huge hours

Stopped giving sound, but remained lit up
Was running the master at 5 and loop level at half - very loud into iso cab
Lamp on rear indicated power tube fuse blown
4 individual power tube fast blow fuses F160mA under chassis
3 had blown
Ordered direct replacements, and MT160mA version as manual says 'medium blo'
Replaced all 4 like-for-like with F160mA, and one quickly went again (#2) but amp still giving sound
Replaced fuse again
Took out tubes 2&3
Halved speaker ohms
Ran okay
Moved that pair of tubes to sockets 2&3
Ran okay
Went to a new set of JJ EL34 IIs
All four put in for bias
All 4 in, power off standby, bias was 67mV(!)
Reduced to minimum bias on dial - around 25mV
After a few seconds, fuse #3 blew
Replaced that fuse, swapped tubes 3 & 4
Ran okay
Decided it must be the fuses as there was no consistent failure
Put in MT160mA in all slots
Biased up to 30mV
Sounded a bit flat, lower gain (obvs)
Upped it to 34mV, and much better gain structure
Still not convinced there was any issue with the power tubes

Can’t understand why the manual would say medium and the amp be loaded with fast
Never seen a medium blo fuse in this position in an amp

Sent a message to Engl's online cust service, then another to different email
No responses after many weeks

It has run fine for a good while since, but I have to wonder what was blowing the fuses and whether a medium blo is going to set me up for a bigger failure in future


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PostPosted: Mon, Apr 15, 2019 6:02am 
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6 weeks after submitting the online form with all of the info above, and this question
'Is it right to run the medium blo fuses as the manual says, even though it was fitted in the factory with fast blo?'
a reply came from the AMD of Engl Sales & Marketing:
"sorry for my late answer. I am sorry to hear that you had these problems with the amp. I would always recommend to use the fuses that we have mentioned in the manual. If you want to get more into detail and talk to our technicians about this please feel free to write them at ..."
No real answer there. Forwarding on the query to tech support would have been useful.
It is curious that using their own online tech support form (there is no email or telephone number), the answer came 6 weeks later from the AMD of Sales.

I have forwarded the info onto the new address and will report back on the results.


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PostPosted: Mon, Apr 15, 2019 10:22am 
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I am pleased to say the response from Engl tech support was almost immediate
They explained that there must have been a problem with the online forms getting through as they are usually forwarded to them

The answer was detailed and talked me through the expected resistance of the medium blo fuse - which is the correct part
and reassured me that the (correct) fuse blowing would be only due to an issue with a power tube
I checked the resistance of the fuses I used, and they are in the correct range
the interesting bit was that they do not use the fast blo fuse in the factory
to get the medium blow replacements, I had to order them internationally, so either the retailer replaced them with the more readily available fast blow part, or they sold the amp to someone before me, who returned it having changed out the fuses with the incorrect part
I will be asking the retailer if they know anything.
In the meantime, I can enjoy the amp and feel happy that it was a power tube issue.


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