Search found 383 matches

by McBarry
Tue May 07, 2019 3:41 am
Forum: Mark Series
Topic: Mark III+ blowing fuses
Replies: 16
Views: 2516

Re: Mark III+ blowing fuses

Totes agree with Woodbutcher65 re caps..
ALSO check the Sprague on the B+ to ground - it's mounted near the power tubes.
And if the ground polarity switch is in use, the Sprague attached to it would immediately be suspect..

Keep us posted, esp for future readers.. Cheers, Dave
by McBarry
Tue May 07, 2019 3:27 am
Forum: Vintage Amps (Before 1991)
Topic: Solo Head 50 low output
Replies: 6
Views: 922

Re: Solo Head 50 low output

If the circuit voltages are within 10% of spec, then chase a signal through and see where it fades excessively.
But it does sound like it's time for experienced eyes/hands to look inside and get U a diagnosis..
by McBarry
Tue May 07, 2019 3:22 am
Forum: Vintage Amps (Before 1991)
Topic: Fake???
Replies: 13
Views: 1712

Re: Fake???

Hmm.. faceplate looks just "too" shiny.. Back looks rather bare of any info at all.. Wot are the tranny codes ? The O/T looks very Fenderish too Guts shots will tell in a millisecond.. Backplate timber looks non-orig as do the supports. And missing a couple of mounting screws on the backplate timber...
by McBarry
Mon Jun 11, 2018 9:59 pm
Forum: Mark Series
Topic: Mark III blue stripe 6ow - low output on clean channel
Replies: 11
Views: 4119

Re: Mark III blue stripe 6ow - low output on clean channel

Hey Casey, just back on after ages away.. Totes agree with Jon - LDR , esp if one was replaced.. A pic will help tell if wrongly orientated. I'd also wonder if he pulled the preamp board to do the LDR. Not strictly necessary, but for 100% guarantee the underside has no anomalies it is to only way to...
by McBarry
Mon Jun 11, 2018 9:40 pm
Forum: Mark Series
Topic: Export Simulclass No-Stripe - worth getting?
Replies: 6
Views: 2558

Re: Export Simulclass No-Stripe - worth getting?

Nice score..!!

Time for some juicy pics..!

Of course, I know you'll "hate" it and need to throw it towards Canberra for a new house... LOL LOL..

db :lol: :lol:
by McBarry
Tue May 29, 2018 9:30 am
Forum: Vintage Amps (Before 1991)
Topic: 81 Mesa Mark IIB troubleshooting, changed PT, tubes, caps
Replies: 7
Views: 3029

Re: 81 Mesa Mark IIB troubleshooting, changed PT, tubes, cap

a few thoughts.. have U verified ALL voltages against schematic are correct and stable ? Physical layout - has anything been re-routed - lots google pics of chassis shots that can help U.. Is oscillation pre-amp or power amp? Consider that something caused the original p/trans to fail.. Speaking of ...
by McBarry
Tue May 29, 2018 9:21 am
Forum: Vintage Amps (Before 1991)
Topic: Price of an original Mark 1 Combo
Replies: 13
Views: 3819

Re: Price of an original Mark 1 Combo

Quite a few changes there.. lots of non-original wiring.. the transformer between PSU PCB and preamp PCB looks definitely out of place..is it a choke ?? Or reverb tranny..?? Both usually mounted underneath.. the black heatshrunk leads mention make me wonder it's a choke.. Transformer star washers ar...
by McBarry
Sun Jan 14, 2018 5:18 am
Forum: Mark Series
Topic: Mark III broke down
Replies: 12
Views: 60050

Re: Mark III broke down

G'Day Arne,
Stephan nailed it - SLOW-BLOW fuses should be your first priority..
Theory being they can absorb a short burst over the rating..

If it still happens, it's bench time to record what's going on and begin diagnosing..

Good luck - you're def on the right path..

Cheers, Dave
by McBarry
Tue Sep 26, 2017 7:51 am
Forum: Mark Series
Topic: 1975 Mark I...one of the first 150?
Replies: 2
Views: 1544

Re: 1975 Mark I...one of the first 150?

Whoaaa.. that baby has LIVED..!! And early... from the re-stamped Fender OT, to the funky soldering..a real classic.. CONGRATS..! The extra PCB on side of chassis - a rectifier board ?? Looks unmolested.. Heartily suggest changing filter caps - even moreso if intermittent use.. And the toex ... bloo...
by McBarry
Fri Mar 17, 2017 6:03 am
Forum: Vintage Amps (Before 1991)
Topic: Mesa Boogie Early Mark 1 ?
Replies: 24
Views: 8134

Re: Mesa Boogie Early Mark 1 ?

Bummer.. luckily they're plentiful..
The exact Carling part no is 110 - 63.
63 is the short bat - the next up is the 73 which is considerably longer. Avoid it..
I'm a fan of Sylvania 6L6's - they're a little hard to come by over this side of the pond though..
by McBarry
Fri Mar 10, 2017 7:43 pm
Forum: Vintage Amps (Before 1991)
Topic: Mesa Boogie Early Mark 1 ?
Replies: 24
Views: 8134

Re: Mesa Boogie Early Mark 1 ?

Couple random thoughts.. The sby switch is at an odd angle - ? mounted rotated or mech is broken/breaking.. New white cap off phase inverter.. assume leaky cap replacement ? Filters yr pointing to are bias and look orig - forty yr old... replace. Someone might get date codes off the Atoms - I'm thin...
by McBarry
Mon Feb 27, 2017 6:09 pm
Forum: Vintage Amps (Before 1991)
Topic: Very sick 1988 Mark III Blue Stripe...please help.
Replies: 3
Views: 1633

Re: Very sick 1988 Mark III Blue Stripe...please help.

G'Day Paul, I'm in Oz.. postage/freight from here is even more horrific - I feel yr pain.. truly..! Some of the things U describe seem almost normal - EQ touchy.. It'd need a bench, chase a signal, check for anomalies - poss to find no actual fault but abberation of "normal" with some tweaking to ma...
by McBarry
Wed Feb 22, 2017 5:43 am
Forum: Mark Series
Topic: Mark IIC+ repair. Need help!
Replies: 11
Views: 2734

Re: Mark IIC+ repair. Need help!

That sounds def intermittent and equally poss electronic OR mechanical in aetiology.. U/someone NEEDS to narrow down the error area ie: V1, V2, V3 etc etc etc etc.. and which channel.. or both... Some random thoughts without chassis on my bench...: Assuming all voltages are in spec and STABLE, witho...
by McBarry
Tue Feb 14, 2017 2:08 pm
Forum: Vintage Amps (Before 1991)
Topic: Mark 3 popping when switching channels.
Replies: 4
Views: 2104

Re: Mark 3 popping when switching channels.

there's a relay but I'm not home to see the schematic.
greying memory says the R2 channel, but a perusal of schem will nail it in a heartbeat.
by McBarry
Tue Feb 14, 2017 2:00 pm
Forum: Vintage Amps (Before 1991)
Topic: Redplating problem
Replies: 18
Views: 7022

Re: Redplating problem

JMMP - while not worked on a Mk4 for ages, redplating is almost exclusively a lack of bias. Lovetoboogie is steering U towards that and I reckon you'll find the culprit easily. Tubes out, track the bias supply through each component and see where it's failing. Something is dropping the voltage (poss...