Vintage BGW Model 100 Amp Repair

Fixing an old pro audio amp.

[@Maxxarcade]

Right now I'm using LF356 IC's, and it sounds great. I've tried 3 different types, and it works fine with all of them. That's one of the reasons I love these old amps, they are very flexible.

[@tommee10533]

Looks like a straight forward amp to work on. Looked the engineers had the tech in mind when the designed it.It also been in my experience that vintage amps have been under rated as far as watts. Great vid, nice job on the repair also.

[@MrQuist125]

Nice work. love to see old amps come back to life.

[@Maxxarcade]

As of October 30th 2019, this amp is still running strong, providing 24/7 duty in a jukebox.

[@krist0sh]

Nice amp! Seeing those resistors left a cool texture to the board after getting so hot.

[@johnhodgson5313]

I have a 100B to drive my electrostatic headphones. Warm sound, as others have pointed out. Those old Beckman meters were great, I considered it the best of the portables until the Fluke 87 came out. One of the features was the accuracy up to 20 KHz. Only the top models were true RMS, but if you have a fairly low distortion sine wave, it makes no difference.

[@johnhodgson5313]

oops, didn't remember doing this.

[@DizzzyKipper]

Nice tutorial,Really enjoyed it.I love the vintage electronics.

[@Maxxarcade]

It has a warm yet neutral sound. Though it does need a reasonably large input signal being a pro amp. I'm looking forward to trying it with my ATH-M50 headphones later. I love these older amps with the headphones being driven by the speaker outputs, as opposed to newer home receivers with crappy headphone amp IC's.

[@Maxxarcade]

Yep, seen it many times. When they are in a high current circuit, they explode and give off hot blobs like an arc welder. When they are in an audio signal path, they make crackling noises in the signal. I try to avoid using them most of the time unless specifically called for.

[@frugalaudio]

I still see 250s and 750s. I've probably seen only a couple 100s in 25+ years doing audio. BGW made good solid amps.

[@beachsandinspector]

Depending on the IC used in the preamp, you may be able to find a verly low noise version, but maybe not given the age of this Amp, some of the PSSU filter caps were made very well, I hvae a powersupply here that I made and the filter caps are huge and some 20 years later seem to as good as the day I bought them.

[@Maxxarcade]

Aside from possibly upgrading the amps for the mids and tweeters eventually, The rack is complete. I'm mainly waiting to add the rest of the speakers if I can ever afford to.

[@slimjim119]

sounds good nice older amp

[@Maxxarcade]

LOL I call them the same thing. They love to randomly short or get DC leakage. For audio, I usually replace them with Nichicon KL, KT, or FG depending on the circuit.

[@stevew270]

Dude, you have a gift!

[@call5sam]

Great video! Can you explain a little more about the matching transformers?

[@KaidoFujimi]

top job max

[@Maxxarcade]

The bass usually seems boosted on camera because of weird room acoustics. I can never get a good balance between what I hear in person and what the camera picks up. Some day I want to get some acoustic tile, but it's so expensive.

[@Trance88]

Another job well done! Did you find some good replacement knobs and fix the potentiometers that wouldn't go silent? This amp has a really nice flat sound to it. Some of the other amps you fixed seemed to have boosted bass compared to this one.

[@classof2k10]

Nice little amp! :3 I still need to get my amp fixed... >.>

[@tyttuut]

I wonder if I can find one of those... they're so cool.

[@bigpopparand1]

Nice Amp

[@mcselationcompu]

Just a quick way to calculate output wattage - square the output AC voltage then divide by load impedance.

[@sffitx]

In a earlier video you said you repair arcade machine for a living, what study do you need to do so? Also it would be interesting to know how many spl can your 10kw audio rig can pull off. Always interesting vid, keep it up!

[@RGD-Repairs]

your so lucky, i can never come across and sweet deals on ebay.

[@TimKaseyMythHealer]

I have a Hafler amp that stopped working a few years ago. I wish I knew what to check. I have a fluke 179, and if you could explain what I need to test, and how to test it? I would love to fix it myself. Also, I have a Symetrix 528 vocal processor, and the parametric EQ is producing a DC hum (sounds like it). If I disengage the parametric EQ portion, the DC hum goes away. I'm not sure how to test the components. Any suggestions, or KZbin videos on what/how to test would be great.

[@TechStories79]

That's awesome!! how's your main racks of amps moving along, is it complete yet?

[@Maxxarcade]

Ya, it burned through the top resin layer and exposed the fiberglass underneath.

[@CoolMusicToMyEars]

The Wavetek - Beckman will have a very limited AC Bandwidth Although can measure AC output on a Scope the scope is GND !

[@Nick-zo5dp]

I have a car audio amp that needs some work turns on but no audio . do you take on projects from viewers ?

[@dos541]

what was that switch on the board between the two volume knobs for

[@admmaiden]

Question,if you have DC across your speaker terminals,where and what do you test for the fault?

[@djshavo951]

i have a Crown XLS 602 that has this same problem on both channels. and ideas where I can get parts for crown? things been sitting for years now.. nice amp btw I have a larger BGW 375 watt per ch. still works like new too

[@francistheodorecatte]

those resistors got nice and toasty warm o_o

[@ajbrn70]

could your find a adcom gfa 555 ll to repair or upgrade. would be great

[@Maxxarcade]

I use a desoldering gun, so there really isn't much to see. Though you can see it in action on my Yamaha RX-300U repair video.

[@satansoft]

How do you find matching op-amp ?

[@blueribb99]

Did you ever find out why you still had sound with the volume controls fully CCW ?

[@call5sam]

It appears from the bottom side look that this amp uses "glob top" construction. Do you have a method to replace these if those parts are bad?

[@accordinglyryan]

Thanks; damn nice song.

[@TH3L0LB0Y]

Hey hope your fine miss your videos 🥺

[@vacuumboy6.0]

can you show how to un solder connections ?

[@bryantreblando]

how did you calculate the amplifier wattage? by using calculator

[@blazer406]

What's the name of the song starting at 15:36?

[@mPDC-gh8jy]

How to get the circuit diagram? Manufacturing company will supply a circuit diagram to the user?

[@accordinglyryan]

Song @ 14:30?

[@thompi8]

realy like your videos have try to se all your videos problem is your type part3 but i cant find the part 1 or 2 so its alot jumping. but nevermind its still fun your are verry good to solved problem who are with electricial and components. question what did you do with that crest ca6 your rigg is big but havent seing that one in your rigg and crest is the best amplifired i used ok crown is good to ;D

[@Satan6666ful]

I have a BGW 480 watt Millennium 2 tmc -2 power amp and I was wondering how to run it thru my Marshall amp Its a jcm 800 with no direct inputs any Ideas ? thanx

[@Maxxarcade]

It's still the same. That has to do with the controls themselves, and I haven't bothered replacing them yet.

[@vultur97]

Hi do you know what transistors i can use instead of the original transistors? Sorry for my english I`m from Romania :D

[@johnpetty9310]

I bought one of these from Ebay, and it "Hums" when i powered up. Can anybody recommend a good shop that can fix it? I currently live in Vancouver WA.

[@AbbiaTheSnake]

What's the song at 14:08? It's beautiful

[@kakashi32001]

hey Mr, I have a QSC 1300 U.S.A Series power amp, and one channel is not working the other channel works great ,What I need to do? can you help me?

[@FixthisCD]

Those TO3 are tanks. When you use your 'current limiter' with the light bulb, that is basically a light bulb in series correct?

[@Maxxarcade]

Yep, in series with the AC input.

[@FixthisCD]

Thank you

[@emolatur]

It's entirely likely that the output transistors of that channel weren't really seeing any "abuse." With it locked to the rail, one was likely solid on and the other solid off... they were both effectively in switch mode, with no dissipation. That's why they survived.

[@Maxxarcade]

+emolatur That's a possibility, though I'm not sure those transistors would be able to saturate enough for that. Their internal resistance might be too high compared to something more modern. But they have an oversized heatsink attached, so they probably stayed at a safe temperature until the resistors burned open. I wonder what happened to the speakers though LOL.

[@christopherhawkins5362]

yep I was the agent in England for BGW and still have most manuals

[@Maxxarcade]

+christopher hawkins Do you have one for the 6000 Proline?

[@MrTopsoil911]

+Maxxarcade do u currently still have that power amp??

[@sherinpm007]

What is the function of switch in the middle of the main board?

[@Maxxarcade]

For bridging.

[@zekelowther]

i liked the 2nd channel haha

[@johncunningham5435]

I have the identical Wavetek HD 110; good meter with high energy fusing but it not a TRUE RMS meter unfortunately. But if you have a clean sine wave it compares pretty close to my Fluke RMS tester

[@Maxxarcade]

Ya, I was surprised how well it worked. It was actually a junk box find that my Dad gave me. One time I forgot to turn it off, and it was still running several days later LOL. I found the website just now, and I can't believe how expensive it was.

[@analogaudiorules1724]

out of all your amplifiers you are planning to sell, you should keep this one personally.

[@Maxxarcade]

It's not in my collection anymore, but I still get to see it once in a while. I sold it to my boss and it's been running in a jukebox at a bar for the last couple years.

[@rockermarco]

OMG What a, SCORE!!!

[@Citroable]

Do you have the skill to make your own amp?

[@TheLoudtrout]

Chopin Étude 19 (Op. 25 No. 7) I believe

[@the-more-yuno]

One Summer's Day by PonyEveningStar

[@vacuumboy6.0]

*face palm* i dont have one can i do it with a standard gun?

[@1monstertech]

that thing kinda looks like an old Crown D75 or D60

[@Maxxarcade]

Stereo/Mono bridge.

[@Acc0919mc]

Ohhh the freaking board looks a little toasted... O.o

[@1monstertech]

he already has, he built a tube amp, go look back at his videos that are 3 years old

[@call5sam]

I just bought one of these amps. I have tried to find service data to no avail. Could you supply me the schematic?

[@Centar1964]

It's easier just to do 13.5x13.5/8

[@SorinG2010]

You didn't replace the tantalum caps you hate those :-)

[@TradieTrev]

WTF KZbin unsubbed me from you!! Heads up if you recently lost any subs

[@Maxxarcade]

/watch?v=_umhQJPUnWk

[@john-ls8wq]

I have 2 of them got them from a friend of mine one had a bad power switch and the other one has a channel out going to drop it off at the repair shop before too long from now I sold my massive pa system it was huge took up my whole shop a production company owns it now running concerts so I just use these in my house with a audio centron rma800 and a crown amplifier that I saved out of my stuff

[@MrTopsoil911]

A power amp?? 30 watts/channel lol. Maybe for a dog house club. I sold mine $60 not enuff power for me. All power amps sound good low volume til u crank til cliping

[@analogaudiorules1724]

Its not all about power lol

[@AbbiaTheSnake]

Nope

[@RRROBERT1990]

it's not that hard... you just need to understand a basic electronics, first you need to learn how a bipolar transistor works it is the "heart" or the "brain" of an electronic amplifier...

[@Maxxarcade]

/watch?v=_umhQJPUnWk