Bogner - Harlow Compressor (gut shots)  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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mr coffee
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Post by mr coffee »

Anybody looked under the hood to see what compressor VGA\VCA this thing is using? And where they put Rupert's littlr tranny in the circuit? And what kind of EQ they're using before and after the Tranny?

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Post by okgb »

I'd be curious to see any of the other pedals as well , did they just slap the same xfmr on the output
of every pedal, seemed like a good idea for hype if nothing else

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liquidfunkateer
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Post by liquidfunkateer »

Love it, so much that I want a second one :P
Bogner Harlow 1.jpeg
Bogner Harlow 2.jpeg
Bogner Harlow 3.jpeg
Bogner Harlow 4.jpeg
Bogner Harlow 5.jpeg
Bogner Harlow 6.jpeg
Bogner Harlow 7.jpeg
Bogner Harlow 8.jpeg
Bogner Harlow 9.jpeg
Bogner Harlow 10.jpeg
Bogner Harlow 11.jpeg
Bogner Harlow 12.jpeg
Any advice for safe degooping?

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liquidfunkateer
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Post by liquidfunkateer »

V1 one here.
viewtopic.php?t=31756
I want to clean the goop. No experience, any advice?

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Post by liquidfunkateer »

Episode 2.
Hot air gun
Low setting 350° C
Heat applied intermitently from 20 to 25 cm
Scratching with a small cutter and a small screwdriver
it worked fine for a first time degooping.
Attachments
work.jpeg
main bot dark.jpeg
main board front.jpeg
main board back.jpeg
goop top.jpeg
goop bottom.jpeg
Brain top 6.jpeg
Brain top 5.jpeg
Brain top 4.jpeg
Brain top 3.jpeg
Brain top 2.jpeg
Brain top 1.jpeg
brain light 4.jpeg
Brain light 3.jpeg
brain light 2.jpeg
brain light 1.jpeg

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liquidfunkateer
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Post by liquidfunkateer »

R.I.P. R109, rest in the goop
R116 isn't readable, I'll measure it along with the rest
Three bipolar caps - Two Nichicon ES, 10µF 50v - One UKW, 100µF 35v
The two ICs, U102 and U103 are TL072CP that loose cable connects PIN4 of each ICs

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Post by liquidfunkateer »

All right, degooping completed, part 2 here.
I'd be curious to see the Bogner Lyndhurst as well.

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Post by Lithium_Grim »

Looking at the trannies on the main board now. They are marked 12x or i2x. Does anyone know what type of trannies those are?

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Post by szukalski »

2X is a 4401 I think.

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Post by Lithium_Grim »

I received the board from liquidfunkateer (alex) and am tracing it as we speak. Here is a first schematic sketch of the degooped part:

<removed due to alterations>

In purple the designations as found on the degooped PCB and the now desoldered pcb:

Image

Questions:

1. Can anyone spot any obviuous errors?
2. I am wondering what kind of JFEt is used. Any ideas (measurements are in the picture)?
3. C9 (C115) looks weird in the polarity, however i measured it multiple times to verify it.[/list]
Last edited by Lithium_Grim on 12 Feb 2024, 18:15, edited 8 times in total.
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Post by modman »

liquidfunkateer has been promoted to the honory rank of Degoop Doctor
If I missed anybody else who hacked into a gooped, untraced pedal, please contact me in pm.

Thanks so much for your contributions liquidfunkateer!
Please, support freestompboxes.org on Patreon for just 1 pcb per year! Or donate directly through PayPal

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Post by Lithium_Grim »

And a small update:

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Post by Lithium_Grim »

Any ideas on the JFET?

Q1 measured @ DCA75 as N-Ch JFET symmetrical Source/Drain
Vgs[off[=-1,64V @ Id=4,8uA
Vgs[on]=0,32V @ Id=5,00mA
gfs=4,0mA/V@ Id=3,0mA to 5,0mA
Idss=3,67mA @ Vds=3,00V
Rds[on]=270,6 Ohm @ Id=5,0mA and Vgs=0,0V
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Post by Lithium_Grim »

Ok here is the full version. Still not 100% verified, but I did multiple runs on all traces.

Image

I am still looking for input on the transistors. The Hfe of the BJT (U2/U3) seems to be higher than the MMBT4401. Any suggestions?
I am also still looking for suggestions on the JFET. Anyone?
Lastly, I'll try to find a variac and determine the ratios on the Neve transformer. To be continued!
Last edited by Lithium_Grim on 12 Feb 2024, 21:15, edited 3 times in total.
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Post by Lithium_Grim »

And some more info on the trannies:
Image
Image
Image
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Post by bajaman »

wow - excellent work here
my guess is that the fet is a BF245A smd equivalent (https://www.onsemi.com/pdf/datasheet/bf245a-d.pdf)
The vgs and idss fall into line with this device and it was the jfet used in the classic Urei 1176 studio compressor
I would think any small signal NPN transistors with a reasonable hfe would work here.
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Post by Lithium_Grim »

bajaman wrote: 12 Feb 2024, 22:57 my guess is that the fet is a BF245A smd equivalent (https://www.onsemi.com/pdf/datasheet/bf245a-d.pdf)
The vgs and idss fall into line with this device and it was the jfet used in the classic Urei 1176 studio compressor
Thanks bajaman! Since the BJT is a SMD, what equivalent BJT would you suggest? MMBT5088 (the savior of the universe)?
Dito for the FET. It is a SMD version with no readable markings. Any equivalent suggestion to the BF245A? 2N4416 MMBF5457?

I got my idea from here https://www.utmel.com/components/bf245- ... eet?id=493
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Post by bajaman »

The bjt transistors are most likely MMBT4401 type and the jfet MMBF5457
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Post by Lithium_Grim »

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Post by Lithium_Grim »

And here is the adjusted schematic.

Image

Anyone see any obvious mistakes or points of further investigation?
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